Evaluation of carcinogenic effect of jute batching oil (JBO-P) fractions following topical application to mouse skin

Abstract

Jute batching oil (JBO-P), a mineral oil fraction used in the processing of jute fibers, was, as reported in our earlier studies, found to be tumorigenic following repeated topical application to mouse skin. In the present investigation an attempt has been made to identify the carcinogenic constituents of this oil. The JBO was fractionated into (1) PAH free fraction, (2) fraction containing twoand three-ring PAHs and (3) more than three-ring PAH fractions by an enrichment procedure. These three JBO fractions along with unfractionated and reconstituted oil were then subjected to the in vivo assay of complete carcinogenic activity of JBO-P and its fractions following its topical application to mouse skin. The results showed that only unfractionated and reconstituted JBO-P samples per se were able to produce benign skin tumours, while all the other three fractions, i.e. PAH-free fraction, two- and three-ring PAH-containing fraction and more than threering PAH-containing fraction failed to produce tumours up to 40 weeks after application. In an extended study, mice belonging to the groups exposed to various fractions of JBO were promoted with 12-O-tetradecanoyl phorbol-13-acetate (TPA), a potent skin tumour promoter, for the two stage initiation-promotion protocol for skin carcinogenesis. After 14 weeks of promotion with TPA, all the surviving animals exposed to the fraction having more than three-ring PAHs developed benign tumours on their backs, while the other two fractions failed to do so. In view of these findings it can be concluded that none of the three JBO-P fractions possess complete carcinogenic activity, whereas only the fraction containing more than three-ring PAHs may act as a skin tumour initiator.