In vitro α-amylase inhibitory activity and in vivo hypoglycemic effect of methanol extract of Citrus macroptera Montr. fruit.

Objective: To investigate the therapeutic effects of methanol extract of Citrus macroptera Montr.fruit in α-amylase inhibitory activity (in vitro) and hypoglycemic activity in normal and glucose induced hyperglycemic rats (in vivo).

Methods: Fruits of Citrus macroptera without rind was extracted with pure methanol following cold extraction and tested for presence of phytochemical constituents, α-amylase inhibitory activity, and hypoglycemic effect in normal rats and glucose induced hyperglycemic rats.

Results: Presence of saponin, steroid and terpenoid were identified in the extract. The results showed that fruit extract had moderate α-amylase inhibitory activity [IC50 value=(3.638±0.190) mg/mL] as compared to acarbose. Moreover at 500 mg/kg and 1 000 mg/kg doses fruit extract significantly (P<0.05 and P<0.01 respectively) reduced fasting blood glucose level in normal rats as compared to glibenclamide (5 mg/kg). In oral glucose tolerance test, 500 mg/kg dose significantly reduced blood glucose level (P<0.05) at 2 h but 1 000 mg/kg dose significantly reduced blood glucose level at 2 h and 3 h (P<0.05 and P<0.01 respectively) whereas glibenclamide (5 mg/kg) significantly reduced glucose level at every hour after administration. Overall time effect is also considered extremely significant with F value=23.83 and P value=0.0001 in oral glucose tolerance test.

Conclusion: These findings suggest that the plant may be a potential source for the development of new oral hypoglycemic agent.