Biotransformation of cannabinoids bySyncephalastrum racemosum

Incubation of four common cannabinoids with vegetative cultures of the fungus Syncephalastrum racemosum yielded a number of polar metabolites. Major metabolites of Δ9-tetrahydrocannabinol, Δ8-tetrahydrocannabinol, cannabidiol and cannabinol were eluted from preparative thin-layer chromatographic plates and analyzed by gas-liquid chromatography mass spectrometry. The mass spectrum of each of the compounds examined showed a molecular ion corresponding to a monohydroxylated derivative of the parent cannabinoid. Identification of the major metabolite of each cannabinoid as the product of hydroxylation in the penultimate (4′) position of the n-pentyl sidechain was made by analysis of the mass spectra of underivatized and TMS derivatized metabolites and by comparison with model compounds. A number of prominent fragment ions in the mass spectra were identified as arising through known fragmentation pathways of cannabinoids.