Ghani Md Ahsan, Barril Celia, Bedgood Danny R, Prenzler Paul D
School of Agricultural and Wine Sciences, Faculty of Science, Charles Sturt University, Wagga Wagga 2650, Australia.
Graham Centre for Agricultural Innovation, Charles Sturt University, Wagga Wagga 2650, Australia.
Antioxidants (Basel). 2019 Sep 2;8(9):366. doi: 10.3390/antiox8090366.
An improved system for measuring antioxidant activity via thiobarbituric acid reactive substances and ferric thiocyanate assays is reported, on the basis of oxidation of a linoleic acid (LA) emulsion. Oxidation times were reduced from 20 h to 5 h by increasing the reaction temperature from 37 °C to 50 °C and with an acceptable precision of <10% coefficient of variation (CV). Antioxidants varying in polarity and chemical class-250 µM Trolox, quercetin, ascorbic acid and gallic acid-were used for method optimisation. Further reductions in reaction time were investigated through the addition of catalysts, oxygen initiators or increasing temperature to 60 °C; however, antioxidant activity varied from that established at 37 °C and 20 h reaction time-the method validation conditions. Further validation of the method was achieved with catechin, epicatechin, caffeic acid and α-tocopherol, with results at 50 °C and 5 h comparable to those at 37 °C and 20 h. The improved assay has the potential to rapidly screen antioxidants of various polarities, thus making it useful in studies where large numbers of plant extracts require testing. Furthermore, as this assay involves protection of a lipid, the assay is likely to provide complementary information to well-established tests, such as the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay.
报道了一种基于亚油酸（LA）乳液氧化，通过硫代巴比妥酸反应物质和硫氰酸铁测定来测量抗氧化活性的改进系统。通过将反应温度从37℃提高到50℃，氧化时间从20小时减少到5小时，变异系数（CV）<10%，精度可接受。使用极性和化学类别不同的抗氧化剂——250μM的Trolox、槲皮素、抗坏血酸和没食子酸——来优化方法。通过添加催化剂、氧气引发剂或将温度提高到60℃来研究进一步缩短反应时间；然而，抗氧化活性与在37℃和20小时反应时间（方法验证条件）下确定的活性不同。用儿茶素、表儿茶素、咖啡酸和α-生育酚对该方法进行了进一步验证，在50℃和5小时的结果与在37℃和20小时的结果相当。改进后的测定方法有可能快速筛选各种极性的抗氧化剂，因此在需要测试大量植物提取物的研究中很有用。此外，由于该测定涉及对脂质的保护，该测定可能为成熟的测试（如2,2-二苯基-1-苦基肼（DPPH）测定）提供补充信息。
