Onoda Keita, Kato Mai, Tsunematsu Yuta, Eto Fumihiro, Sato Michio, Yoshioka Yasukiyo, Yoshida Takuya, Tamura Kentaro, Yao Ikuko, Dohra Hideo, Watanabe Kenji, Miyoshi Noriyuki
Graduate School of Integrated Pharmaceutical and Nutritional Sciences, University of Shizuoka, Shizuoka 422-8526, Japan.
Department of Optical Imaging, Hamamatsu University School of Medicine, Hamamatsu 431-3192, Japan.
J Agric Food Chem. 2023 Mar 15;71(10):4292-4297. doi: 10.1021/acs.jafc.2c08478. Epub 2023 Feb 8.
Diosgenin is an aglycone of dioscin, a major bioactive steroidal saponin found in plants, including Himalayan Paris (), fenugreek (), and yam ( spp.). We have previously demonstrated that a species of natural yam, , contains a promising bioactive compound diosgenin, which induces anti-carcinogenic and anti-hypertriacylglycerolemic activities. Here, we found for the first time that Japanese yam () bulbils are richer in diosgenin than the edible tubers (rhizomes) and leaves. LC-MS and imaging-MS analyses revealed that diosgenin accumulated in the peripheral region of bulbils. Additionally, we performed RNA-seq analysis of , and multiple sequence alignment identified (CYP90), the orthologous gene of CYP90G4 in , CYP90B50 in , CYP90G6 in , and CYP90G in , which encodes a diosgenin biosynthetic rate-limiting enzyme. The expression levels of CYP90 were significantly upregulated in bulbils than in its rhizomes and leaves. Since diosgenin is one of the most promising functional food factors executing several favorable bioactivities, bulbils rich in diosgenin would be a beneficial natural resource.
薯蓣皂苷元是薯蓣皂苷的苷元，薯蓣皂苷是一种主要的生物活性甾体皂苷，存在于多种植物中，包括重楼（）、胡芦巴（）和山药（薯蓣属 spp.）。我们之前已证明，一种天然山药，含有一种有前景的生物活性化合物薯蓣皂苷元，其具有诱导抗癌和抗高甘油三酯血症的活性。在此，我们首次发现日本薯蓣（）的珠芽中薯蓣皂苷元的含量比可食用块茎（根茎）和叶子更高。液相色谱 - 质谱联用（LC - MS）和成像质谱分析表明，薯蓣皂苷元在日本薯蓣珠芽的外周区域积累。此外，我们对日本薯蓣进行了RNA测序分析，多重序列比对鉴定出（CYP90），它是重楼中CYP90G4、中CYP90B50、中CYP90G6和中CYP90G的直系同源基因，编码一种薯蓣皂苷元生物合成限速酶。CYP90在日本薯蓣珠芽中的表达水平显著高于其根茎和叶子。由于薯蓣皂苷元是最有前景的功能性食品因子之一，具有多种有益的生物活性，富含薯蓣皂苷元的日本薯蓣珠芽将是一种有益的自然资源。
