title: An investigation of the main mutagenic components of a carcinogenic oil by fractionation and testing in the modified Ames assay.
abstract: A low-viscosity carcinogenic oil was extracted with dimethylsulphoxide (DMSO) and the extract fractionated into 1-3 ring aromatic components, 4-6 ring polycyclic aromatic compounds (PCAs) and polar materials. Each of these fractions was tested in the Mobil modified Ames assay at the same concentration as in the DMSO extract, alongside unfractionated DMSO extracts from the same oil and two reference oils. In addition the fractions were combined in various ways to examine inhibitory or additive effects. Clear positive findings were obtained with the DMSO extract of the main test oil, with some reduction in activity in a sample (the starting material for fractionation) that was back-extracted to remove DMSO. Of the three fractions tested on their own and assessed in terms of mutagenicity index, the 1-3 ring aromatic fraction had the greatest mutagenic activity, showing similar activity to the starting material, whereas the 4-6 ring PCA fraction had much lower activity and the polar fraction showed the lowest activity with an absence of doubling in one of the tests. The polar fraction showed signs of an inhibitory effect on the response to the 1-3 ring aromatic fraction and to a questionable extent on that of the 4-6 ring PCA fraction. Although a low level of the 4-6 ring PCA fraction showed some inhibitory effect on the response to the 1-3 ring aromatic fraction, a low level of the 1-3 ring aromatic fraction added to the 4-6 ring PCA fraction enhanced the response.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: BP Product Stewardship Group, BP Oil Technology, Sunbury-on-Thames, Middlesex, UK.
authors.forename: A J
authors.initials: AJ
authors.lastname: Ingram
authors.forename: D V
authors.initials: DV
authors.lastname: Scammells
authors.forename: K
authors.initials: K
authors.lastname: May
mesh_terms: D002273:Carcinogens / Q000737:chemistry* / Q000633:toxicity; D005591:Chemical Fractionation; D004121:Dimethyl Sulfoxide; D008899:Mineral Oil / Q000737:chemistry* / Q000633:toxicity; D009152:Mutagenicity Tests; D009153:Mutagens / Q000032:analysis* / Q000633:toxicity; D012475:Salmonella / Q000235:genetics
chemical_list: D002273:Carcinogens; D009153:Mutagens; D008899:Mineral Oil; D004121:Dimethyl Sulfoxide