Department of Food Science and Technology, Ferdowsi University of Mashhad, Faculty of Agriculture, P.O. Box 91775-1163, Mashhad, Iran.
Sci Rep. 2022 May 24;12(1):8765. doi: 10.1038/s41598-022-12803-3.
The activity and capacity of gallic acid (GA) and methyl gallate (MG) in scavenging DPPH were determined in different solvents. Based on the bimolecular rate constants k, both antioxidants showed highest activities in EtOH, followed by in MeOH, t-BuOH, MeCN, 2-PrOH, acetone, THF, ethyl acetate, and 1,4-dioxane. GA indicated better activities (k value, M s) than MG in the alcoholic solvents (51-1939 vs. 25-1530) and in MeCN (203 vs. 187) whereas MG was of higher activities in the polar aprotic solvents (1.7-41 vs. 1.6-13). The highest stoichiometries for GA vs. MG were in 2-PrOH (6.67 vs. 5.37), followed by EtOH (5.84 vs. 4.57), MeOH (5.34 vs. 3.8) ~ acetone (5.02 vs. 4.44), MeCN (3.68 vs. 3.05) ~ t-BuOH (3.14 vs. 2.99), THF (2.34 vs. 2.2), ethyl acetate (1.2 vs. 0.93), and 1,4-dioxane (0.34 vs. 0.35).
没食子酸（GA）和甲基没食子酸（MG）在不同溶剂中清除 DPPH 的活性和能力在不同溶剂中进行了测定。根据双分子速率常数 k，两种抗氧化剂在乙醇中表现出最高的活性，其次是甲醇、叔丁醇、乙腈、2-丙醇、丙酮、四氢呋喃、乙酸乙酯和 1,4-二恶烷。GA 在醇溶剂（51-1939 比 25-1530）和乙腈（203 比 187）中表现出比 MG 更高的活性，而 MG 在极性非质子溶剂中的活性更高（1.7-41 比 1.6-13）。GA 与 MG 的最高化学计量比在 2-丙醇中（6.67 比 5.37），其次是乙醇（5.84 比 4.57）、甲醇（5.34 比 3.8）丙酮（5.02 比 4.44）、乙腈（3.68 比 3.05）叔丁醇（3.14 比 2.99）、四氢呋喃（2.34 比 2.2）、乙酸乙酯（1.2 比 0.93）和 1,4-二恶烷（0.34 比 0.35）。
