In vitro inhibitory effects of methanol extracts of four Centaurea species on α-amylase and α-glucosidase

Aim: Medicinal plants have been used in traditional folk medicine for thousands of years against various diseases, including diabetes. Some Centaurea species are among these medicinal plants. The aim of this study was to scientifically and comparatively evaluate the antidiabetic activities of methanol extracts obtained from the capitulum and non-capitulum aerial parts of Centaurea cuneifolia, C. kilaea, C. solstitialis subsp. solstitialis and C. stenolepis against α-glucosidase and α-amylase for the first time except C. kilaea. Materials and Methods: Methanol extracts from Centaurea species were obtained by maceration method. Antidiabetic activity was performed by two known in vitro methods such as alpha-glucosidase and alpha amylase inhibitory activity. Results: Among the extracts, Centaurea cuneifolia capitula (CCC) and C. solstitialis subsp. solstitialis capitula (CSSC) methanol extracts with IC50 values of 164.30 and 463.70 μg/mL exhibited the best inhibitory activity against α-amylase and α-glucosidase enzymes. Conclusion: This is the first study on anti α-amylase and anti α-glucosidase activity of three Centaurea species except Centauera kilaea. These results indicate that CCC and CSSC have inhibitory effects against alpha amylase and alpha glucosidase. At the same time, the extracts were generally found to be active against the alpha amylase enzyme. In addition, it was found remarkable that only the capitulum of Centaurea species were effective against alpha glucosidase enzyme. However, in vivo studies are needed to fully reveal the antidiabetic effect and bioactivity-directed fractionation, and isolation studies are needed to reveal the compounds responsible for the antidiabetic effect.