Antioxidant potential and oxidative DNA damage preventive activity of unexplored endemic species of Curcuma.

Free radical scavenging activity, ferrous ion chelating capacity, reducing power and genoprotective effect of the aqueous leaf extracts of four unexplored endemic Curcuma spp. (C. vamana, C. neilgherrensis, C. mutabilis, C. haritha) were found to be dose-dependent and were highest in C. vamana. DNA protection property of the extracts was evaluated against H2O2/UV-induced oxidative damage. DNA-methyl green displacement assay showed that these extracts were free of DNA intercalating compounds. Further, hemolysis assay also showed that the extracts were non-toxic to human erythrocytes. The results highlight C. vamana as a promising source for herbal preparations possessing high antioxidant potential and genoprotective activity.

Reduction of UV-induced mitotic delay by caffeine in BUdR-substituted plasmodia of Physarum polycephalum.

Chromosomal DNA of the synchronously mitotic plasmodia of P. polycephalum was substituted with 5-bromo-2'-deoxyuridine, by growing the plasmodia during S phase, on a medium containing this nucleoside analog. A strong synergism was observed between bromodeoxyuridine and UV-irradiation, in late G2-irradiated plasmodia in that, the mitotic delay obtained in them was much more than a simple sum of the delays induced by these two agents individually. It was also observed that the mitotic delay in this system is reduced significantly by different concentrations of caffeine applied immediately after irradiation and there was a stage specificity in this effect. The reduction in mitotic delay was maximum (80%) in those plasmodia irradiated 20-30 min before control metaphase, when mitogenic factors also reach their maximum activity in this system. It is proposed that the mitotic delay reducing effect of caffeine is due to its ability to promote the activity of the mitogenic factors, largely independent of the system which is responsible for monitoring the state of the chromosomal DNA.