Quantification of antidiabetic extracts and compounds in bitter gourd varieties

Several studies have shown blood glucose lowering effects of bitter gourd compounds. Previous experiments with db/db mice revealed that the lipid and the saponin extracts are more effective in lowering glycated haemoglobin levels and excessive body weight gain than the hydrophilic extract or the whole fruit. Therefore, saponin, lipid, and hydrophilic extracts were quantified in bitter gourd varieties using a modified extraction method. Fatty acids were quantified via gas chromatography mass spectrometry. Saponins were quantified photometrically using their haemolytic properties. White bitter gourd varieties were found to contain significantly lower saponin concentrations (0.25%) compared to green varieties (0.67%). The lipid extract contained high amounts of conjugated linoleic and linolenic acids (up to 65.89%). Quantification of the most effective antidiabetic compounds in bitter gourd varieties may help to identify the most effective varieties and to establish the bitter gourd or bitter gourd extracts as effective blood glucose lowering dietary components or supplements. (C) 2010 Elsevier Ltd. All rights reserved.