Dependence of Chemical Radioprotection on the Stability of Radiation-induced Oxygen-sensitive Sites

Kesavan, P.C.; Afzal, S.M.J.

doi:10.1080/09553007514551331

Cited by 10 publications

(3 citation statements)

References 17 publications

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“…For instance, it is evident from table 1 and from the trend analysis (p < 0.01) that caffeine at 80 mg/kg administered 60 min before irradiation exerts maximal radioprotection. The fact that caffeine concentration and the time of administration are critical for optimal radioprotection had been discussed earlier (Kesavan and Afzal 1975, Kesavan and Ahmad 1976, Kesavan et al 1978. The present data are consistent with the view that caffeine affords radioprotection by fast reactions with radiation-induced species such as OH • radicals, hydrated electrons, singlet oxygen etc.…”

Section: Resultssupporting

confidence: 90%

“…Contrary to several reports during the 1960s and 1970s that caffeine potentiates the DNA damage induced by a variety of physical and chemical agents (Kihlman 1977), Kesavan et al (1973) clearly demonstrated in the barley seed system that caffeine protects against the oxic pathway of γ -ray-induced damage, and that it acts as a radiosensitiser only in the absence of oxygen, or the pathway mediated by it. They also hypothesised (Kesavan and Afzal 1975, Kesavan and Ahmad 1976, Kesavan et al 1978 that radioprotection against the oxic pathway of radiobiological damage could possibly be due to a mutually annihilatory reaction of caffeine molecules with the γ -radiation-induced oxygen reactive sites.…”

Section: Introductionmentioning

confidence: 99%

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Caffeine protects mice against whole-body lethal dose of gamma-irradiation

et al. 1999

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Administration of caffeine (1,3,7-trimethylxanthine), a major component of coffee, to Swiss mice at doses of 80 or 100 mg/kg body weight 60 min prior to whole-body lethal dose of gamma-irradiation (7.5 Gy) resulted in the survival of 70 and 63% of animals, respectively, at the above doses in contrast to absolutely no survivors (LD-100/25 days) in the group exposed to radiation alone. Pre-treatment with a lower concentration of caffeine (50 mg/kg) did not confer any radioprotection. The protection exerted by caffeine (80 mg/kg), however, was reduced from 70 to 50% if administered 30 min prior to irradiation. The trend statistics reveal that a dose of 80 mg/kg administered 60 min before whole-body exposure to 7.5 Gy is optimal for maximal radioprotection. However, caffeine (80 mg/kg) administered within 3 min after irradiation offered no protection. While there is documentation in the literature that caffeine is an antioxidant and radioprotector against the oxic pathway of radiation damage in a wide range of cells and organisms, this is the first report demonstrating unequivocally its potent radioprotective action in terms of survival of lethally whole-body irradiated mice.

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Section: Resultssupporting

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Caffeine protects mice against whole-body lethal dose of gamma-irradiation

et al. 1999

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“…Data from several experiments reveal that caf elicits radioprotection only if the 02-sensitive sites are available in the irradiated seeds (Kesavan 1973, Kesavan and Afzal 1975, Nadkarni and Kesavan 1975, Afzal and Kesavan 1979, and that the concentration of caf must be optimal (Kesavan and Ahmad 1976). This implicates a physicochemical rather than a biochemical pathway of action (Kesavan 1983).…”

Section: Introductionmentioning

confidence: 95%

Differential Modification of Oxic and Anoxic Components of Radiation Damage inBacillus MegateriumSpores by Caffeine

Kesavan¹,

Powers²

1985

International Journal of Radiation Biology and Related Studies

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Studies were carried out on the effect of caffeine on the X-irradiation sensitivity of B. megaterium spores with the following results: Caffeine exerts a concentration-dependent modifying action on oxygen-dependent components of X-ray-induced damage in B. megaterium spore suspensions causing an 'over-O2 effect' at about 1 X 10(-4) mol dm-3, and as the concentration is increased to 1 X 10(-3) mol dm-3 or above, a small but consistent protection is seen. In the absence of O2, at a wide range of concentrations (8.5 X 10(-5) to 1 X 10(-1) mol dm-3), caffeine enhances the inactivation constant, k, from 1.17 to about 1.50 kGy-1. Both ethanol and t-butanol (5 X 10(-2) mol dm-3) remove the 'over O2-effect' produced by 1.10(-4) mol dm-3 caffeine in O2; such an effect, however, is not accompanied by reduction in the H2O2 concentrations in the spore suspensions. Ethanol prevents caffeine-induced anoxic sensitization, as well as H2O2 buildup. t-BuOH has no influence on either the low dose part of the log fraction survival curve or on the H2O2 yield in the spore suspensions. Caffeine reacts with radiation-induced eaq and .OH with rate constants of 1.5 X 10(10) and 6.9 X 10(9) dm3 mol-1s-1, respectively.

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Radioprotection by caffeine pre- and post-treatment in the bone marrow chromosomes of mice given whole-body γ-irradiation

Farooqi

Kesavan

1992

Mutation Research/Fundamental and Molecular Mechanisms of Mutag

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Dependence of Chemical Radioprotection on the Stability of Radiation-induced Oxygen-sensitive Sites

Cited by 10 publications

References 17 publications

Caffeine protects mice against whole-body lethal dose of gamma-irradiation

Caffeine protects mice against whole-body lethal dose of gamma-irradiation

Differential Modification of Oxic and Anoxic Components of Radiation Damage inBacillus MegateriumSpores by Caffeine

Radioprotection by caffeine pre- and post-treatment in the bone marrow chromosomes of mice given whole-body γ-irradiation

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