SCREENING & CHARACTERIZATION OF ANTIOXIDANT COMPOUNDS FROM NATURAL PRODUCTS

本项目的目的是评估抗氧化剂 3-脱氢莽草酸（DHS）的活性，可用作 安全的天然抗氧化剂。 DHS是 由3-脱氢奎尼酸通过3-脱氢奎尼酶的作用产生 在细菌合成芳香族氨基酸中。 对DHS进行了评价， 在散装油中，在悬浮于 水介质中，和在水包玉米油乳液中。 DHS显示， 抗氧化活性与丁基化羟基甲苯相当 (BHT)或叔丁基对苯二酚（TBHQ），但 在其他两个试验中显示出很小的活性。 来定义 这种活性差异的机制基础，氧化 DHS在这些实验系统中的产物被鉴定， 两种主要的氧化产物，没食子酸和 从油悬浮液中鉴定出原儿茶酸 包括国土安全部 这两种化合物都显著抑制了 在相同的试验条件下，油的氧化。 48小时后 孵化，原儿茶酸是油中的主要成分， 占总抗氧化剂部分的66%，而DHS和 没食子酸分别以28%和6%存在。 国土安全部仍然 在整个测定期间在脂质体系统中保持完整。 较小 在玉米油乳液中观察到大量没食子酸， 氧化，但未检测到原儿茶酸。 这些结果 表明，DHS作为油中抗氧化剂的优越性是 这是由于其在脂质体系中转化为 原儿茶酸和没食子酸，它们可以协同作用。

The objective of this project was to evaluate the antioxidant activity of 3-dehydroshikimic acid (DHS) which could be used as a safe, naturally occurring antioxidant in processed foods. DHS is produced from 3-dehydroquinate through the action of 3-dehydroquinase in aromatic amino acid synthesis by bacteria. DHS was evaluated for antioxidant activity in a bulk oil, in liposomes suspended in an aqueous medium, and in a corn oil in water emulsion. DHS showed antioxidant activity comparable to that of butylated hydroxytoluene (BHT) or tertiary butylhydroquinone (TBHQ) in the bulk oil medium, but showed little activity in the other two assays. To define the mechanistic basis for this difference in activity, the oxidation products of DHS in these experimental systems were identified and quantified using GC/MS. Two major oxidation products, gallic acid and protocatechuic acid, were identified from the oil suspension containing DHS. Both of these compounds significantly suppressed oxidation of oil under the same assay conditions. At 48 hours of incubation, protocatechuic acid was the major component in oil, representing 66% of the total antioxidant fraction whereas DHS and gallic acid were present at 28% and 6%, respectively. DHS remained intact in the liposomal system throughout the assay period. Smaller amounts of gallic acid were observed in the corn oil emulsion upon oxidation, but protocatechuic acid was not detected. These results suggest that the superiority of DHS as an antioxidant in oils is the result of its ability to undergo conversion in lipid systems to protocatechuic acid and gallic acid which may act synergistically.