Journal of Physics B: Atomic and Molecular Physics, 1971
Molecular spectra of BaF have been observed in thermal emission from a high temperature vacuum gr... more Molecular spectra of BaF have been observed in thermal emission from a high temperature vacuum graphite furnace. New bands, mostly involving higher vibrational quanta, have been identified in almost all the known systems of this molecule and the respective vibrational analyses have been confirmed or modified, utilizing the additional data so obtained. A new band system I has also been recorded in the ultraviolet region.
Electronic spectrum of the diatomic molecule CaF was investigated in thermal emission using a hig... more Electronic spectrum of the diatomic molecule CaF was investigated in thermal emission using a high temperature vacuum graphite furnace. The ultraviolet system C Π - × Σ for which only fragmentary data were available so far, was recorded in much extended form with bands showing clear multiplet sub-heads. In other systems too, numerous new sequences and additional bands have been
Reactions of superoxide-crown ether complex with curcumin have been studied in acetonitrile. Opti... more Reactions of superoxide-crown ether complex with curcumin have been studied in acetonitrile. Optical absorption spectra showed that curcumin on reaction with superoxide forms a blue color intermediate absorbing at 560 nm, which subsequently decayed in a few hours with the development of the absorption band corresponding to the parent curcumin. The regeneration was 100% at low superoxide concentrations (1:1, or 1:2 or 1:3 of curcumin:superoxide) but reduced to 60% at high superoxide concentration (>1:5). The regeneration of curcumin is confirmed by HPLC analysis. Stopped-flow studies in acetonitrile following either the decay of parent curcumin at 420 nm or formation of 560 nm absorption have been used to determine the rate constant for the reaction of superoxide with curcumin. EPR studies confirmed the disappearance of characteristic superoxide signal in presence of curcumin with the formation of new featureless signal with g = 2.0067. Based on these studies it is concluded that at low superoxide concentrations curcumin effectively causes superoxide dismutation without itself undergoing any chemical change. At higher concentrations of superoxide, curcumin inhibits superoxide activity by reacting with it.
... However, the formation of the water-soluble complex is based on a tedious procedure of reflux... more ... However, the formation of the water-soluble complex is based on a tedious procedure of refluxing CD with c60 in water for 18-48 h. We have now developed a simple and novel method of makingwater-soluble complexes of c60 with CD at room temperature. ...
Caffeine (1,3,7-trimethyl xanthine), an ingredient of coffee, has been investigated for its poten... more Caffeine (1,3,7-trimethyl xanthine), an ingredient of coffee, has been investigated for its potential antioxidant activity against oxidative damage to rat liver microsomes. Such damage was induced by three reactive oxygen species of cardinal importance in causing membrane damage in vivo namely hydroxyl radical (.OH), peroxyl radical (ROO.) and singlet oxygen (1O2). The results obtained showed that caffeine was an effective inhibitor of lipid peroxidation, at millimolar concentrations, against all the three reactive species. The extent of inhibition was high against peroxidation induced by .OH, medium against 1O2 and low against ROO. In general, the antioxidant ability of caffeine was similar to that of the established biological antioxidant glutathione and significantly higher than ascorbic acid. Investigations into the possible mechanisms involved in the observed antioxidant effect reveal that the quenching of these reactive species by caffeine may be one of the possible factor responsible. The rate constant of caffeine with .OH was 7.3 x 10(9) M-1 s-1 and with 1O2 it was 2.9 x 10(7) M-1 s-1. Considering their potential for damage, half-life estimates and generation in biological systems, the ability of caffeine to inhibit oxidative damage induced by these reactive species in membranes suggest one more positive attribute of caffeine, whose daily intake as coffee may be considerable in most populations.
Journal of Physics B: Atomic and Molecular Physics, 1971
Molecular spectra of BaF have been observed in thermal emission from a high temperature vacuum gr... more Molecular spectra of BaF have been observed in thermal emission from a high temperature vacuum graphite furnace. New bands, mostly involving higher vibrational quanta, have been identified in almost all the known systems of this molecule and the respective vibrational analyses have been confirmed or modified, utilizing the additional data so obtained. A new band system I has also been recorded in the ultraviolet region.
Electronic spectrum of the diatomic molecule CaF was investigated in thermal emission using a hig... more Electronic spectrum of the diatomic molecule CaF was investigated in thermal emission using a high temperature vacuum graphite furnace. The ultraviolet system C Π - × Σ for which only fragmentary data were available so far, was recorded in much extended form with bands showing clear multiplet sub-heads. In other systems too, numerous new sequences and additional bands have been
Reactions of superoxide-crown ether complex with curcumin have been studied in acetonitrile. Opti... more Reactions of superoxide-crown ether complex with curcumin have been studied in acetonitrile. Optical absorption spectra showed that curcumin on reaction with superoxide forms a blue color intermediate absorbing at 560 nm, which subsequently decayed in a few hours with the development of the absorption band corresponding to the parent curcumin. The regeneration was 100% at low superoxide concentrations (1:1, or 1:2 or 1:3 of curcumin:superoxide) but reduced to 60% at high superoxide concentration (>1:5). The regeneration of curcumin is confirmed by HPLC analysis. Stopped-flow studies in acetonitrile following either the decay of parent curcumin at 420 nm or formation of 560 nm absorption have been used to determine the rate constant for the reaction of superoxide with curcumin. EPR studies confirmed the disappearance of characteristic superoxide signal in presence of curcumin with the formation of new featureless signal with g = 2.0067. Based on these studies it is concluded that at low superoxide concentrations curcumin effectively causes superoxide dismutation without itself undergoing any chemical change. At higher concentrations of superoxide, curcumin inhibits superoxide activity by reacting with it.
... However, the formation of the water-soluble complex is based on a tedious procedure of reflux... more ... However, the formation of the water-soluble complex is based on a tedious procedure of refluxing CD with c60 in water for 18-48 h. We have now developed a simple and novel method of makingwater-soluble complexes of c60 with CD at room temperature. ...
Caffeine (1,3,7-trimethyl xanthine), an ingredient of coffee, has been investigated for its poten... more Caffeine (1,3,7-trimethyl xanthine), an ingredient of coffee, has been investigated for its potential antioxidant activity against oxidative damage to rat liver microsomes. Such damage was induced by three reactive oxygen species of cardinal importance in causing membrane damage in vivo namely hydroxyl radical (.OH), peroxyl radical (ROO.) and singlet oxygen (1O2). The results obtained showed that caffeine was an effective inhibitor of lipid peroxidation, at millimolar concentrations, against all the three reactive species. The extent of inhibition was high against peroxidation induced by .OH, medium against 1O2 and low against ROO. In general, the antioxidant ability of caffeine was similar to that of the established biological antioxidant glutathione and significantly higher than ascorbic acid. Investigations into the possible mechanisms involved in the observed antioxidant effect reveal that the quenching of these reactive species by caffeine may be one of the possible factor responsible. The rate constant of caffeine with .OH was 7.3 x 10(9) M-1 s-1 and with 1O2 it was 2.9 x 10(7) M-1 s-1. Considering their potential for damage, half-life estimates and generation in biological systems, the ability of caffeine to inhibit oxidative damage induced by these reactive species in membranes suggest one more positive attribute of caffeine, whose daily intake as coffee may be considerable in most populations.
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