title: NMR assignments of the major cannabinoids and cannabiflavonoids isolated from flowers of Cannabis sativa.
abstract: The complete 1H- and 13C-NMR assignments of the major Cannabis constituents, delta9-tetrahydrocannabinol, tetrahydrocannabinolic acid, delta8-tetrahydrocannabinol, cannabigerol, cannabinol, cannabidiol, cannabidiolic acid, cannflavin A and cannflavin B have been determined on the basis of one- and two-dimensional NMR spectra including 1H- and 13C-NMR, 1H-1H-COSY, HMQC and HMBC. The substitution of carboxylic acid on the cannabinoid nucleus (as in tetrahydrocannabinolic acid and cannabidiolic acid) has a large effect on the chemical shift of H-1" of the C5 side chain and 2'-OH. It was also observed that carboxylic acid substitution reduces intermolecular hydrogen bonding resulting in a sharpening of the H-5' signal in cannabinolic acid in deuterated chloroform. The additional aromaticity of cannabinol causes the two angular methyl groups (H-8 and H-9) to show identical 1H-NMR shifts, which indicates that the two aromatic rings are in one plane in contrast to the other cannabinoids. For the cannabiflavonoids, the unambiguous assignments of C-3' and C-4' of cannflavin A and B were determined by HMBC spectra.
authors.affiliation: Division of Pharmacognosy, Section Metabolomics, Institute of Biology, Leiden University, PO Box 9502, 2300 RA Leiden, The Netherlands.
authors.forename: Young Hae
authors.initials: YH
authors.lastname: Choi
authors.forename: Arno
authors.initials: A
authors.lastname: Hazekamp
authors.forename: Anja M G
authors.initials: AM
authors.lastname: Peltenburg-Looman
authors.forename: Michel
authors.initials: M
authors.lastname: Frédérich
authors.forename: Cornelis
authors.initials: C
authors.lastname: Erkelens
authors.forename: Alfons W M
authors.initials: AW
authors.lastname: Lefeber
authors.forename: Robert
authors.initials: R
authors.lastname: Verpoorte
mesh_terms: D002186:Cannabinoids / Q000737:chemistry* / Q000302:isolation & purification; D002188:Cannabis / Q000737:chemistry*; D005419:Flavonoids / Q000737:chemistry* / Q000302:isolation & purification; D035264:Flowers / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure
chemical_list: D002186:Cannabinoids; D005419:Flavonoids