Studies On The Therapeutic Approach For The Prevention Of Diabetes By Bacterial Douchi Extracts

The douchi, is a fermented soy bean product, it has played important roles in Chinese diet for centuries as a seasoning or a Chinese traditional medicine. Some remarkable effects of douchi onα-glucosidase inhibitory activity, ACE inhibitory activity, antioxidant activity, and anti-hypertensive activity have been known but they are mainly produced by natural fermentation. Our group has successfully prepared the bacterial douchi made by pure starter fermentation.The aims of the present study were to extract bioactive components from bacterial douchi by water and 70% ethanol, to determine the content of peptide and phenolic compounds, and to investigate their antioxidative and antidiabetic activities by using laboratory test and animal model.The water and ethanol extract of douchi were evaluated for their glucation inhibitory and antioxidant properties in vitro and in vivo. Inhibitory activity on protein glycation of douchi extract was conducted by determining the value of IC50. Antioxidant activities of douchi extract were conducted by determining the 1,1-diphenyl-2-picrylhdrazyl (DPPH) and 2,2'-Azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) free radical scavenging activities, and chelating ability of ferrous ions by ferric reducing/antioxidant power (FRAP). The ethanol extract of all samples were significantly superior to those of water extract of all samples.Thirty two male Sprague-Dawley (SD) rats (240-260g) were randomized into normal control group, high fructose-fed control group, high fructose-fed with 3% ethanol extract douchi group, and high fructose-fed with 3% water extract douchi group for eight weeks. The rats were sacrificed at 8wk and blood was drawn from the abdominal vein, and tissues were collected and relevant biochemistry parameters were determined by standard methods. Antioxidant enzymatic activities of douchi extract in high fructose-fed rats and an index of lipid peroxidation (thiobarbituric acid reactive substances) (TBARS) were determined. Superoxide dismutase (SOD) activity was increased in the liver, kidney, and pancreas by treading with ethanol extract and water extracts. Catalase (CAT) activity was significantly increased in the liver but not in the kidney and pancreas. On the other hand, there was no significantly difference on glutathione peroxidase (GSH-Px) activity. GSH values were significantly increased in the pancreas by treating with ethanol extract and in the liver by treading with water extract. The fasting blood glucose and HbA1C levels were lower in the both of douchi extract treated groups and significantly lower in water extract treated group. And the AUCglucose value was significantly lower in the water and ethanol extracts treated groups.The present results showed that ethanol and water extracts of bacterial douchi significantly delayed the progression of high fructose-induced glucose intolerance, hyperinsulinemia, dyslipidemia and oxidative stress in rats. Bacterial douchi extracts might have beneficial effect on diabetic prevention.