Castoreum is the exudate from the castor sacs of the mature North American Beaver and the European Beaver within the zoological realm. Castoreum is derived from the Greek word Kastor meaning beaver. Castoreum is obtained from the animal source Caster Canadensis. The castor sacs are not true glands (endocrine or exocrine) on a cellular level, hence references to these structures as preputial glands or castor glands are misnomers. Castor sacs are a type of scent gland.
There are at least twenty-four compounds known to be constituents of beaver castoreum. Some of these have pheromonal activity. These are the phenols,4-ethylphenol and 1,2-dihydroxybenzene (catechol) and the ketones acetophenone and 3-hydroxyacetophenone. Five additional compounds noted are 4-methyl-1,2-dihydroxybenzene (4-methylcatechol), 4-methoxyacetophenone, 5-methoxysalicylic acid, salicylaldehyde, and 3-hydroxybenzoic acid. Other neutral compounds are oxygen-containing monoterpenes such as 6-methyl-l-heptanol, 4,6-dimethyl-l-heptanol, isopinocamphone, pinocamphone, two linalool oxides and their acetates. Other compounds are: benzoic acid, benzyl alcohol, borneol, o-cresol, 4-(4'-hydroxyphenyl)-2-butanone, hydroquinone, phenol. All those compounds are gathered from plant food. It also contains Nupharamine alkaloids and castoramine and cis-cyclohexane-1,2-diol.