干旱胁迫下黄芩代谢变化揭示药材活性成分复杂性的生物学本质

Biological Essence of Component Complexity in Herbal Medicine:Based on Changed Metabolism of Scutellaria baicalensis Under Drought Stress

目的:研究黄芩在干旱条件下的差异初生代谢和次生代谢产物含量变化的生物学本质。方法:利用超高液相色谱-电喷雾串联飞行时间质谱法(UHPLC-ESI-Q-TOF-MS/MS)分析代谢变化。结果:在干旱条件下黄芩根部得到具显著差异的化合物11种(VIP值≥2)。干旱条件下柠檬酸含量降低、莽草酸含量升高,表明在逆境条件下初生代谢减弱,次生代谢增强。在次生代谢产物中,干旱处理组通过生物合成和转化提高次生代谢产物的含量,调节各成分含量的比例,黄芩苷,汉黄芩苷,黄芩苷,汉黄芩素,白杨素,圣草酚,5,2’,6’-三羟基-7,8-二甲氧基黄酮,5,8-二羟基-6,7-二甲氧基黄酮,3,5,7,2’,6’-五羟基黄酮等生物活性和药理活性较强的多酚羟基的游离黄酮类化合物含量显著升高。黄芩大量的化合物犹如复杂的缓冲溶液,不断通过生物合成和转化来快速精确维持活性氧平衡,从而对不断变化的环境胁迫做出应答。该结果阐明了道地药材质量形成的本质和药材成分复杂的本质原因。结论:含量较低而活性较高的成分也是决定药材质量重要因素,高含量成分和高活性相结合可更好评价道地药材质量。

Objective:To investigate the biological essence of the content variation of differential primary and secondary metabolites in fresh roots of Scutellaria baicalensis under drought stress.Method:The changes of metabolites were analyzed by ultra-high-performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight mass/mass(UHPLC-ESI-Q-TOF-MS/MS).Result:A total of11 differential compounds were identified from the roots of S.baicalensis(VIP≥2).Under drought stress,citric acid content increased and shikimic acid content decreased,indicating that the drought stress weakened the primary metabolism but strengthened secondary metabolism.Drought stress raised the content and regulated the proportion of various secondary metabolites by modulating the biosynthesis and biotransformation of them.To be specific,the content of free flavonoids with many phenolic hydroxyl groups and high biological activity and pharmacological activity,such as baicalin,wogonoside,baicalein,wogonin,chrysin,eriodictyol,5,2’,6’-trihydroxy-7,8-dimethoxyflavone,5,8-dihydroxy-6,7-dimethoxyflavone,and 3,5,7,2’,6’-pentahydroxyflavanone,was significantly increased.The massive compounds,like an intricate buffer,maintain metabolism stable as quickly and accurately as possible through biosynthesis and biotransformation,thus responding to the changing environment,which reveals how the quality of genuine regional drugs is influenced and why compounds in herbal medicine are complex.Conclusion:Secondary metabolites with low content but high activity are important influencing factors of medicinal material quality and metabolites with high content and high activity are evaluation indicators of genuine regional drug quality.