Search PubMed⌕ Search

Biomedical subjects

Soumyakanti Adhikari

Publications and source records attributed to Soumyakanti Adhikari.

4 recordsLinked to original sources
PubMed2006

Folic acid as a Fenton-modulator: possible physiological implication.

Acting as a redox switch, folic acid (1) might be a promising iron modulator to protect cellular machinery against oxidative stress and iron overload. The vitamin 1 can directly control the iron concentration by oxidizing it even if present in chelated forms. In addition, during its role as a reducing agent for the biologically relevant reactive oxygen species (ROS), it furnishes 6-formyl pterin. This folate-derived intermediate possesses a stronger Fe2+-oxidizing capacity than 1. Thus, compound 1 can reduce the iron toxicity in two ways. Although, the Fe2+-oxidizing capacity is nullified in the presence of a strong biological reductant like ascorbic acid, this property may play a predominant role during pathogenesis when the cellular ascorbic acid levels deplete significantly. The iron-modulatory property of 1 was also confirmed with the L929 mouse fibroblast cell line.

Animals↗
PubMed2004

Antioxidant properties of Plumbago zeylanica, an Indian medicinal plant and its active ingredient, plumbagin.

Plumbago zeylanica (known as "Chitrak") is a useful Indian medicinal plant. The root of the plant and its constituents are credited with potential therapeutic properties including anti-atherogenic, cardiotonic, hepatoprotective and neuroprotective properties. To examine possible mechanisms of action of P. zeylanica (Chitrak), in relation to its reported beneficial properties, antioxidant effects of the aqueous/alcoholic extracts of root, corresponding to medicinal preparations, and the active ingredient, plumbagin, were studied. Methods used included: ferric reducing/antioxidant power (FRAP), radical scavenging of 1,1-diphenyl-2-picryl hydrazyl (DPPH) and 2,2'-azobis-3-ethylbenzthiazoline-6-sulfonic acid (ABTS), lipid peroxidation in rat liver mitochondria induced by different agents, and estimating phenolic and flavonoid content. In FRAP/DPPH assays, boiled ethanolic extracts were the most effective, while in the ABTS assay boiled aqueous extracts were the most efficient. These extracts also significantly inhibited lipid peroxidation induced by cumene hydroperoxide, ascorbate-Fe(2+) and peroxynitrite and contained high amounts of polyphenols and flavonoids. To examine the mechanisms of action in detail, antioxidant and pulse radiolysis studies with plumbagin were conducted. The hydroxyl (.OH), alkyl peroxyl (CCl(3)OO.), linoleic acid peroxyl (LOO.), and glutathiyl (GS.) radicals generate a phenoxyl radical upon reaction with plumbagin. The bimolecular rate constants were: .OH, 2.03 x 10(9) dm(3)mol(-1)s(-1); CCl(3)OO., 1.1 x 10(9) dm(3)mol(-1)s(-1); LOO., 6.7 x 10(7) dm(3)mol(-1)s(-1); and GS., 8.8 x 10(8) dm(3)mol(-1)s(-1). In conclusion, our studies reveal that extracts of P. zeylanica and its active ingredient plumbagin have significant antioxidant abilities that may possibly explain some of the reported therapeutic effects.

Antioxidants↗
PubMed2002

Protective activities of some phenolic 1,3-diketones against lipid peroxidation: possible involvement of the 1,3-diketone moiety.

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.

Animals↗