Alpha amylase inhibitors derived from plants pose a new commercial dimension in designing potent drug targets for the treatment of postprandialhyper glycemia (PPHG), a major concern for type-2 Diabetes. A large number of traditionally known medicinal plants are being screened for their natural amylase inhibitors. The present study was carried out to screen six ornamental plants wildly grown in tropical countries namely Catharanthus roseus, Cassia fistula, Hibiscus rosasinensis, Nyctanthes arbortristis, Pongamia pinnata and Rosa damascene for the availability of such alpha amylase inhibitors. Sequential solvent extraction of the leaves and flowers of the six plants was performed and a total of 60 extracts were evaluated for their alpha amylase inhibitory potential against porcine pancreatic alpha amylase using starch as substrate. Results from this study indicated that ten extracts have shown a maximum inhibition ranging from 75-92%. The methanol extract of the flowers of Rosa damascena exhibited a maximum inhibition of 92%. Concentration dependent inhibitory activity of this extract was performed with the concentrations ranging from 10-100μg/ml was performed and the IC50 value (the half maximal inhibitory concentration) was calculated and found to be 70.33+ 0.14 which is much less than that of the standard antidiabetic drug Acarbose which was calculated to be 83.23+ 0.34. Further sixteen extracts showed inhibition in the range 50- 75% and twenty seven extracts have shown inhibition in the range 30-55%. The other extracts also have shown inhibition but not statistically significant. The outcome of the present study gives a new dimension for further evaluation and isolation of effective alpha amylase inhibitors from these ornamental plants. Out of all the plants screened till now, Rosa damascena is suggested as a potent ornamental medicinal plant with efficient in-vitro amylase inhibitory potential.
