Journal of Natural Medicines ( IF 2.5 ) Pub Date : 2022-01-27 , DOI: 10.1007/s11418-021-01589-9 Kritamorn Jitrangsri 1 , Kazuaki Kamata 2 , Mana Akiba 2 , Yoshie Yajiri 2 , Masami Ishibashi 1 , Jin Tatsuzaki 2 , Tsutomu Ishikawa 2
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18α-Glycyrrhizin is an epimer of 18β-glycyrrhizin, a major component of licorice (Glycyrrhiza sp.), which is widely used as a traditional medicine. Whether 18α-glycyrrhizin is a real natural product has been debated in the long history of glycyrrhizin chemistry because 18β-glycyrrhizin is epimerizable to a more thermodynamically stable 18α-glycyrrhizin under aqueous alkali conditions. We improved the preparation of 18α-glycyrrhizin from 18β-glycyrrhizin by successive epimerization reactions of 18β-glycyrrhizin, trimethyl esterification of the resulting epimerized mixture, and alkaline hydrolysis of a purified 18α-glycyrrhizin trimethyl ester. Approaches to the possible presence of 18α-glycyrrhizin in licorice extracts by HPLC using synthetic 18α-glycyrrhizin as a positive standard strongly suggested that 18α-glycyrrhizin could naturally exist as a minor congener of glycyrrhizin derivatives in Glycyrrhiza species.
Graphical abstract
中文翻译：
18α-甘草甜素是真正的天然产物吗？改进从 18β-甘草甜素制备 18α-甘草甜素作为 HPLC 分析甘草提取物的阳性标准
18α-甘草甜素是18β-甘草甜素的差向异构体，是甘草的主要成分（Glycyrrhizasp.)，它被广泛用作传统药物。18α-甘草甜素是否是真正的天然产物在甘草甜素化学的悠久历史中一直存在争议，因为在碱性水溶液条件下 18β-甘草甜素可差向异构化为热力学更稳定的 18α-甘草甜素。我们通过 18β-甘草甜素的连续差向异构反应、所得差向异构混合物的三甲酯化和纯化的 18α-甘草甜素三甲酯的碱性水解改进了从 18β-甘草甜素制备 18α-甘草甜素的方法。使用合成的 18α-甘草甜素作为阳性标准，通过 HPLC 分析甘草提取物中可能存在 18α-甘草甜素的方法强烈表明，18α-甘草甜素可以作为甘草中甘草甜素衍生物的次要同源物自然存在物种。
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