Mukai Kazuo, Hirata Masayuki, Ito Junya, Shiomi Taiki, Nakagawa Kiyotaka, Nagaoka Shin-Ichi
Department of Chemistry, Faculty of Science, Ehime University.
Food and Biodynamic Chemistry Laboratory, Graduate School of Agricultural Science, Tohoku University.
J Oleo Sci. 2020;69(1):7-22. doi: 10.5650/jos.ess19217.
Recently, singlet-oxygen (O) quenching and aroxyl-radical (ArO·) scavenging rates (k and k, respectively) of eight vegetable oils were measured in the ethanol/chloroform/DO solution. Furthermore, the k and k values and concentrations of four tocopherols and four tocotrienols contained in the vegetable oils were measured. In this study, the concentrations of nine fatty acids (including stearic, oleic, linoleic, and linolenic acids) comprising the above-mentioned eight vegetable oils were determined by gas chromatography. The k and k values for ethyl stearate, ethyl oleate, ethyl linoleate, methyl linolenate, and glyceryl trioleate in the ethanol/chloroform/DO solution were measured by UV-vis spectrophotometry. Based on the results obtained for the above-mentioned fatty acid esters, the k and k values were estimated for nine fatty acids. Furthermore, comparisons of k values observed for the vegetable oils with the sum of the product {∑k [AO-i]} of the k values obtained for each antioxidant-i (AO-i) and the concentrations ([AO-i]) of AO-i (i.e., four tocopherols (& four tocotrienols) and nine fatty acids) contained in vegetable oils were performed. Based on the results, a detailed comparison of the contributions of the tocopherols (and tocotrienols) and the fatty acids to the O-quenching rate constants (k) was performed. This indicated that both the tocopherols (and tocotrienols) and the fatty acids contribute to the O- quenching. A similar comparison was conducted for the ArO· -scavenging rate constants (k). The results suggested that only the tocopherols (and tocotrienols) contained in the oils contributed to the ArO· -scavenging, with negligible contribution from the fatty acids.
最近，在乙醇/氯仿/DO溶液中测量了8种植物油的单线态氧（O）猝灭速率和芳氧基自由基（ArO·）清除速率（分别为k和k）。此外，还测量了植物油中所含4种生育酚和4种生育三烯酚的k和k值以及浓度。在本研究中，通过气相色谱法测定了构成上述8种植物油的9种脂肪酸（包括硬脂酸、油酸、亚油酸和亚麻酸）的浓度。通过紫外可见分光光度法测量了乙醇/氯仿/DO溶液中硬脂酸乙酯、油酸乙酯、亚油酸乙酯、亚麻酸甲酯和三油酸甘油酯的k和k值。基于上述脂肪酸酯的测量结果，估算了9种脂肪酸的k和k值。此外，将植物油的k值与每种抗氧化剂-i（AO-i）（即4种生育酚（和4种生育三烯酚）和9种脂肪酸）的k值与AO-i的浓度（[AO-i]）的乘积之和{∑k[AO-i]}进行了比较。基于这些结果，对生育酚（和生育三烯酚）以及脂肪酸对O猝灭速率常数（k）的贡献进行了详细比较。这表明生育酚（和生育三烯酚）以及脂肪酸都对O猝灭有贡献。对ArO·清除速率常数（k）进行了类似的比较。结果表明，油中所含的只有生育酚（和生育三烯酚）对ArO·清除有贡献，脂肪酸的贡献可忽略不计。
