Evaluation of the alpha-glucosidase and alpha-amylase inhibitory potential of the Costus speciosus (J. Koenig) Sm. harvested in Vietnam

Abstract

This study aimed to evaluate the inhibitory activity of α-glucosidase and α-amylase enzymes using aqueous and 40% ethanol extracts from the aerial parts of Costus speciosus harvested in Binh Phuoc province, tested in vitro. The enzyme inhibition activity was measured using α-amylase from porcine pancreas and α-glucosidase from Saccharomyces cerevisiae. Results showed that both the aqueous extract and the ethanol extract from the aerial parts of Costus speciosus showed significant α-glucosidase inhibition, with IC₅₀ values of 18.51 and 77.25 µg/ml, respectively. Both extracts demonstrated lower IC₅₀ values compared to the positive control, acarbose (IC₅₀=122.20 µg/ml). For α-amylase inhibition, the aqueous extract and ethanol extract exhibited relatively low inhibition rates of 3.79 and 3.12%, respectively, compared to acarbose, which had an IC₅₀ of 50 µg/ml for α-amylase inhibition. The study demonstrated that the aqueous and ethanol extracts of the Costus speciosus aerial parts exhibited in vitro inhibitory effects on α-glucosidase. However, the extracts showed poor inhibitory effects on α-amylase activity. These findings provide additional scientific evidence supporting the use of Costus speciosus in Vietnam for its hypoglycaemic properties.