Alpha glucosidase inhibitory effect, anti-microbial activity and UPLC analysis of Rhus verniciflua under various extract conditions

In the present study, crude extract of Rhus verniciflua stem was screened for its alpha-glucosidase inhibitory effects and anti-microbial activity using different extraction ratios of water to alcohol. Ultra performance liquid chromatography (UPLC) was used to quantify compounds (fustin, gallic acid, 3', 4', 7-trihydroxyflavone, and fisetin). Ethanolic extract showed higher alpha-glucosidase inhibitory effect than methanolic extract, whereas distilled water extract did not inhibit alpha-glucosidase at all. Especially, neat alcoholic (methanolic or ethanolic) extracts exhibited stronger inhibitory activities compared to their corresponding aqueous mixtures. Analysis of the UPLC chromatogram showed that fustin (from 28.5 to 151.7 mg/g extract) was the major compound of R. verniciflua stem. One-hundred percent ethanolic extracts produced inhibition zones against Staphylococcus aureus with the largest diameters (15 mm). The result from this study provides suitable support for the use of R. verniciflua in the treatment of diabetes and for the control of infectious disease caused by S. aureus.