Phenolic acid compounds from Phellodendron chinense and their activity on α-glucosidase inhibition

The non-alkaloid chemical constituents of dried Phellodendron chinense barks were investigated. A total of 14 phenolic compounds (1-14) were isolated from the 95% ethanol extract of Phellodendron chinense by the utilization of silica gel, medium pressure liquid chromatography, Sephadex LH-20 column chromatography, and preparative liquid chromatography. Among of the isolated compounds, isophellolactone (1) was identified as a new compound. The isolated 14 compounds were further tested the activity on α-glucosidase inhibition. The results for the first time demonstrated that quininic acid ester 3-6 and 8 exhibited good α-glucosidase inhibitory activity. Polyhydroxy hexa-membered carbon ring in quinine ester derivatives is possibly the essential group for the α-glucosidase inhibitory activity.