A Study for A New Method for Evaluation of Phototoicity

Park, Hyun Chul; Moon, Kee Chan; Kim, Soo Nam

Abstract

The present study was carried out to find a simple and safe in. vitro test for phtotoxic drugs. Authors selected two strains of Salmonella typhimurium(TA98 and TA102) which have been used in Ames test for the detsction of mutagenecity af various chemical substances. Both strains are genuine products of genetic enzineering. The etrain TA98 should be highly vulnerable to ultraviolet radition because it lacks normal I)NA excision repair gene. The strain TA102 was chosen as control since it maintained the DNA repair gene. These strains were subjected to increasing dosea of UVA with or without pretreatment of 8 methoxypsoralsn(8-MOP) which is a prototype of photatoxic druge. The authors made use of a perforated stain-less steel template which provided a simple and eosy monitoring of ultraviolet irradiation effects i.e. clear zones due to inhibition of the atrains could be determined. By using this methad, the authors acquired the following results .' I. 8-MOP alone exerted no inhibition on both strains at concentration upto 100mg /ml. 2. UVA irradiation alone showed no growth inhibition at dose upto 5J/cm. 3. UVA irradiation after pretreatment with 8 MOP resulted varying growth inhibition in proportion to irradiation doses. 4. Authors found a suitable concentration of 8-MOP for this test is 10pg/ml. With this ccncentrstion, minimal phatatoxic dose of UVA were O.l J/cm for the strain TA98 and 1.0J/cm for the strain TA102 respectively.