Department of Agricultural Chemistry, National Taiwan University, Taipei 10617, Taiwan.
School of Food Safety, Taipei Medical University, Taipei 11042, Taiwan.
J Agric Food Chem. 2020 Jun 10;68(23):6430-6438. doi: 10.1021/acs.jafc.0c01616. Epub 2020 May 27.
The conversion of sesame lignans is of interest because the derived products may have potential applications. Here, in investigating the transformation of sesamin and sesamolin, main endogenous sesame lignans in sesame seeds, in both acidic aqueous and anhydrous systems, 7,7'-samin was identified as one of the major products of sesamolin in both systems catalyzed with common inorganic acids, but sesaminol was not generated. In investigating the effect of different oxidizing agents on the acid-catalyzed conversion of sesame lignans, 7,7'-samin was still the major product of sesamolin, whereas sesamolin as well as 7,7'-samin stereoselectively rendered 7,7'-samin in the presence of hydrogen peroxide. Hydrogen peroxide may play a role in stabilizing the transitional oxonium ions, derived from acid hydrolysis of sesamolin or 7,7'-samin by forming a seven-membered ring intermediate through hydrogen bonding, to consequently produce 7,7'-samin as the final product.
芝麻木脂素的转化很有意义，因为其衍生产品可能具有潜在的应用。在这里，我们研究了芝麻素和芝麻林素这两种芝麻种子中主要的内源性芝麻木脂素在酸性水相和无水体系中的转化。结果表明，在这两种体系中，均以常见无机酸为催化剂，芝麻林素转化的主要产物之一是 7,7'-芝麻林醇，但并未生成芝麻醇。在研究不同氧化剂对酸催化芝麻木脂素转化的影响时，7,7'-芝麻林醇仍然是芝麻林素的主要产物，而过氧化氢的存在使得芝麻林素和 7,7'-芝麻林醇立体选择性地生成 7,7'-芝麻林醇。过氧化氢可能通过氢键形成七元环中间体，稳定酸水解生成的过渡态氧鎓离子，从而生成 7,7'-芝麻林醇作为最终产物。
