Protective Activities of Some Phenolic 1,3-Diketones against Lipid Peroxidation: Possible Involvement of the 1,3-Diketone Moiety
✍ Scribed by Birija S. Patro; Shyam Rele; Gajanan J. Chintalwar; Subrata Chattopadhyay; Soumyakanti Adhikari; Tulsi Mukherjee
- Publisher
- John Wiley and Sons
- Year
- 2002
- Tongue
- English
- Weight
- 132 KB
- Volume
- 3
- Category
- Article
- ISSN
- 1439-4227
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✦ Synopsis
The protective activities of four ginger-derived phenolic 1,3diketones (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-a ¡-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 ironindependent 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.