Identification of gallicin from Myricaria laxiflora and its antibiotic & antioxidant activity

Myricaria Laxiflora is a rare and endangered riparian shrub in Three Gorges zone, China. Locally, the plants are widely used as a traditional herbal medicine for scald and arthritis, but the pharmacological activity has not been elucidated, and the mechanism was far from clear. In order to explore the possible pharmacological mechanism, 6 compounds were extracted here by chloroform in the 95% ethanol precipitation under different pH value. After investigation of the antimicrobial activity in vitro through eight microorganisms, we found the compounds in different pH condition showed specific inhibitory activity to bacteria and fungus. In pH=7 extract, we isolated a gallic acid derivant named methyl 3-hydroxy-4,5-dimethoxybenzoate (gallicin) by 1D, 2D NMR and MS identification, and this compound showed obvious antimicrobial activities. The minimum inhibitory concentration of this compound was 5 mg/ml against Staphylococcus aureus and Rhizopus, and 10 mg/ml against E. coli. Furthermore, just like propyl gallate, gallicin showed fairly active for oxidation resistance in the presence of H₂O₂.