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Introduction: The correlation between the quality and geographical origin of herbal medicine was traced back to Tang Dynasty in China, more than 1200 years, and the effects of ecological environments on the secondary metabolites such as flavonoids have been confirmed. However, little is known about how the adversity impacts on the quality. Reactive oxygen species (ROS) may be medium between the ecological environment and the secondary metabolism., Materials and Methods: The fresh roots of Scutellaria baicalensis Georgi were treated with 0.002 μmol/L, 0.2 μmol/L, and 20 μmol/L H2O2, respectively. A stress model was established to elucidate the change of secondary metabolism, anti-oxidant enzyme system, and enzymes relating to flavonoids., Results: The activities of superoxide dismutase, catalase and peroxidase decreased. Too much H2O2, firstly, boosted transformation of flavonoids glycoside into aglucon with the most remarkable activities through UDP-glucuronate baicalein 7-O-glucuronosyltransferase (UBGAT), and β-glucuronidase (GUS), then regulated the gene expression of phenylalanine ammonialyase, GUS, and UBGAT, and increased the contents of flavones, motivated the flavonoid glycoside converting into aglucon. With this action, the flavones displaced the anti-oxidant enzymes. The higher the dosage, the more baicalein and wogonin increased, the later they took action., Conclusion: The plant secondary metabolites to keep ROS constant are identical to the effective materials in clinic. They are closely linked. H2O2 can improve flavones, especially the aglucon, and further increased the quality of herbal medicine, which possesses very important value in medical practice., Summary: H2O2 decreasing the activities of CAT and POD lead to accumulation of more H2O2. Excess of H2O2 up-regulated PAL, BUG, promote biosynthesis of flavones, and enhance the nonenzyme system. "↑" and "↓" represent activity or content "up" and "down" respectively.

Background: Nowadays, more and more herbal drugs of traditional Chinese medicine (TCM) rely on cultivation rather than natural resources because of overexploitation, and the study on quality of cultivated herbal medicines has become a hotspot in the research field of ecology of TCM resources. Though some of molecular biology techniques could improve the contents of secondary metabolites, those chemical compositions may differ from what we require from natural products, resulting in different treatment efficacy., Objective: To explore ways and means of improving TCM quality by means of regulating secondary metabolism from the perspective of natural physiological ecology., Materials and Methods: H(2)O(2) and paraquat as carriers of ROS, propyl gallate as a ROS scavenger, and ethephon as a ROS inductive agent were sprayed on Schisandra chinensis (Turcz.) Baill., Results: The hypo-concentration ROS could enhance the activities of POD, PPO, as well as CAT, and propyl gallate acted on the opposite side, but they all failed to break the homeostasis between ROS and oxidase activity and to exert any effect on the contents of the schisandrin, deoxyschizandrin, and schisandrin B. The hypso-concentration ROS could break the homeostasis, reduce the activities of POD, PPO, as well as CAT, and improve the quality of S. chinensis fruit. The ethephon could effectively improve the quality of S. chinensis without the limitation of metabolic regulation., Conclusion: The conclusions accord with the hypothesis that ROS regulates secondary metabolism.