Phytochemical compositions, antioxidant and antimicrobial activities analysis of extracts from Vaccinium bracteatum Thunb. leaves

Vaccinium bracteatum Thunb. is an edible plant, which has been used for many food products and is also a resource of traditional Chinese medicine. In this study, the antioxidant and antimicrobial activities of ethanol extracts from its leaves were investigated. To study the characteristic compositions, twelve compounds of extracts accumulated by the D-101 macroporous adsorption resin (VBE) were identified by HPLC-DAD and HPLC-ESI/MS techniques, including chlorogenic acid and its isomers, and eight flavonoid compounds. The contents of total flavonoids, orientin and isoorientin in the accumulated part were 601.4, 44.7, and 96.1 mg/g, respectively, which were far more than that in the raw materials. Furthermore, the antioxidant activities were estimated by DPPH, ABTS, and FRAP assays, which showed that the high content accompanied with strong antioxidant activities. Besides, compared to the same type of bamboo leaves (AOB), the accumulated part possesses better activities. At the last, the antimicrobial activities of VBE were assessed by a serial two-fold dilution assay, the results showed that it had good antimicrobial activities. Taken together, extracts from Vaccinium bracteaturn Thunb. leaves have better antioxidant activities, which can be used as a natural antioxidant.