Mutagenicity of nitroscanate, an antischistosomal drug

Mutagenicity of sulfoscanate: a comparative study

The mutagenic activity of sulfoscanate (SSC) (4-isothiocyanate-4'-nitrodiphenyl sulphide) has been compared with that of the following reported drugs: (a) nitroscanate (NSC) (4-isothiocyanate-4'-nitrodiphenyl ether) which is a veterinary anthelmintic drug and (b) amoscanate (ASC) (4-isothiocyanate-4'-nitrodiphenyl amine) which is effective against schistosomes. SSC has been found to be a very potent mutagen towards TA98 and TA100 inducing 26.0 and 475.5revertants/nmole, respectively. NSC was found to induce mutations at a rate of 11.1 and 21.5revertants/nmole in TA98 and TA100, respectively. ASC was found to be non-mutagenic as such, but the urine of animals given the drug displayed mutagenicity. When SSC was tested in TA98/1,8-DNP(6), deficient in O-acetyltransferase, the activity decreased to 10.0revertants/nmole. However, in case of NSC the mutagenic activity was reduced to 0.24revertants/nmole, indicating the importance of O-acetyltransferase in generating N-acetoxyarylamine. In TA98NR, deficient in nitroreductase, the mutagenicity of SSC and NSC was totally absent. The positional isomers of SSC, 4-isothiocyanate-3'-nitro- and 4-isothiocyanate-2'-nitrodiphenyl sulphide, were found to be non-mutagenic in both TA98 and TA100. Our comparison of the mutagenic activity of SSC, NSC and ASC indicates that the pattern of activity is SSC>NSC>ASC.

Genotoxicity of potential metabolites of nitroscanate--an antischistosomal drug

The potential metabolites of nitroscanate(4-isothiocyanato-4'-nitrodiphenyl ether) such as 4-amino-4'-nitrodiphenyl ether (ANDE), 4-acetamido-4'-nitrodiphenyl ether (AcNDE), 4-acetamido-4'-nitrosodiphenyl ether (4-N = 0), 4-acetamido-4'-hydroxylaminodiphenyl ether (4-NHOH), 4-acetamido-4'-acetohydroxamicdiphenyl ether [4-N(OH)Ac], 4-acetamido-4'-formohydroxamicdiphenyl ether [4-N(OH)CHO] and 4-acetamido-4'-acetylaceto-hydroxamicdiphenyl ether [4-N(OAc)Ac] were synthesized and investigated in the standard Salmonella mutagenicity test using TA98, TA98NR, TA98/1,8-DNP6, TA100 and TA100NR as indicator strains, in the presence and absence of hepatic S9. The relative order of activity among nitro and its reduction products, 4-N = 0 and 4-NHOH in TA98 and TA100 was 4-N = 0 > 4-NHOH > AcNDE. In nitroreductase deficient strain TA98NR, AcNDE was inactive, but expressed a slight activity in TA100NR while 4-N = 0 and 4-NHOH showed a large increase in specific activity in both the strains. In O-acetyltransferase deficient strain TA98/1,8-DNP6, AcNDE was inactive, while 4-N = O and 4-NHOH showed a sharp fall in activity. The hydroxylamine derived products with an activity order 4-N(OAc)Ac > 4-N(OH)CHO > 4-N(OH)Ac in both TA98 and TA100, showed 3-6 times increase in the specific activity for the latter two compounds in the presence of S9 mix, which was inhibited in the presence of paraoxan, indicating N-deacylation as an important metabolic activation pathway. Except the 4-NO in TA100, the observed mutagenicity of nitroscante (NSC) was higher than those of potential metabolites and the nor-isothiocyanato derivative 4'-nitrodiphenyl ether, thereby showing that -NCS function has a potentiating effect on the mutagenicity of this drug.