Alpha-amylase and Alpha-glucosidase Inhibitory Activities of Philippine Indigenous Medicinal Plants

In the Philippines, medicinal plants still provide the first line of therapeutic remedies and their reported efficacy in traditional treatments provides an opportunity for drug discovery and development. The study aimed to evaluate in vitro commonly used Philippine medicinal plants for their alpha-amylase and alpha-glucosidase inhibitory activities as potential sources of antidiabetic agents. The study emphasised the inhibitory activities of 54 medicinal plants against α-amylase and α-glucosidase enzymes. The findings revealed 7 medicinal plants with the highest alpha-glucosidase inhibitory activity of ≥ 50% and 3 with alpha-amylase inhibitory activity of ≥ 20%. Ethyl acetate extract of Cycas sp. exhibited the highest α-glucosidase inhibitory activity with 83.87% ± 1.52 followed by the aqueous extract of cf. Calyptranthera sp. With 82.07% ± 0.14 with Acarbose as the reference standard (99.71% ± 0.63) at 10µg/mL (w/v) concentration. For the alpha-amylase inhibitory assay, the highest bioactivity was observed in ethyl acetate extract of Curcuma longa L. (39.44% ± 1.56) with Acarbose as the reference standard (51.59% ± 0.98) at 10µg/mL (w/v) concentration. These findings suggest the potential of the above-mentioned plants as sources of alpha-amylase and alpha-glucosidase inhibitors that may be used as antidiabetic agents.