JWH-251 is a synthetic cannabinoid from the phenylacetylindole family, which acts as a cannabinoid agonist with about 5x selectivity for CB₁ with a K_i

Dissociation constant

In chemistry, biochemistry, and pharmacology, a dissociation constant is a specific type of equilibrium constant that measures the propensity of a larger object to separate reversibly into smaller components, as when a complex falls apart into its component molecules, or when a salt splits up into...

 of 29nM and 146nM at CB₂. Similar to the related 2'-methoxy compound JWH-250

JWH-250

JWH-250 or is an analgesic chemical from the phenylacetylindole family, which acts as a cannabinoid agonist at both the CB1 and CB2 receptors, with a Ki of 11nM at CB1 and 33nM at CB2...

, the 2'-chloro compound JWH-203

JWH-203

JWH-203 is an analgesic chemical from the phenylacetylindole family, which acts as a cannabinoid agonist with approximately equal affinity at both the CB1 and CB2 receptors, having a Ki of 8.0nM at CB1 and 7.0nM at CB2...

, and the 2'-bromo compound JWH-249

JWH-249

JWH-249 is a synthetic cannabinoid from the phenylacetylindole family, which acts as a cannabinoid agonist with about 2.4x selectivity for CB1 with a Ki of 8.4nM ± 1.8 and 20nM ± 2 at CB2...

, JWH-251 has a phenylacetyl

Acetyl

In organic chemistry, acetyl is a functional group, the acyl with chemical formula COCH3. It is sometimes represented by the symbol Ac . The acetyl group contains a methyl group single-bonded to a carbonyl...

 group in place of the naphthoyl ring used in most aminoalkylindole cannabinoid compounds.