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Protective Activities of Some Phenolic 1,3‐Diketones against Lipid Peroxidation: Possible Involvement of the 1,3‐Diketone Moiety
Author(s) -
Patro Birija S.,
Rele Shyam,
Chintalwar Gajanan J.,
Chattopadhyay Subrata,
Adhikari Soumyakanti,
Mukherjee Tulsi
Publication year - 2002
Publication title -
chembiochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.05
H-Index - 126
eISSN - 1439-7633
pISSN - 1439-4227
DOI - 10.1002/1439-7633(20020402)3:4<364::aid-cbic364>3.0.co;2-s
Subject(s) - chemistry , lipid peroxidation , antioxidant , radiolysis , vanillin , moiety , thiobarbituric acid , organic chemistry , radical
The protective activities of four ginger‐derived phenolic 1,3‐diketones ( 1 – 4 ) and curcumin ( 5 ) against lipid peroxidation was studied by using different biologically relevant model systems and pulse radiolysis. The extraordinary activity of 5 vis‐à‐vis 1 – 4 against Fe 2+ ‐mediated peroxidation may be attributed to the additional phenolic hydroxy group in the former, which lends it better iron‐chelating and radical‐scavenging properties. In iron‐independent peroxidation, however, the ginger constituent [6]‐dehydrogingerdione ( 1 ) showed activity comparable to that of 5 ; this indicates its higher affinity for the lipid peroxide radical (LOO . ), due to its higher hydrophobicity. A very high rate constant for the reaction between 1 and Cl 3 COO . , measured by pulse radiolysis, not only confirmed this, but also established the superior antioxidant efficacy of 1 in comparison to vitamins E and C. This was also evident from the results obtained from a liposomal peroxidation study with 1 and vitamin C. This study also established a synergistic effect of the latter on the antioxidant activity of 1 . HPLC analysis of the products of the reaction between 1 and Cl 3 COO . revealed the formation of higher concentrations of ferulic acid ( 7 ), along with vanillin ( 6 ). The presence of ascorbate affected the generation of 7 more than it did that of 6 . On this basis, a mechanism for the antioxidant action of 1 has been proposed, which suggests the contribution of the phenolic group as well as the active methylene group of the 1,3‐diketones.