Biological evaluation of pyridone alkaloids on the endocannabinoid system

Naturally occurring pyridone alkaloids as well as synthetic derivatives were previously shown to induce neurite outgrowth. However, the molecular basis for this biological effect remains poorly understood. In this work, we have prepared new pyridones, and tested the effect of thirteen 4-hydroxy-2-pyridone derivatives on the components of the endocannabinoid system. Investigation of binding affinities towards CB₁ and CB₂ receptors led to the identification of a compound binding selectively to CB₁ (12). Compound 12 and a closely related derivative (11) also inhibited anandamide (AEA) hydrolysis by fatty acid amide hydrolase. Interestingly, none of the compounds tested showed any effect on 2-AG hydrolysis by monoacylglycerol lipase at 10μM. Assessment of AEA uptake did, however, lead to the identification of four inhibitors with IC₅₀ values in the submicromolar range and high selectivity over the other components of the endocannabinoid system.