Abstract

• The key process in the development of highly effective and safe herbal medicine is isolation and identification of pharmacologically active compounds from medicinal plants and evaluation of their biological activities. In the present work, catechin, a flavanol was isolated from the ethyl acetate soluble portion of the 70 % ethanol extract from D. bulbifera tubers. The isolated catechin was characterized by using UV, FT IR, 1H NMR, 13C NMR, HSQC, COSY and HMBC spectroscopic methods. The hypoglycemic effects of pet ether, ethyl acetate and water soluble portions of the hydroalcoholic extract and isolated catechin were evaluated on alloxan induced diabetic mice. The percent reduction of blood glucose level (% R) was significant after 4 h administration of tested sample. % R of pet ether, ethyl acetate and water soluble portions, isolated catechin and antidiabetic drug, metformin were found to be 28.83 %, 41.29 %, 31.52 %, 41.62 % and 41.87 %, respectively. % R of ethyl acetate portion and isolated catechin were nearly the same as % R of metformin. The histological examination of pancreatic islet on tested mice was performed by staining with Haematoxylin and Eosin and it was found that ethyl acetate and water soluble portions as well as isolated catechin enhanced the regeneration of the alloxan damaged islet cells.