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Tragopogon porrifolius improves serum lipid profile and increases short-term satiety in rats
Appetite 72 (2014) 1–7
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Tragopogon porrifolius improves serum lipid profile and increases short-term satiety in rats q Nadine Zeeni a, Costantine F. Daher a,⇑, Lea Saab a, Mohamad Mroueh b a b
Lebanese American University, School of Arts and Sciences, Department of Natural Sciences, PO Box 36, Byblos, Lebanon Lebanese American University, School of Pharmacy, PO Box 36, Byblos, Lebanon
a r t i c l e
i n f o
Article history: Received 19 July 2013 Received in revised form 21 September 2013 Accepted 23 September 2013 Available online 4 October 2013 Keywords: Tragopogon porrifolius Satiety High-fat diet Cholesterol Lipid profile
a b s t r a c t Tragopogon porrifolius (white salsify) is an edible plant commonly used in folk medicine in Lebanon and neighbouring countries. This study investigates the effect of the aqueous extract of the aerial part of T. porrifolius on lipemia and appetite regulation using a rat model. Food intake, abdominal fat percentage, blood lipid profile, liver weight and liver enzymes were assessed following 4 weeks of extract intake via drinking water (50, 100, or 250 mg/kg body weight) in standard high-carbohydrate and high-fat dietary conditions. In a separate study, the short term effect of a preload of T. porrifolius extract on food intake was evaluated. Results showed that consumption of the plant extract for a period of four weeks resulted in a marked improvement of the lipid profile (triglycerides, total cholesterol, LDL and HDL cholesterol). Body weight, food intake and intra-abdominal fat were also lower in animals given the plant extract (100 and 250 mg/kg). In addition, T. porrifolius extract preload produced a dose dependent decrease in food intake observed over 24 h. The intake of T. porrifolius aqueous extract therefore improved lipemia and increased satiety in rats with no visible adverse effects. Ó 2013 Elsevier Ltd. All rights reserved.
Introduction Human obesity is a growing global epidemic. It increases the risk of coronary heart disease, hypertension, stroke, diabetes and certain cancers (Ezzati, Lopez, Rodgers, Murray, et al., 2004; Folsom et al., 1989; Lee and Paffenbarger, 1992; Sellers, Kushi, Potter, et al., 1992; World Health Organization, 2009). According to the World Health Organization (World Health Organization, 2009), the incidence of obesity worldwide has more than doubled in the past 30 years. Global estimates from 2008 revealed that 1.5 billion adults were overweight, of which 500 million were obese. Obesity and its related health problems impose a significant economic burden not only on obese people but also on the rest of society. For example, in the United States alone, about 10% ($147 billion) of the annual US health care budget is spent on obesity due to increased need for medical care and the loss of economic productivity (Finkelstein, Trogdon, Cohen, & Dietz, 2009; Withrow & Alter, 2011). The rise in obesity incidence throughout many countries seems to be driven mainly by changes in the global food system which is producing and effectively marketing more cheap energy-dense processed foods (Hurt, Frazier, McClave, & Kaplan, 2011; Swinburn, Sacks, Hall, et al., 2011). Normally, increases in q
Conflict of interest: The authors report no conflicts of interest.
⇑ Corresponding author.
E-mail address: [email protected] (C.F. Daher). 0195-6663/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.appet.2013.09.023
the consumption of refined fats and carbohydrates are accompanied by a loss of diversity in diet composition leading to the loss of vegetable and herb benefits. While they are not always parallel, obesity is often accompanied by hyperlipidemia. The metabolic features of obese people include increased serum total cholesterol, triglycerides and LDL cholesterol which are proven risk factors for cardiovascular disease (Di Angelantonio et al., 2009; Harchaoui, Visser, Kastelein, et al., 2009; Kannel & Vasan, 2009). Indeed, treatment of hyperlipidemia is a primary approach in cardiovascular disease prevention (Baigent et al., 2010; Graham, Atar, Borch-Johnsen, et al., 2007). Therefore, it is important to identify and promote natural functional foods that can help manage weight and hyperlipidemia in this obesogenic environment. Satiety is an internal state that leads to termination of eating under normal physiological conditions. Increased appetite, due to impaired central mechanisms regulating food intake, could cause obesity (Astrup & Raben, 1992; Rosenbaum, Kissileff, Mayer, et al., 2010). Recent efforts have been made to identify various methods that help limit food intake, among which is increasing the satiating power of foods. Tragopogon porrifolius, family Asteraceae, is an annual or biennial herb indigenous to the Middle East as well as Asia Minor. Its roots, leafy shoots and open flowers are used both cooked and raw (as a salad) (Gupta, Talwar, Jain, et al., 2003). While both roots and shoots are edible, in Lebanon, the shoots are more frequently
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consumed than the roots. T. porrifolius is commonly used in folk medicine in Lebanon and neighbouring countries. It has been reported to possess antibilious, diuretic and laxative effects (Formisano et al., 2010; Spina, Cuccioloni, Sparapani, et al., 2007). Phytochemical analysis of T. porrifolius revealed the presence of acylated pentacyclic triterpene saponins (Warashina, Miyase, & Ueno, 1991), flavonoids, and different types of bibenzyls and dihydroisocoumarins (Sareedenchai et al., 2009; Zidorn, Lohwasser, Pschorr, et al., 2005). The nutritional value of this plant has been attributed to its monounsaturated and essential fatty acids, vitamins, polyphenols, and fructo-oligosaccharides (FOS) components (Formisano, Rigano, Senatore, et al., 2010; Konopinski, 2009). In fact, the FOS content, which is estimated to be 4–11% (Beirao-da-costa, Januario, Leitao, & Simao, 2005; Konopinski, 2009; Riu-Aumatell, Vargas, Vichi, et al., 2011) was behind its use in a human study to supplement baby food (Flickinger, Hatch, Wofford, et al., 2002). To the best of our knowledge, no studies were conducted on the effects of T. porrifolius on lipemia and food intake. Therefore, the primary objective of this study was to evaluate the effects of T. porrifolius water extract intake on blood lipid profile and the eating behavior of rats. We used a 4-week model in which rats were given the extract via drinking water (at doses of 50, 100, or 250 mg/kg body weight) with a standard high-carbohydrate or a high-fat diet. The secondary objective was to assess the short term effects of T. porrifolius water extract on food intake.
Materials and methods Plant collection and extraction T. porrifolius was collected from Tyre, South Lebanon, during May and June 2011. The plant was initially identified by Dr. Ahmad Houri, a Lebanese plant expert and further confirmed according to descriptions reported by Chevallier (1996). Aerial parts were airdried in shadow, powdered and soaked in preboiled water with occasional stirring for 30 min. The aqueous extract was then filtered, lyophilized and stored in a well-sealed dry box at 4 °C.
HPLC analysis of the T. porrifolius aqueous extract The analysis of phenolic acids and flavonoids was performed on a Shimadzo HPLC system (Shimadzu Corp., Kyoto, Japan) consisting of LC 10-ADVP pump, SCL 10A system controller coupled with a photo-diode array detector (SPD-M20A), FCV-10AL Low Pressure Gradient, Rheodyne injector (Model 7125), DGU-20A online degasser, Shim-pack VP-ODS column, 4.6 mm i.d. 150 mm), Pre-column (10 4.6 mm i.d. 5 lm) equipped with LC solution 1.23 SP1 software (Shimadzu, Kyoto, Japan). The column was operated at 25 °C. The mobile phase consisted of 10:2:88-water:acetic acid:methanol v/v (solvent A) and 90:2:8-water:acetic acid: methanol v/v (solvent B) at a flow rate of 1.5 ml/min. The gradient elution program was as follows: 0–15 min solvent A, 15–30 min solvent B followed by washout period for 10 min and the wavelength of detection was set at 280 nm. The phenolic acids and flavonoids were identified by matching the retention time and their spectral characteristics with those of the standard compounds. All phenolic acids and flavonoid standards (gallic acid, chlorogenic acid, vanillic acid, Syringic acid, caffeic acid, ellagic acid, ferulic acid, myricetin, quercetin, luteolin, kampferol, apigenin) were purchased from Sigma–Aldrich Co. (St. Louis, MO, USA). All HPLC solvents were purchased from Merck (Germany). The standard stock solutions (0.2 mg/ml) were prepared by dissolving each
standard in methanol and diluted with the mobile phase in the range 10–60 lg/ml. Study 1 Animals and diets Sixty-four adult male Sprague–Dawley rats (Lebanese American University Stock) aged initially 8–10 weeks were housed in a temperature and humidity-controlled room under a 12:12 light/dark cycle (lights on at 0800 h). The rats were allocated into 8 weightmatched groups of 8 rats each. Animals received the aqueous extract via drinking water in one of 3 doses (50, 100, or 250 mg/ kg bodyweight) based on the assumption that each rat consumes 10 ml/100 g of body weight (Waynforth & Flecknell, 1992). The control groups were not provided with any extract. Animals were fed either a standard high-carbohydrate (HC) diet or a high-fat diet (HF) (Table 1). The HF diet consists of the HC diet enriched with 10% coconut oil. The diets were given ad libitum for 4 weeks and food intake as well as body weight gain were monitored three times a week during the whole experimental period. Food intake, corrected for spillage, was recorded at 8 am by measuring the difference in food cup weight before and after presentation to the rats. All experimental protocols were approved by the Animal Ethical subcommittee of the Lebanese American University, which complies with Guide for the Care and Use of Laboratory Animals (National Research Council., 2011). Body composition At the end of the 4th week, blood samples were collected from the inferior vena cava of anesthetized fasted (overnight) rats. Following sacrifice by exsanguination, the intra-abdominal fat (epididymal, mesenteric and retroperitoneal) and the liver were removed from animals, after which they were cleaned, blotted on a filter paper then weighed. Blood analysis Serum was separated by centrifugation at 2000g for 15 min and stored at 80 °C for subsequent analysis. Serum lipids (total cholesterol, HDL cholesterol, LDL cholesterol and triglycerides) and liver enzyme activities of aspartate transaminase (AST), alanine transaminase (ALT) and lactate dehydrogenase (LDH) were determined using the relevant Spinreact kits (Spinreact, Spain). All serum samples were run in duplicate and analyzed within the same assay. Table 1 Nutrient composition of the HC and HF diets.
Protein (% wt) Carbohydrates (% wt) Fat (% wt) Fat breakdown Saturated fat MUFA PUFA Fiber (% wt) Metabolizable energy (kJ/g) Energy (protein) Energy (carbohydrate) Energy (fat)
High carbohydrate (HC)*
High fat (HF)**
19 65.3 9.6
17.1 58.8 19.6
18% 29% 47% 4.3 17.7 18% 70% 20%
57% 16% 23% 3.9 19.9 14% 50% 36%
MUFA: mono-unsaturated fatty acids PUFA: poly-unsaturated fatty acids * Laboratory rodent starter diet No. 1, Hawa Chicken Co., Safra, Lebanon. ** HC diet enriched with 10% coconut oil.
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Stool analysis During the last week of extract treatment, fresh stool samples were collected from all rats in order to determine triglyceride and cholesterol content as described previously by Daher, Baroody, and Howland (2003). Briefly, fresh stool samples from each rat were collected and dried overnight at 60 °C in the oven. Dry powdered samples of similar masses were subjected to lipid extraction in 2 ml hexane at 40 °C for 2 h with continuous agitation. After centrifugation (20 min; 5000g), 200 lL from the supernatant were transferred into clean test tubes, hexane evaporated, and TAG and cholesterol were determined using TAG and cholesterol kits respectively (Spinreact, Spain). Study 2 Thirty-two adult male Sprague–Dawley rats (Lebanese American University Stock) aged initially 8–10 weeks were used. Animals were fasted from food and water overnight and allocated into 4 weight-matched groups of 8 rats each. Rats were then given a preload of standard HC food (same as above) to be fully consumed and were provided with plain water or water containing the T. porrifolius extract in one of the 3 doses (50, 100, or 250 mg/kg bodyweight). After 1 h, a known pre-weighed food sample was given and food consumption was measured at 1, 6 and 24 h postloading. This one-day experiment was repeated 3 times with a one-week interval in between and the groups were crossed-over. Statistical analysis Dietary intake was analyzed separately using a three-way repeated measures ANOVA with treatment (Tragopogon versus Control) and diet (HC versus HF) as the between-subject factors
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and time as the within-subjects factor. Data of body weight gain, blood lipids, liver enzymes, liver weight, and abdominal fat weight were analyzed using a two-way ANOVA with treatment (Tragopogon versus Control) and diet (HC versus HF) as the main effects. Descriptive data are presented as means ± SEM. Significant main effect differences were tested using Tukey–Kramer’s post hoc test for multiple comparisons. All data were analyzed with the statistical package SPSS 18 and statistical significance was defined as P 6 0.05. Results HPLC analysis The T. porrifolius aqueous extract was subjected to HPLC analysis against a standard mixture of phenolic acids and the results are displayed in Fig. 1. The HPLC chromatogram showed several peaks and two of the peaks (numbers 2 and 5, Fig. 1B), were identified as chlorogenic acid and caffeic acid based on their retention time and UV spectra. The percentage of chlorogenic acid and caffeic acid were 24.87 and 19.25 lg/mg of extract, respectively. Study 1 Body weight and food intake There was a significant effect of T. porrifolius extract treatment on the energy intake of the rats (p = 0.014) (Fig. 2). For example, animals given the plant extract had a lower energy intake than animals given plain water both in standard HC and in HF dietary conditions. Body weight gain was significantly affected by extract treatment (p < 0.001). More specifically, rats given 100 mg/kg or
Fig. 1. (A) HPLC chromatogram of a standard mixture of phenolic acids. Peaks: 1 = gallic acid; 2 = chlorogenic acid; 3 = vanillic acid; 4 = syringic acid; 5 = caffeic acid; 6 = ellagic acid; 7 = myricetin; 8 = quercetin; 9 = luteolin; 10 = kaempferol; 11 = apigenin. (B) HPLC chromatogram of Tragopogon porrifolius aqueous extract.
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Fig. 2. Weekly energy intake (kJ/100 g) of rats fed a high-carbohydrate (A) or highfat diet (B) and either provided with plain water or with T. porrifolius water extract. Data are expressed as mean ± SEM. P < 0.05 is considered significant.
Fig. 3. Body weight gain (A) and abdominal fat (B) after 4 weeks in rats fed a standard chow or high-fat diet and either provided with regular water or with T. porrifolius water extract. Data are expressed as the mean ± SEM. P < 0.05 is considered significant.
250 mg/kg of the plant extract had significantly lower body weight gain than the animals given plain water (p < 0.001 for both comparisons) or the plant extract in its lowest dose (p = 0.006 and p < 0.001). The body weight gain of the HF-fed animals was higher than the weight gain of the HC-fed animals but the difference did not reach significance (p = 0.128) (Fig. 3A).
significantly higher than the levels of animals receiving 50 mg/ kg, 100 mg/kg, and 250 mg/kg body weight of the T. porrifolius extract both in the high-carbohydrate and high-fat groups. However, there was no significant interaction between diet and treatment (Table 2). LDL cholesterol levels were significantly affected by both diet (p < 0.001) and treatment (p = 0.001). LDL cholesterol was higher in HF compared to HC-fed animals. In addition, animals drinking plain water had significantly higher LDL levels compared to those receiving 50 mg/kg (p = 0.003), 100 mg/kg (p = 0.018) or 250 mg/ kg (p = 0.009) of the plant extract. There was no significant interaction of diet and treatment with LDL levels (Table 2). HDL cholesterol levels were also significantly affected by both diet (p < 0.001) and treatment (p = 0.015). Animals receiving 250 mg/kg of the plant extract had significantly higher HDL levels compared to those drinking plain water (p = 0.015). In addition HDL cholesterol was higher in HF compared to HC-fed animals. There was no significant interaction of diet with treatment regarding HDL cholesterol levels (Table 2). Serum triglyceride levels were also affected by diet (p = 0.006) and treatment (p = 0.001). Triglycerides were higher in HF compared to HC-fed rats. Also, T. porrifolius treatment decreased the triglyceride levels in animals receiving either HC or HF diets. However, while significance was reached at all doses in the highfat fed animals, it was only reached at 50 mg/kg in the animals fed the HC diet.
Abdominal fat A significant interaction between diet and treatment (p = 0.047) was observed regarding the intra-abdominal fat percentage of the rats. The intra-abdominal fat percentage was significantly higher in rats given the high-fat diet (0.89 ± 0.05% of body weight) compared to the standard HC diet (0.65 ± 0.05% of body weight). Also, intraabdominal fat was lower in rats given 100 mg/kg extract (0.65 ± 0.07% of body weight) and 250 mg/kg (0.68 ± 0.07% of body weight) compared to those drinking plain water (0.96 ± 0.07% of body weight) (p = 0.02 and 0.04 respectively). When considering only the HF-fed animals, intra-abdominal fat was significantly affected by treatment (p = 0.005) with lower values in rats given all extract doses compared to those drinking plain water (p = 0.05, p = 0.007, p = 0.012 for 50, 100 and 250 mg/kg respectively) (Fig. 3B). Serum lipids Total serum cholesterol levels were significantly affected by treatment (p < 0.001) as well as diet (p = 0.002). More specifically, animals fed the high-fat diet had significantly higher serum cholesterol levels than animals fed the high carbohydrate diet. Also, cholesterol levels of animals drinking plain water were
Stool lipids Determination of triglyceride content in stools revealed a significant dose-dependent increase with T. porrifolius water extract
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Table 2 Serum lipid parameters for rats fed a standard high-carbohydrate or high-fat diet and either provided with regular water or with T. porrifolius water extract (n = 8). Data are expressed as the mean ± SEM. P < 0.05 was considered significant. Serum lipids (mg/dl)
High-carbohydrate diet Control
Dose 1 50 mg/kg
Dose 2 100 mg/kg
Dose 3 250 mg/kg
Control
High-fat diet Dose 1 50 mg/kg
Dose 2 100 mg/kg
Dose 3 250 mg/kg
Diet
Statistical significance Treatment
Interaction between diet and treatment
Cholesterol Triglycerides LDL HDL LDL/HDL ratio
91.4 ± 7.1 115 ± 5.1 49.6 ± 4.2 18.4 ± 2.4 2.70 ± 0.22
72.6 ± 4.7* 92.7 ± 5.8* 32.2 ± 4.3* 21.8 ± 2.5 1.48 ± 0.17*
67.5 ± 5.7* 101 ± 9.2 23.4 ± 5.5* 23.9 ± 2.8 0.98 ± 0.11*
68.7 ± 6.1* 103 ± 7.9 23.8 ± 4.6* 24.1 ± 2.3* 0.99 ± 0.12*
113 ± 6.8 129 ± 6.1 60.2 ± 4.2 27 ± 2.5 2.23 ± 0.21
86 ± 7.8* 104 ± 7.1* 36.5 ± 5.5* 28.2 ± 2.5 1.29 ± 0.11*
92.1 ± 5.9* 103 ± 6.5* 40.7 ± 6.5 30.8 ± 2.6 1.32 ± 0.12*
92.4 ± 7.3* 107 ± 6.7* 31.3 ± 3.9* 39.2 ± 4.1* 0.80 ± 0.09*
p = 0.002 p = 0.006 p < 0.001 p < 0.001 n.s.s.
p < 0.001 p = 0.001 p = 0.001 p = 0.015 p < 0.001
n.s.s. n.s.s. n.s.s. n.s.s. n.s.s.
n.s.s. non statistically significant (P > 0.05). Statistical difference with regard to the control group having the same diet.
*
Fig. 5. Food intake (kJ) of rats fed a standard chow diet and either provided with regular water or with T. porrifolius water extract in one of three doses (50, 100, or 250 mg/kg bodyweight). Data are expressed as the mean ± SEM. P < 0.05 is considered significant.
Liver weight and liver enzymes There were no effects of treatment and diet on the liver weight of the different animals (p = 0.27 and p = 0.12 respectively). Regarding liver enzyme activities, there was no significant effect of diet. However, AST and ALT as well as the LDH enzyme activity levels in the liver were significantly lower in animals receiving the T. porrifolius extract (at any dose) compared to those given plain water (p < 0.005 at all doses) (Table 3). Study 2 Fig. 4. Stool cholesterol (A) and triglycerides (B) after 4 weeks in rats fed a standard chow or high-fat diet and either provided with regular water or with T. porrifolius water extract. Data are expressed as the mean ± SEM. P < 0.05 is considered significant.
treatment (p < 0.001). This increase was significant at all doses used. A similar dose-dependent significant increase in stool cholesterol content was also observed (p < 0.001). There was no significant effect of diet on cholesterol or triglyceride excretion in stools (Fig. 4).
Food intake decreased dose-dependently reaching significance at 250 mg/kg body weight. More precisely, a significant effect of treatment on food intake was found when comparing the control animals with those receiving 250 mg/kg after 1 h (p = 0.05), 18 h (p = 0.034) and 24 h (p = 0.05) (Fig. 5). Discussion The objective of the current study was to investigate the influence of T. porrifolius administration on rat serum lipid profile, food
Table 3 Effect of T. porrifolius aqueous extract on serum enzymes AST, ALT and LDH in rats fed a standard chow or high-fat diet (n = 8). Data are expressed as the mean ± SEM. Enzymes (U/l)
AST ALT LDH *
P < 0.05.
Regular fat diet
High-fat diet
Control
Dose 1 50 mg/kg
Dose 2 100 mg/kg
Dose 3 250 mg/kg
Control
Dose 1 50 mg/kg
Dose 2 100 mg/kg
Dose 3 250 mg/kg
27.6 ± 1.9 30.6 ± 1.3 28.3 ± 1.4
18.6 ± 0.9* 21.2 ± 1.2* 26.2 ± 1.3*
14.7 ± 0.9* 17.7 ± 1.1* 24.1 ± 1.3*
10.9 ± 1.1* 13.9 ± 1.3* 22 ± 2.1*
29.3 ± 2.5 31.2 ± 1.9 31.1 ± 1.5
22.1 ± 2.1* 24.2 ± 1.8* 25 ± 1.2*
21.2 ± 1.8* 23.1 ± 1.4* 24.1 ± 1.5*
19.2 ± 1.6* 21.3 ± 2.1* 20.8 ± 2.4*
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intake and body composition. Results showed improved lipid profiles associated with all doses of T. porrifolius administered during the 4-week period. Moreover, the plant extract caused a significant decrease in food intake both with the long and short term treatments. Similar to previous findings (Huang, Chiang, Yao, & Chiang, 2004; Kimball, Childs, Applebaum-Bowden, & Sembrowich, 1983; Narayan & Calhoun, 1976), HF-fed animals exhibited higher total and LDL cholesterol than the other animals. In addition, chronic T. Porrifolius extract intake significantly decreased total and LDL cholesterol, and increased HDL cholesterol levels. Also, there was a decrease in triglyceride levels with doses of 50 and 100 mg/kg body weight in animals fed the HF diet. Calculation of the LDL/ HDL revealed a great improvement associated with the chronic extract intake with maximum decrease observed with the highest dose. An improvement in the LDL/HDL ratio suggests that the plant has a potential cardio-protective effect. The lipid-lowering effect of the plant extract may be partly attributed to its FOS content, which was shown to lower triglycerides, phospholipids and cholesterol in rat serum through decreased synthesis in the liver (Fiordaliso, Kok, Desager, et al., 1995; Williams, 1999). Apart from FOS, chlorogenic acid and caffeic acid may also play a role in the decrease in lipemia. Indeed, a recent study investigating the efficacy of chlorogenic and caffeic acid supplementation (at 0.02% wt/wt) in mice with diet-induced obesity found that both components significantly lowered body weight and visceral fat mass. Chlorogenic acid also lowered TG (in plasma, liver and heart) and cholesterol (in plasma, adipose tissue and heart) concentrations (Cho et al., 2010). Furthermore, it was shown that a 3-week chlorogenic acid intravenous infusion (5 mg/kg body weight/day) resulted in a significant decrease in fasting plasma cholesterol and TGs in rats (de Sotillo & Hadley, 2002). In the present study, it was evident that T. porrifolius extract enhanced TG and cholesterol excretion in the stools which could partially explain the improved effects on lipemia. In study 1, animals fed the high fat diet had higher body weight gain and intra-abdominal fat compared to the other dietary group. These results are in agreement with the literature showing that body weight and fat depot, particularly intra-abdominal fat increases with the consumption of a high fat diet in rats (Huang et al., 2004; Narayan & Calhoun, 1976). Body weight gain and energy intake were also lower in the animals given the 100 mg/kg and the 250 mg/kg water extracts compared to those without plant treatment. The plant extract therefore reduces body weight and long term food intake both with a normal and a high-fat diet. Also, there was a significant interaction effect of diet and treatment on intra-abdominal fat. T. porrifolius seems to have a more pronounced body-fat lowering effect in high-fat dietary conditions which mimic the everyday intake in the Western diet. This marked effect in high-fat diet conditions is interesting especially in the context of a global increase in the consumption of calorically-dense nutrient-poor diets. In study 2, rats given the 250 mg/kg body weight T. porrifolius extract exhibited lower energy intake than control animals at 1, 18 and 24 h after being given the pre-weighed food sample. These results revealed a short-term satiety effect induced by the plant extract intake. The mechanism through which T. porrifolius reduces food intake and leads to lower body weight gain and intra-abdominal fat could be attributed to its FOS and chlorogenic acid contents. FOS are considered as small dietary fibers with low caloric value, and are thought to have a role in increasing satiety. They have a prebiotic effect and serve as a substrate for microflora in the large intestine, increasing the overall gastrointestinal tract (GI Tract) health (Le Blay, Michel, Blottière, & Cherbut, 2003). Fiber intake is associated with increased satiety and lower body weight through
increased gastrointestinal viscosity (Burton-Freeman, 2000; Howarth, Saltzman, & Roberts, 2001). Recently, FOS was shown to cause a decrease in food intake in women (Hess, Birkett, Thomas, & Slavin, 2011), and to suppress high-fat diet-induced fat accumulation in mice (Nakamura, Natsume, Yasuda, et al., 2011). Similarly, human intake of instant coffee enriched with chlorogenic acid induced a reduction in body fat and body mass, an effect that was partly attributed to a reduction in glucose absorption (Thom, 2007). Liver weight measurements have long been regarded as useful indices of stress in safety evaluation. In evaluating relative liver weight increases, it has been clear for some time that such increases may represent a stress response to high intake levels of a foreign compound (Gilbert & Golberg, 1965). In the present study, liver weight remained unchanged with the plant extract at all doses. Also T. porrifolius extracts did not increase the activity of liver enzymes tested (AST, ALT and LDH), but on the contrary, a reduced activity of these enzymes was noted suggesting a hepato-protective effect. In conclusion, the present study showed that T. porrifolius water extract has potential benefits on lipemia and satiety with no visible adverse effects. FOS, caffeic acid and chlorogenic acid present in the plant could be responsible for the aforementioned activities. However, the effects obtained may not necessarily be due or restricted to these components as herbs often contain families of compounds that interact with each other (Thomson Healthcare., 2007). These findings provide new evidence that edible wild plants such as T. porrifolius could become a useful tool for specialists dealing with problems of obesity and its co-morbidities. Further experiments examining the effects of the extract on a Mediterraneantype diet that is high in unsaturated fatty acids and low in saturated fatty acids could be undertaken in the near future.
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N. Zeeni et al. / Appetite 72 (2014) 1–7 Folsom, A. R., Kaye, S. A., Potter, J. D., & Prineas, R. J. (1989). Association of incident carcinoma of the endometrium with body weight and fat distribution in older women. Early findings of the Iowa Women’s Health Study. Cancer Research, 49, 6828–6831. Formisano, C., Rigano, D., Senatore, F., et al. (2010). Volatile constituents of the aerial parts of white salsify (Tragopogon porrifolius L., Asteraceae). Natural Product Research, 24(7), 663–668. Gilbert, D., & Golberg, L. (1965). Liver response tests. III. Liver enlargement and stimulation of microsomal processing activity. Food and Cosmetics Toxicology, 3, 417–432. Graham, I., Atar, D., Borch-Johnsen, K., et al. (2007). European guidelines on cardiovascular disease prevention in clinical practice. Executive summary. Fourth Joint Task Force of the European Society of Cardiology and other societies on cardiovascular disease prevention in clinical practice. European Journal of Cardiovascular Prevention Rehabilitation, 14(Suppl. 2), E1–E40. Gupta, K., Talwar, G., Jain, V., et al. (2003). Salad crops: root, bulb, and tuber crops. Encyclopaedia of Food Science and Nutrition. London: Academic Press (pp. 5060–5073). . Harchaoui, K. E., Visser, M. E., Kastelein, J. J., et al. (2009). Triglycerides and cardiovascular risk. Current Cardiology Reviews, 5, 216–222. Hess, J. R., Birkett, A. M., Thomas, W., & Slavin, J. L. (2011). Effects of short-chain fructooligosaccharides on satiety responses in healthy men and women. Appetite, 56(1), 128–134. Howarth, N. C., Saltzman, E., & Roberts, S. B. (2001). Dietary fiber and weight regulation. Nutrition Reviews, 59(5), 129–139. Huang, B. W., Chiang, M. T., Yao, H. T., & Chiang, W. (2004). The effect of high-fat and high-fructose diets on glucose tolerance and plasma lipid and leptin levels in rats. Diabetes, Obesity & Metabolism, 6(2), 120–126. Hurt, R. T., Frazier, T. H., McClave, S. A., & Kaplan, L. M. (2011). Obesity epidemic. Overview, pathophysiology, and the intensive care unit conundrum. JPEN. Journal of Parenteral and Enteral Nutrition, 35(5 Suppl.), 4S–13S. Kannel, W. B., & Vasan, R. S. (2009). Triglycerides as vascular risk factors. New epidemiologic insights. Current Opinion in Cardiology, 24, 345–350. Kimball, T. J., Childs, M. T., Applebaum-Bowden, D., & Sembrowich, W. L. (1983). The effect of training and diet on lipoprotein cholesterol, tissue lipoprotein lipase and hepatic triglyceride lipase in rats. Metabolism, 32(5), 497–503. Konopinski, M. (2009). Influence of intercrop plants and varied tillage on yields and nutritional value of salsify (Tragopogon porrifolius L.) roots. Acta Scientiarum Polonorum, 8(2), 27–36. Le Blay, G. M., Michel, C. D., Blottière, H. M., & Cherbut, C. J. (2003). Raw potato starch and short-chain fructo-oligosaccharides affect the composition and metabolic activity of rat intestinal microbiota differently depending on the caecocolonic segment involved. Journal of Applied Microbiology, 94(2), 312–320. Lee, I. M., & Paffenbarger, R. S. Jr., (1992). Quetelet’s index and risk of colon cancer in college alumni. Journal of the National Cancer Institute, 84, 1326–1331.
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Nakamura, Y., Natsume, M., Yasuda, A., et al. (2011). Fructooligosaccharides suppress high-fat diet-induced fat accumulation in C57BL/6J mice. BioFactors. http://dx.doi.org/10.1002/biof.14. Narayan, K. A., & Calhoun, W. K. (1976). The influence of some dietary factors and/or treadmill exercise on rat and chicken tissue lipids and serum lipoproteins. Advances in Experimental Medicine and Biology, 67, 383–401. National Research Council. (2011). Guide for the Use and Care of Laboratory Animals. Publication, 8th ed. NIH, Washington. Riu-Aumatell, M., Vargas, L., Vichi, S., et al. (2011). Characterization of volatile composition of white salsify (Tragopogon porrifolius L.) by headspace solidphase microextraction (HS-SPME) and simultaneous distillation-extraction (SDE) coupled to GC-MS. Food Chemistry, 129, 557–567. Rosenbaum, M., Kissileff, H. R., Mayer, L. E., et al. (2010). Energy intake in weightreduced humans. Brain Research, 1350, 95–102. Sareedenchai, V., Ganzera, M., Ellmerer, E. P., et al. (2009). Phenolic compounds from Tragopogon porrifolius L.. Biochemical Systematics and Ecology, 37, 234–236. Sellers, T. A., Kushi, L. H., Potter, J. D., et al. (1992). Effect of family history, body-fat distribution, and reproductive factors on the risk of postmenopausal breast cancer. New England Journal of Medicine, 326, 1323–1329. Spina, M., Cuccioloni, M., Sparapani, L., et al. (2007). Comparative evaluation of flavonoid content in assessing quality of wild and cultivated vegetables for human consumption. Journal of the Science of Food and Agriculture, 88, 294–304. Swinburn, B. A., Sacks, G., Hall, K. D., et al. (2011). The global obesity pandemic. Shaped by global drivers and local environments. Lancet, 378(9793), 804–814. Thom, E. (2007). The effect of chlorogenic acid enriched coffee on glucose absorption in healthy volunteers and its effect on body mass when used longterm in overweight and obese people. Journal of International Medical Research, 35, 900–908. Thomson Healthcare. (2007). Physician Desk Reference (PDR) for Herbal Medicine (4th ed). Thomson Reuters. Warashina, T., Miyase, T., & Ueno, A. (1991). Novel acylated saponins from Tragopogon porrifolius. Isolation and the structures of tragopogonsaponins. A-R Chemical & Pharmaceutical Bulletin, 39, 388–396. Waynforth, H. B., & Flecknell, P. A. (1992). Experimental and surgical technique in the rat. London: Academic Press (pp. 168–173). Williams, C. M. (1999). Effects of inulin on lipid parameters in humans. Journal of Nutrition, 129(7 Suppl.). 1471S-3S. Withrow, D., & Alter, D. A. (2011). The economic burden of obesity worldwide. A systematic review of the direct costs of obesity. Obesity Reviews, 12(2), 131–141. World Health Organization. (2009). Global health risks. Mortality and burden of disease attributable to selected major risks. Geneva: World Health Organization. Zidorn, C., Lohwasser, U., Pschorr, S., et al. (2005). Bibenzyls and dihydroisocoumarins from white salsify (Tragopogon porrifolius subsp. porrifolius). Phytochemistry, 66, 1691–1697.
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Research report
Tragopogon porrifolius improves serum lipid profile and increases short-term satiety in rats q Nadine Zeeni a, Costantine F. Daher a,⇑, Lea Saab a, Mohamad Mroueh b a b
Lebanese American University, School of Arts and Sciences, Department of Natural Sciences, PO Box 36, Byblos, Lebanon Lebanese American University, School of Pharmacy, PO Box 36, Byblos, Lebanon
a r t i c l e
i n f o
Article history: Received 19 July 2013 Received in revised form 21 September 2013 Accepted 23 September 2013 Available online 4 October 2013 Keywords: Tragopogon porrifolius Satiety High-fat diet Cholesterol Lipid profile
a b s t r a c t Tragopogon porrifolius (white salsify) is an edible plant commonly used in folk medicine in Lebanon and neighbouring countries. This study investigates the effect of the aqueous extract of the aerial part of T. porrifolius on lipemia and appetite regulation using a rat model. Food intake, abdominal fat percentage, blood lipid profile, liver weight and liver enzymes were assessed following 4 weeks of extract intake via drinking water (50, 100, or 250 mg/kg body weight) in standard high-carbohydrate and high-fat dietary conditions. In a separate study, the short term effect of a preload of T. porrifolius extract on food intake was evaluated. Results showed that consumption of the plant extract for a period of four weeks resulted in a marked improvement of the lipid profile (triglycerides, total cholesterol, LDL and HDL cholesterol). Body weight, food intake and intra-abdominal fat were also lower in animals given the plant extract (100 and 250 mg/kg). In addition, T. porrifolius extract preload produced a dose dependent decrease in food intake observed over 24 h. The intake of T. porrifolius aqueous extract therefore improved lipemia and increased satiety in rats with no visible adverse effects. Ó 2013 Elsevier Ltd. All rights reserved.
Introduction Human obesity is a growing global epidemic. It increases the risk of coronary heart disease, hypertension, stroke, diabetes and certain cancers (Ezzati, Lopez, Rodgers, Murray, et al., 2004; Folsom et al., 1989; Lee and Paffenbarger, 1992; Sellers, Kushi, Potter, et al., 1992; World Health Organization, 2009). According to the World Health Organization (World Health Organization, 2009), the incidence of obesity worldwide has more than doubled in the past 30 years. Global estimates from 2008 revealed that 1.5 billion adults were overweight, of which 500 million were obese. Obesity and its related health problems impose a significant economic burden not only on obese people but also on the rest of society. For example, in the United States alone, about 10% ($147 billion) of the annual US health care budget is spent on obesity due to increased need for medical care and the loss of economic productivity (Finkelstein, Trogdon, Cohen, & Dietz, 2009; Withrow & Alter, 2011). The rise in obesity incidence throughout many countries seems to be driven mainly by changes in the global food system which is producing and effectively marketing more cheap energy-dense processed foods (Hurt, Frazier, McClave, & Kaplan, 2011; Swinburn, Sacks, Hall, et al., 2011). Normally, increases in q
Conflict of interest: The authors report no conflicts of interest.
⇑ Corresponding author.
E-mail address: [email protected] (C.F. Daher). 0195-6663/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.appet.2013.09.023
the consumption of refined fats and carbohydrates are accompanied by a loss of diversity in diet composition leading to the loss of vegetable and herb benefits. While they are not always parallel, obesity is often accompanied by hyperlipidemia. The metabolic features of obese people include increased serum total cholesterol, triglycerides and LDL cholesterol which are proven risk factors for cardiovascular disease (Di Angelantonio et al., 2009; Harchaoui, Visser, Kastelein, et al., 2009; Kannel & Vasan, 2009). Indeed, treatment of hyperlipidemia is a primary approach in cardiovascular disease prevention (Baigent et al., 2010; Graham, Atar, Borch-Johnsen, et al., 2007). Therefore, it is important to identify and promote natural functional foods that can help manage weight and hyperlipidemia in this obesogenic environment. Satiety is an internal state that leads to termination of eating under normal physiological conditions. Increased appetite, due to impaired central mechanisms regulating food intake, could cause obesity (Astrup & Raben, 1992; Rosenbaum, Kissileff, Mayer, et al., 2010). Recent efforts have been made to identify various methods that help limit food intake, among which is increasing the satiating power of foods. Tragopogon porrifolius, family Asteraceae, is an annual or biennial herb indigenous to the Middle East as well as Asia Minor. Its roots, leafy shoots and open flowers are used both cooked and raw (as a salad) (Gupta, Talwar, Jain, et al., 2003). While both roots and shoots are edible, in Lebanon, the shoots are more frequently
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N. Zeeni et al. / Appetite 72 (2014) 1–7
consumed than the roots. T. porrifolius is commonly used in folk medicine in Lebanon and neighbouring countries. It has been reported to possess antibilious, diuretic and laxative effects (Formisano et al., 2010; Spina, Cuccioloni, Sparapani, et al., 2007). Phytochemical analysis of T. porrifolius revealed the presence of acylated pentacyclic triterpene saponins (Warashina, Miyase, & Ueno, 1991), flavonoids, and different types of bibenzyls and dihydroisocoumarins (Sareedenchai et al., 2009; Zidorn, Lohwasser, Pschorr, et al., 2005). The nutritional value of this plant has been attributed to its monounsaturated and essential fatty acids, vitamins, polyphenols, and fructo-oligosaccharides (FOS) components (Formisano, Rigano, Senatore, et al., 2010; Konopinski, 2009). In fact, the FOS content, which is estimated to be 4–11% (Beirao-da-costa, Januario, Leitao, & Simao, 2005; Konopinski, 2009; Riu-Aumatell, Vargas, Vichi, et al., 2011) was behind its use in a human study to supplement baby food (Flickinger, Hatch, Wofford, et al., 2002). To the best of our knowledge, no studies were conducted on the effects of T. porrifolius on lipemia and food intake. Therefore, the primary objective of this study was to evaluate the effects of T. porrifolius water extract intake on blood lipid profile and the eating behavior of rats. We used a 4-week model in which rats were given the extract via drinking water (at doses of 50, 100, or 250 mg/kg body weight) with a standard high-carbohydrate or a high-fat diet. The secondary objective was to assess the short term effects of T. porrifolius water extract on food intake.
Materials and methods Plant collection and extraction T. porrifolius was collected from Tyre, South Lebanon, during May and June 2011. The plant was initially identified by Dr. Ahmad Houri, a Lebanese plant expert and further confirmed according to descriptions reported by Chevallier (1996). Aerial parts were airdried in shadow, powdered and soaked in preboiled water with occasional stirring for 30 min. The aqueous extract was then filtered, lyophilized and stored in a well-sealed dry box at 4 °C.
HPLC analysis of the T. porrifolius aqueous extract The analysis of phenolic acids and flavonoids was performed on a Shimadzo HPLC system (Shimadzu Corp., Kyoto, Japan) consisting of LC 10-ADVP pump, SCL 10A system controller coupled with a photo-diode array detector (SPD-M20A), FCV-10AL Low Pressure Gradient, Rheodyne injector (Model 7125), DGU-20A online degasser, Shim-pack VP-ODS column, 4.6 mm i.d. 150 mm), Pre-column (10 4.6 mm i.d. 5 lm) equipped with LC solution 1.23 SP1 software (Shimadzu, Kyoto, Japan). The column was operated at 25 °C. The mobile phase consisted of 10:2:88-water:acetic acid:methanol v/v (solvent A) and 90:2:8-water:acetic acid: methanol v/v (solvent B) at a flow rate of 1.5 ml/min. The gradient elution program was as follows: 0–15 min solvent A, 15–30 min solvent B followed by washout period for 10 min and the wavelength of detection was set at 280 nm. The phenolic acids and flavonoids were identified by matching the retention time and their spectral characteristics with those of the standard compounds. All phenolic acids and flavonoid standards (gallic acid, chlorogenic acid, vanillic acid, Syringic acid, caffeic acid, ellagic acid, ferulic acid, myricetin, quercetin, luteolin, kampferol, apigenin) were purchased from Sigma–Aldrich Co. (St. Louis, MO, USA). All HPLC solvents were purchased from Merck (Germany). The standard stock solutions (0.2 mg/ml) were prepared by dissolving each
standard in methanol and diluted with the mobile phase in the range 10–60 lg/ml. Study 1 Animals and diets Sixty-four adult male Sprague–Dawley rats (Lebanese American University Stock) aged initially 8–10 weeks were housed in a temperature and humidity-controlled room under a 12:12 light/dark cycle (lights on at 0800 h). The rats were allocated into 8 weightmatched groups of 8 rats each. Animals received the aqueous extract via drinking water in one of 3 doses (50, 100, or 250 mg/ kg bodyweight) based on the assumption that each rat consumes 10 ml/100 g of body weight (Waynforth & Flecknell, 1992). The control groups were not provided with any extract. Animals were fed either a standard high-carbohydrate (HC) diet or a high-fat diet (HF) (Table 1). The HF diet consists of the HC diet enriched with 10% coconut oil. The diets were given ad libitum for 4 weeks and food intake as well as body weight gain were monitored three times a week during the whole experimental period. Food intake, corrected for spillage, was recorded at 8 am by measuring the difference in food cup weight before and after presentation to the rats. All experimental protocols were approved by the Animal Ethical subcommittee of the Lebanese American University, which complies with Guide for the Care and Use of Laboratory Animals (National Research Council., 2011). Body composition At the end of the 4th week, blood samples were collected from the inferior vena cava of anesthetized fasted (overnight) rats. Following sacrifice by exsanguination, the intra-abdominal fat (epididymal, mesenteric and retroperitoneal) and the liver were removed from animals, after which they were cleaned, blotted on a filter paper then weighed. Blood analysis Serum was separated by centrifugation at 2000g for 15 min and stored at 80 °C for subsequent analysis. Serum lipids (total cholesterol, HDL cholesterol, LDL cholesterol and triglycerides) and liver enzyme activities of aspartate transaminase (AST), alanine transaminase (ALT) and lactate dehydrogenase (LDH) were determined using the relevant Spinreact kits (Spinreact, Spain). All serum samples were run in duplicate and analyzed within the same assay. Table 1 Nutrient composition of the HC and HF diets.
Protein (% wt) Carbohydrates (% wt) Fat (% wt) Fat breakdown Saturated fat MUFA PUFA Fiber (% wt) Metabolizable energy (kJ/g) Energy (protein) Energy (carbohydrate) Energy (fat)
High carbohydrate (HC)*
High fat (HF)**
19 65.3 9.6
17.1 58.8 19.6
18% 29% 47% 4.3 17.7 18% 70% 20%
57% 16% 23% 3.9 19.9 14% 50% 36%
MUFA: mono-unsaturated fatty acids PUFA: poly-unsaturated fatty acids * Laboratory rodent starter diet No. 1, Hawa Chicken Co., Safra, Lebanon. ** HC diet enriched with 10% coconut oil.
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Stool analysis During the last week of extract treatment, fresh stool samples were collected from all rats in order to determine triglyceride and cholesterol content as described previously by Daher, Baroody, and Howland (2003). Briefly, fresh stool samples from each rat were collected and dried overnight at 60 °C in the oven. Dry powdered samples of similar masses were subjected to lipid extraction in 2 ml hexane at 40 °C for 2 h with continuous agitation. After centrifugation (20 min; 5000g), 200 lL from the supernatant were transferred into clean test tubes, hexane evaporated, and TAG and cholesterol were determined using TAG and cholesterol kits respectively (Spinreact, Spain). Study 2 Thirty-two adult male Sprague–Dawley rats (Lebanese American University Stock) aged initially 8–10 weeks were used. Animals were fasted from food and water overnight and allocated into 4 weight-matched groups of 8 rats each. Rats were then given a preload of standard HC food (same as above) to be fully consumed and were provided with plain water or water containing the T. porrifolius extract in one of the 3 doses (50, 100, or 250 mg/kg bodyweight). After 1 h, a known pre-weighed food sample was given and food consumption was measured at 1, 6 and 24 h postloading. This one-day experiment was repeated 3 times with a one-week interval in between and the groups were crossed-over. Statistical analysis Dietary intake was analyzed separately using a three-way repeated measures ANOVA with treatment (Tragopogon versus Control) and diet (HC versus HF) as the between-subject factors
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and time as the within-subjects factor. Data of body weight gain, blood lipids, liver enzymes, liver weight, and abdominal fat weight were analyzed using a two-way ANOVA with treatment (Tragopogon versus Control) and diet (HC versus HF) as the main effects. Descriptive data are presented as means ± SEM. Significant main effect differences were tested using Tukey–Kramer’s post hoc test for multiple comparisons. All data were analyzed with the statistical package SPSS 18 and statistical significance was defined as P 6 0.05. Results HPLC analysis The T. porrifolius aqueous extract was subjected to HPLC analysis against a standard mixture of phenolic acids and the results are displayed in Fig. 1. The HPLC chromatogram showed several peaks and two of the peaks (numbers 2 and 5, Fig. 1B), were identified as chlorogenic acid and caffeic acid based on their retention time and UV spectra. The percentage of chlorogenic acid and caffeic acid were 24.87 and 19.25 lg/mg of extract, respectively. Study 1 Body weight and food intake There was a significant effect of T. porrifolius extract treatment on the energy intake of the rats (p = 0.014) (Fig. 2). For example, animals given the plant extract had a lower energy intake than animals given plain water both in standard HC and in HF dietary conditions. Body weight gain was significantly affected by extract treatment (p < 0.001). More specifically, rats given 100 mg/kg or
Fig. 1. (A) HPLC chromatogram of a standard mixture of phenolic acids. Peaks: 1 = gallic acid; 2 = chlorogenic acid; 3 = vanillic acid; 4 = syringic acid; 5 = caffeic acid; 6 = ellagic acid; 7 = myricetin; 8 = quercetin; 9 = luteolin; 10 = kaempferol; 11 = apigenin. (B) HPLC chromatogram of Tragopogon porrifolius aqueous extract.
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Fig. 2. Weekly energy intake (kJ/100 g) of rats fed a high-carbohydrate (A) or highfat diet (B) and either provided with plain water or with T. porrifolius water extract. Data are expressed as mean ± SEM. P < 0.05 is considered significant.
Fig. 3. Body weight gain (A) and abdominal fat (B) after 4 weeks in rats fed a standard chow or high-fat diet and either provided with regular water or with T. porrifolius water extract. Data are expressed as the mean ± SEM. P < 0.05 is considered significant.
250 mg/kg of the plant extract had significantly lower body weight gain than the animals given plain water (p < 0.001 for both comparisons) or the plant extract in its lowest dose (p = 0.006 and p < 0.001). The body weight gain of the HF-fed animals was higher than the weight gain of the HC-fed animals but the difference did not reach significance (p = 0.128) (Fig. 3A).
significantly higher than the levels of animals receiving 50 mg/ kg, 100 mg/kg, and 250 mg/kg body weight of the T. porrifolius extract both in the high-carbohydrate and high-fat groups. However, there was no significant interaction between diet and treatment (Table 2). LDL cholesterol levels were significantly affected by both diet (p < 0.001) and treatment (p = 0.001). LDL cholesterol was higher in HF compared to HC-fed animals. In addition, animals drinking plain water had significantly higher LDL levels compared to those receiving 50 mg/kg (p = 0.003), 100 mg/kg (p = 0.018) or 250 mg/ kg (p = 0.009) of the plant extract. There was no significant interaction of diet and treatment with LDL levels (Table 2). HDL cholesterol levels were also significantly affected by both diet (p < 0.001) and treatment (p = 0.015). Animals receiving 250 mg/kg of the plant extract had significantly higher HDL levels compared to those drinking plain water (p = 0.015). In addition HDL cholesterol was higher in HF compared to HC-fed animals. There was no significant interaction of diet with treatment regarding HDL cholesterol levels (Table 2). Serum triglyceride levels were also affected by diet (p = 0.006) and treatment (p = 0.001). Triglycerides were higher in HF compared to HC-fed rats. Also, T. porrifolius treatment decreased the triglyceride levels in animals receiving either HC or HF diets. However, while significance was reached at all doses in the highfat fed animals, it was only reached at 50 mg/kg in the animals fed the HC diet.
Abdominal fat A significant interaction between diet and treatment (p = 0.047) was observed regarding the intra-abdominal fat percentage of the rats. The intra-abdominal fat percentage was significantly higher in rats given the high-fat diet (0.89 ± 0.05% of body weight) compared to the standard HC diet (0.65 ± 0.05% of body weight). Also, intraabdominal fat was lower in rats given 100 mg/kg extract (0.65 ± 0.07% of body weight) and 250 mg/kg (0.68 ± 0.07% of body weight) compared to those drinking plain water (0.96 ± 0.07% of body weight) (p = 0.02 and 0.04 respectively). When considering only the HF-fed animals, intra-abdominal fat was significantly affected by treatment (p = 0.005) with lower values in rats given all extract doses compared to those drinking plain water (p = 0.05, p = 0.007, p = 0.012 for 50, 100 and 250 mg/kg respectively) (Fig. 3B). Serum lipids Total serum cholesterol levels were significantly affected by treatment (p < 0.001) as well as diet (p = 0.002). More specifically, animals fed the high-fat diet had significantly higher serum cholesterol levels than animals fed the high carbohydrate diet. Also, cholesterol levels of animals drinking plain water were
Stool lipids Determination of triglyceride content in stools revealed a significant dose-dependent increase with T. porrifolius water extract
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Table 2 Serum lipid parameters for rats fed a standard high-carbohydrate or high-fat diet and either provided with regular water or with T. porrifolius water extract (n = 8). Data are expressed as the mean ± SEM. P < 0.05 was considered significant. Serum lipids (mg/dl)
High-carbohydrate diet Control
Dose 1 50 mg/kg
Dose 2 100 mg/kg
Dose 3 250 mg/kg
Control
High-fat diet Dose 1 50 mg/kg
Dose 2 100 mg/kg
Dose 3 250 mg/kg
Diet
Statistical significance Treatment
Interaction between diet and treatment
Cholesterol Triglycerides LDL HDL LDL/HDL ratio
91.4 ± 7.1 115 ± 5.1 49.6 ± 4.2 18.4 ± 2.4 2.70 ± 0.22
72.6 ± 4.7* 92.7 ± 5.8* 32.2 ± 4.3* 21.8 ± 2.5 1.48 ± 0.17*
67.5 ± 5.7* 101 ± 9.2 23.4 ± 5.5* 23.9 ± 2.8 0.98 ± 0.11*
68.7 ± 6.1* 103 ± 7.9 23.8 ± 4.6* 24.1 ± 2.3* 0.99 ± 0.12*
113 ± 6.8 129 ± 6.1 60.2 ± 4.2 27 ± 2.5 2.23 ± 0.21
86 ± 7.8* 104 ± 7.1* 36.5 ± 5.5* 28.2 ± 2.5 1.29 ± 0.11*
92.1 ± 5.9* 103 ± 6.5* 40.7 ± 6.5 30.8 ± 2.6 1.32 ± 0.12*
92.4 ± 7.3* 107 ± 6.7* 31.3 ± 3.9* 39.2 ± 4.1* 0.80 ± 0.09*
p = 0.002 p = 0.006 p < 0.001 p < 0.001 n.s.s.
p < 0.001 p = 0.001 p = 0.001 p = 0.015 p < 0.001
n.s.s. n.s.s. n.s.s. n.s.s. n.s.s.
n.s.s. non statistically significant (P > 0.05). Statistical difference with regard to the control group having the same diet.
*
Fig. 5. Food intake (kJ) of rats fed a standard chow diet and either provided with regular water or with T. porrifolius water extract in one of three doses (50, 100, or 250 mg/kg bodyweight). Data are expressed as the mean ± SEM. P < 0.05 is considered significant.
Liver weight and liver enzymes There were no effects of treatment and diet on the liver weight of the different animals (p = 0.27 and p = 0.12 respectively). Regarding liver enzyme activities, there was no significant effect of diet. However, AST and ALT as well as the LDH enzyme activity levels in the liver were significantly lower in animals receiving the T. porrifolius extract (at any dose) compared to those given plain water (p < 0.005 at all doses) (Table 3). Study 2 Fig. 4. Stool cholesterol (A) and triglycerides (B) after 4 weeks in rats fed a standard chow or high-fat diet and either provided with regular water or with T. porrifolius water extract. Data are expressed as the mean ± SEM. P < 0.05 is considered significant.
treatment (p < 0.001). This increase was significant at all doses used. A similar dose-dependent significant increase in stool cholesterol content was also observed (p < 0.001). There was no significant effect of diet on cholesterol or triglyceride excretion in stools (Fig. 4).
Food intake decreased dose-dependently reaching significance at 250 mg/kg body weight. More precisely, a significant effect of treatment on food intake was found when comparing the control animals with those receiving 250 mg/kg after 1 h (p = 0.05), 18 h (p = 0.034) and 24 h (p = 0.05) (Fig. 5). Discussion The objective of the current study was to investigate the influence of T. porrifolius administration on rat serum lipid profile, food
Table 3 Effect of T. porrifolius aqueous extract on serum enzymes AST, ALT and LDH in rats fed a standard chow or high-fat diet (n = 8). Data are expressed as the mean ± SEM. Enzymes (U/l)
AST ALT LDH *
P < 0.05.
Regular fat diet
High-fat diet
Control
Dose 1 50 mg/kg
Dose 2 100 mg/kg
Dose 3 250 mg/kg
Control
Dose 1 50 mg/kg
Dose 2 100 mg/kg
Dose 3 250 mg/kg
27.6 ± 1.9 30.6 ± 1.3 28.3 ± 1.4
18.6 ± 0.9* 21.2 ± 1.2* 26.2 ± 1.3*
14.7 ± 0.9* 17.7 ± 1.1* 24.1 ± 1.3*
10.9 ± 1.1* 13.9 ± 1.3* 22 ± 2.1*
29.3 ± 2.5 31.2 ± 1.9 31.1 ± 1.5
22.1 ± 2.1* 24.2 ± 1.8* 25 ± 1.2*
21.2 ± 1.8* 23.1 ± 1.4* 24.1 ± 1.5*
19.2 ± 1.6* 21.3 ± 2.1* 20.8 ± 2.4*
6
N. Zeeni et al. / Appetite 72 (2014) 1–7
intake and body composition. Results showed improved lipid profiles associated with all doses of T. porrifolius administered during the 4-week period. Moreover, the plant extract caused a significant decrease in food intake both with the long and short term treatments. Similar to previous findings (Huang, Chiang, Yao, & Chiang, 2004; Kimball, Childs, Applebaum-Bowden, & Sembrowich, 1983; Narayan & Calhoun, 1976), HF-fed animals exhibited higher total and LDL cholesterol than the other animals. In addition, chronic T. Porrifolius extract intake significantly decreased total and LDL cholesterol, and increased HDL cholesterol levels. Also, there was a decrease in triglyceride levels with doses of 50 and 100 mg/kg body weight in animals fed the HF diet. Calculation of the LDL/ HDL revealed a great improvement associated with the chronic extract intake with maximum decrease observed with the highest dose. An improvement in the LDL/HDL ratio suggests that the plant has a potential cardio-protective effect. The lipid-lowering effect of the plant extract may be partly attributed to its FOS content, which was shown to lower triglycerides, phospholipids and cholesterol in rat serum through decreased synthesis in the liver (Fiordaliso, Kok, Desager, et al., 1995; Williams, 1999). Apart from FOS, chlorogenic acid and caffeic acid may also play a role in the decrease in lipemia. Indeed, a recent study investigating the efficacy of chlorogenic and caffeic acid supplementation (at 0.02% wt/wt) in mice with diet-induced obesity found that both components significantly lowered body weight and visceral fat mass. Chlorogenic acid also lowered TG (in plasma, liver and heart) and cholesterol (in plasma, adipose tissue and heart) concentrations (Cho et al., 2010). Furthermore, it was shown that a 3-week chlorogenic acid intravenous infusion (5 mg/kg body weight/day) resulted in a significant decrease in fasting plasma cholesterol and TGs in rats (de Sotillo & Hadley, 2002). In the present study, it was evident that T. porrifolius extract enhanced TG and cholesterol excretion in the stools which could partially explain the improved effects on lipemia. In study 1, animals fed the high fat diet had higher body weight gain and intra-abdominal fat compared to the other dietary group. These results are in agreement with the literature showing that body weight and fat depot, particularly intra-abdominal fat increases with the consumption of a high fat diet in rats (Huang et al., 2004; Narayan & Calhoun, 1976). Body weight gain and energy intake were also lower in the animals given the 100 mg/kg and the 250 mg/kg water extracts compared to those without plant treatment. The plant extract therefore reduces body weight and long term food intake both with a normal and a high-fat diet. Also, there was a significant interaction effect of diet and treatment on intra-abdominal fat. T. porrifolius seems to have a more pronounced body-fat lowering effect in high-fat dietary conditions which mimic the everyday intake in the Western diet. This marked effect in high-fat diet conditions is interesting especially in the context of a global increase in the consumption of calorically-dense nutrient-poor diets. In study 2, rats given the 250 mg/kg body weight T. porrifolius extract exhibited lower energy intake than control animals at 1, 18 and 24 h after being given the pre-weighed food sample. These results revealed a short-term satiety effect induced by the plant extract intake. The mechanism through which T. porrifolius reduces food intake and leads to lower body weight gain and intra-abdominal fat could be attributed to its FOS and chlorogenic acid contents. FOS are considered as small dietary fibers with low caloric value, and are thought to have a role in increasing satiety. They have a prebiotic effect and serve as a substrate for microflora in the large intestine, increasing the overall gastrointestinal tract (GI Tract) health (Le Blay, Michel, Blottière, & Cherbut, 2003). Fiber intake is associated with increased satiety and lower body weight through
increased gastrointestinal viscosity (Burton-Freeman, 2000; Howarth, Saltzman, & Roberts, 2001). Recently, FOS was shown to cause a decrease in food intake in women (Hess, Birkett, Thomas, & Slavin, 2011), and to suppress high-fat diet-induced fat accumulation in mice (Nakamura, Natsume, Yasuda, et al., 2011). Similarly, human intake of instant coffee enriched with chlorogenic acid induced a reduction in body fat and body mass, an effect that was partly attributed to a reduction in glucose absorption (Thom, 2007). Liver weight measurements have long been regarded as useful indices of stress in safety evaluation. In evaluating relative liver weight increases, it has been clear for some time that such increases may represent a stress response to high intake levels of a foreign compound (Gilbert & Golberg, 1965). In the present study, liver weight remained unchanged with the plant extract at all doses. Also T. porrifolius extracts did not increase the activity of liver enzymes tested (AST, ALT and LDH), but on the contrary, a reduced activity of these enzymes was noted suggesting a hepato-protective effect. In conclusion, the present study showed that T. porrifolius water extract has potential benefits on lipemia and satiety with no visible adverse effects. FOS, caffeic acid and chlorogenic acid present in the plant could be responsible for the aforementioned activities. However, the effects obtained may not necessarily be due or restricted to these components as herbs often contain families of compounds that interact with each other (Thomson Healthcare., 2007). These findings provide new evidence that edible wild plants such as T. porrifolius could become a useful tool for specialists dealing with problems of obesity and its co-morbidities. Further experiments examining the effects of the extract on a Mediterraneantype diet that is high in unsaturated fatty acids and low in saturated fatty acids could be undertaken in the near future.
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