Metabolism of monoterpenes: specificity of the dehydrogenases responsible for the biosynthesis of camphor, 3-thujone, and 3-isothujone.

Sage (Salvia officinalis) is shown to contain two electrophoretically distinct dehydrogenases for the respective oxidations of (+)-borneol to (+)-camphor, and of (+)-cis-sabinol to (+)-sabinone en route to (-)-3-isothujone. Similarly, tansy (Tanacetum vulgare) is shown to contain two electrophoretically distinct dehydrogenases for the respective oxidations of (-)-borneol to (-)-camphor and of (+)-cis-sabinol to (+)-sabinone en route to (+)-3-thujone. These results demonstrate that separate dehydrogenases are responsible for the biosynthesis of camphor from borneol and of the thujyl ketones via cis-sabinol, and they also indicate that the previously reported oxidations of various thujanols by the borneol dehydrogenases are only coincidental activities not relevant to the formation of 3-thujone and 3-isothujone.