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目的研究黄芩愈伤组织中多酚氧化酶活性变化规律及其与黄芩苷次生合成之间的关系。方法采用紫外分光光度法测定多酚氧化酶活性,采用高效液相色谱法测定黄芩苷的量。研究不同添加物(抗坏血酸、氯化钠、苯甲酸、聚乙烯吡咯烷酮、硫酸铜)对多酚氧化酶和黄芩苷量的影响。结果在黄芩愈伤组织生长周期的前20 d,黄芩苷基本没有合成,多酚氧化酶的活性低水平表达;20～35 d,黄芩苷大量合成,多酚氧化酶的活性有所降低,但降低趋势较小;35～50 d,多酚氧化酶活性高水平表达,黄芩苷次生合成受到抑制。结论多酚氧化酶的高水平表达不利于黄芩苷的次生合成,抗坏血酸、氯化钠、苯甲酸等均可抑制多酚氧化酶的活性,促进黄芩苷次生合成,其中以添加0.02%的抗坏血酸效果最为明显,可使黄芩苷的量提高17.6%(82.3 mg/g),而聚乙烯吡咯烷酮、硫酸铜对多酚氧化酶的活性有着明显的促进作用,抑制了黄芩苷的积累。
Objective To study the changes of polyphenol oxidase activity in callus of Scutellaria baicalensis Georgi and its relationship with the secondary synthesis of baicalin. Methods The activity of polyphenol oxidase was determined by ultraviolet spectrophotometry. The content of baicalin was determined by high performance liquid chromatography. The effects of different additives (ascorbic acid, sodium chloride, benzoic acid, polyvinylpyrrolidone and copper sulfate) on the contents of polyphenol oxidase and baicalin were studied. Results In the first 20 days of the growth period of Scutellaria baicalensis, there was no synthesis of baicalin and the expression of polyphenol oxidase was low. From 20 to 35 days, baicalin was synthesized in a large amount and the activity of polyphenol oxidase decreased. The trend of decrease was small. From 35 to 50 d, the polyphenol oxidase activity was expressed at high level and the secondary synthesis of baicalin was inhibited. Conclusion The high level expression of polyphenol oxidase is not conducive to the secondary synthesis of baicalin. Ascorbic acid, sodium chloride and benzoic acid can inhibit the activity of polyphenol oxidase and promote the secondary synthesis of baicalin. The addition of 0.02% Ascorbic acid has the most obvious effect, which can increase the amount of baicalin by 17.6% (82.3 mg / g), while polyvinylpyrrolidone and copper sulfate have a significant promoting effect on the activity of polyphenol oxidase and inhibit the accumulation of baicalin.