Bidirectional solid fermentation using Trametes robiniophila Murr. for enhancing efficacy and reducing toxicity of rhubarb(Rheum palmatum L.)

Objective: To investigate the potential of bidirectional solid fermentation of rhubarb(Rheum palmatum L.) for reducing its toxicity and enhancing its medicinal efficacy.Methods: The fungus Trametes robiniophila Murr. was inoculated into rhubarb. The chemical ingredients as well as antioxidant, antibacterial, and anticancer activities of fermented and unfermented rhubarb extracts were then determined.Results: After fermentation, levels of anthraquinone glycosides(purgative ingredients)decreased significantly, while the level of anthraquinone aglycone increased. The level of gallic acid was also reduced after fermentation. Ethanol extract of rhubarb(0.8 mg/m L) exhibited DPPH-scavenging activity of 7.6% ± 0.8%, while the blank control(0.8 mg/m L rhubarb)showed 31.3% ± 2.0% activity. Antibacterial activities in fermented samples were found to be enhanced compared with unfermented samples and anticancer activity was evident at concentrations of 2000 and 5000 mg/m L.Conclusion: Bidirectional solid fermentation appears to be an effective processing method that can be used to improve the efficacy and reduce the toxicity of rhubarb.