Antibacterial Effects of Schisandra chinensis Extract on Escherichia coli and its Applications in Cosmetic

Schisandra chinensis (Turcz.) Baill (S. chinensis), an edible traditional medicine herb, has a strong constitution, which extract has good antibacterial activity. The study investigated its antibacterial properties on E. coli, to find a candidate for the development as new preservative. In vitro antibacterial assay showed that S. chinensis extract (SCE) effectively inhibited the growth of test bacteria with MBC of 18 mg/mL. In model cosmetic system of O/W emulsions, SCE possessed a great antibacterial capacity. The growth curves of E. coli treated with SCE exhibited an extended lag phase and restricted log phase. Scanning electron microscopy showed that the treated E. coli cells exhibited wrinkled and withered surfaces, and disappearing outmost layer, suggesting S. chinensis extract can damage S. aureus cell member and wall, in addition, the leakage of periplasm enzyme AKPase and the increased activities of Na+/K+-ATPase and Ca++-ATPase in cell membrane were also consistent with the microscopy results. Moreover, the S. chinensis extract can decrease the activities of dehydrogenase and total ATPase and the content of intracellular proteins, and bind with S. aureus DNA by electrostatic and groove binding. The results indicated that SCE might be a candidate cosmetic preservative for its good antibacterial activity and multiple targets on E. coli.