AM251
Encyclopedia
AM-251 is an inverse agonist
at the CB1
cannabinoid receptor. AM-251 is structurally very close to SR141716A (rimonabant)
, which both are biarylpyrazole cannabinoid receptor antagonist
s. In AM-251 the p-chloro group attached to the phenyl substituent at C-5 of the pyrazole
ring is replaced with a p-iodo
group. The resulting compound exhibits slightly better binding affinity for the CB1 receptor
(with a Ki value of 7.5nM) than SR141716A, which has a Ki value of 11.5nM, AM-251 is, however, about two-fold more selective for the CB1 receptor when compared to SR141716A.
Inverse agonist
In the field of pharmacology, an inverse agonist is an agent that binds to the same receptor as an agonist but induces a pharmacological response opposite to that agonist....
at the CB1
Cannabinoid receptor type 1
The cannabinoid receptor type 1, often abbreviated to CB1, is a G protein-coupled cannabinoid receptor located in the brain. It is activated by endocannabinoid neurotransmitters including anandamide and by the compound THC, found in the psychoactive drug cannabis.-Expression:The CB1 receptor is...
cannabinoid receptor. AM-251 is structurally very close to SR141716A (rimonabant)
Rimonabant
Rimonabant is an anorectic antiobesity drug that has been withdrawn from the market. It is an inverse agonist for the cannabinoid receptor CB1...
, which both are biarylpyrazole cannabinoid receptor antagonist
Cannabinoid receptor antagonist
The discovery of the endogenous cannabinoid system led to the development of CB1 receptor antagonists. The first cannabinoid receptor "antagonist," rimonabant, was described in 1994. Rimonabant blocks the CB1 receptor selectively and it has been shown to decrease food intake and regulate...
s. In AM-251 the p-chloro group attached to the phenyl substituent at C-5 of the pyrazole
Pyrazole
Pyrazole refers both to the class of simple aromatic ring organic compounds of the heterocyclic diazole series characterized by a 5-membered ring structure composed of three carbon atoms and two nitrogen atoms in adjacent positions, and to the unsubstituted parent compound...
ring is replaced with a p-iodo
Iodo
Iodo may refer to;*Socotra Rock*Iodo , South Korean film directed by Kim Ki-young*Iodine, chemical element...
group. The resulting compound exhibits slightly better binding affinity for the CB1 receptor
Cannabinoid receptor type 1
The cannabinoid receptor type 1, often abbreviated to CB1, is a G protein-coupled cannabinoid receptor located in the brain. It is activated by endocannabinoid neurotransmitters including anandamide and by the compound THC, found in the psychoactive drug cannabis.-Expression:The CB1 receptor is...
(with a Ki value of 7.5nM) than SR141716A, which has a Ki value of 11.5nM, AM-251 is, however, about two-fold more selective for the CB1 receptor when compared to SR141716A.