TABLE 2.2 Compounds That Bind to Cannabinoid Receptors

Compound			Properties
Agonists (receptor activators)
	Plant-derived compounds
		9-THC	Main psychoactive cannabinoid in marijuana plant; largely responsible for psychological and physiological effects (except in discussions of the different forms of THC, THC is used as a synonym for 9-THC).
		8-THC	Slightly less potent than 9-THC and much less abundant in marijuana plant but otherwise similar.
		11-OH-9-THC	Bioactive compound formed when body breaks down 9-THC; presumed to be responsible for some effects of marijuana.
	Cannabinoid agonists found in animals
		Anandamide (arachidonyl-ethanolamide)	Found in animals ranging from mollusks to mammals; appears to be primary endogenous cannabinoid agonist in mammals; chemical structure very different from plant cannabinoids and related to prostaglandins.
		2-AG (arachidonyl glycerol)	Endogenous agonist; structurally similar to anandamide; more abundant but less potent than anandamide.
	THC analogues
		Dronabinol	Synthetic THC; marketed in the United States as Marinol for nausea associated with chemotherapy and for AIDS-related wasting.
		Nabilone	THC analogue; marketed in the United Kingdom as Cesamet for same indications as dronabionol.
		CP 55,940	Synthetic cannabinoid; THC analogue; that is, it is structurally similar to THC.
		Levonantradol	THC analogue.
		HU-210	THC analogue, 100- to 800-fold greater potency than THC97.
	Chemical structure unlike THC or anandamide
		WIN-55,212-2	Chemical structure different from known cannabinoids, but binds to both cannabinoid receptors; chemically related to cyclo-oxygenase inhibitors, which include antiinflammatory drugs.
Antagonists (receptor blockers)
	SR 141716A		Synthetic CB1 antagonist; developed in 1994132.
	SR 144528		Synthetic CB2 antagonist; developed in 1997133.

SOURCES: Mechoulam et al., 1998;109 Felder and Glass, 1998;43 and British Medical Association.17