The ginsenoside Rh2 (Rh2) is a saponin of medicinal ginseng, and it has attracted much attention for its pharmacological activities. In this study, we investigated the interaction of Rh2 with biological membranes using model membranes. We examined the effects of various lipids on the membrane-disrupting activity of Rh2 and found that cholesterol and sphingomyelin (SM) had no significant effect. Furthermore, the effects of Rh2 on acyl chain packing (DPH anisotropy) and water molecule permeability (GP₃₄₀ values) did not differ significantly between bilayers containing SM and saturated phosphatidylcholine. These results suggest that the formation of the liquid-ordered (Lo) phase affects the behavior of Rh2 in the membrane rather than a specific interaction of Rh2 with a particular lipid. We investigated the effects of Rh2 on the Lo and liquid-disordered (Ld) phases using surface tension measurements and fluorescence experiments. In the surface tension–area isotherms, we compared the monolayers of the Ld and Lo lipid compositions and found that Rh2 is abundantly bound to both monolayers, with the amount being greater in the Ld phase than in the Lo phase. In addition, the hydration state of the bilayers, mainly consisting of the Lo or Ld phase, showed that Rh2 tends to bind to the surface of the bilayer in both phases. At higher concentrations, Rh2 tends to bind more abundantly to the relatively shallow interior of the Ld phase than the Lo phase. The phase-dependent membrane behavior of Rh2 is probably due to the phase-selective affinity and binding mode of Rh2.

中文翻译：

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三萜皂甙人参皂甙 Rh2 在由鞘磷脂、磷脂酰胆碱和胆固醇组成的模型膜中有序和无序相中的行为

人参皂甙Rh2（Rh2）是药用人参的皂甙，因其药理活性而备受关注。在这项研究中，我们使用模型膜研究了 Rh2 与生物膜的相互作用。我们检查了各种脂质对 Rh2 的膜破坏活性的影响，发现胆固醇和鞘磷脂 (SM) 没有显着影响。此外，Rh2 对酰基链堆积（DPH 各向异性）和水分子渗透性（GP ₃₄₀值）在含有 SM 和饱和磷脂酰胆碱的双层之间没有显着差异。这些结果表明，液态有序 (Lo) 相的形成影响膜中 Rh2 的行为，而不是 Rh2 与特定脂质的特定相互作用。我们使用表面张力测量和荧光实验研究了 Rh2 对 Lo 和液体无序 (Ld) 相的影响。在表面张力-面积等温线中，我们比较了 Ld 和 Lo 脂质组合物的单层，发现 Rh2 与两个单层大量结合，Ld 相中的量比 Lo 相中的量大。此外，主要由 Lo 或 Ld 相组成的双层的水合状态表明，Rh2 在两相中都倾向于与双层表面结合。在较高浓度下，与 Lo 相相比，Rh2 倾向于更丰富地结合到 Ld 相的相对较浅的内部。Rh2的相位依赖性膜行为可能是由于Rh2的相位选择性亲和力和结合模式。