Several studies have suggested that some kind of Dioscorea species (yam) or yam-contained herbal medicines have cognitive enhancement effect. However, it has been unknown what is a crucial factor for cognitive enhancement in each Dioscorea species. In this study, we aimed to investigate whether one of the main and brain-penetrating components in yams, diosgenin, can be a novel criterion to assess memory enhancement effect of yam extracts. Although our previous studies showed that administration of diosgenin or diosgenin-rich yam extract enhanced cognitive function in normal mice and healthy humans, we have never evaluated whether the effect depends on diosgenin content or not. Therefore, we compared memory enhancement effects of low diosgenin-contained general yam water extract with diosgenin-rich yam extract on cognitive function in normal mice. We found that unlike diosgenin-rich yam, administration of general yam water extract did not enhance object recognition memory in normal mice. LC–MS/MS analyses revealed that after administration of general yam, diosgenin concentration in the brain did not reach to the effective dose because of the low diosgenin content in the original yam extract. On the other hand, when diosgenin was artificially added into general yam, the extract showed memory enhancement in normal mice and promoted neurite outgrowth in neurons. Our study suggests that diosgenin is actually an active compound in yams for memory enhancement, and diosgenin content can be a criterion for predicting cognitive enhancement effect of yam extracts.

多项研究表明，薯Di（山药）或含山药的草药具有认知增强作用。然而，未知每个薯Di中增强认知的关键因素是什么种类。在这项研究中，我们旨在调查薯ms中薯and皂甙元是否是山药中的主要成分和渗透脑的成分之一，可以作为评估山药提取物记忆增强作用的新标准。尽管我们先前的研究表明，施用薯os皂甙元或富含薯os皂甙元的山药提取物可增强正常小鼠和健康人的认知功能，但我们从未评估过这种作用是否取决于薯os皂甙元的含量。因此，我们比较了含有薯di皂甙元的普通山药水提取物与富含薯gen皂甙元的山药提取物对正常小鼠认知功能的记忆增强作用。我们发现，与富含薯os皂甙元的山药不同，普通山药水提取物的施用不会增强正常小鼠的对象识别记忆。LC-MS / MS分析表明，服用普通山药后，脑中薯os皂素的浓度未达到有效剂量，因为原始山药提取物中薯os皂素的含量低。另一方面，当将薯os皂甙元人工添加到普通山药中时，提取物在正常小鼠中显示出记忆增强，并促进了神经元中的神经突生长。我们的研究表明，薯os皂甙元实际上是山药中用于增强记忆力的活性化合物，薯di皂甙元的含量可以作为预测山药提取物认知增强作用的标准。