Bio-assay guided isolation of alpha -glucosidase inhibitory constituents from Hibiscus mutabilis leaves.

摘要

Introduction - The increasing demand for natural-product-based medicines and health-care products for the management of diabetes encouraged investigation of this commonly available Indian plant. Objectives - To establish the anti-diabetic ( alpha -glucosidase inhibitory) activity of H. mutabilis leaf extract, isolate and identify the constituents responsible for the activity, and validate a HPLC method for quantification of the active constituents for standardisation of the extract. Material and methods - The methanolic extract of leaves was partitioned between water, n-butanol and ethyl acetate. Bio-assay guided fractionation, based on inhibition of alpha -glucosidase, allowed isolation and identification of the active components. The active components were quantified using RP-HPLC-DAD validated for linearity, limit of detection, limit of quantification, precision, accuracy and robustness for this plant extract and the partitioned fractions. Results - Ferulic acid and caffeic acid were identified as the alpha -glucosidase inhibitors present in H. mutabilis. They were partitioned into an ethyl acetate fraction. The HPLC-DAD calibration curve showed good linearity (r2