The chemical analysis of a sample of Delta(9)-THC which had been stored in an ethanol/propylene glycol solution for 5 years resulted in the isolation of several hydroxylated Delta(9)-THC derivatives the main of which were trans-cannabitriol monoethyl ether (4) and trans-propanediol ethers 7 and 8 cis-Cannabitriol monoethyl ether (5) and the oxidised derivatives 3 and 6 were detected in lesser amounts The structure elucidation of the unprecedented cannabinoids 3 5 7 and 8 was achieved mainly by NMR techniques Full NMR assignment of compounds 4 and 6 were also made The detection of cannabitriol (6) and the corresponding solvent-adduct analogues (compounds 4-8) was in agreement with the decomposition mechanisms previously proposed for Delta(9)-THC The isolation of the endoperoxide 3 represents indirect evidence of the existence of unstable precursors that were suspected to be intermediates in the non-enzymatic oxidation pathway of Delta(9)-THC Both isomers of cannabitriol monoethyl ether exhibited weak affinity at either CB1 (K-1=2 25 6 30 mu M) or CB2 cannabmoid receptors (K-1=1 97 3 13 mu M) the trans Isomer always being more potent than the cis isomer (C) 2010 Elsevier Ltd All rights reserved