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Effects of black seeds (Nigella sativa) on male infertility: A systematic review
Accepted Manuscript Title: Effects of black seeds (Nigella sativa) on male infertility: A systematic review Author: Reza Mahdavi Javad Heshmati Nazli Namazi PII: DOI: Reference:
S2210-8033(15)00027-5 http://dx.doi.org/doi:10.1016/j.hermed.2015.03.002 HERMED 100
To appear in: Received date: Revised date: Accepted date:
20-8-2014 8-2-2015 18-3-2015
Please cite this article as: Mahdavi R, Heshmati J, Namazi N, Effects of black seeds (Nigella sativa) on male infertility: A systematic review, Journal of Herbal Medicine (2015), http://dx.doi.org/10.1016/j.hermed.2015.03.002 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
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Effects of black seeds (Nigella sativa) on male infertility: A systematic review
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Reza Mahdavi a, Javad Heshmatib, Nazli Namazi a,*
Nutrition Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
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Student Research Center, Tehran University of Medical Sciences, Tehran, Iran
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*Corresponding Author: Nazli Namazi Nutrition Research Center, Tabriz University of Medical Sciences, Tabriz, Iran E-mail:[email protected]
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Highlights
Nigella sativa positively influence sperm parameters, semen, Leydig cells, reproductive
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organs and sexual hormones. Antioxidant properties of Nigella sativa are the main mechanisms in male reproductive
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health.
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Thymoquinone plays a key role in neutralizing free radicals.
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Effects of black seeds (Nigella sativa) on male infertility: A systematic review
Abstract
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Following an increase in free radicals, DNA damage and lipid peroxidation in human sperm may occur. Antioxidant components in medicinal herbs such as Nigella sativa (NS) have been
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indicated to improve spermatogenesis and steroidogenesis. The aim of the present study was to
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conduct a systemic review summarizing the effects of NS on male infertility. A number of electronic databases were searched namely Pubmed, Science Direct, Google scholar and
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Springer from the period January 2000 until June 2014. Searching was limited to articles in the English language. Patents and abstracts from symposiums and congress were excluded because
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they contained insufficient information for evaluation and comparison with other studies. The outcome of this study indicated that NS can positively influence sperm parameters, semen,
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Leydig cells, reproductive organs and sexual hormones. The main potential mechanism is
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through the antioxidant properties of NS. Thymoquinone (TQ) and unsaturated fatty acids are the
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main antioxidant components of NS. NS and TQ derived from NS can improve male fertility parameters through promoting antioxidant defence. Although the findings of this review suggest that NS is a good candidate for male infertility treatment, there is insufficient evidence to make recommendations for its use as an adjunct therapy in infertile men. More clinical trials are recommended to demonstrate the efficacy of NS on male infertility.
Key words: Oxidative stress, infertility, male, Nigella sativa, spermatogenesis, herbal medicine
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1. Introduction Infertility is defined as an inability of a couple to achieve a pregnancy after 12 months of intercourse without contraception (Gurunath et al. 2011). Infertility among men is more
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prevalent than among women. It affects almost one in 20 men and male infertility is a factor in about 50 % of infertile couples. The remaining 50% is due to female problems, both male and
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female problems and unknown causes of infertiity (Gurunath et al. 2011). The main aetiologies
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of male infertility include anatomical abnormalities, some conditions such as varicocele, renal failure and liver cirrhosis, side effects of medications, lifestyle and environmental factors, which
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may act alone or in combination (Krausz 2011). About 60 % of reasons for infertility are related to sperm dysfunction. Therefore, increasing spermatozoa counts, functionality and sperm quality
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can improve fertility status (Wright et al. 2014, Agarwal et al. 2014). The sperm cell membrane includes a large amount of polyunsaturated fatty acids and
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phospholipids which are vulnerable to oxidative stress (Aitken et al. 2014, Gharagozloo and Aitken 2011). Oxidative stress has deleterious effects on the structure, function, motility and
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survival of sperm. Smoking, alcohol ingestion, infection, exposure to environmental toxins or radiation can trigger rising mitochondrial production of reactive oxygen species (ROS) and oxidative stress. Following a rise in free radicals, DNA damage, lipid peroxidation, protein and biomembrane damage in sperm may occur (Aitken et al. 2014, Agarwal et al. 2014). Ingredients with antioxidant properties can transfer electrons to oxidizing agents and inhibit free radical production and sperm damage (Adedara et al. 2014). Antioxidant components have been indicated to improve spermatogenesis and steroidogenesis (Menezo et al. 2014a, Menezo et al. 2014b). Current evidence demonstrates that some medicinal herbs can scavenge free radicals and prevent the deleterious consequences of oxidative status (Sen et al. 2010, Atanassova et al. 2011,
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Awah et al. 2012). One of the medicinal plants with antioxidant characteristics is Nigella sativa (Ismail et al. 2010, Ashraf et al. 2011). Nigella sativa (NS), or ‘black seeds’, is a plant of the Ranunculaceae family. It grows widely in
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many Middle Eastern countries. Its seed is black in colour and bitter in taste (Randhawa and Alghamdi 2011). Nigella sativa has many different chemical ingredients including
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thymoquinone (TQ) (30-48%) (Ahmad et al. 2013), flavonoids, anthocyanins, alkaloids and
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essential fatty acids, particularly linoleic and oleic acid. It has been traditionally used for the treatment of different diseases such as respiratory and digestive disorders, kidney and liver
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dysfunction and rheumatism (Ahmad et al. 2013) in different forms (powder, oil and extract) (Paarakh 2010). Previous studies have indicated many medical properties of black seeds,
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including immunomodulatory activities as well as anti-inflammatory, antimicrobial and
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antioxidative effects (Paarakh 2010, Tembhurne et al. 2014). No toxic effects of NS were
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observed in animal models (Ahmad et al. 2013) and no serious side effects were observed in clinical trials (Paarakh 2010). The aim of the present study was to review the existing literature
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and assess the effects of NS on male infertility.
2. Material and Methods
The authors searched a number of electronic databases, namely Pubmed, Science Direct, Google scholar and Springer from the period January 2000 until June 2014. The following keywords were selected based on Mesh terms: Nigella sativa, black seeds, infertility, oxidative stress, free radicals, sperm and semen. These keywords were searched individually and in combination. Two reviewers extracted data independently, and then the titles and abstracts of each article were assessed to delete duplication of data. Searching was limited to articles in the English language.
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Patents and abstracts from symposiums and congress were excluded because they contained insufficient information for evaluation and comparison with other studies. Based on the above
Characteristics of the evaluated studies have been summarised in Table 1. 3. Results and discussions
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criteria, 24 articles were excluded and 13 eligible articles were evaluated in this study (Figure 1).
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Apparently only one clinical trial has evaluated the effects of NS in childless men. Kolahdooz et
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al., in a randomized double-blind placebo-controlled clinical trial, indicated that 5mL of NS oil improved sperm count and motility, semen volume, semen pH and its round cells after two
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months treatment in infertile men. The inclusion criteria were as follows: men with abnormal sperm morphology (<30 %) or sperm count (less than 20 × 106/mL) or type A and B motility
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(below 25 and 50 %, respectively) who had not received drug or hormone therapy in the past
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three months. The authors reported that the antioxidant properties of NS may neutralize free
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radicals in semen and improve sperm parameters. Furthermore the authors noted that NS oil included some unsaturated fatty acids such as linoleic acid (about 60%) and oleic acid (about
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20%) which can improve sperm parameters such as sperm count and sperm motility and also reduced abnormal sperms (Kolahdooz et al. 2014). Based on El-Tohamy et al., a combination of 50% black seeds and 50 % common meal (soy protein) fed to rabbits improved reaction time, latency period, semen volume and sperm quality (total sperm, motile sperm, sperm concentration and total functioning sperm fraction) after 29 weeks compared to a diet of mixed seeds and soy protein. In addition, in rabbits fed NS, free radicals, malondialdehyde (MDA), reactive nitrogen species and peroxynitrite in the seminal plasma were lower than in other groups (El-Tohamy et al. 2010). Flavonoids, anthocyanins, carotene, isothiocyanates and carotenoids are antioxidant components of NS which can
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contribute to antioxidant defence and scavenge ROS (Alenzi et al. 2013). As reported in Mohammad et al’s study, 300 mg/kg body weight of NS seeds taken for 60 days increased the weight of the reproductive organs, the number of mature Leydig cells, number of spermatocytes,
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total sperm count and motility in male albino rats. They suggested that the effects of NS on the pituitary gland triggered a rise in spermatogenesis hormones, and that the increase in the weight
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of reproductive organs proved this fact. Also, the authors found that NS can affect oxidative
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phosphorylation enzymes and increase sperm motility (Mohammad et al. 2009).
In Wahba et al’s study, pre-treatment with 250 mg/kg of NS oil showed an increased weight of
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testis, sperm count and movement, increased glutathione concentration, as well as reduced abnormal sperm and MDA levels in sodium valproate-intoxicated rats after four weeks. NS oil
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also appeared to repair testicular degeneration. In this study, sodium valproate was used as a
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testicular toxin. It increased lipid peroxidation and abnormal sperms, decreased sperm count,
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motility and viability, semen quality and quantity. TQ has demonstrated some protective roles in relation to oxidative status, such as superoxide anion scavenger, direct cytoprotective effects and
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indirect antioxidant and androgen activities (Hala 2011). Therefore, it may protect sperm and semen against a testicular toxin.
In Ping et al’s study, male rats were divided into three groups (nicotine: 0.5 mg/100 g body weight; NS oil: 6 μL/100 g body weight and a control group). In the NS oil group, higher sperm motility, more live and normal sperms, smaller lumen diameter, thinner spermatogonia and wider spermatid-sperm layers were observed compared to the nicotine and control groups after 100 days. The results suggested that the alkaloid and phenol components can stimulate the secretion of testosterone and follicle-stimulating hormone (FSH). It has been suggested that increased levels of testosterone and FSH levels in testicular tissue can trigger an increase in sperm
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concentration. Moreover, TQ can affect oxidative phosphorylation enzymes and protect cells against free radicals (Cho Ping et al. 2014). Abdul karim et al compared the effects of 0.5% to 1% NS oil and seeds on reproductive traits in male chickens. Adding either NS oil or seeds to the
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diet increased sperm count and motility, percentage of viability and ejaculation volume and decreased sperm abnormalities after nine weeks. In the second experiment hens and cocks were
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treated with NS it was found that 0.5 or 1% NS oil or seeds improved fertility and hatchability in hens
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and cocks after four weeks (Abdulkarim and Al-Sardary 2009).
Since TQ is the main active component of NS and it is a fat-soluble constituent (Naga et al.
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2013, Paarakh 2010), most studies evaluated the effects of NS oil in infertility models to get the best results. It appears that NS oil is the best form of NS for therapeutic use. However, the effects of
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alternative NS extracts were also evaluated in some studies. Al-Saaidi et al indicated that an alcoholic extract of NS in two doses (0.5 and 1.5 g/kg) increased reproductive parameters such
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as weight, sperm count, sperm motility, grade activity and viability, size of testis and epididymis, Sertoli and Leydig cells, testosterone levels and follicle-stimulating hormone, as well as reducing
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abnormal luteinizing hormone and cholesterol levels after 53 days in rats. These authors suggested that constituents of NS such as vitamins and minerals (zinc, copper, magnesium) could increase size of testis and epididymis. NS could also affect some metabolic enzymes, steroid hormone secretions and serum protein enzymes. Following the rise of FSH and testosterone levels, concentration of normal sperm increases (Al-Sa'aidi et al. 2009). Furthermore, in Paradin et al’s study, male rats received 200 and 400 mg/kg body weight alcoholic extract of NS for 60 days. After intervention, a significant difference in testis and epididymitis weight, daily sperm production, sperm count, testosterone levels, LH and fertility index were observed, particularly at the higher dose of NS (Parandin et al. 2012). In this study, increasing LH levels appeared to
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trigger rising testosterone secretions. No possible mechanisms except the antioxidant properties of NS were reported by Paradin et al. In some studies, the effect of supplementation with TQ was evaluated. The possible protective
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effects of TQ on spermatogenesis in rats were studied by Kanter et al. In their study, rats were orally given 50 mg/kg body weight of TQ. After 12 weeks treatment, endothelial nitric oxide
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synthase and inducible nitric oxide synthase decreased. In the treated group with NS, the
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expression of proliferating cell nuclear antigen in testis was also increased. The authors reported that TQ could prevent mitochondrial degeneration and the antioxidant properties of TQ can
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improve spermatogenesis in rats (Kanter et al 2010). Al-Zahrani et al also demonstrated that supplementation with 5 mg/kg TQ in mice exposed to the heat stress improved semen quality
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and reversed histopathological changes after 75 days. In this study, heat stress decreased sperm
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concentration and triggered histopathological changes (seminiferous tubules degeneration) with
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no effects on testosterone levels. They suggested that polar ingredients such as polyphones and
2012).
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flavonoids contained in NS may be responsible for neutralizing free radicals (Al-Zahrani et al.
Some chronic conditions such as dyslipidaemia and diabetes can disturb reproductive stages (Kasturi et al. 2008). Rising ROS levels in some chronic diseases are the main reason for the increase in damaged cells (Del Vecchio et al. 2014, Singh et al. 2014). According to Bashandy et al, oral administration of 0.5 mL/day NS oil in hyperlipidaemic rats improved sperm motility, sperm count, enhanced seminal vesicle weight and testosterone levels and decreased abnormal sperm after two months. The authors reported that lipid dysfunction was associated with low fertility index and sperm abnormality (Bashandy 2007). Testosterone levels in hyperlipidaemic rats were lower than normal rats. Some potential reasons are as follows: 1) an increase in
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degenerated Leydig cells; 2) a reduction in diameter of Leydig cell nucleus; 3) a fluctuation in luteinizing hormone concentration; and 4) a reduction in 17-beta hydroxysteroid dehydrogenase. Furthermore, enhancing TC, TG and LDL-c levels and decreasing HDL-c levels triggers free
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radical production, impaired antioxidant defence, lipid peroxidation and hypothalamic-pituitarygonadal axis disorders. Therefore, hyperlipidaemia indirectly lowered sperm quality and other
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factors of the fertility index. Fatty acid peroxidation in the sperm membrane leads to abnormality
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in sperm function, DNA damage, apoptosis and finally a reduction in sperm count. On the other hand, in hyperlipidaemia epididymis dysfunction there may be observed declines in sperm
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motility and an increase in sperm abnormalities. However, NS oil constituents such as unsaturated fatty acids and TQ can improve dyslipidaemia and antioxidant defence (Singh et al.
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2014). As shown in Wafai et al.’s study, aqueous extract of NS and TQ could suppress
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cyclooxygenase-2 enzyme expression and lipid peroxidation, and raise SOD levels in diabetic
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rats (Al Wafai 2013). Zohra et al treated diabetic rats by adding 2% NS seeds to their diet for 30 days. This addition improved testosterone levels and testis tissue (through reducing MDA levels
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and oxidative stress), semen quantity and mobility, and it reduced blood glucose and oxidative stress parameters (lipid peroxidation product level, glutathione peroxidase, superoxide dismutase and catalase) (Zohra et al. 2012). As in other studies (Sultan et al. 2014, Ahmad and Beg 2014), they suggested that the antioxidant characteristics of TQ led to an improved antioxidant status in diabetic rats.
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4. Conclusion Nigella sativa and its main constituent, thymoquinone can improve sperm parameters, semen, Leydig cells, reproductive organs and sexual hormones in animal studies. The main potential
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mechanism is the antioxidant properties of NS which play a key role in free radical scavenging. Although the findings of this review suggest that NS is a good candidate for male infertility
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treatment, to date there is insufficient evidence to make recommendations for its use as an
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adjunct therapy in infertile men. Based on the positive effects of black seed in the cited research albeit the differences in dose, type of NS extract, methods of the studies and limited clinical
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trials, more clinical trials are recommended to demonstrate the efficacy of NS on male infertility.
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REFERENCES
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Abdulkarim, S. M. and Al-Sardary, S. Y.. Effect of black seed (Nigella sativa) on some reproductive traits in ross broiler breeder male chickens. Journal of Bombay Veterinary College 2009; 17(1): 19-28. Adedara, I. A., Lawal, T. A., Adesina, A. A., Oyebiyi, O. O., Ebokaiwe, A. P. and Farombi, E. O.. Sperm functional parameters and erythrocytes oxidant-antioxidant imbalance during municipal landfill leachate treatment withdrawal in rats. Environmental toxicology and pharmacology 2014; 37(1): 460-467. Agarwal, A., Virk, G., Ong, C. and du Plessis, S. S.. Effect of Oxidative Stress on Male Reproduction. The world journal of men's health 2014; 32(1): 1-17. Ahmad, A., Husain, A., Mujeeb, M., Alam Khan, Sh., Najmi, Abul., Siddique, N., et al. A review on therapeutic potential of Nigella sativa: A miracle herb. Asian Pac J Trop Biomed 2013; 3(5): 337-352. Ahmad, S. and Beg, Z. H.. Mitigating role of thymoquinone rich fractions from Nigella sativa oil and its constituents, thymoquinone and limonene on lipidemic-oxidative injury in rats. SpringerPlus 2014; 3(1): 316. Aitken, R. J., Smith, T. B., Jobling, M. S., Baker, M. A. and De Iuliis, G. N. Oxidative stress and male reproductive health. Asian journal of andrology 2014; 16(1): 31. Al-Sa'aidi, J. A. A., Al-Khuzai, A. L. D. and Al-Zobaydi, N. F. H. Effect of alcoholic extract of Nigella sativa on fertility in male rats. Iraq J Verterin Sci 2009; 23, 123-8.
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Al-Zahrani, S., Mohany, M., Saleh, K. and Badr, G.. Thymoquinone and vitamin E supplementation improve the reproductive characteristics of heat stressed male mice. Journal of Medicinal Plants Research 2012; 6(3): 493-499. Al Wafai, R. J. Nigella sativa and thymoquinone suppress cyclooxygenase-2 and oxidative stress in pancreatic tissue of streptozotocin-induced diabetic rats. Pancreas 2013; 42(5): 841849. Alenzi, F. Q., Alsakran Altamimi, M. A., Kujan, O., Tarakji, B., Tamimi, W., Bagader, O., AlShangiti, A., Talohi, A. N., Alenezy, A. K. and Al-Swailmi, F. Antioxidant Properties of Nigella sativa. Journal of Molecular and Genetic Medicine 2013;7(3):10-17. Ashraf, S. S., Rao, M. V., Kaneez, F. S., Qadri, S., Al-Marzouqi, A. H., Chandranath, I. S. and Adem, A. Nigella sativa extract as a potent antioxidant for petrochemical-induced oxidative stress. Journal of chromatographic science 2011; 49(4):321-326. Atanassova, M., Georgieva, S. and Ivancheva, K. Total phenolic and total flavonoid contents, antioxidant capacity and biological contaminants in medicinal herbs. Journal of the University of Chemical Technology and Metallurgy 2011; 46(1): 81-88. Awah, F. M., Uzoegwu, P. N., Ifeonu, P., Oyugi, J. O., Rutherford, J., Yao, X., Fehrmann, F., Fowke, K. R. and Eze, M. O. Free radical scavenging activity, phenolic contents and cytotoxicity of selected Nigerian medicinal plants. Food Chemistry 2012; 131(4): 12791286. Bashandy, A. E. S. Effect of Fixed Oil 0f Nige1la Sativa 011 Male Fertility in Normal and Hyperlipidemic Rats. Int. J. Pharmacol 2007;3(1): 27-33. Cho Ping, N., Hashim, N. H. and Hasan Adli, D. S. Effects of Nigella sativa (Habbatus sauda) Oil and Nicotine Chronic Treatments on Sperm Parameters and Testis Histological Features of Rats. Evidence-Based Complementary and Alternative Medicine 2014; 2:121-27. Del Vecchio, L., Carini, M., Cavalli, A. and Locatelli, F. Oxidative Stress and Chronic Renal Disease “Clinical Aspects. Systems Biology of Free Radicals and Antioxidants 2014; 2625-2644. El-Tohamy, M. M., El-Nattat, W. S. and El-Kady, R. I. The beneficial effects of Nigella sativa, Raphanus sativus and Eruca sativa seed cakes to improve male rabbit fertility, immunity and production. J. Am. Sci 2010; 6(10):1247-1255. Gharagozloo, P. and Aitken, R. J. The role of sperm oxidative stress in male infertility and the significance of oral antioxidant therapy. Human reproduction 2011; 26(7): 1628-1640. Gurunath, S., Pandian, Z., Anderson, R. A. and Bhattacharya, S. Defining infertility: a systematic review of prevalence studies. Human reproduction update 2011;17(5): 575-588. Hala, M. A. Protective effect of Nigella sativa, linseed and celery oils against testicular toxicity induced by sodium valproate in male rats. Journal of American Science 2011; 7(5). Ismail, M., Al-Naqeep, G. and Chan, K. W. Nigella sativa-thymoquinone-rich fraction greatly improves plasma antioxidant capacity and expression of antioxidant genes in hypercholesterolemic rats. Free Radical Biology and Medicine 2010; 48(5): 664-672. Kanter, M. Thymoquinone reestablishes spermatogenesis after testicular injury caused by chronic toluene exposure in rats. Toxicology and industrial health 2010;13: 121-27. Kasturi, S. S., Tannir, J. and Brannigan, R. E. The metabolic syndrome and male infertility. Journal of andrology 2008; 29(3): 251-259.
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Kolahdooz, M., Nasri, S., Modarres, S. Z., Kianbakht, S. and Huseini, H. F. Effects of Nigella sativa seed oil on abnormal semen quality in infertile men: A randomized, double-blind, placebo-controlled clinical trial. Phytomedicine 2014; 21(6): 901-905. Krausz, C. Male infertility: pathogenesis and clinical diagnosis. Best practice & research Clinical endocrinology & metabolism 2011;25(2): 271-285. Menezo, Y., Entezami, F., Lichtblau, I., Belloc, S., Cohen, M. and Dale, B. Oxidative stress and fertility: incorrect assumptions and ineffective solutions? Zygote 2014a; 22(01): 80-90. Menezo, Y., Evenson, D., Cohen, M. and Dale, B. In Genetic Damage in Human SpermatozoaSpringer 2014b; 2: 173-189. Mohammad, M. A., Mohamad, M. M. J. and Dradka, H. Effects of black seeds (Nigella Sativa) on spermatogenesis and fertility of male albino rats. Res J Med Med Sci 2009; 4(2):386390. Naga, M. A., El-Aziz, M. A. A., Zeid, S. M., Daba, M.-H. Y. and El-Gamal, N. K. Amelioration of Doxorubicin-induced genotoxicity in isolated cultured human lymphocytes by Thymoquinone 2013; 14(2): 131-39. Paarakh, P. M. Nigella sativa Linn. A comprehensive review. Indian J Nat Prod Resour 2010; 1: 409-29. Parandin, R., Yousofvand, N. and Ghorbani, R. The enhancing effects of alcoholic extract of Nigella sativa seed on fertility potential, plasma gonadotropins and testosterone in male rats. Iranian Journal of Reproductive Medicine 2012; 10(4): 355-362. Randhawa, M. A. and Alghamdi, M. S. Anticancer activity of Nigella sativa (black seed)—A review. The American journal of Chinese medicine 2011; 39(06): 1075-1091. Sen, S., Chakraborty, R., Sridhar, C., Reddy, Y. S. R. and De, B. Free radicals, antioxidants, diseases and phytomedicines: current status and future prospect. International journal of pharmaceutical sciences review and research 2010; 3(1): 91-100. Singh, R., Devi, S. and Gollen, R. Role of free radical in atherosclerosis, diabetes and dyslipidemia.Diabetes/metabolism research and reviews 2014;13(1):42-49. Sultan, M. T., Butt, M. S., Karim, R., Iqbal, S. Z., Ahmad, S., Zia-Ul-Haq, M., Aliberti, L., Ahmad, A. N. and De Feo, V. Effect of Nigella sativa fixed and essential oils on antioxidant status, hepatic enzymes, and immunity in streptozotocin induced diabetes mellitus. BMC complementary and alternative medicine 2014; 14(1): 193. Tembhurne, S. V., Feroz, S., More, B. H. and Sakarkar, D. M. A review on therapeutic potential of Nigella sativa (kalonji) seeds. Journal of Medicinal Plants Research 2014; 8(3): 167177. Wright, C., Milne, S. and Leeson, H. Sperm DNA damage caused by oxidative stress: modifiable clinical, lifestyle and nutritional factors in male infertility. Reproductive biomedicine online 2014. Zohra, G., Khaled, H., Mongi, S., Zouheir, S., Khaled, M. Z., Abdelfattah, E. F. and Ahmed, H. Effect of Nigella sativa seeds on reproductive system of male diabetic rats. African Journal of Pharmacy and Pharmacology 2012; 6(20): 1444-1450.
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Conflict of Interest
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Authors declared no conflict of interest
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Fig 1: Flow chart of study selection procedures
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Additional records identified through other sources (n =7)
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Screening
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Records after duplicates removed (n =24)
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Identification
Records identified through database searching (n =34)
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Records screened (n =19)
Full-text articles excluded (n =2)
Evaluating
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Eligibility
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Full-text articles assessed for eligibility (n =15)
Records excluded (n =4)
Studies included in qualitative synthesis (n =13)
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Table
Elshama et al, 2013
Wafai et al, 2013
Zahrani et al, 2012
Paradin et al, 2012
albino rats
Rats with type 1 diabetes
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Result
↑Sperm count, sperm motility
NS oil
6μL/100 g body weight
Nicotine
0.5 mg/100 g body weight for 100 days 1000 mg/kg/day
↑Sperm motility ↑Normal sperm and live ↓Lumen diameter Spermatogonia thinner ↑Spermatid-sperm width
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Sprague-Dawley male rats
Dose
2.5 mL oil (two times a day) for 2 months
NS oil
ed
Ping et al, 2014
78 infertile men
Intervention
Aqueous suspension of Nigella powder
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Kolahdooz et al, 2014
Study Sample
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Author/Year
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Table 1- Characteristics of the eligible studies
NS oil and TQ
Sperm morphology improvement ↑Semen volume ↑Semen pH ↑Round cells
↓Testosterone level
Normal sperm count ↑Sperm mortality & livability ↑Abdominal sperm count 30 mg/kg for 60 days
Suppressed pancreatic tissue lipid peroxidation ↓Malondialdehyde levels ↑ Superoxide dismutase levels ↓Cyclooxygenase-2 mRNA expression.
Male mice in heat stress conditions
TQ
5mg/kg for 75 days
Restore free radical levels ↑Semen quality Histopathological changes induced by heat stress
Male rats
Alcoholic extract of NS
200 and 400 mg/kg body weight for 60 days
↑Epididymidis weight ↑Sperm count ↑Epididymal sperm reserve ↑Daily sperm production ↑ Testosterone concentration, LH and fertility index Page 16 of 18
Wahba et al, 2011
Male rats
NS oil
El-Tohamy et al, 2010
Male rabbits
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NS seed
Added 2% to diet for 30 days
Al-Saaidi et al, 2009
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ed
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Adult male albino rats
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Mohammad et al, 2009
NS Seed
White male rats
↑Semen quantity and mobility ↑Testosterone levels and testis ↓Blood glucose level ↓lipid peroxidation improvement in antioxidant activities of: Glutathione peroxidase Superoxide dismutase Catalase Lactate dehydrogenase Gamma glutamyl transferase Alkaline phosphatase Aspartate and alanine aminotransferase ↑Serum testosterone levels ↓Testicular lipid peroxides (MDA) ↑Glutathione ↓Testicular degenerative lesions
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Rats with type 2 diabetes
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Ghilisi et al, 2012
250 mg/kg for 4 weeks
50% of soybean for 29 weeks
NS seed
300 mg/kg body weight for 60 days
Alcoholic extract of NS
0.5 and 1.5 g/kg for 53 days
↑Semen Characteristic
↓Free radical in the seminal plasma ↓Testosterone plasma ↑Normal sperm count ↓Sperm motility ↑Sperm count and motility ↑Spermatogenesis at primary and secondary spermatocyte stages ↓Excitation time ↑Body weight gain ↑ Seminiferous tubules thickness and diameters ↑Account of spermatogonia ↑Primary and secondary spermatocytes ↑Spermatids, free spermatozoa ↑Account of sertoli and Leydig cells
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Experiment II: 10 hens and 1 cock
NS seed and oil 0.5 and 1% of diet for 9 weeks
↑Percentages fertility and hatchability
64 male (age: 3 months) Normal and hyperlipidemic
NS oil
↑Seminal vesicle weight ↓Testosterone level ↓Sperm mortality, count ↓Sperm abnormality ↑Fertility Index
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breeder males
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Bashandy et al, 2007
Experiment I: broiler
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Abdulkarim et al,2009
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↑Diameter of Leydig cells ↑Height of epithelial cells ↑Testosterone and follicle stimulating hormone ↑Leutinizing hormone and cholesterol ↑Ejaculation volume ↑Sperm mass motility ↑Progressive motility, viability percentage, count, and Total sperm output. ↓Ejaculation time and sperm abnormalities
0.5 mL/rat For 2 months
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NS: Nigella sativa; TQ: Thymoquinone
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S2210-8033(15)00027-5 http://dx.doi.org/doi:10.1016/j.hermed.2015.03.002 HERMED 100
To appear in: Received date: Revised date: Accepted date:
20-8-2014 8-2-2015 18-3-2015
Please cite this article as: Mahdavi R, Heshmati J, Namazi N, Effects of black seeds (Nigella sativa) on male infertility: A systematic review, Journal of Herbal Medicine (2015), http://dx.doi.org/10.1016/j.hermed.2015.03.002 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
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Effects of black seeds (Nigella sativa) on male infertility: A systematic review
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Reza Mahdavi a, Javad Heshmatib, Nazli Namazi a,*
Nutrition Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
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Student Research Center, Tehran University of Medical Sciences, Tehran, Iran
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*Corresponding Author: Nazli Namazi Nutrition Research Center, Tabriz University of Medical Sciences, Tabriz, Iran E-mail:[email protected]
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Highlights
Nigella sativa positively influence sperm parameters, semen, Leydig cells, reproductive
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organs and sexual hormones. Antioxidant properties of Nigella sativa are the main mechanisms in male reproductive
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health.
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Thymoquinone plays a key role in neutralizing free radicals.
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Effects of black seeds (Nigella sativa) on male infertility: A systematic review
Abstract
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Following an increase in free radicals, DNA damage and lipid peroxidation in human sperm may occur. Antioxidant components in medicinal herbs such as Nigella sativa (NS) have been
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indicated to improve spermatogenesis and steroidogenesis. The aim of the present study was to
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conduct a systemic review summarizing the effects of NS on male infertility. A number of electronic databases were searched namely Pubmed, Science Direct, Google scholar and
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Springer from the period January 2000 until June 2014. Searching was limited to articles in the English language. Patents and abstracts from symposiums and congress were excluded because
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they contained insufficient information for evaluation and comparison with other studies. The outcome of this study indicated that NS can positively influence sperm parameters, semen,
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Leydig cells, reproductive organs and sexual hormones. The main potential mechanism is
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through the antioxidant properties of NS. Thymoquinone (TQ) and unsaturated fatty acids are the
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main antioxidant components of NS. NS and TQ derived from NS can improve male fertility parameters through promoting antioxidant defence. Although the findings of this review suggest that NS is a good candidate for male infertility treatment, there is insufficient evidence to make recommendations for its use as an adjunct therapy in infertile men. More clinical trials are recommended to demonstrate the efficacy of NS on male infertility.
Key words: Oxidative stress, infertility, male, Nigella sativa, spermatogenesis, herbal medicine
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1. Introduction Infertility is defined as an inability of a couple to achieve a pregnancy after 12 months of intercourse without contraception (Gurunath et al. 2011). Infertility among men is more
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prevalent than among women. It affects almost one in 20 men and male infertility is a factor in about 50 % of infertile couples. The remaining 50% is due to female problems, both male and
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female problems and unknown causes of infertiity (Gurunath et al. 2011). The main aetiologies
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of male infertility include anatomical abnormalities, some conditions such as varicocele, renal failure and liver cirrhosis, side effects of medications, lifestyle and environmental factors, which
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may act alone or in combination (Krausz 2011). About 60 % of reasons for infertility are related to sperm dysfunction. Therefore, increasing spermatozoa counts, functionality and sperm quality
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can improve fertility status (Wright et al. 2014, Agarwal et al. 2014). The sperm cell membrane includes a large amount of polyunsaturated fatty acids and
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phospholipids which are vulnerable to oxidative stress (Aitken et al. 2014, Gharagozloo and Aitken 2011). Oxidative stress has deleterious effects on the structure, function, motility and
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survival of sperm. Smoking, alcohol ingestion, infection, exposure to environmental toxins or radiation can trigger rising mitochondrial production of reactive oxygen species (ROS) and oxidative stress. Following a rise in free radicals, DNA damage, lipid peroxidation, protein and biomembrane damage in sperm may occur (Aitken et al. 2014, Agarwal et al. 2014). Ingredients with antioxidant properties can transfer electrons to oxidizing agents and inhibit free radical production and sperm damage (Adedara et al. 2014). Antioxidant components have been indicated to improve spermatogenesis and steroidogenesis (Menezo et al. 2014a, Menezo et al. 2014b). Current evidence demonstrates that some medicinal herbs can scavenge free radicals and prevent the deleterious consequences of oxidative status (Sen et al. 2010, Atanassova et al. 2011,
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Awah et al. 2012). One of the medicinal plants with antioxidant characteristics is Nigella sativa (Ismail et al. 2010, Ashraf et al. 2011). Nigella sativa (NS), or ‘black seeds’, is a plant of the Ranunculaceae family. It grows widely in
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many Middle Eastern countries. Its seed is black in colour and bitter in taste (Randhawa and Alghamdi 2011). Nigella sativa has many different chemical ingredients including
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thymoquinone (TQ) (30-48%) (Ahmad et al. 2013), flavonoids, anthocyanins, alkaloids and
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essential fatty acids, particularly linoleic and oleic acid. It has been traditionally used for the treatment of different diseases such as respiratory and digestive disorders, kidney and liver
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dysfunction and rheumatism (Ahmad et al. 2013) in different forms (powder, oil and extract) (Paarakh 2010). Previous studies have indicated many medical properties of black seeds,
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including immunomodulatory activities as well as anti-inflammatory, antimicrobial and
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antioxidative effects (Paarakh 2010, Tembhurne et al. 2014). No toxic effects of NS were
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observed in animal models (Ahmad et al. 2013) and no serious side effects were observed in clinical trials (Paarakh 2010). The aim of the present study was to review the existing literature
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and assess the effects of NS on male infertility.
2. Material and Methods
The authors searched a number of electronic databases, namely Pubmed, Science Direct, Google scholar and Springer from the period January 2000 until June 2014. The following keywords were selected based on Mesh terms: Nigella sativa, black seeds, infertility, oxidative stress, free radicals, sperm and semen. These keywords were searched individually and in combination. Two reviewers extracted data independently, and then the titles and abstracts of each article were assessed to delete duplication of data. Searching was limited to articles in the English language.
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Patents and abstracts from symposiums and congress were excluded because they contained insufficient information for evaluation and comparison with other studies. Based on the above
Characteristics of the evaluated studies have been summarised in Table 1. 3. Results and discussions
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criteria, 24 articles were excluded and 13 eligible articles were evaluated in this study (Figure 1).
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Apparently only one clinical trial has evaluated the effects of NS in childless men. Kolahdooz et
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al., in a randomized double-blind placebo-controlled clinical trial, indicated that 5mL of NS oil improved sperm count and motility, semen volume, semen pH and its round cells after two
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months treatment in infertile men. The inclusion criteria were as follows: men with abnormal sperm morphology (<30 %) or sperm count (less than 20 × 106/mL) or type A and B motility
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(below 25 and 50 %, respectively) who had not received drug or hormone therapy in the past
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three months. The authors reported that the antioxidant properties of NS may neutralize free
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radicals in semen and improve sperm parameters. Furthermore the authors noted that NS oil included some unsaturated fatty acids such as linoleic acid (about 60%) and oleic acid (about
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20%) which can improve sperm parameters such as sperm count and sperm motility and also reduced abnormal sperms (Kolahdooz et al. 2014). Based on El-Tohamy et al., a combination of 50% black seeds and 50 % common meal (soy protein) fed to rabbits improved reaction time, latency period, semen volume and sperm quality (total sperm, motile sperm, sperm concentration and total functioning sperm fraction) after 29 weeks compared to a diet of mixed seeds and soy protein. In addition, in rabbits fed NS, free radicals, malondialdehyde (MDA), reactive nitrogen species and peroxynitrite in the seminal plasma were lower than in other groups (El-Tohamy et al. 2010). Flavonoids, anthocyanins, carotene, isothiocyanates and carotenoids are antioxidant components of NS which can
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contribute to antioxidant defence and scavenge ROS (Alenzi et al. 2013). As reported in Mohammad et al’s study, 300 mg/kg body weight of NS seeds taken for 60 days increased the weight of the reproductive organs, the number of mature Leydig cells, number of spermatocytes,
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total sperm count and motility in male albino rats. They suggested that the effects of NS on the pituitary gland triggered a rise in spermatogenesis hormones, and that the increase in the weight
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of reproductive organs proved this fact. Also, the authors found that NS can affect oxidative
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phosphorylation enzymes and increase sperm motility (Mohammad et al. 2009).
In Wahba et al’s study, pre-treatment with 250 mg/kg of NS oil showed an increased weight of
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testis, sperm count and movement, increased glutathione concentration, as well as reduced abnormal sperm and MDA levels in sodium valproate-intoxicated rats after four weeks. NS oil
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also appeared to repair testicular degeneration. In this study, sodium valproate was used as a
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testicular toxin. It increased lipid peroxidation and abnormal sperms, decreased sperm count,
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motility and viability, semen quality and quantity. TQ has demonstrated some protective roles in relation to oxidative status, such as superoxide anion scavenger, direct cytoprotective effects and
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indirect antioxidant and androgen activities (Hala 2011). Therefore, it may protect sperm and semen against a testicular toxin.
In Ping et al’s study, male rats were divided into three groups (nicotine: 0.5 mg/100 g body weight; NS oil: 6 μL/100 g body weight and a control group). In the NS oil group, higher sperm motility, more live and normal sperms, smaller lumen diameter, thinner spermatogonia and wider spermatid-sperm layers were observed compared to the nicotine and control groups after 100 days. The results suggested that the alkaloid and phenol components can stimulate the secretion of testosterone and follicle-stimulating hormone (FSH). It has been suggested that increased levels of testosterone and FSH levels in testicular tissue can trigger an increase in sperm
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concentration. Moreover, TQ can affect oxidative phosphorylation enzymes and protect cells against free radicals (Cho Ping et al. 2014). Abdul karim et al compared the effects of 0.5% to 1% NS oil and seeds on reproductive traits in male chickens. Adding either NS oil or seeds to the
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diet increased sperm count and motility, percentage of viability and ejaculation volume and decreased sperm abnormalities after nine weeks. In the second experiment hens and cocks were
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treated with NS it was found that 0.5 or 1% NS oil or seeds improved fertility and hatchability in hens
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and cocks after four weeks (Abdulkarim and Al-Sardary 2009).
Since TQ is the main active component of NS and it is a fat-soluble constituent (Naga et al.
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2013, Paarakh 2010), most studies evaluated the effects of NS oil in infertility models to get the best results. It appears that NS oil is the best form of NS for therapeutic use. However, the effects of
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alternative NS extracts were also evaluated in some studies. Al-Saaidi et al indicated that an alcoholic extract of NS in two doses (0.5 and 1.5 g/kg) increased reproductive parameters such
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as weight, sperm count, sperm motility, grade activity and viability, size of testis and epididymis, Sertoli and Leydig cells, testosterone levels and follicle-stimulating hormone, as well as reducing
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abnormal luteinizing hormone and cholesterol levels after 53 days in rats. These authors suggested that constituents of NS such as vitamins and minerals (zinc, copper, magnesium) could increase size of testis and epididymis. NS could also affect some metabolic enzymes, steroid hormone secretions and serum protein enzymes. Following the rise of FSH and testosterone levels, concentration of normal sperm increases (Al-Sa'aidi et al. 2009). Furthermore, in Paradin et al’s study, male rats received 200 and 400 mg/kg body weight alcoholic extract of NS for 60 days. After intervention, a significant difference in testis and epididymitis weight, daily sperm production, sperm count, testosterone levels, LH and fertility index were observed, particularly at the higher dose of NS (Parandin et al. 2012). In this study, increasing LH levels appeared to
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trigger rising testosterone secretions. No possible mechanisms except the antioxidant properties of NS were reported by Paradin et al. In some studies, the effect of supplementation with TQ was evaluated. The possible protective
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effects of TQ on spermatogenesis in rats were studied by Kanter et al. In their study, rats were orally given 50 mg/kg body weight of TQ. After 12 weeks treatment, endothelial nitric oxide
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synthase and inducible nitric oxide synthase decreased. In the treated group with NS, the
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expression of proliferating cell nuclear antigen in testis was also increased. The authors reported that TQ could prevent mitochondrial degeneration and the antioxidant properties of TQ can
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improve spermatogenesis in rats (Kanter et al 2010). Al-Zahrani et al also demonstrated that supplementation with 5 mg/kg TQ in mice exposed to the heat stress improved semen quality
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and reversed histopathological changes after 75 days. In this study, heat stress decreased sperm
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concentration and triggered histopathological changes (seminiferous tubules degeneration) with
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no effects on testosterone levels. They suggested that polar ingredients such as polyphones and
2012).
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flavonoids contained in NS may be responsible for neutralizing free radicals (Al-Zahrani et al.
Some chronic conditions such as dyslipidaemia and diabetes can disturb reproductive stages (Kasturi et al. 2008). Rising ROS levels in some chronic diseases are the main reason for the increase in damaged cells (Del Vecchio et al. 2014, Singh et al. 2014). According to Bashandy et al, oral administration of 0.5 mL/day NS oil in hyperlipidaemic rats improved sperm motility, sperm count, enhanced seminal vesicle weight and testosterone levels and decreased abnormal sperm after two months. The authors reported that lipid dysfunction was associated with low fertility index and sperm abnormality (Bashandy 2007). Testosterone levels in hyperlipidaemic rats were lower than normal rats. Some potential reasons are as follows: 1) an increase in
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degenerated Leydig cells; 2) a reduction in diameter of Leydig cell nucleus; 3) a fluctuation in luteinizing hormone concentration; and 4) a reduction in 17-beta hydroxysteroid dehydrogenase. Furthermore, enhancing TC, TG and LDL-c levels and decreasing HDL-c levels triggers free
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radical production, impaired antioxidant defence, lipid peroxidation and hypothalamic-pituitarygonadal axis disorders. Therefore, hyperlipidaemia indirectly lowered sperm quality and other
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factors of the fertility index. Fatty acid peroxidation in the sperm membrane leads to abnormality
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in sperm function, DNA damage, apoptosis and finally a reduction in sperm count. On the other hand, in hyperlipidaemia epididymis dysfunction there may be observed declines in sperm
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motility and an increase in sperm abnormalities. However, NS oil constituents such as unsaturated fatty acids and TQ can improve dyslipidaemia and antioxidant defence (Singh et al.
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2014). As shown in Wafai et al.’s study, aqueous extract of NS and TQ could suppress
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cyclooxygenase-2 enzyme expression and lipid peroxidation, and raise SOD levels in diabetic
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rats (Al Wafai 2013). Zohra et al treated diabetic rats by adding 2% NS seeds to their diet for 30 days. This addition improved testosterone levels and testis tissue (through reducing MDA levels
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and oxidative stress), semen quantity and mobility, and it reduced blood glucose and oxidative stress parameters (lipid peroxidation product level, glutathione peroxidase, superoxide dismutase and catalase) (Zohra et al. 2012). As in other studies (Sultan et al. 2014, Ahmad and Beg 2014), they suggested that the antioxidant characteristics of TQ led to an improved antioxidant status in diabetic rats.
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4. Conclusion Nigella sativa and its main constituent, thymoquinone can improve sperm parameters, semen, Leydig cells, reproductive organs and sexual hormones in animal studies. The main potential
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mechanism is the antioxidant properties of NS which play a key role in free radical scavenging. Although the findings of this review suggest that NS is a good candidate for male infertility
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treatment, to date there is insufficient evidence to make recommendations for its use as an
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adjunct therapy in infertile men. Based on the positive effects of black seed in the cited research albeit the differences in dose, type of NS extract, methods of the studies and limited clinical
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trials, more clinical trials are recommended to demonstrate the efficacy of NS on male infertility.
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REFERENCES
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Abdulkarim, S. M. and Al-Sardary, S. Y.. Effect of black seed (Nigella sativa) on some reproductive traits in ross broiler breeder male chickens. Journal of Bombay Veterinary College 2009; 17(1): 19-28. Adedara, I. A., Lawal, T. A., Adesina, A. A., Oyebiyi, O. O., Ebokaiwe, A. P. and Farombi, E. O.. Sperm functional parameters and erythrocytes oxidant-antioxidant imbalance during municipal landfill leachate treatment withdrawal in rats. Environmental toxicology and pharmacology 2014; 37(1): 460-467. Agarwal, A., Virk, G., Ong, C. and du Plessis, S. S.. Effect of Oxidative Stress on Male Reproduction. The world journal of men's health 2014; 32(1): 1-17. Ahmad, A., Husain, A., Mujeeb, M., Alam Khan, Sh., Najmi, Abul., Siddique, N., et al. A review on therapeutic potential of Nigella sativa: A miracle herb. Asian Pac J Trop Biomed 2013; 3(5): 337-352. Ahmad, S. and Beg, Z. H.. Mitigating role of thymoquinone rich fractions from Nigella sativa oil and its constituents, thymoquinone and limonene on lipidemic-oxidative injury in rats. SpringerPlus 2014; 3(1): 316. Aitken, R. J., Smith, T. B., Jobling, M. S., Baker, M. A. and De Iuliis, G. N. Oxidative stress and male reproductive health. Asian journal of andrology 2014; 16(1): 31. Al-Sa'aidi, J. A. A., Al-Khuzai, A. L. D. and Al-Zobaydi, N. F. H. Effect of alcoholic extract of Nigella sativa on fertility in male rats. Iraq J Verterin Sci 2009; 23, 123-8.
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Al-Zahrani, S., Mohany, M., Saleh, K. and Badr, G.. Thymoquinone and vitamin E supplementation improve the reproductive characteristics of heat stressed male mice. Journal of Medicinal Plants Research 2012; 6(3): 493-499. Al Wafai, R. J. Nigella sativa and thymoquinone suppress cyclooxygenase-2 and oxidative stress in pancreatic tissue of streptozotocin-induced diabetic rats. Pancreas 2013; 42(5): 841849. Alenzi, F. Q., Alsakran Altamimi, M. A., Kujan, O., Tarakji, B., Tamimi, W., Bagader, O., AlShangiti, A., Talohi, A. N., Alenezy, A. K. and Al-Swailmi, F. Antioxidant Properties of Nigella sativa. Journal of Molecular and Genetic Medicine 2013;7(3):10-17. Ashraf, S. S., Rao, M. V., Kaneez, F. S., Qadri, S., Al-Marzouqi, A. H., Chandranath, I. S. and Adem, A. Nigella sativa extract as a potent antioxidant for petrochemical-induced oxidative stress. Journal of chromatographic science 2011; 49(4):321-326. Atanassova, M., Georgieva, S. and Ivancheva, K. Total phenolic and total flavonoid contents, antioxidant capacity and biological contaminants in medicinal herbs. Journal of the University of Chemical Technology and Metallurgy 2011; 46(1): 81-88. Awah, F. M., Uzoegwu, P. N., Ifeonu, P., Oyugi, J. O., Rutherford, J., Yao, X., Fehrmann, F., Fowke, K. R. and Eze, M. O. Free radical scavenging activity, phenolic contents and cytotoxicity of selected Nigerian medicinal plants. Food Chemistry 2012; 131(4): 12791286. Bashandy, A. E. S. Effect of Fixed Oil 0f Nige1la Sativa 011 Male Fertility in Normal and Hyperlipidemic Rats. Int. J. Pharmacol 2007;3(1): 27-33. Cho Ping, N., Hashim, N. H. and Hasan Adli, D. S. Effects of Nigella sativa (Habbatus sauda) Oil and Nicotine Chronic Treatments on Sperm Parameters and Testis Histological Features of Rats. Evidence-Based Complementary and Alternative Medicine 2014; 2:121-27. Del Vecchio, L., Carini, M., Cavalli, A. and Locatelli, F. Oxidative Stress and Chronic Renal Disease “Clinical Aspects. Systems Biology of Free Radicals and Antioxidants 2014; 2625-2644. El-Tohamy, M. M., El-Nattat, W. S. and El-Kady, R. I. The beneficial effects of Nigella sativa, Raphanus sativus and Eruca sativa seed cakes to improve male rabbit fertility, immunity and production. J. Am. Sci 2010; 6(10):1247-1255. Gharagozloo, P. and Aitken, R. J. The role of sperm oxidative stress in male infertility and the significance of oral antioxidant therapy. Human reproduction 2011; 26(7): 1628-1640. Gurunath, S., Pandian, Z., Anderson, R. A. and Bhattacharya, S. Defining infertility: a systematic review of prevalence studies. Human reproduction update 2011;17(5): 575-588. Hala, M. A. Protective effect of Nigella sativa, linseed and celery oils against testicular toxicity induced by sodium valproate in male rats. Journal of American Science 2011; 7(5). Ismail, M., Al-Naqeep, G. and Chan, K. W. Nigella sativa-thymoquinone-rich fraction greatly improves plasma antioxidant capacity and expression of antioxidant genes in hypercholesterolemic rats. Free Radical Biology and Medicine 2010; 48(5): 664-672. Kanter, M. Thymoquinone reestablishes spermatogenesis after testicular injury caused by chronic toluene exposure in rats. Toxicology and industrial health 2010;13: 121-27. Kasturi, S. S., Tannir, J. and Brannigan, R. E. The metabolic syndrome and male infertility. Journal of andrology 2008; 29(3): 251-259.
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Kolahdooz, M., Nasri, S., Modarres, S. Z., Kianbakht, S. and Huseini, H. F. Effects of Nigella sativa seed oil on abnormal semen quality in infertile men: A randomized, double-blind, placebo-controlled clinical trial. Phytomedicine 2014; 21(6): 901-905. Krausz, C. Male infertility: pathogenesis and clinical diagnosis. Best practice & research Clinical endocrinology & metabolism 2011;25(2): 271-285. Menezo, Y., Entezami, F., Lichtblau, I., Belloc, S., Cohen, M. and Dale, B. Oxidative stress and fertility: incorrect assumptions and ineffective solutions? Zygote 2014a; 22(01): 80-90. Menezo, Y., Evenson, D., Cohen, M. and Dale, B. In Genetic Damage in Human SpermatozoaSpringer 2014b; 2: 173-189. Mohammad, M. A., Mohamad, M. M. J. and Dradka, H. Effects of black seeds (Nigella Sativa) on spermatogenesis and fertility of male albino rats. Res J Med Med Sci 2009; 4(2):386390. Naga, M. A., El-Aziz, M. A. A., Zeid, S. M., Daba, M.-H. Y. and El-Gamal, N. K. Amelioration of Doxorubicin-induced genotoxicity in isolated cultured human lymphocytes by Thymoquinone 2013; 14(2): 131-39. Paarakh, P. M. Nigella sativa Linn. A comprehensive review. Indian J Nat Prod Resour 2010; 1: 409-29. Parandin, R., Yousofvand, N. and Ghorbani, R. The enhancing effects of alcoholic extract of Nigella sativa seed on fertility potential, plasma gonadotropins and testosterone in male rats. Iranian Journal of Reproductive Medicine 2012; 10(4): 355-362. Randhawa, M. A. and Alghamdi, M. S. Anticancer activity of Nigella sativa (black seed)—A review. The American journal of Chinese medicine 2011; 39(06): 1075-1091. Sen, S., Chakraborty, R., Sridhar, C., Reddy, Y. S. R. and De, B. Free radicals, antioxidants, diseases and phytomedicines: current status and future prospect. International journal of pharmaceutical sciences review and research 2010; 3(1): 91-100. Singh, R., Devi, S. and Gollen, R. Role of free radical in atherosclerosis, diabetes and dyslipidemia.Diabetes/metabolism research and reviews 2014;13(1):42-49. Sultan, M. T., Butt, M. S., Karim, R., Iqbal, S. Z., Ahmad, S., Zia-Ul-Haq, M., Aliberti, L., Ahmad, A. N. and De Feo, V. Effect of Nigella sativa fixed and essential oils on antioxidant status, hepatic enzymes, and immunity in streptozotocin induced diabetes mellitus. BMC complementary and alternative medicine 2014; 14(1): 193. Tembhurne, S. V., Feroz, S., More, B. H. and Sakarkar, D. M. A review on therapeutic potential of Nigella sativa (kalonji) seeds. Journal of Medicinal Plants Research 2014; 8(3): 167177. Wright, C., Milne, S. and Leeson, H. Sperm DNA damage caused by oxidative stress: modifiable clinical, lifestyle and nutritional factors in male infertility. Reproductive biomedicine online 2014. Zohra, G., Khaled, H., Mongi, S., Zouheir, S., Khaled, M. Z., Abdelfattah, E. F. and Ahmed, H. Effect of Nigella sativa seeds on reproductive system of male diabetic rats. African Journal of Pharmacy and Pharmacology 2012; 6(20): 1444-1450.
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Conflict of Interest
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Authors declared no conflict of interest
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Fig 1: Flow chart of study selection procedures
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Additional records identified through other sources (n =7)
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Screening
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Records after duplicates removed (n =24)
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Identification
Records identified through database searching (n =34)
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Records screened (n =19)
Full-text articles excluded (n =2)
Evaluating
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Eligibility
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Full-text articles assessed for eligibility (n =15)
Records excluded (n =4)
Studies included in qualitative synthesis (n =13)
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Table
Elshama et al, 2013
Wafai et al, 2013
Zahrani et al, 2012
Paradin et al, 2012
albino rats
Rats with type 1 diabetes
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Result
↑Sperm count, sperm motility
NS oil
6μL/100 g body weight
Nicotine
0.5 mg/100 g body weight for 100 days 1000 mg/kg/day
↑Sperm motility ↑Normal sperm and live ↓Lumen diameter Spermatogonia thinner ↑Spermatid-sperm width
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Sprague-Dawley male rats
Dose
2.5 mL oil (two times a day) for 2 months
NS oil
ed
Ping et al, 2014
78 infertile men
Intervention
Aqueous suspension of Nigella powder
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Kolahdooz et al, 2014
Study Sample
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Author/Year
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Table 1- Characteristics of the eligible studies
NS oil and TQ
Sperm morphology improvement ↑Semen volume ↑Semen pH ↑Round cells
↓Testosterone level
Normal sperm count ↑Sperm mortality & livability ↑Abdominal sperm count 30 mg/kg for 60 days
Suppressed pancreatic tissue lipid peroxidation ↓Malondialdehyde levels ↑ Superoxide dismutase levels ↓Cyclooxygenase-2 mRNA expression.
Male mice in heat stress conditions
TQ
5mg/kg for 75 days
Restore free radical levels ↑Semen quality Histopathological changes induced by heat stress
Male rats
Alcoholic extract of NS
200 and 400 mg/kg body weight for 60 days
↑Epididymidis weight ↑Sperm count ↑Epididymal sperm reserve ↑Daily sperm production ↑ Testosterone concentration, LH and fertility index Page 16 of 18
Wahba et al, 2011
Male rats
NS oil
El-Tohamy et al, 2010
Male rabbits
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NS seed
Added 2% to diet for 30 days
Al-Saaidi et al, 2009
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ed
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Adult male albino rats
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Mohammad et al, 2009
NS Seed
White male rats
↑Semen quantity and mobility ↑Testosterone levels and testis ↓Blood glucose level ↓lipid peroxidation improvement in antioxidant activities of: Glutathione peroxidase Superoxide dismutase Catalase Lactate dehydrogenase Gamma glutamyl transferase Alkaline phosphatase Aspartate and alanine aminotransferase ↑Serum testosterone levels ↓Testicular lipid peroxides (MDA) ↑Glutathione ↓Testicular degenerative lesions
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Rats with type 2 diabetes
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Ghilisi et al, 2012
250 mg/kg for 4 weeks
50% of soybean for 29 weeks
NS seed
300 mg/kg body weight for 60 days
Alcoholic extract of NS
0.5 and 1.5 g/kg for 53 days
↑Semen Characteristic
↓Free radical in the seminal plasma ↓Testosterone plasma ↑Normal sperm count ↓Sperm motility ↑Sperm count and motility ↑Spermatogenesis at primary and secondary spermatocyte stages ↓Excitation time ↑Body weight gain ↑ Seminiferous tubules thickness and diameters ↑Account of spermatogonia ↑Primary and secondary spermatocytes ↑Spermatids, free spermatozoa ↑Account of sertoli and Leydig cells
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Experiment II: 10 hens and 1 cock
NS seed and oil 0.5 and 1% of diet for 9 weeks
↑Percentages fertility and hatchability
64 male (age: 3 months) Normal and hyperlipidemic
NS oil
↑Seminal vesicle weight ↓Testosterone level ↓Sperm mortality, count ↓Sperm abnormality ↑Fertility Index
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breeder males
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Bashandy et al, 2007
Experiment I: broiler
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Abdulkarim et al,2009
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↑Diameter of Leydig cells ↑Height of epithelial cells ↑Testosterone and follicle stimulating hormone ↑Leutinizing hormone and cholesterol ↑Ejaculation volume ↑Sperm mass motility ↑Progressive motility, viability percentage, count, and Total sperm output. ↓Ejaculation time and sperm abnormalities
0.5 mL/rat For 2 months
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NS: Nigella sativa; TQ: Thymoquinone
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