Phytochemical composition and chronic hypoglycemic effect of Rhizophora mangle cortex on STZ-NA-induced diabetic rats

Abstract

Type 2 diabetes is a major health problem in Mexico, as it is in other countries, is a chronic condition that develops when the body cannot produce enough insulin or cannot use it appropriately. Both insulin deficiency and insulin resistance lead to high blood glucose levels. In Mexico, people with diabetes are known to use the decoction of red mangrove (Rhizophora mangle L., Rhizophoraceae) bark to control blood glucose levels. Therefore, in this study, we sought to investigate the chronic hypoglycemic and hypolipidemic effects of R. mangle; we also elucidate some of the major phytochemical compounds of R. mangle. To analyze the hypoglycemic and hypolipidemic effects, we used rats with streptozotocin–nicotinamide-induced hyperglycemia; the rats were classified into four groups (six rats each), based on the treatment given, as follows: group 1, non-hyperglycemic control; group 2, hyperglycemic control; group 3, glibenclamide (5mg/kg body weight); and group 4, Rhizophora ethanol–water extract (90mg/kg). The extract or glibenclamide was orally administered, dissolved in 1.5ml of physiological NaCl-solution, twice a day (in the morning and in the evening) over a period of 42 days. The methanolic extract was used to elucidate the main compounds present in R. mangle via conventional phytochemical methods, such as TLC, HLPC, UPLC–DAD–MS, and NMR. The following compounds were detected: cinchonains Ia and Ib, catechin-3-O-rhamnopyranoside, epicatechin, lyoniside, and nudiposide. The daily administration of Rhizophora ethanol–water extract, similar to the traditional usage to control type 2 diabetes, was shown to exert chronic hypoglycemic and hypolipidemic effects. This effect may be associated whit the constituents in the extract. These findings suggest that R. mangle and its constituents could be potentially used to treat type 2 diabetes.