Tobacco, volatile flavor additives

Indole is used as a chemical intermediate, a perfume fixative, and as a synthetic flavor. In addition, it is possibly a kairomone (a volatile chemical released by a plant to attract phytophagus insects). Indole is also a component of tobacco smoke, and occurs naturally in coal tar, jasmine oil, and orange-blossom oil. It is also a bacterial decomposition product of tryptophan in the gut. 

Many flavorful tobacco additives listed by Doull et al. are structurally identical with or similar to highly polar, volatile components identified in the aqueous alcohol-soluble portion of cigarette MSS and tobacco. 

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