In vitro α-glucosidase and α-amylase enzyme inhibitory effects and free radical scavenging activity of Garcinia schomburgkiana extracts

The genus Garcinia (Clusiaceae) is distributed in tropical and subtropical region of America, Africa and South East Asia. Garcinia schomburgkiana Pierre has been traditionally used for medicinal purposes as anti-inflammatory and anti- diabetic agent [1]. Thus, the aim of the present study was to evaluate the alpha α-amylase and alpha α-glucosidase inhibitory activities and in vitro antioxidant activities of the extracts. The plant extracts were examined using DPPH scavenging method, ABTS radical scavenging assay, and lipiperoxidation assay for antioxidant activity. The 80 % ethanolic extracts of G. schomburgkiana bark, leaves and fruits were prepared by sonication technique. The study revealed that the different parts of the plant extracts possessed the potent activities. The strongest activity of the extract was bark extract that exhibited significant α-amylase and α-glucosidase inhibitory activities with IC50 value of 20.04±1.33 µg / mL, 2.81±0.43 µg / mL, respectively and well compared with standard acarbose drug. For in vitro antioxidant activities, the bark extract exhibited IC50 value of 28.96±1.62 µg / mL, 9.79±0.14 µg / mL and 574.89±14.68 µg / mL for DPPH scavenging method, ABTS radical scavenging assay, and lipiperoxidation assay, respectively. Thus, the bark of G. schomburgkiana should be recommended as the high quality material for pharmaceutical and nutraceutical development in treatment of hyperglycemia, diabetes and the related condition of oxidative stress. The active compounds should be elucidated for standardization in the future study.