In vitro antidiabetic activity of Treculia africana leaf extracts: identification of chlorogenic acid and α-mangostin

Objective This research studied two extracts from Treculia africana leaves for their potential against hyperglycaemia-related disorders.Methods The influence of the extracts on alpha-glucosidase activity and albumin glycation was investigated, and cell viability was estimated in HT-29 human colorectal cells. Phenolic and flavonoid contents and antiradical activity were also detected. The extracts were examined using HPLC-DAD analysis.Key findings The methanol and dichloromethane leaf extracts showed a significant concentration-dependent inhibition of alpha-glucosidase activity (IC50= 3.73 and 21.28 mu g/ml, respectively). Both extracts also inhibited ribose-induced glycation of bovine serum albumin from 250 mu g/ml. Phytochemical analysis revealed the presence of chlorogenic acid and alpha-mangostin in the extracts. The extracts did not change HT-29 cell viability up to 250 mu g/ml, thus showing very low cytotoxicity.Conclusions The methanol leaf extract of T. africana inhibited alpha-glucosidase activity in a concentration-dependent manner, supporting the use of the leaves in traditional medicine to control hyperglycaemia. Chlorogenic acid and alpha-mangostin, the latter identified for the first time in this species, were found in the T. africana leaves. Further, in vivo studies and pilot clinical trials should be conducted using standardized T. africana leaf extracts to evaluate their potential effectiveness in diabetes mellitus.