Antimicrobial activity of saponin-rich fraction from Camellia oleifera cake and its effect on cell viability of mouse macrophage RAW 264.7

BACKGROUND: As a by-product of oil production, several million tons of Camellia oleifera cake is discarded every year in China. The aim of this study was to evaluate the antimicrobial activity of a saponin-rich fraction isolated from C. oleifera cake and investigate its effect on the cell viability of RAW 264.7, a macrophage-like cell line present in almost all mouse tissues. RESULTS: The saponin-rich fraction was isolated from C. oleifera cake in several steps and had a saponin content of 95.42 +/- 0.10% (w/w). It showed significant inhibitory activity against the bacteria Staphylococcus aureus, Escherichia coli and Bacillus subtilis and the fungi Mucor racemosus, Aspergillus oryzae, Rhizopus stolonifer, Saccharomyces cerevisiae and Penicillium glaucum, with minimum inhibitory concentrations of 31.3, 31.3, 62.5, 250, 250, 250, 31.3 and 125 mu g ml-1 respectively. In addition, mouse macrophage RAW 264.7 pretreated with the saponin-rich fraction (80200 mu g mL-1) exhibited a significant loss of cell viability in a dose-dependent manner. CONCLUSION: These results may be useful for the future application of saponins from C. oleifera cake. However, the potential use of the saponin-rich fraction as an antimicrobial agent should be decided according to the target micro-organisms in order to avoid causing harm in humans. Copyright (c) 2012 Society of Chemical Industry