Solar and artificial ultraviolet-B induced erythrocytes hemolysis with photosensitizers

Aim of this study was to monitor the solar ultraviolet-B intensity and to compare the phototoxic effect of different intensity of natural and artificial ultraviolet-B on human red blood cells in presence of compounds as riboflavin and chloroquine. Photohemolysis of erythrocytes was studied under natural solar radiation and artificial ultraviolet-B radiation of 312 nm. Monitoring of solar ultraviolet-B radiation was performed in Garhwal region of Uttarakhand, India. Level of solar ultraviolet-B measured show seasonal and altitudinal variations. Monthly average of solar UV-B intensity was minimum in the month of December and January (0.299 mw/cm2) and maximum in the month of July and August (1.027 mw/cm2). Natural solar radiation intensities 0.402 mw/cm2 and 0.824 mw/cm2 of the month of January and June were used in the photohemolysis experiment. Two intensities of artificial UV-B i.e. 0.824 mw/cm2 and a double intensity 1.65 mw/cm2 were also used. Results on human erythrocytes hemolysis indicate that haemolysis was highest i.e. 71% in chloroquine + artificial ultraviolet-B intensity (1.65 mw/cm2) followed by 62% in chloroquine + artificial ultraviolet-B (0.824 mw/cm2) exposed groups and 54% in natural solar radiation intensity 0.824 mw/cm + chloroquine. Natural solar UV-B alone caused 17% hemolysis and show dose response relationship. A difference in phototoxicity was observed in natural solar and artificial UV-B of same intensity. Artificial UV-B was found more toxic. Riboflavin was more phototoxic in presence of solar light, while chloroquine was more phototoxic with artificial UV-B.