Hydroxyl radical reactions of (4-hydroxy, 3-methoxy-5-bromophenyl) pentenone, a curcuminoid antioxidant

S.N. Guha, K.I. Priyadarsini, T.P.A. Devasagayam, Sreejayan [No Value], M.N.A. Rao, Sapre A.V. Mukherjee T. (Editor)

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Abstract

Reactions of hydroxyl radical (OH) with (4-hydroxy, 3-methoxy-5-bromophenyl) pentenone (BP), were studied in aqueous solutions using the pulse radiolysis technique. BP, showed high reactivity with OH and gave rise to different radicals at different pHs. On the basis of our studies of this compound with more specific oxidizing radicals such as N3, Tl(II), etc. it was inferred that hydroxyl radicals lead mainly to one electron oxidation at pH 10 where BP is present as the phenoxide ion. Whereas at pH 5 (phenolic form), oxidation is only a minor process, the major being the formation of addition products. The one electron reduction potential of the phenoxyl radical derived from BP at pH 6 was estimated using promethazine as the redox standard to be 910 ± 15 mV vs NHE. The physicochemical properties of the phenoxyl radicals were compared with those of the other curcuminoid antioxidants. Reactions of hydroxyl radical (OH) with (4-hydroxy, 3-methoxy-5-bromophenyl) pentenone (BP), were studied in aqueous solutions using the pulse radiolysis technique. BP, showed high reactivity with OH and gave rise to different radicals at different pHs. On the basis of our studies of this compound with more specific oxidizing radicals such as N3, Tl(II), etc. it was inferred that hydroxyl radicals lead mainly to one electron oxidation at pH 10 where BP is present as the phenoxide ion. Whereas at pH 5 (phenolic form), oxidation is only a minor process, the major being the formation of addition products. The one electron reduction potential of the phenoxyl radical derived from BP at pH 6 was estimated using promethazine as the redox standard to be 910±15 mV vs NHE. The physicochemical properties of the phenoxyl radicals were compared with those of the other curcuminoid antioxidants.
Original languageUndefined/Unknown
Pages (from-to)43-46
Number of pages4
JournalRadiation Physics and Chemistry
Volume49
Issue number1
DOIs
Publication statusPublished - 1997

Cite this

Guha, S. N., Priyadarsini, K. I., Devasagayam, T. P. A., [No Value], S., Rao, M. N. A., & Mukherjee T., S. A. V. (Ed.) (1997). Hydroxyl radical reactions of (4-hydroxy, 3-methoxy-5-bromophenyl) pentenone, a curcuminoid antioxidant. Radiation Physics and Chemistry, 49(1), 43-46. https://doi.org/10.1016/S0969-806X(96)00104-1