ANTIOXIDANT ACTIVITIES AND HYPOLIPIDEMIC EFFECTS OF AN AQUEOUS EXTRACT FROM FLOWER BUDS OF CLEISTOCALYX OPERCULATUS (ROXB.) MERR. AND PERRY

Abstract

ABSTRACT The antioxidant activities and hypolipidemic effects of aqueous extract from Cleistocalyx operculatus flower buds (COB) (Roxb.) Merr. and Perry, a commonly used material for drink preparation in Vietnam, were investigated in vitro and in diabetic rats. In vitro, the aqueous extract of COB which has highest phenolic and flavonoid contents showed a strong antioxidant effect and highest pancreatic lipase inhibitory activity when compared with green tea and guava leaf extracts. Oral administration of aqueous extract from COB (500 mg/kg body weight/day) on streptozotocin-induced diabetic rats for 8 weeks resulted in significant reduction in the levels of glucose, total cholesterol and triglyceride in plasma as well as the concentration of glucose and sorbitol in the lens. In addition, COB showed significant recovery in the activities of antioxidant enzymes (superoxide dismutase, glutathione S-transferase) and glutathione level in liver with markedly decrease in the lipid peroxide level in liver and lens of the COB-treated diabetic rats. These results indicated that COB showed antioxidant activities, prevention of sorbitol accumulation in lens and hypolipidemic effects in addition to its antidiabetic effects and may be considered as a promising material for the prevention of diabetic complications and metabolic syndrome. PRACTICAL APPLICATIONS In recent years, research on traditional medicinal plants for the management of diabetes has attracted the interest of medical scientists. A suitable plant material for antidiabetes and prevention of diabetic complications should possess various biological components, such as antihyperglycemia, antioxidant activities and antihyperlipidemia, without side effects. In this study, the aqueous extract from Cleistocalyx operculatus flower buds (COB) with high polyphenolic and flavonoid content has shown beneficial biological functions in vitro and in diabetic rats, including antioxidant activity, hypolipidemic and hypoglycemic effects. The results of our study suggest that COB might have a potential role in the management of the prediabetic state and the prevention of diabetic complications. Therefore, there is the possibility for the development of C. operculatus as a beverage for the prevention of diabetes, as well as the prevention of the metabolic syndrome.