Antimutagenic effects of betel leaf extract against the mutagenicity of two tobacco-specific N-nitrosamines.

Epidemiological studies have implicated chewing tobacco alone to be more hazardous than chewing tobacco with betel quid. Experimental studies have shown that betel leaf is antimutagenic against standard mutagens like benzo[a]pyrene and dimethylbenz[a]anthracene. Since the tobacco-specific N-nitrosamines (TSNA) are the only carcinogens present in unburnt forms of tobacco, including chewing tobacco, we tested the effect of an extract of betel leaf against the mutagenicity of the two important TSNA, viz., N'-nitrosonornicotine and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone, using the Ames Salmonella/microsome assay with TA100 +S9 and the in vivo micronucleus test. In both the test systems it was observed that betel leaf extract suppressed the mutagenic effects of both the nitrosamines to a significant extent.