Antidiabetic effects of three Korean sorghum phenolic extracts in normal and streptozotocin-induced diabetic rats

Food Research International 44 (2011) 127–132

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Food Research International j o u r n a l h o m e p a g e : w w w. e l s ev i e r. c o m / l o c a t e / f o o d r e s

Antidiabetic effects of three Korean sorghum phenolic extracts in normal and streptozotocin-induced diabetic rats Ill-Min Chung a, Eun-Hye Kim a, Min-A Yeo a, Sun-Jin Kim a, Myong–Cheol Seo b, Hyung-In Moon c,d,⁎ a

Department of Applied Life science, Kon Kuk University, Seoul 143-701, South Korea Functional Cereal Crop Research Division, National Institute of Crop Science, RDA, Suwon 441–857, Korea Cardiovascular Medical Research Center, College of Korean Medicine, Dongguk University, Gyeong–Ju 780–714, South Korea d Inam Neuroscience Research Center, Wonkwang University Sanbon Medical Center, Kyunggi–Do 435–040, South Korea b c

a r t i c l e

i n f o

Article history: Received 22 September 2010 Accepted 31 October 2010 Keywords: Sorghum bicolor Korean sorghum Antidiabetic Phenolic components

a b s t r a c t The present study evaluated the antidiabetic effects from phenolic extracts of three varieties (Hwanggeumchal sorghum, Chal sorghum, and Heuin sorghum) from Korean sorghum (Sorghum bicolor L. Monech) in normal and streptozotocin-induced diabetic rats. Hwanggeumchal sorghum phenolic extracts in the streptozotocininduced diabetic rats showed significant hypoglycemic activity for 14 days and significantly decreased the serum glucose, total cholesterol, triglycerides, urea, uric acid, creatinine, aspartate amino transferase and alanine amino transferase while it increased the serum insulin in diabetic rats but not in normal rats (p b 0.05) (at doses of 100 and 250 mg/kg for 14 days). A comparison was made between the action of Hwanggeumchal sorghum phenolic extracts and glibenclamide (600 μg/kg), a known antidiabetic drug. Twenty-four of the 29 phenolic components monitored were detected by high performance liquid chromatography. The antidiabetic effect of the Hwanggeumchal sorghum phenolic extracts was similarly effective with that observed with glibenclamide. Phenolic components were analyzed using high performance liquid chromatography, and a total of 29 phenolic components were detected in the Korean sorghum studied. The relationships of antidiabetic effects and phenolic components of Hwanggeumchal sorghum phenolic extracts were significantly higher than that of Chal sorghum and Heuin sorghum phenolic extracts. © 2010 Elsevier Ltd. All rights reserved.

1. Introduction Diabetes mellitus is a serious, complex chronic condition that is a major source of ill health all over the world. The total number of people with diabetes is projected to rise from 4% of the population worldwide and is expected to increase to 5.4% in 2025. Hyperglycemia and hyperlipidemia are involved in the development of microvascular and macrovascular complications of diabetes, which are the major causes of morbidity and mortality of diabetes (Holman & Turner, 1991; Taskinen, 2002). There is an increasing demand by patients to use natural products with antidiabetic activity, due to the side effects associated with the use of insulin and oral hypoglycemic agents. On the other hand, plant products are generally considered to be less toxic with fewer side effects than synthetic products. Consequently, plant-derived materials have received increased attention as biochemical active agents in antihyperglycemia and antihyperlipidemia

⁎ Corresponding author. Cardiovascular Medical Research Center, College of Korean Medicine, Dongguk University, Gyeong-Ju 780-714 and, Inam Neuroscience Research Center, Wonkwang University Sanbon Medical Center, Kyunggi-Do 435-040, South Korea. Fax: +82 54 770 2654. E-mail address: [email protected] (H.-I. Moon). 0963-9969/$ – see front matter © 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.foodres.2010.10.051

therapies. The study of such medicines might offer a natural key to unlock the diabetologists pharmacy for the future. So, some herbal (and/or supplements) drugs are a good source of natural antidiabetic agents (Ozsoy-Sacan, Karabulut-Bulan, Bolkent, Yanardag, & Ozgey, 2004). Phenolic compounds can be classified as simple phenols and phenolic acids such as gallic acid, benzoic acid, syringic acid, chlorogenic acid, and other associates, and polyphenols, which are classified into many groups such as flavonoids, tannins, stilbenes, and so on. Flavonoids are a group of polyphenolic compounds with known health-beneficial properties, which include free radical scavenging, inhibition of hydrolytic and oxidative enzymes, and anti-inflammatory action (Yildiz, Karakaplan, & Aydin, 1998). Grain polyphenols are abundant in the human diet, particularly in fruit, vegetables and pulses which have been consistently associated with a decreased risk of nutritional disease. They constitute one of the most abundant groups of natural metabolites and are now recognized for their important contribution to both human and animal diet and health (Spencer, Abd El Mohsen, Minihane, & Mathers, 2008). Sorghum bicolor L. Monech (Gramineae) is a drought resistant low input cereal crop grown throughout the world, and can be an alternative source of oil having clinical advantages. Genus sorghum includes many species and subspecies, including grain sorghum, grass sorghum, sweet sorghum and broomcorn. It is used as food, animal feed, fibers as in

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wall board, fences, biodegradable packing material and for ethanol production (Rooney & Waniska, 2000). Sorghum is an important food for people living in the semi-arid tropical areas of Africa and Asia (Murthy & Kumar, 1995). Sorghum flour is rich in phytochemical components with a potential to impact human health in a beneficial manner (Kamath, Chandrashekar, & Rajini, 2004). The storage proteins of sorghum constitute 50–60% of the total protein of the grain and have been classified into three main groups, according to their molecular weight, extractability and structure. Phenolic compounds in sorghum occur as phenolic acids, flavonoids and condensed tannins (Paulis & Wall, 1979; Serna-Saldivar & Rooney, 1995). Condensed tannins (proanthocyanidins) occur in sorghums with pigmented test which have dominant B1B2 genes. The tannins in sorghums have the highest levels of antioxidants of any cereal analyzed (Gu et al., 2004). Sorghum tannins are 15–30 times more effective at quenching peroxyl radicals than simple phenolics, thus they are potential biological antioxidants. Despite their possible beneficial effects as antioxidants, tannins have been linked to reduced protein digestibility of sorghum because they bind with proteins and inhibit enzymes (Duodu et al., 2002). The objective of the present study was to determine contents of phenolic components in three varieties phenolic extracts (Hwanggeumchal sorghum (HGS), Chal sorghum (CS), and Heuin sorghum (HS)) from Korean sorghum commonly cultivated in Korea as well as to give animal experiments about their antidiabetic effect. The relationship between phenolic components content and antidiabetic effect in three varieties sorghum phenolic extracts was also investigated. To the best of our knowledge, this is the first report on the antidiabetic effect of Korean sorghum phenolic extracts.

2. Materials and methods 2.1. Grain materials and sample extracts for animal experiments Three Korean sorghum cultivars were provided by the Department of Functional Crop, National Institute of Crop Science, Rural Development Administration, South Korea. The botanical identification was made by one of the authors, Dr. Ill-Min Chung on Kon Kuk University (Seoul, South Korea). Voucher herbarium specimens were deposited with the reference number (KNICS-579) in the Herbarium of the Department of Functional Crop. The seeds were stored at 4 °C. Sorghum cultivars used in this study were Hwanggeumchal sorghum (HGS), Chal sorghum (CS), and Heuin sorghum (HS) (Fig. 1). The three varieties of sorghum (each 300 g) were ground and refluxed three times (12 h, 24 h, 48 h) with 10 mL of acetonitrile and 2 mL of 0.1 N hydrochloric acid and stirred for 2 h at room temperature. The suspension was filtered through No. 42 Whatman filter paper. The

extracts were gathered and the acetonitrile and hydrochloric acid were evaporated under reduced pressure at 45 °C in a rotary vacuum evaporator (Buchi RII, Buchi, Switzerland), followed by lyophilization. The stock solutions were kept at 4 °C in the dark until further analysis. Prior to analysis, the solution was filtered through a 1.0 μm syringe filter. 2.2. Chemical composition of Korean sorghum Methods for analyses of crude protein, lipid, and ash were AOAC 990.03, 920.39, and 942.05, respectively. Crude fiber was analyzed by the filter bag technique using the ANKOM A200 (http://www.ankom. com/media/documents/CrudeFiber_1108_A200.pdf). 2.3. Analysis of phenolic components Twenty-nine phenolic compound standards, flavonoids as catechin, naringin, naringenin, myricetin, quercetin, biochanin A, formononetin, hesperetin, kaempferol, rutin, gallic acid, pyrogallol, homogentisic acid, protocatechuic acid, gentisic acid, p-hydroxybenzoic acid, chlorogenic acid, vanillic acid, caffeic acid, syringic acid, vanillin, cinnamic acid, p-coumaric acid, ferulic acid, veratric acid, salicylic acid, benzoic acid, o-coumaric acid, and resveratrol were purchased from Sigma Aldrich (MO, USA) and Extrasynthese (Gernay, France) and used for calibration curves. The standard stock solutions (50, 100, 250, and 500 ppm) were made with dimethylsulfoxide (DMSO). All standard calibration curves showed high degrees of linearity (r2 N 0.99) (data not shown). Sample compounds were identified on the basis of the retention times of standard materials and were quantified by comparing their peak areas with those of standard curves. Sample preparation for analysis of phenolic compounds followed Kim et al. (2006).Two grams of freezedried three sorghum powder was mixed with 10 mL of acetonitrile and 2 mL of 0.1 N hydrochloric acid and stirred for 2 h at room temperature. The suspension was filtered through No. 42 Whatman filter paper. The phenolic extracts were freeze-dried below −40 °C, and the residues were redissolved in 10 mL of 80% aqueous methanol (HPLC grade) (J. T. Baker, NJ, USA), filtered through a 0.45 μm nylon membrane filter (TITAN, TN, USA). The 20 μL filtrate was loaded on the HPLC system, a Shimadzu SPD-M10A HPLC system with a photodiode array detector (Tokyo, Japan) equipped with a Midas autoinjector. Separation was achieved on a 250 mm× 4.6 mm i.d., 5 μm, YMC-Pack ODS AM-303 (YMC, Kyoto, Japan) column. The absorbance of each sample solution was measured at 280 nm. The mobile phase was distilled water with 0.1% glacial acetic acid (solvent A) and acetonitrile with 0.1% glacial acetic acid (solvent B). The gradient was 0 min, 92% A; 0–2 min, 90% A;2–27 min, 70% A; 27–50 min, 10% A; 50–51 min, 0% A; 51–60 min, 0% A; 60–63 min, 92% A. Run time was 60 min using a flow rate of 1 mL/

Fig. 1. Photograph of three Korean sorghum cultivars. Hwanggeumchal sorghum (HGS), Chal sorghum (CS), Heuin sorghum (HS).

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min. The 29 standards and all solvents used (J. T. Baker, NJ, USA) were of HPLC grade.

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Group 9: Diabetic rats administered i.p. HGS (100 mg/kg b.w.) in 1 mL acacia gum with saline, daily, for 14 days using an intragastric tube. Group 10: Diabetic rats administered i.p. HGS (250 mg/kg b.w.) in 1 mL acacia gum with saline, daily, for 14 days using an intragastric tube. Group 11: Diabetic rats administered i.p. CS (100 mg/kg b.w.) in 1 mL acacia gum with saline, daily, for 14 days using an intragastric tube. Group 12: Diabetic rats administered i.p. CS (250 mg/kg b.w.) in 1 mL acacia gum with saline, daily, for 14 days using an intragastric tube. Group 13: Diabetic rats administered i.p. HS (100 mg/kg b.w.) in 1 mL acacia gum with saline, daily, for 14 days using an intragastric tube. Group 14: Diabetic rats administered i.p. HS (250 mg/kg b.w.) in 1 mL acacia gum with saline, daily, for 14 days using an intragastric tube. Group 15: Diabetic rats administered i.p. glibenclamide (600 μg/kg b.w.) in 1 mL acacia gum with saline, daily, for 14 days using an intragastric tube.

2.4. Animals Adult male Wistar rats with body weights of 200–250 g were purchased from the Japan SLC, Inc (Shizuoka Prefecture, Japan), housed in specific pathogen-free facilities, and provided with autoclaved water and standard food. The animals were housed at a controlled temperature (20–22 °C) and relative humidity of 55–59% with a normal 12 h light and dark cycle. All experiments conducted on mice were in accordance with the guidelines for the care and use of laboratory animals approved by Dongguk University College of Korean Medicine. 2.5. Experimental induction of diabetes in rats Male adult Wistar rats were injected with streptozotocin (Sigma Co, USA). Streptozotocin was dissolved in saline immediately before use and injected intraperitonially (i.p.) in a single dose (70 mg/ kg, i.p.). Five days after injection, rats with a fasting blood glucose higher than 180 mg/dL were used for the experiments. Six rats were used in each experiment. Each animal was used once only in all the experiments. The food was removed from cages 12 h before testing.

2.8. Biochemical assays 2.6. Sorghum extracts and drug administration Sorghum extracts were suspended in acacia gum with saline and administered orally through orogastric tubes at the following doses of 100 and 250 mg/kg body wt. Glibenclamide was suspended in acacia gum with saline and administered orally through orogastric tubes at the following doses of 600 μg/kg body wt. Glibenclamide (purity ≥ 99%) was purchased from Sigma Co (USA). The volume of the above three doses was kept constant at 1 mL. 2.7. Experimental design In the experiment, a total of 135 rats (72 diabetic rats, 63 normal rats) were used. Diabetes was induced in rats 5 days before starting the treatment. The rats were divided into 15 groups. In the experiment nine rats were used in each group. Group 1: Normal control rats administered i.p. 1 mL acacia gum with saline, daily, for 14 days using an intragastric tube. Group 2: Normal control rats administered i.p. HGS (100 mg/kg b.w.) in 1 mL acacia gum with saline, daily, for 14 days using an intragastric tube. Group 3: Normal control rats administered i.p. HGS (250 mg/kg b.w.) in 1 mL acacia gum with saline, daily, for 14 days using an intragastric tube. Group 4: Normal control rats administered i.p. CS (100 mg/kg b.w.) in 1 mL acacia gum with saline, daily, for 14 days using an intragastric tube. Group 5: Normal control rats administered i.p. CS (250 mg/kg b.w.) in 1 mL acacia gum with saline, daily, for 14 days using an intragastric tube. Group 6: Normal control rats administered i.p. HS (100 mg/kg b.w.) in 1 mL acacia gum with saline, daily, for 14 days using an intragastric tube. Group 7: Normal control rats administered i.p. HS (250 mg/kg b.w.) in 1 mL acacia gum with saline, daily, for 14 days using an intragastric tube. Group 8: Diabetic control rats administered i.p. 1 mL acacia gum with saline, daily, for 14 days using an intragastric tube.

Biochemical assays of male adult Wistar rats were determined using a modified method of Eidi et al (Eidi, Eidi, & Darzi, 2009). After 14 days of treatments, blood samples were drawn from the heart. Serum glucose, insulin, total cholesterol, triglycerides, urea, uric acid, creatinine, aspartate amino transferase (AST) and alanine amino transferase (ALT) levels were determined. Serum glucose was estimated by the oxidase method (Barham & Trinder, 1972). The serum insulin was estimated by using a radioimmunoassay kit (Diasorin, Italy), total cholesterol and triglyceride by the method of Rifai (Rifai, Bachorik, & Albers, 1999). The serum urea was assayed by the method of Tomas (Tomas, 1998a), while uric acid was measured by the method of Fossati et al (Fossati, Prgncipe, & Berti, 1980). Serum creatinine was estimated by the method of Tomas (Tomas, 1998b). Serum AST and ALT were assayed by the method of Moss and Henderson (Moss & Henderson, 1999). 2.9. Statistical analysis All the data were expressed as mean ± SEM. Statistical analysis was carried out using one-way ANOVA followed by the Tukey post hoc test. The criterion for statistical significance was p b 0.05. 3. Results and discussion 3.1. Chemical and phenolic components in three Korean sorghum varieties Major chemical components differed among the three sorghum varieties (Table 1). Starch content of the tested samples was similar to that of most sorghum cultivars (∼70%), except Chal Sorghum had only 66.3% starch. Chal Sorghum had significantly higher (N13%) crude

Table 1 Chemical composition of Korean sorghum varieties (%, db).a Korean sorghum

Starch

Crude protein

Crude fat

Crude fiber

Ash

Hwanggeumchal sorghum Chal sorghum Heuin sorghum

73.2a

11.63b

3.23c

2.62b

1.43c

66.3b 72.8a

13.42a 11.23b

3.78a 3.41b

2.82a 1.83c

1.92a 1.61b

a

Means in a column with different letters differ (P b 0.05).

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Fig. 2. Chromatogram of phenolic component analysis by HPLC. Hwanggeumchal sorghum (HGS), Chal sorghum (CS), Heuin sorghum (HS). 1. Gallic acid; 2. Pyrogallol; 3. Homogentisic acid; 4. Protocatechuic acid; 5. Gentisic acid; 6. Chlorogenic acid; 7. p-Hydroxybenzoic acid; 8. Vanillic acid; 9. Caffeic acid; 10. Syringic acid; 11. Vanillin; 12. p-Coumaric acid; 13. Ferulic acid; 14. Veratric acid; 15. m-Coumaric acid; 16. Benzoic acid; 17. o-Coumaric acid; 18. Resveratrol; 19. t-Cinnamic acid; 20. β-Resorcylic acid; 21. Rutin; 22. Hesperidin; 23. MyricetinG; 24. Quercetin; 25. Naringenin; 26. Hesperetin; 27.Formononetin; 28.Biochanin A; 29.Naringin.

protein content than the rest of the samples. Twenty-four of the 29 phenolic components monitored were detected; only major peak B and C were not detected in the sorghum studied (Fig. 2). Overall, phenolic components concentration was greater in HGS than CS and HS. Sorghum varieties also contained different types of phenolic components in varying numbers, ranging from A to E. Two peaks were more detected in only HGS (e.g., B and C). The above indicates that two peaks (B and C) may play a more important role in the

antidiabetic effects of Korean sorghum. So, single component evaluation and further investigations on the effects on antidiabetic are necessary. 3.2. Antidiabetic activities of three Korean sorghum varieties Loss of body weight is a characteristic condition in diabetes, owing to defect in glucose metabolism and excessive breakdown of tissue

I.-M. Chung et al. / Food Research International 44 (2011) 127–132 Table 2 Effect of animal body weight after 14 days of treatment (100, 250 mg/kg b.w./day, i.p.). Experimental groups

1 - Normoglycemic control 2 - Control + HGS (100 mg/kg b.w.) 3 - Control + HGS (250 mg/kg b.w.) 4 - Control + CS (100 mg/kg b.w.) 5 - Control + CS (250 mg/kg b.w.) 6 - Control + HS (100 mg/kg b.w.) 7 - Control + HS (250 mg/kg b.w.) 8 - Diabetic 9 - Diabetic + HGS (100 mg/kg b.w.) 10 - Diabetic + HGS (250 mg/kg b.w.) 11 - Diabetic + CS(100 mg/kg b.w.) 12 - Diabetic + CS (250 mg/kg b.w.) 13 - Diabetic + HS (100 mg/kg b.w.) 14 - Diabetic + HS(250 mg/kg b.w.) 15 - Diabetic + glibenclamide

Body weight (g) Day 0

Day 14

211.2 ± 13.2 214.0 ± 16.2 212.1 ± 13.4 228.9 ± 13.5 238.3 ± 16.3 231.4 ± 17.2 231.4 ± 12.7 233.2 ± 16.3 232.4 ± 13.4 235.7 ± 18.3 229.0 ± 13.5 231.3 ± 19.6 231.0 ± 15.7 222.6 ± 18.1 239.2 ± 11.9

253.2 ± 11.3* 245.6 ± 13.0 234.5 ± 16.3 239.1 ± 13.4 247.3 ± 21.3 248.5 ± 23.7 240.9 ± 23.7 214.5 ± 27.8 223.6 ± 26.8 221.1 ± 13.6 211.1 ± 21.3 216.4 ± 18.0 219.0 ± 17.9 213.3 ± 19.4 226.7 ± 26.9

Values are mean ± SEM for nine rats. ⁎p b 0.05 when compared to day 0.

protein (Sezik, Asla, Yesilada, & Ito, 2005). After 14 days of treatment, group I ~ 7 increased significantly (p b 0.05) in weight, when compared to day 0. The STZ-induced diabetic rats had significantly lost weight, compared to the control. However, diabetic rats that were subsequently treated with sorghum phenolic extracts did not significantly lose weight compared to the control (Table 2). There was a significant elevation in serum glucose, total cholesterol, triglycerides, urea, uric acid, creatinine, AST and ALT while the serum insulin level was decreased significantly in the diabetic rats. Table 3 shows the effects of the sorghum phenolic extracts on serum glucose, insulin, triglycerides and total cholesterol in normal and diabetic rats. The results showed that serum glucose, triglycerides and total cholesterol of diabetic rats increased while serum insulin decreased, when compared with normal rats. The administration of the HGS extracts at doses of 250 mg/kg body wt and glibenclamide tended to bring serum glucose (p b 0.001), insulin (p b 0.001), triglycerides (p b 0.001) and total cholesterol (p b 0.001) significantly toward normal values, while normal rats did not exhibit any significant alterations in these parameters during the experiment. The HGS phenolic extract treatment groups were found to be similar effective with glibenclamide. The administration of the HGS phenolic extracts at dose of 1 mg/kg body wt did not change serum glucose (p N 0.05), insulin

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(p N 0.05), triglycerides (p N 0.05) and total cholesterol (p N 0.05) levels in normal rats. Table 4 showed the effect of the sorghum phenolic extracts on the serum urea, uric acid, creatinine, AST and ALT in normal and diabetic rats. The results showed that serum urea, uric acid, creatinine, AST and ALT increased when compared with normal rats. The administration of the HGS phenolic extracts (250 mg/kg body wt) and glibenclamide significantly decreased the serum urea (p b 0.001), uric acid (p b 0.001), creatinine (p b 0.001), AST (p b 0.001) and ALT (p b 0.001) when compared with the control diabetic rats. The HGS phenolic extract treatment at a dose of 250 mg/kg body weight was found to be similarly effective with that observed with glibenclamide. The administration of the HGS phenolic extracts (100 mg/kg body wt) did not change the serum urea (p N 0.05), uric acid (p N 0.05), creatinine (p N 0.05), AST (p N 0.05), or ALT (p N 0.05) levels in normal rats. The results indicated that the HGS phenolic extract treatment significantly decreased serum glucose, triglycerides, cholesterol, urea, uric acid, creatinine, AST and ALT while it increased the serum insulin levels in treated diabetic rats compared with the control diabetic rats. The result also showed that the HGS phenolic extract treatment exhibited a significant decrease in the level of serum lipids in diabetic rats. The data showed that the uric acid levels were increased in diabetic rats. This may be due to a metabolic disturbance in diabetes reflected in the high activities of xanthine oxidase, lipid peroxidation and increased triglycerides and cholesterol (Madinov, Balabolkin, Markov, & Markova, 2000). Moreover, protein glycation in diabetes may lead to muscle wasting and an increased release of purine, the main source of uric acid as well as in the activity of xanthine oxidase (Anwar & Meki, 2003). The data showed that the HGS phenolic extract treatment decreased the serum urea and creatinine levels in diabetic rats. Elevation of the serum urea and creatinine, as significant markers, is related to renal dysfunction in diabetic hyperglycemia (Almadal & Vilstrup, 1988). Serum enzymes including AST and ALT are used in the evaluation of hepatic disorders. An increase in these enzyme activities reflects active liver damage. Inflammatory hepatocellular disorders result in extremely elevated transaminase levels (Hultcrantz, Glaumann, Lindberg, & Nilsson, 1986). In accordance with these findings, streptozotocin treatment has a significant role in the alteration of liver functions since the activity of AST and ALT was significantly higher than those of normal values. As a result, it may be concluded that the HGS phenolic extracts were more useful effective in comparison with glibenclamide in attenuating the increased serum parameters resulting from damage of STZ-induced diabetic rats and that the HGS phenolic extract treatment

Table 3 Effect of Korean sorghum phenolic extracts on mean values of serum glucose, insulin, triglycerides and total cholesterol after 14 days of treatment (100, 250 mg/kg b.w./day, i.p.). Experimental groups

Glucose (mg/dL)

Insulin (IU/L)

Triglycerides (mg/dL)

Total cholesterol (mg/dL)

1 - Normoglycemic control 2 - Control + HGS (100 mg/kg b.w.) 3 - Control + HGS (250 mg/kg b.w.) 4 - Control + CS (100 mg/kg b.w.) 5 - Control + CS (250 mg/kg b.w.) 6 - Control + HS (100 mg/kg b.w.) 7 - Control + HS (250 mg/kg b.w.) 8 - Diabetic 9 - Diabetic + HGS (100 mg/kg b.w.) 10 - Diabetic + HGS (250 mg/kg b.w.) 11 - Diabetic + CS (100 mg/kg b.w.) 12 - Diabetic + CS (250 mg/kg b.w.) 13 - Diabetic + HS (100 mg/kg b.w.) 14 - Diabetic + HS (250 mg/kg b.w.) 15 - Diabetic + glibenclamide

93.3 ± 4.74 82.4 ± 2.01 78.4 ± 1.41 92.7 ± 2.46 92.3 ± 2.44 92.7 ± 2.53 91.4 ± 2.89 543.2 ± 6.69 538.3 ± 7.84 424.2 ± 5.12c 541.2 ± 6.57 532.1 ± 5.41 536.1 ± 5.97 511.2 ± 4.96a 414.3 ± 35.3b

11.3 ± 0.34 11.9 ± 0.31 11.7 ± 0.36 11.4 ± 0.32 11.9 ± 0.23 11.8 ± 0.13 11.9 ± 0.85 1.02 ± 0.13 1.43 ± 0.12 1.78 ± 0.16b 1.03 ± 0.17 1.08 ± 0.11 1.06 ± 0.35 1.17 ± 0.56 1.89 ± 0.07a

73.4 ± 4.45 111.9 ± 3.42 101.4 ± 3.51 79.7 ± 2.45 78.7 ± 2.77 77.2 ± 2.56 75.8 ± 3.85 114.2 ± 5.34 105.3 ± 3.53 79.2 ± 4.31c 111.3 ± 4.34 107.4 ± 4.28 113.4 ± 2.89 106.4 ± 4.63 89.4 ± 3.22a

68.8 ± 1.37 58.6 ± 2.00 57.4 ± 1.96 68.9 ± 1.43 66.4 ± 1.21 63.6 ± 1.75 62.5 ± 1.67 106.7 ± 2.44 93.2 ± 1.45 78.4 ± 2.42c 105.3 ± 3.21 101.9 ± 2.11 103.2 ± 2.38 101.7 ± 2.29 84.2 ± 3.19b

Values are mean ± SEM for nine rats. a p b 0.05 vs. diabetic group. b p b 0.01 vs. diabetic group. c p b 0.001 vs. diabetic group.

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Table 4 Effect of Korean sorghum extracts on mean values of serum urea, uric acid, creatinine, AST and ALT for all groups after 14 days of treatment (100, 250 mg/kg b.w./day, i.p.). Experimental groups

Urea (mg/dL)

Uric acid (mg/dL)

Creatinine (mg/dL)

AST (IU/L)

ALT (IU/L)

1 - Normoglycemic control 2 - Control + HGS (100 mg/kg b.w.) 3 - Control + HGS (250 mg/kg b.w.) 4 - Control + CS (100 mg/kg b.w.) 5 - Control + CS (250 mg/kg b.w.) 6 - Control + HS (100 mg/kg b.w.) 7 - Control + HS (250 mg/kg b.w.) 8 - Diabetic 9 - Diabetic + HGS (100 mg/kg b.w.) 10 - Diabetic + HGS (250 mg/kg b.w.) 11 - Diabetic + CS (100 mg/kg b.w.) 12 - Diabetic + CS (250 mg/kg b.w.) 13 - Diabetic + HS (100 mg/kg b.w.) 14 - Diabetic + HS (250 mg/kg b.w.) 15 - Diabetic + glibenclamide

38.5 ± 2.1 39.7 ± 1.4 44.3 ± 1.1 40.2 ± 1.6 41.3 ± 3.1 41.4 ± 3.1 41.1 ± 4.3 117.4 ± 4.8 110.1 ± 5.8 89.3 ± 4.1b 111.6 ± 3.7 104.2 ± 2.5 108.2 ± 3.6 99.3 ± 4.1 a 98.7 ± 5.2

0.96 ± 0.04 0.87 ± 0.05 0.84 ± 0.05 0.98 ± 0.06 0.91 ± 0.13 0.95 ± 0.19 0.91 ± 0.23 1.42 ± 0.23 1.24 ± 0.35 0.90 ± 0.11a 1.39 ± 0.63 1.31 ± 0.32 1.35 ± 0.19 1.21 ± 0.21 a 1.13 ± 0.06

0.47 ± 0.06 0.61 ± 0.08 0.74 ± 0.02 0.55 ± 0.03 0.63 ± 0.07 0.57 ± 0.13 0.61 ± 0.21 0.64 ± 0.03 0.59 ± 0.10 0.54 ± 0.06a 0.61 ± 0.11 0.58 ± 0.09 0.59 ± 0.09 0.56 ± 0.02 0.55 ± 0.02

126.4 ± 9.3 156.3 ± 11.9 138.9 ± 16.8 127.4 ± 11.5 119.9 ± 14.3 126.7 ± 12.5 121.3 ± 11.4 211.3 ± 14.3 196.9 ± 11.6 141.9 ± 9.8c 204.5 ± 11.9 194.2 ± 11.6 201.3 ± 11.4 183.2 ± 12.8 152.3 ± 15.4

83.4 ± 4.2 88.1 ± 3.6 63.5 ± 4.1 84.1 ± 4.1 79.3 ± 5.2 85.7 ± 3.8 83.5 ± 2.5 153.2 ± 13.2 158.0 ± 13.1 94.9 ± 7.0b 151.6 ± 17.3 143.1 ± 11.4 151.4 ± 11.4 137.1 ± 9.0 82.5 ± 6.1b

a

Values are mean ± SEM for nine rats. a p b 0.05 vs. diabetic group. b p b 0.01 vs. diabetic group. c p b 0.001 vs. diabetic group.

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