Table 1

Binding affinity and in vivo potency of Δ⁹-THC, WIN 55,212-2 and indole-derived cannabinoids

Compound	K_i	SA	MPE	RT	RI	Rat DD
	nM
Δ⁹-THC	41	0.92	2.7	2.5	NT	1.8
WIN 55,212-2	24	0.19	1.4	1.5	NT	NT


R	R′	K_i	SA	MPE	RT	RI	Rat DD
		nM
n-Methyl	CH₃	>10,000	NT	NT	NT	NT	NT
n-Ethyl	CH₃	1180 ± 44	NT	NT	NT	NT	NT
n-Propyl	CH₃	164 ± 22	18.7	84.7	99.1	87.2	45.9
n-Butyl	CH₃	22 ± 1.5	2.6	0.23	4.1	12.9	7.3
n-Pentyl	CH₃	9.5 ± 4.5	0.70	0.25	4.3	1.9	<8.5
n-Hexyl	CH₃	48 ± 13	<2.7	9.5	17.1	16.0	19.8
n-Heptyl	CH₃	>10,000	117	>261	>261	>261	>261
n-Methyl	H	>10,000	>35.1	>35.1	>35.1	NT	NT
n-Ethyl	H	1390 ± 123	NT	NT	NT	NT	NT
n-Propyl	H	1050 ± 55	NT	NT	NT	NT	NT
n-Butyl	H	8.9 ± 1.8	0.34	1.3	3.3	NT	NT
n-Pentyl	H	9 ± 5	0.44	∼0.09	1.7	3.9	NT
n-Hexyl	H	9.8 ± 2	0.96	0.73	1.5	NT	NT
n-Heptyl	H	128 ± 17	56.9	17.6	>81.3	NT	NT

For all tables, “no max” indicates that the compound produced only slightly greater than 50% of the presumed maximal effect. “∼dose” indicates an estimated ED₅₀ because the dose-effect curve was not linear. “>dose” indicates that 50% activity was not achieved at this dose, which was the highest dose of the compound that was tested. “NT” = not tested. All ED₅₀values are expressed as micromoles per kilogram. SA, suppression of spontaneous activity; MPE, % maximum possible antinociceptive effect in the tail-flick assay; RT, rectal temperature; RI, ring immobility; rat DD, drug discrimination in rats.