Mutagenic potency of chlorofuranones and related compounds in Salmonella

One of the mutagenic byproducts associated with chlorinated humic waters and kraft pulp bleaching effluents was recently identified as 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone. This compound and several related chlorofuranones and precursors were synthesized and evaluated for direct-acting mutagenicity in Salmonella typhimurium tester strain TA100. Mutagenicity was greatest for 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone, its 5-methoxy derivative, and the precursor in their synthesis, 3-(dichloromethyl)-2,4,4-trichloro-2-butenoic acid. Several of the compounds were tested in the presence of added rat liver homogenate S9 fraction, and in all cases mutagenicity was substantially reduced. An important structural feature which may govern the mutagenic response in these instances appears to be the cis arrangement of CHCl2 and Cl substituents on a carbon-carbon double bond. These compounds may also be transformed in vitro to the same acyclic chlorine substituted alpha, beta-unsaturated aldehyde derivative, which is proposed to be the agent responsible for the observed mutagenicity.