Comparative study of hypoglycemic and antibacterial activity of organic extracts of four Bangladeshi plants

Objective:To examine hypoglycemic and antibacterial activity against some Gram-positive and Gram-negative bacteria of organic extracts of four Bangladeshi plants.Methods:An in vivo hypoglycemic effect on mice model was used to check the hypoglycemic effect of four Bangladeshi herbal organic extracts viz.,roots of Curculigo recurvata W.T.Aiton(Satipata)(C.recurvata),leaf of Amorphophallus bulbifer Roxb.(Olkachu)(A.bulbifer),whole plant of Thunbergia grandiflora Roxb.(Nillata)(T.grandiflora)and leaf of Steudnera colocasiifolia K.Koch(Yunnan)(S.colocasiifolia)using glibenclamide as a positive control and water as a negative control.They were also tested for antibacterial activity on three Grampositive and four Gram-negative bacteria by disk diffusion method.C.recurvata,A.bulbifer and T.grandiflora were extracted with methanol and S.colocasiifolia was extracted with ethanol.Results:Among all the plant extract,only ethanol extract of S.colocasiifolia leaves at 800 mg/kg dose significantly(P<0.01)reduced fasting glucose level in normal mice as compared to standard drug glibenclamide(5 mg/kg).Ethanol extract of S.colocasiifolia leaves at 800 mg/kg dose decreased 20.28%of blood glucose level after 2 h of administration in normal mice,where glibenclamide decreased 39.63%.Methanol extract of T.grandiflora didn’t show any zone of inhibition against the tested bacteria,but other three extracts showed a wide range of zone of inhibition.However,none of the extract showed antibacterial activity against all the tested bacteria.Methanol extract of C.recurvata showed maximum zone of inhibition against Bacillus cereus[(10.50±0.50)mm],Salmonella typhi[(16.20±1.26)mm],Escherichia coli[(13.00±1.00)mm]and ethanol extract of S.colocasiifolia showed maximum zone of inhibition against Staphylococcus aureus[(11.20±1.26)mm],Bacillus subtilis[(12.00±0.50)mm],Salmonella paratyphi[(10.80±0.29)mm].Only methanol extract of A.bulbifer showed(8.50±0.50)mm and(7.20±0.76)mm zone of inhibition against Pseudomomas aeruginosa at 1000 and 800μg/disk dose respectively.Conclusions:Through our study,it was found that S.colocasiifolia could be considered as very promising and beneficial hypoglycemic agent.Although C.recurvata and S.colocasiifolia showed comparable high antibacterial activity,further studies should be needed to develop new antibacterial agent from them.S.colocasiifolia may be a potential source for the development of new oral hypoglycemic agent.