Variously substituted 2-oxopyridine derivatives: Extending the structure-activity relationships for allosteric modulation of the cannabinoid CB2 receptor.

We previously reported the 2-oxopyridine-3-carboxamide derivative EC21a as the first small synthetic CB2R positive allosteric modulator which displayed antinociceptive activity in vivo in an experimental mouse model of neuropathic pain. Herein, we extended the structure-activity relationships of EC21a through structural modifications regarding the p-fluoro benzyl moiety at position 1 and the amide group in position 3 of the central core. The characterization in vitro was assessed through radioligand binding experiments and functional assays (GTPγS, cAMP, ßarrestin2). Among the new compounds, the derivatives A1 (SV-10a) and A5 (SB-13a) characterized respectively by fluorine atom or by chlorine atom in ortho position of the benzylic group at position 1 and by a cycloheptane-carboxamide at position 3 of the central core, showed positive allosteric behavior on CB2R. They enhanced the efficacy of CP55,940 in [35S]GTPγS assay, and modulated CP55,940-dependent ßarrestin2 recruitment and cAMP inhibition. The obtained results extend our knowledge of the structural requirements for interaction with the allosteric site of CB2R.

PSNCBAM-1 analogs: Structural evolutions and allosteric properties at cannabinoid CB1 receptor.

Allosteric modulation of the CB1Rs could represent an alternative strategy for the treatment of diseases in which these receptors are involved, without the undesirable effects associated with their orthosteric stimulation. PSNCBAM-1 is a reference diaryl urea derivative that positively affects the binding affinity of orthosteric ligands (PAM) and negatively affects the functional activity of orthosteric ligands (NAM) at CB1Rs. In this work we reported the design, synthesis and biological evaluation of three different series of compounds, derived from structural modifications of PSNCBAM-1 and its analogs reported in the recent literature. Almost all the new compounds increased the percentage of binding affinity of CP55940 at CB1Rs, showing a PAM profile. When tested alone in the [35S]GTPγS functional assay, only a few derivatives lacked detectable activity, so were tested in the same functional assay in the presence of CP55940. Among these, compounds 11 and 18 proved to be functional NAMs at CB1Rs, dampening the orthosteric agonist-induced receptor functionality by approximately 30%. The structural features presented in this work provide new CB1R-allosteric modulators (with a profile similar to the reference compound PSNCBAM-1) and an extension of the structure-activity relationships for this type of molecule at CB1Rs.

Modification on the 1,2-dihydro-2-oxo-pyridine-3-carboxamide core to obtain multi-target modulators of endocannabinoid system.

Several preclinical evidence indicate that the modulation of the endocannabinoid system (ECS) represents a promising therapeutic approach for different diseases. However, only few modulators of this system have reached so far an advanced stage of clinical development, mainly due to limited efficacy and CB1 receptor-dependent side effects. Those limitations might be overcome by multi-target compounds that exert pro-cannabinoid activities through the modulation of two or more targets in the ECS. This approach can offer a safer and more effective pharmacological strategy as compared to the modulation of a single target. In this work, we report the synthesis and biological characterization of new 6-aryl-1,2-dihydro-2-oxo-pyridine-3-carboxamide derivatives. Our results identified several compounds exhibiting interesting multi-target profiles within the ECS. In particular, compound B1 showed moderate-to-high affinity for cannabinoid receptors (Ki CB1R = 304 nM, partial agonist, Ki CB2R = 3.1 nM, inverse agonist) and a potent inhibition of AEA uptake (IC50 = 62 nM) with moderate inhibition of FAAH (IC50 = 2.9 µM). The corresponding 2-alkoxypyridine analogue B14 exhibited significant inhibitor activity on both FAAH (IC50 = 69 nM) and AEA uptake (IC50 = 76 nM) without significantly binding to both cannabinoid receptor subtypes. Molecular docking analysis was carried out on the three-dimensional structures of CB1R and CB2R and of FAAH to rationalize the structure-activity relationships of this series of compounds.

Allosteric modulators targeting cannabinoid cb1 and cb2 receptors: implications for drug discovery.

Allosteric modulators of cannabinoid receptors hold great therapeutic potential, as they do not possess intrinsic efficacy, but instead enhance or diminish the receptor's response of orthosteric ligands allowing for the tempering of cannabinoid receptor signaling without the desensitization, tolerance and dependence. Allosteric modulators of cannabinoid receptors have numerous advantages over the orthosteric ligands such as higher receptor type selectivity, probe dependence and biased signaling, so they have a great potential to separate the therapeutic benefits from side effects own of orthosteric ligands. This review aims to give an overview of the CB1 and CB2 receptor allosteric modulators highlighting the structure-activity relationship and pharmacological profile of each classes, and their future promise.

Characterization of the Saffron Derivative Crocetin as an Inhibitor of Human Lactate Dehydrogenase 5 in the Antiglycolytic Approach against Cancer.

Inhibition of lactate dehydrogenase (LDH) represents an innovative approach to tackle cancer because this peculiar glycolytic metabolism is characteristic of most invasive tumor cells. An investigation into the biological properties of saffron extracts led to the discover of their LDH-inhibition properties. In particular, the most important saffron components, crocetin, was found to inhibit LDH (IC50 = 54.9 ± 4.7 µM). This carotenoid was independently produced by chemical synthesis, and its LDH-inhibition properties manifested via its antiproliferative activity against two glycolytic cancer cell lines (A549 and HeLa, IC50 = 114.0 ± 8.0 and 113.0 ± 11.1 µM, respectively). The results described in this article suggest that saffron may be a helpful alimentary component in the prevention of cancer that potentially contributes to the efficacy of approved cancer therapies.