title: Antioxidative effects of curcumin and its analogues against the free-radical-induced peroxidation of linoleic acid in micelles.
abstract: Curcumin (1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione, 1) is a yellow ingredient isolated from turmeric (curcumin longa). Many health benefits have been claimed for curcumin, and these have generally been ascribed to its radical-trapping antioxidant properties. In order to find more active antioxidants with 1 as the lead compound, we synthesized curcumin analogues, i.e., 1,7-bis(3,4-dihydroxyphenyl)-1,6-heptadiene-3,5-dione (2), 1-(3,4-dihydroxyphenyl)-7-(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione (3), 1-(4-hydroxy-3-methoxyphenyl)-7-(4-hydroxyphenyl)-1,6-heptadiene-3,5-dione (4), 1,7-bis (4-hydroxyphenyl)-1,6-heptadiene-3,5-dione (5), 1,7-bis(3,4-dimethoxyphenyl)-1,6-heptadiene-3,5-dione (6), 1,7-bis(4-methoxyphenyl)-1,6-heptadiene-3,5-dione (7), and 1,7-diphenyl-1,6-heptadiene-3,5-dione (8). Antioxidative effects of curcumin and these analogues against the peroxidation of linoleic acid were studied in sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CTAB) micelles. The peroxidation was initiated thermally by a water-soluble initiator 2,2'-azobis(2-amidinopropane hydrochloride) (AAPH), and reaction kinetics were monitored by the formation of linoleic acid hydroperoxides. Kinetic analysis of the antioxidation process demonstrates that these compounds, except 6, 7 and 8, are effective antioxidants in micelles by H-atom abstraction from the phenolic groups. Compounds 2 and 3, which bear ortho-diphenoxyl functionality, possess significantly higher antioxidant activity than curcumin and other analogues, and the 4-hydroxy-3-methoxyphenyl group also plays an important role in the antioxidative activity. In addition, the synergistic antioxidant effect of these compounds with alpha-tocopherol (vitamin E) in micelles was also studied by following the formation of linoleic acid hydroperoxides and the consumption of alpha-tocopherol. It was found that these compounds could not synergistically interact with alpha-tocopherol in micelles.
authors.affiliation: State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou, Gansu 730000, China.
authors.forename: Fang
authors.initials: F
authors.lastname: Dai
authors.forename: Wei-Feng
authors.initials: WF
authors.lastname: Chen
authors.forename: Bo
authors.initials: B
authors.lastname: Zhou
authors.forename: Li
authors.initials: L
authors.lastname: Yang
authors.forename: Zhong-Li
authors.initials: ZL
authors.lastname: Liu
mesh_terms: D000975:Antioxidants / Q000737:chemistry*; D003474:Curcumin / Q000031:analogs & derivatives* / Q000737:chemistry*; D005609:Free Radicals / Q000737:chemistry; D008041:Linoleic Acids / Q000737:chemistry*; D015227:Lipid Peroxidation; D008054:Lipid Peroxides / Q000737:chemistry*; D008823:Micelles; D015394:Molecular Structure; D024502:alpha-Tocopherol / Q000737:chemistry
chemical_list: D000975:Antioxidants; D005609:Free Radicals; D008041:Linoleic Acids; D008054:Lipid Peroxides; D008823:Micelles; C008285:linoleic acid hydroperoxide; D024502:alpha-Tocopherol; D003474:Curcumin