Modulation of radioresponse of glyoxalase system by curcumin.

Human beings have been exposed to radiation for many years. It is quite possible that antioxidant phytochemicals consumed in their diet might be providing a variable degree of radioprotection. However, their radiomodifying ability is not well understood. In the present work, curcumin (diferuloyl methane), a phytochemical present in the rhizome of Curcuma longa Linn. has been examined for its radioprotective property using the glyoxalase system which is vital for various biological functions. Curcumin (5, 25 and 50 mg/kg body weight) in olive oil was given orally to Swiss albino male mice (7-8 weeks old) daily for 2 weeks and irradiated with different doses of gamma-radiation (0-6 Gy) at 0.027 Gy per second dose rate on last day of the treatment. The specific activities of glyoxalase I and II were determined in the liver and spleen. The treatment of curcumin prior to irradiation restored the specific activity of glyoxalase system to almost the control level which was suggestive of the radioprotective ability of curcumin. Free radical scavenging and electron/hydrogen donation are probable attributes for the protective effect of curcumin.

Inhibition of radiation-induced changes of glyoxalase I activity in mouse spleen and liver by phenothiazines.

Swiss albino mice (male) were irradiated with gamma-rays at a dose-rate of 0.05 Gy s-1, and the activities of glyoxalase I (GI) and glyoxalase II (GII) were determined after 24 h in the spleen and liver. Radiation up to 4 Gy increased the activity of GI and decreased that of GII. It was possible that the radiation-induced changes in the activity of the glyoxalase system, particularly that of GI, were suggestive of the regeneration status of the tissue. Phenothiazines such as chlorpromazine (CPZ), promethazine (PMZ) and trimeprazine (TMZ) inhibited the radiation-enhanced activity of GI in a concentration-dependent manner. On the other hand, almost no change in the activity of GII was observed using phenothiazines. The effect of phenothiazines on radiation-induced changes of glyoxalase activity were reversed in the presence of ferrous (Fe2+) ions. However, phenothiazines inhibited the radiation effect in the presence of ferric (Fe3+) ions. This combined effect was predominant in the liver. A possible mechanism for the modifying effect of phenothiazines is suggested.