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Antioxidative effects of curcumin and its analogues against the free‐radical‐induced peroxidation of linoleic acid in micelles
Author(s) -
Dai Fang,
Chen WeiFeng,
Zhou Bo,
Yang Li,
Liu ZhongLi
Publication year - 2009
Publication title -
phytotherapy research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.019
H-Index - 129
eISSN - 1099-1573
pISSN - 0951-418X
DOI - 10.1002/ptr.2517
Subject(s) - curcumin , chemistry , antioxidant , linoleic acid , lipid peroxidation , radical , micelle , organic chemistry , medicinal chemistry , nuclear chemistry , biochemistry , fatty acid , aqueous solution
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 α ‐tocopherol (vitamin E) in micelles was also studied by following the formation of linoleic acid hydroperoxides and the consumption of α ‐tocopherol. It was found that these compounds could not synergistically interact with α ‐tocopherol in micelles. Copyright © 2009 John Wiley & Sons, Ltd.