Table 1.

The binding affinities (K_i and IC₅₀) of selected compounds against CB1 and CB2 receptors.

Compound	IC50 ± SEM (μM)		Ki ± SEM (μM)
	CB1	CB2	CB1	CB2
2 a	3.2 ± 1.0	3.25 ± 0.5	1.62 ± 0.5	1.62 ± 0.51
12 ab	>5.3 ± 1.4	>5.93 ± 0.8	>2.6 ± 0.7	>2.97 ± 0.4
16	20.8 ± 4.9	ND c	10.4 ± 2.5	ND c
16 a	0.242 ± 0.07 d	ND c	0.121 ± 0.04 d	ND c
18 e	24.6 ± 2.6	0.101 ± 0.035	12.3 ± 1.3	0.051 ± 0.01
CP55,940	9.84 nM	8.62 nM	4.9 nM	4.31 nM

^a Represents compound’s affinity up to its solubility limit; ^b racemic compounds; ^c ND = not determined because the percent displacement at 10 μM was low; ^d data from Figure 4, for which CP55,940 K_i = 1.267 ± 0.13 nM; ^e the chromophore nature of the compound may have interfered with the radioligand detection (cf. main text).