MUTAGENIC ACTIVITY OF URBAN AIR SAMPLES AND ITS MODULATION BY CHILI EXTRACTS

Different samples of ambient particulate organic matter were collected during the summer and winter of 1990 in Mexico City. After dichlorome thane extraction, the samples were tested for mutagenicity with deriva tives of Salmonella typhimurium possessing high activity of 'classical ' nitroreductase (YG1021) or O-acetyltransferase (YG1024), and compare d to the mutagenicity of the normal strain YG1020, and to that of a ni troreductase-deficient mutant TA98NR. The two enzyme-overproducing str ains were more sensitive to the mutagenic effect of the extracts than the parent and deficient strains. The sensitivity order, i.e., YG1024 > YG1021 > YG1020 > TA98NR, emphasizes the usefulness of the new Salmo nella strains in analyzing the mutagenicity of complex mixtures and su ggests that some of the direct mutagenic compounds in the urban air sa mples are nitro-aromatics. Investigations were also conducted to analy ze the effect of chili extract on the mutagenicity of an urban air sam ple. The extract itself showed moderate mutagenic activity and an addi tive effect was noted when both the chili and air extracts were presen t. On the other hand, the maximum volume of chili tested produced a de crease in the number of revertants without affecting the background la wn of bacterial growth. The same response was also observed when 1-nit ropyrene, 1,6-dinitropyrene or 1,8-dinitropyrene was used as the genot oxic compound, although potentiation instead of addition occurred at l ow vegetable volumes. At the concentrations found in the chili extract , chlorophyllin and beta-carotene showed an antimutagenic effect again st the nitro-aromatic compounds.