A study of tobacco carcinogenesis. XIII. Tumor promoting subfractions of the weakly acidic fraction

The weakly acidic fraction (WAF) of cigarette smoke particulate matter was fractionated by silica gel chromatography. The various primary subfractions were assayed for potential tumor promoting activity by measuring the incorporation of thymidine H₃ into mouse epidermal DNA as induced by these subfractions. Based on these results and on chemical composition, the primary subfractions were then combined into 4 major subfractions and tested on initiated mouse skin for tumor promoting activity by long term application. Two of these subfractions (40% WAF) were inactive, whereas the other 2 (18 and 35% of WAF) showed tumor promoting activity. The 2 active portions were then further chromatographed and tested by the short term bioassay. Some major components of the resulting active fractions included alkyl 2 cyclopenten 2 ol 1 ones, catechols, hydroquinone, fatty acids, and 3 hydroxypyridines. Among these components, catechol, hydroquinone, 3 hydroxypyridine, 6 methyl 3 hydroxypyridine, linolenic acid, and linoleic acid were inactive as tumor promoters in the experimental animal. The activity of the alkyl 2 cyclopenten 2 ol 1 ones is unknown. Other components remain to be identified.