酶法与微生物转化制备稀有人参皂苷的研究进展

Research Progress on Enzymatic and Microbial Transformation for the Preparation of Rare Ginsenosides

摘要: 人参属植物中原人参二醇(PPD)型皂苷Rb1、Rb2、Rc、Rd等含量较高，而经逐步脱糖基生成的Compound K (CK)、Rg3、Rh2等稀有皂苷在植物体内仅以痕量存在。由于稀有皂苷口服后更易进入血液循环，且在抗炎、代谢调节和抗肿瘤等方面的报道日益增多，其高效制备方法已受到广泛关注。本文围绕PPD型皂苷的去糖基途径，系统综述了近十年来酶法、微生物全细胞发酵以及发酵联合商品酶等转化工艺的研究进展，并与酵母细胞工厂从头合成CK的路线进行了数量级对照。对其中的高滴度结果，补充了底物口径、酶的区域选择性与产酶调控方面的原因；并以专节讨论树脂层析、结晶和膜分离，以及不同上游工艺给下游带来的杂质和回收率问题。此外，本文还对稀有皂苷的产品标示规范、食品法规适用性以及罐内滴度与成品含量的区别等实际问题进行了讨论，并就Rb2/Rc侧链切割、异构体控制、食品级菌株开发等尚待解决的关键问题做了展望。

Abstract: Protopanaxadiol (PPD)-type ginsenosides such as Rb1, Rb2, Rc, and Rd are abundant in Panax species, whereas the rare ginsenosides generated by sequential sugar removal—compound K (CK), Rg3, and Rh2—occur only at trace levels in the plant. Because rare ginsenosides enter the circulation more readily after oral intake and have been increasingly studied for anti-inflammatory, metabolic, and antitumor activities, efficient preparation methods have attracted considerable attention. This review systematically summarizes advances over the past decade in enzymatic hydrolysis, whole-cell microbial fermentation, and fermentation-enzyme hybrid processes along the PPD deglycosylation pathway, and provides a scale comparison with de novo CK biosynthesis in engineered yeast. Record titers are further discussed in terms of substrate basis, enzyme regioselectivity and the regulation of enzyme formation. A separate section reviews resin chromatography, crystallization and membrane separation, together with the downstream consequences of different upstream processes. The review also addresses practical considerations including product labeling specifications, regulatory applicability in the food sector, and the distinction between broth titers and final product contents, and discusses outstanding challenges such as Rb2/Rc side-chain cleavage, stereochemical control, and development of food-grade strains.