influence of total anthocyanins from bitter melon (momordica charantia linn.) as antidiabetic and radical scavenging agents

the majority of the antioxidant and antidiabetic activities of fruits are anthocyanins, a group of polyphenolics that are responsible for the color of many fruits, vegetables and flowers. the harvesting time, storage conditions, maturity, extraction steps etc. are very important for the biological activities based on the alteration of chemical composition. the free radical scavenging and antidiabetic activities of total anthocyanins from bitter melon (momordica charantia linn.) fruit (tamc) were evaluated by considering four harvesting times. the free radical scavenging activities of the tamc samples were assessed using dpph•, dmpd•+ and abts•+ assays against bha, rutin and trolox standards. september as a harvesting period (tamc-s) had effective dpph• (sc50 2.55 ± 0.08 μg/ml), dmpd•+ (sc50 2.68 ± 0.09μg/ml) and abts•+ (sc50 8.19 ± 0.09 μg/ml) scavenging activities compared with other samples and standards. in addition, august (tamc-a) as a harvesting period showed very influential inhibitory activity against α-amylase (ic50 56.86 ± 1.12 μg/ml) and moderate inhibitory activity against α-glucosidase (ic50 88.19 ± 0.74 μg/ml). in comparison, pharmaceutical active ingredients such as acarbose exhibited anti-amylase and anti-glucosidase activities with ic50 values of 93.07 ± 1.49 μg/ml and 77.25 ± 1.20 μg/ml respectively. these results suggest that the correct selection of harvest period can significantly increase anthocyanin quantity because of the pharmaceutic properties of tamc. consequently, tamc may be interesting for incorporation in pharmaceutical preparations for human health, since it can suppress hyperglycaemia and it can be also used as food additives due to its antiradical activity.