The Antioxidant Activity Of Endophytic Fungus Of Rhodiola Sp.and Effect On Accumulation Of Main Bioactive Components Of Their Hosts

Rhodiola. L, a traditional and emerging medicinal plant, grows in the environment of hypoxia, cold, intense ultraviolet radiation at the 2,500 m height above sea level, which as a valuable research resource has the unique antioxidant and anti-hypoxic activity. This study was aimed to screening the antioxidant of 168 fungus and their metabolites from four main Rhodiola species which came from two major distribution areas, Northeast and the Tibetan Plateau of China. It was also studied that accumulation of main active compounds in Rhodiola seedling co-cultured with endophytic fungi.The results showed that there were a large scale of endophytic fungus with antioxidant in Rhodiola plants. Sixty-two (37%) endophytic fungus had DPPH radical scavenging ability above 70%, and 18%,4%,15%,3% of fungus had above 70% of hydroxyl radical scavenging, Fe2+ chelating, superoxide radical scavenging and nitride clearing. Among them, six endophytic fungus, Ra-R-32, ZPRa-R-1, Rb-R-1, Rc-L-2, Rs-R-15, ZPRs-S-13, had remarkable antioxidant capacity. Their concentrations for 50% maximal effect (IC50) were 1.54,1.41,3.03,0.24 and 1.91 mg/mL, respectively. However, IC5o of positive control were 0.32,2.72,9.68,0.59 and 1.70 mg/mL, respectively.To study the changing of active components in Rhodiola plants, HPLC was applied to analyze the chemical composition in every material. The results showed that, among rhizomes of four Rhodiola species, the content of salidroside,p-tyrosol, rosarin, rosavin and rosin of R.sachalinensis were more higher than that in other kinds, they were 13.6949,1.6389,0.1705, 0.0137,0.9564 mg/g; among different parts in R.crenulata, the content of salidroside in rhizome was the highest, and it was 7.2648 mg/g. The content of p-tyrosol in flower was the highest, and it reached 11.1653 mg/g. The content of rosarin, rosavin and rosin was the highest in leaf, and they were 0.0439,0.0853,0.0769 mg/g, respectively. In callus, the contents of salidroside and p-tyrosol were 0.0172,0.3324 mg/g, and 0.0223,0.1266 mg/g, respectively, and both lower than that in wild Rhodiola. L. With the re-culture of tissue culture seedling, the content of every five main components was sharply decreasing during the first two generations, and they were increase in the fourth generation, and they were keeping stable after the sixth generation.The chemical changing of host plant was studied by inoculating endophytic fungi. The accumulation of salidroside and p-tyrosol in culture were drop in first three days, then rose at the fourth day. The contents of salidroside and p-tyrosol were increasing at the sixth day, and they reached 0.0163、0.3207 mg/g, respectively. In the tenth day, the culture seedling was dead with a low content of salidroside and p-tyrosol for 0.0110 and 0.3118 mg/g, respectively.