Agarose gel electrophoresis was performed to study interaction effect of caffeine on photosensitive injury of DNA caused by anthraquinone-2-sulphonic acid disodium(AQS),a model compound of strong photosensitizer,under 254 nm or 365nm UV irradiation Photosensitive injury of DNA induced by AQS under deoxidized condition was used as control.The results show that caffeine may resist effectively the injury effect of photosensitive damage and strong UV irradiation on DNA.The effects depend on the caffeine and AQS concentration,and irradiation time.Caffeine in concentration of 0.01-3.0μg/μL,may prevent DNA from damage induced by UV light,but caffeine in concentration of>5.0μg/μL accelerates the DNA damage.In particular,in the aqueous solution system of DNA,caffeine and AQS,at pH 6.25-7.35,the caffeine in concentration of 2.5-4.50μg/μL may resist the photosensitive injury of DNA caused by AQS under the deoxidized condition and exposure by 254 nm UV for 10 min.And caffeine in concentration of 5μg/μL would present a synergetic effect on the photosensitive injury of DNA.Possible molecular mechanism also is discussed.
