Rare dehydrated ginsenosides barely exist in natural ginseng plants. Herein, the confined microwave technique was utilized to transform the main ginsenosides of Panax notoginseng leaves (PNL) into dehydrated ginsenosides. The main microwave-treated products of dried PNL are dehydrated ginsenoside Rk1, Rg5, notoginsenoside SFt3, and SFt4. Comparatively, the main microwave-treated products of water preimmersed PNL are dehydrated ginsenoside Rk2, Rh3, notoginsenoside SFt3, and SFt4. The impacts of solvent, solid–liquid ratio, microwave temperature and duration on the yield of dehydrated ginsenosides were explored. Based on theoretical calculation, primary ginsenosides in water preimmersed PNL are more prone to deglycosylation at the C-20 site and dehydration elimination reactions at the side chain during microwave treatment. Moreover, reference compounds were used to verify ginsenoside transformation pathway, and the dehydrated ginsenosides were individually purified and identified. In short, this study elucidates novel approach for preparing rare Δ20(21)- and Δ20(22)-dehydrated protopanoxadiol ginsenosides.

中文翻译：

---

密闭微波驱动转化法从三七叶制备稀有脱水原人参皂甙


稀有的脱水人参皂甙几乎不存在于天然人参植物中。在此，利用限制微波技术将三七叶 （PNL） 的主要人参皂甙转化为脱水的人参皂甙。干燥 PNL 的主要微波处理产品是脱水人参皂苷 Rk1、Rg5、三参皂苷 SFt3 和 SFt4。相比之下，水预浸 PNL 的主要微波处理产品是脱水人参皂苷 Rk2、Rh3、三参皂苷 SFt3 和 SFt4。探讨了溶剂、固液比、微波温度和持续时间对脱水人参皂苷产量的影响。根据理论计算，水预浸 PNL 中的伯人参皂苷在微波处理过程中更容易在 C-20 位点发生糖基释放和侧链脱水消除反应。此外，使用参比化合物验证人参皂苷转化途径，并单独纯化和鉴定脱水人参皂甙。简而言之，本研究阐明了制备稀有 Δ20（21） 和 Δ20（22） 脱水原羟基二醇人参皂苷的新方法。