Δ--Tetrahydrocannabinol: Natural Occurrence, Chirality, and Pharmacology.

The -stereoisomers of Δ-THC [(-)- and (+)-] were identified and quantified in a series of low-THC-containing varieties of registered in Europe as fiber hemp and in research accessions of cannabis. While Δ--THC () occurs in cannabis fiber hemp in the concentration range of (-)-Δ--THC [(-)-], it was undetectable in a sample of high-THC-containing medicinal cannabis. Natural Δ--THC () is scalemic (ca. 80-90% enantiomeric purity), and the absolute configuration of the major enantiomer was established as 6a,10a [(-)-] by chiral chromatographic comparison with a sample available by asymmetric synthesis. The major enantiomer, (-)-Δ--THC [(-)-], was characterized as a partial cannabinoid agonist in vitro and elicited a full tetrad response in mice at 50 mg/kg doses. The current legal discrimination between narcotic and non-narcotic cannabis varieties centers on the contents of "Δ-THC and isomers" and needs therefore revision, or at least a more specific wording, to account for the presence of Δ--THCs [(+)- and (-)-] in cannabis fiber hemp varieties.