EFFECT OF PEG ON SECONDARY METABOLITES IN SUSPENSION CELLS OF SCUTELLARIA BAICALENSIS GEORGI

Bin Wang^{1, 2}, Teng-Xiao Zhang², Hong-Wei Du¹, Qian Zhao¹, Xiang-Cai  Meng^{1, *}

¹Department of Pharmacognosy, Heilongjiang University of Chinese Medicine, 24 Heping Road, 150040, Harbin, China - ²School of Food and Pharmaceutical Engineering, Suihua University, No. 18, Huanghe  South Road, 152061, Suihua, China

Introduction: Many factors in nature can affect the normal growth and development of plants. Some adversity factors, such as high temperature and drought, can even lead to plant death due to the emergence of a large number of ROS, which can damage the basic component needed for life. ROS are the initial products of environmental stress and the main substances inducing secondary metabolism of plants. ROS may be the primary trigger promoting the quality formation of medicinal materials. The industrial biosynthesis of secondary metabolites in medicinal plants provided an unprecedented possibility for the large-scale production of active components. Using suspension cells of S. baicalensis as carrier to study the effect of PEG on secondary metabolism and the relationship between related antioxidant enzymes, the activity and gene expression of key enzymes in flavonoids synthesis can provided theoretical basis for the production of flavonoids.

Case Presentation: Different concentrations of PEG-6000 were added to the suspension cell culture system of Scutellaria baicalensis Georgi, shaking culture for 0-96 h and sampling regularly, for determination of O₂^- and H₂O₂ contents, antioxidant enzyme activities, phenylalanine ammoniayase(PAL) activities and gene expression, and the content of flavonoids.The results showed that PEG stress broke the balance of ROS, increased the activities of antioxidant enzyme SOD, CAT, POD, and increased the expression and activity of PAL, with a result of accumulation of flavonoids, the contents of baicalin, wogonoside, baicalein, and wogonin being increased by 17.51%%, 2.71%, 93.00%, and 64.29% for 4%PEG at 24 h respectively, most notably from the aglucons with high activities. 

Conclusion: A dynamic balance system of ROS-antioxidant enzyme-secondary metabolites (flavonoids) existed in suspension cells of S. baicalensis, and they affect each other. PEG treatment of S. baicalensis suspension cells could significantly promoted the bio-synthesis and accumulation of flavonoids to supplement the elimination of ROS by antioxidant enzymes.

Abbreviations: PEG: polyethylene glycol, ROS: Reactive oxygen species, SOD: Superoxide dismutase, CAT: Catelase, POD: Peroxidase, PAL: phenylalanine ammoniayase.