Purity >98%. MJ15 is a potent antagonist of the cannabinoid (CB) receptor CB1 (IC50 = 118.9 pM; Ki = 27.2 pM for rat CB1). It is selective for CB1 over CB2, exhibiting only 46% inhibition of CB2 at a concentration of 10 μM. MJ15 reverses (+)-WIN 55,212-2 inhibition of forskolin-induced cAMP accumulation in a dose-dependent manner in CHO cells expressing human CB1 . MJ15 (40 mg/kg) reduces food intake and body weight gain in a rat model of diet-induced obesity. It also reduces body weight gain and white adipose accumulation in a mouse model of early onset diet-induced obesity.