P.C. Kesavan

Protective effects of chlorogenic acid, curcumin and β-carotene against γ-radiation-induced in vivo chromosomal damage

Abstract The mouse bone marrow micronucleus test was carried out to evaluate the possible role of the dietary constituents chlorogenic acid (CGA), curcumin (CR) and β-carotene (BC) in modulating the in vivo chromosomal damage induced by γ-radiation. The results obtained suggest that oral administration of CGA (50, 100 and 200 mg/kg b.w.), CR (5, 10 and 20 mg/kg b.w.) and BC (0.5 and 2.5 mg/kg b.w.) to mice can significantly reduce the frequencies of micronucleated polychromatic erythrocytes (Mn PCEs) induced by whole body exposure to γ-radiation (1.15) Gy; 0.05 Gy/s). With CGA and CR, this effect was observed after a single administration either 2 h before or immediately after irradiation. However, with BC a 7-day feeding before irradiation was necessary to obtain a significant reduction in the incidence of Mn PCEs. The protective effects of CGA, CR and BC were observed in bone marrow cells sampled 24, 30 and 48 h after exposure to radiation.

Protective Effects of Vitamins C and E Against γ-ray-induced Chromosomal Damage in Mouse

The effects of vitamins C and E on bone marrow chromosomes of the mouse exposed to 1 Gy of whole-body γ-irradiation were studied. These vitamins, dissolved in water/peanut oil, were administered orally as acute doses, either 2 h before, immediately after, or 2 h after irradiation. Both vitamins significantly reduced the frequencies of micronuclei and chromosomal aberrations in bone marrow cells; radioprotection by vitamin E was, however, appreciably greater than that afforded by vitamin C. Administration of the vitamins to mice immediately after irradiation was as effective as that 2 h before irradiation. A sequential treatment consisting of both these vitamins did not result in additional radioprotection over that afforded by vitamin E alone. The probable mechanisms of radioprotection are discussed.

Role of chlorophyllin as an in vivo anticlastogen: protection against gamma-radiation and chemical clastogens

Chlorophyllin was evaluated in the mouse bone marrow micronucleus test for its possible protective effects against chromosomal damage induced by gamma-radiation, cyclophosphamide, N-nitroso-N-ethylurea and urethane. Three doses of chlorophyllin (50, 100 and 200 mg/kg, b.w.) were orally administered to mice 2 h before exposure to the clastogens under investigation. The results obtained demonstrated that chlorophyllin can significantly reduce the incidence of micronucleated polychromatic erythrocytes induced by gamma-radiation (1.15 Gy) and all the three chemical clastogens. However with the exception of cyclophosphamide there was no indication of a dose response for the in vivo anticlastogenic effects of chlorophyllin.

Genotoxicity of garlic, turmeric and asafoetida in mice

The genotoxic effects of orally administered garlic and turmeric were evaluated in bone-marrow cells of mice by performing the micronucleus test. Another spice, asafoetida, was tested for the induction of sister-chromatid exchanges (SCEs) in spermatogonia of mice. Results of the micronucleus test with garlic and turmeric were not significantly different from control values. Orally administered asafoetida, however, showed a weak SCE-inducing effect in spermatogonia.

Protection and potentiation of radiation clastogenesis by caffeine: nature of possible initial events.

Data on the differential modification of the oxic and anoxic components of radiation clastogenesis by caffeine already published in the literature have been briefly reviewed, additional unpublished data relevant for consideration of possible mechanisms have been presented and the possible events in terms of radiation chemistry have been discussed. It is considered that radioprotection against oxic component possibly results from the competition of caffeine with oxygen for e-aq, whereas radiosensitization of the anoxic component is, at least partly, due to restoration of physico-chemical environment achieved by oxygen alone in the irradiated cells. These reactions involve eaq-, oOH and H2O2 formed in the cells exposed to ionizing radiation.

Buthionine sulfoximine mediated enhancement of γ-radiation induced mutation frequency in Drosophila melanogaster

Experiments were carried out to investigate whether or not depletion of the glutathione (GSH) level in Drosophila melanogaster larvae with buthionine sulfoximine (BSO) treatment can result in the modulation of the frequency of sex-linked recessive lethal (SLRL) mutations induced by gamma-radiation. Third instar larvae were fed on BSO for 24 h before exposure to 10 Gy gamma-radiation. Immediately after this the larvae were divided into two batches, which were used for determining the GSH level and the induction of SLRL mutations respectively. The results obtained suggest that the depletion of the GSH level with BSO can lead to an enhancement in the frequency of SLRL mutations (significant at the 5% level). In a subsequent experiment in which adult Drosophila melanogaster male flies were fed on BSO for 72 h before irradiation, a significant increase was observed in the incidence of SLRL mutations.

Protective Effects of Ascorbic Acid against Radiation-Induced Clastogenesis

When considering modification of radiobiological damage by any physical or chemical agent, it is necessary to keep in view the role of molecular oxygen present during irradiation of cells and organisms. It has been known for a long time that the yield of mutations and chromosomal aberrations and other effects such as cell killing, can be considerably enhanced by irradiating under oxic conditions, a phenomenon called the “oxygen effect” in radiobiology (Crabtree and Cramer, 1933; Mottram, 1936; Read, 1952; Gray et al., 1953). Several different approaches revealed that the oxygen effect was attributable not to the direct ionization of the chromosome material but to highly reactive intermediates (free radicals) formed in cells following irradiation (Alper, 1979). The physicochemical nature of the “oxygen effect” became evident from the studies of Johansen and Howard-Flanders (1965) on radiation-induced cell killing in bacteria. They demonstrated a “radioprotectable” fraction of damage which could be deduced from the competitive reactions of the target molecule and a radioprotector with the hydroxyl radical (OH) but not with the hydrogen radical or hydrated electron. The hydroxyl radical was therefore implicated as the major determinant in the radiation-induced cell killing by direct action.