College of Biosystems Engineering and Food Science, National-Local Joint Engineering Laboratory of Intelligent Food Technology and Equipment, Key Laboratory for Agro-Products Nutritional Evaluation of Ministry of Agriculture and Rural Affairs, Key Laboratory of Agro-Products Postharvest Handling of Ministry of Agriculture and Rural Affairs, Zhejiang Key Laboratory for Agro-Food Processing, Zhejiang International Scientific and Technological Cooperation Base of Health Food Manufacturing and Quality Control, Zhejiang University, Hangzhou 310058, China; Fuli Institute of Food Science, Zhejiang University, Hangzhou 310058, China; Ningbo Research Institute, Zhejiang University, Ningbo 315100, China.
College of Biosystems Engineering and Food Science, National-Local Joint Engineering Laboratory of Intelligent Food Technology and Equipment, Key Laboratory for Agro-Products Nutritional Evaluation of Ministry of Agriculture and Rural Affairs, Key Laboratory of Agro-Products Postharvest Handling of Ministry of Agriculture and Rural Affairs, Zhejiang Key Laboratory for Agro-Food Processing, Zhejiang International Scientific and Technological Cooperation Base of Health Food Manufacturing and Quality Control, Zhejiang University, Hangzhou 310058, China; Fuli Institute of Food Science, Zhejiang University, Hangzhou 310058, China; Ningbo Research Institute, Zhejiang University, Ningbo 315100, China.
Food Chem. 2020 Dec 15;333:127430. doi: 10.1016/j.foodchem.2020.127430. Epub 2020 Jun 30.
Phytosterols (PS) are a group of sterols distributed in foods and plants, where it is prone to oxidation. In this work, we studied the reaction mechanism of phytosterols, using density functional theory (DFT) calculation and experimental methods to study the photooxidation of phytosterols. Under LED light illumination, experimental photooxidation of these phytosterols gives rise to the prior three kind oxides of phytosterol: 6α-OH, 7α-OH, and 7β-OH. The mechanistic investigations by DFT suggest that singlet oxygen (O)-mediated photooxidation (Type II mechanism) generated radical adds to the C5 and C6 on the B Ring of steroid nucleus and reaction in C7 initiated from C5 products through rearrangement pathway. Furthermore, the stereoselectivity at C5, C6 and C7 provides a mechanistic guide for phytosterols photooxidation. These efforts are expected to serve as an essential exploratory study for the oxidation mechanism of phytosterols in the complex food matrix and antioxidation technology for phytosterols.
植物甾醇（PS）是一组分布在食物和植物中的甾醇，容易发生氧化。在这项工作中，我们使用密度泛函理论（DFT）计算和实验方法研究了植物甾醇的反应机制，研究了植物甾醇的光氧化。在 LED 光照射下，这些植物甾醇的实验光氧化会导致植物甾醇的前三种氧化物：6α-OH、7α-OH 和 7β-OH。通过 DFT 的机理研究表明，单线态氧（O）介导的光氧化（II 型机理）生成自由基，在甾核 B 环的 C5 和 C6 上加成，并通过重排途径从 C5 产物在 C7 处引发反应。此外，C5、C6 和 C7 的立体选择性为植物甾醇的光氧化提供了一种机理指导。这些努力有望为复杂食品基质中植物甾醇的氧化机制以及植物甾醇的抗氧化技术提供重要的探索性研究。
