Antioxidant and antimicrobial activities of consecutive extracts from Galla chinensis:The polarity affects the bioactivities

The gallotannins of Galla chinensis (GAC) were extracted consecutively by five solvents of different polarity, and the antioxidant and antimicrobial activities of the extracts were evaluated. All of the ether-, ethyl acetate-, ethanol-, and water-extracts presented remarkable antioxidant abilities in the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, ferric reducing antioxidant power (FRAP), β-carotene linoleic acid system, and hydroxyl radical scavenging assays. The minimum inhibitory concentrations (MICs) of these extracts against 3 species of gram-positive bacteria, 3 species of gram-negative bacteria, and 3 species of fungi were also determined using the agar dilution method. All of the extracts showed excellent antibacterial activities, but no antifungal activities. The gallotannins in different extracts were analyzed by the HPLC and HPLC-ESI-MS. The results indicated that the extracts with weaker polarity contained gallotannins with higher molecular weight, and had stronger antioxidant and antibacterial activities.