Arginine reversion and lambda induction in E. coli with benzothiadiazine diuretics irradiated with near-ultraviolet light.

Photoinduced genotoxicity of benzothiadiazine diuretics was studied with regard to mutagenic and lambda prophage-inducing activities in E. coli. Irradiation of E. coli with near-ultraviolet light in the presence of hydrochlorothiazide or methyclothiazide caused mutations of strain Hs30R argF(Am) to the prototrophic phenotype and induction of lambda from the lysogenic bacteria AB1157(lambda). Both drugs showed nearly the same amount of activity. Penfluzide showed much less mutagenic and much less prophage-inducing activity than did hydrochlorothiazide and methyclothiazide.