Factors Affecting Flavonoid Compound Accumulation Of Orostachys Cartilagineus Calluses

Orostachys cartilagineus is a herbaceous and medicinal plant,which belongs to the Crassulaceae family.Flavonoid compound is one of main chemical constituents of Orostachys（DC.）Fisch.plants.A large market demand exists for Orostachys products.However,the raw material for their production is deficiency due to the shortage of wild resource and the problems of artificial cultivation.Therefore,the cells cultured by using the method of plant cell culture as a new material source has an important meaning.In the present study,several factors affecting flavonoids compound accumulation during callus culture were investigated to provide a theoretical basis for further commercial production of O.cartilagineus products.The present study used the uniform design method to combine different groups of MS medium strength and concentrations of 6-BA and NAA,the effects of the combination groups on contents and productivities of total flavonoids and their monomers including quercetin,kaempferide,epicatechin gallate,quercetin 3-O-glucoside and kaempferol-3-O-rutinoside in callus were investigated.A combination group of MS 1×,3.5 mg·L^-1 6-BA,and 0.1 mg·L^-1 NAA was the most favorable for flavonoid accumulation.The concentrations of phosphorus,NH4+/NO3-ratio,and sucrose in culture medium also had important influences,the maximum flavonoids contents and productivities were found at 0.75 mM phosphorus,30/30 mM of NH4+/NO3-ratio,and 40 g·L^-1 sucrose.During callus bioreactor culture,the study of callus growth kinetics indicated that the maximum callus biomass and flavonoid content and productivity were determined at 25 d.Additionally,air volume effects were also investigated and found that 150 mL·min-1 was the suitable air volume.Bioreactor cultured O.cartilagineus calluses possessed a higher antioxidant properties,the radical scavenging spectrum by ESR determination showed the DPPH radical scavenging activities exceeded 80%when extract concentrations were higher than 0.125 mg·mL^-1 and the alkyl radical scavenging activity reached 91.9%at 1 mg·mL^-1 of the callus extract.