Structure-affinity relationships and pharmacological characterization of new alkyl-resorcinol cannabinoid receptor ligands: Identification of a dual cannabinoid receptor/TRPA1 channel agonist.

In our ongoing program aimed at deeply investigating the endocannabinoid system (ES), a set of new alkyl-resorcinol derivatives was prepared focusing on the nature and the importance of the carboxamide functionality. Binding studies on CB1 and CB2 receptors, monoacylglycerol lipase (MAGL) and fatty acid amide hydrolase (FAAH) showed that some of the newly developed compounds behaved as very potent cannabinoid receptor ligands (Ki in the nanomolar range) while, however, none of them was able to inhibit MAGL and/or FAAH. Derivative 11 was a potent CB1 and CB2 ligand, with Ki values similar to WIN 55,212, exhibiting a CB1 and CB2 agonist profile in vitro. In the formalin test of peripheral acute and inflammatory pain in mice, this compound showed a weak and delayed antinociceptive effect against the second phase of the nocifensive response, exhibiting, interestingly, a quite potent transient receptor potential ankyrin type-1 (TRPA1) channel agonist activity. Moreover, derivative 14, characterized by lower affinity but higher CB2 selectivity than 11, proved to behave as a weak CB2 competitive inverse agonist.

Resorcinol-sn-glycerol derivatives: novel 2-arachidonoylglycerol mimetics endowed with high affinity and selectivity for cannabinoid type 1 receptor.

Since the discovery of the endocannabinoid system, evidence has been progressively accumulating to suggest that 2-arachidonoylglycerol (2-AG) rather than anandamide (AEA) is the endogenous ligand for both cannabinoid (CB) receptors. Moreover, other studies have shown that another lipid molecule, 2-arachidonyl-glycerol ether (2-AGE, noladin ether), which acts as a full agonist at cannabinoid receptors, might occur in tissues. Having previously designed a resorcinol-AEA hybrid model, in this paper we have explored the cannabinoid receptor binding properties, the CB1 functional activity, and the stability to plasma esterases of a novel series of compounds characterized by the conversion of the amide head into the glycerol-ester or glycerol-ether head, typical of 2-AG or the "putative" endocannabinoid 2-AGE, respectively. Glyceryl esters 39 and 41 displayed greater potency for CB1 (Ki in the nanomolar range) than for CB2 receptors plus the potential to be exploited as useful hits for the development of novel 2-AG mimetics.

The interactions of the 5-HT3 receptor with quipazine-like arylpiperazine ligands: the journey track at the end of the first decade of the third millennium.

The 5-HT(3) receptor (5-HT(3)R) occupies a special place among the serotonin receptor subtypes because it has been shown to be a ligand-gated ion channel, which is involved in a number of physiological functions and important pathologies. 5-HT(3)R antagonists have shown an outstanding efficacy in the control of the emesis induced by anticancer chemotherapy and few adverse side-effects, so as to revolutionize the treatment of nausea in cancer patients. This review covers the authors' work performed during the past decade in the development of 5-HT(3)R ligands belonging to the class of arylpiperazine derivatives related to quipazine (quipazine-like arylpiperazines, QLAs) and represents the extension of the review previously published in Current Topics in Medicinal Chemistry in 2002. The discussion is focused mainly on the most significant structure-affinity relationships emerged in the progress of the work and shows how the original ideas have evolved in the recent years.

New resorcinol-anandamide "hybrids" as potent cannabinoid receptor ligands endowed with antinociceptive activity in vivo.

Bearing in mind the pharmacophoric requirements of both (-)-trans-Delta(9)-tetrahydrocannabinol (THC) and anandamide (AEA), we designed a novel pharmacophore consisting of both a rigid aromatic backbone and a flexible chain with the aim to develop a series of stable and potent ligands of cannabinoid receptors. In this paper we report the synthesis, docking studies, and structure-activity relationships of new resorcinol-anandamide "hybrids" differing in the side chain group. Compounds bearing a 2-methyloctan-2-yl group at position 5 showed a significantly higher affinity for cannabinoid (CB) receptors, in particular when an alkyloxy chain of 7 or 10 carbon atoms was also present at position 1. Derivative 32 was a potent CB(1) and CB(2) ligand, with K(i) values similar to that of WIN 55-212 and potent antinociceptive activity in vivo. Moreover, derivative 38, although less potent, proved to be the most selective ligand for CB(2) receptor (K(i)(CB(1)) = 1 muM, K(i)(CB(2)) = 35 nM).

Design, synthesis, binding, and molecular modeling studies of new potent ligands of cannabinoid receptors.

In our ongoing program aimed at the design, synthesis, and biological evaluation of novel cannabinoid receptor ligands derived from olivetol and hexyl-resorcinol, we have designed a structural model for new derivatives on the basis of a previous study. Here we report the synthesis, binding, and molecular modeling studies of new potent compounds with high affinity toward CB(1) and CB(2) receptors. Compounds with amidic 'heads' with alkyloxy chains varying in length from 8 to 12 carbon atoms showed nanomolar affinity for both receptors, depending on the type of aromatic backbone. Two of the new compounds, although not very potent, exhibit selectivity for CB(1) receptors (CB(1)/CB(2)=0.07 and 0.08, respectively). Molecular modeling studies fitted this new class of cannabinoid ligands into a CB(1) receptor model, and the qualitative analysis of the results was in general agreement with the CB(1) affinity constants observed experimentally for these derivatives.

Design, synthesis, and binding studies of new potent ligands of cannabinoid receptors.

Despite their different chemical structures, delta9-tetrahydrocannabinol (THC) and anandamide (AEA) have common pharmacological properties. This study was aimed at finding new cannabinoid receptor ligands that overcome the instability of AEA and its analogues. To this end we planned the synthesis of a series of compounds which retained both a rigid structure, like that of plant cannabinoids, and a flexible portion similar to that of anandamide. Binding studies on CB1 and CB2 receptors, anandamide membrane transporter (AMT), and fatty acid amide hydrolase (FAAH) showed that some of the newly developed compounds have high affinity and specificity for cannabinoid CB1 and CB2 receptors. Compound 25 is a potent CB1 and CB2 ligand, with affinity constants significantly lower than AEA and similar to WIN 55-212, compound 52 is a potent CB2 ligand, although not very selective over CB1 receptors, and compound 43 is CB2 ligand, with at least a 26-fold selectivity over CB1 receptors. Compound 25 behaved as a inverse agonist at CB1 receptors as assessed in the cyclic AMP functional assay.

Synthesis and in vitro pharmacological activity of oxypropanol analogs of labetalol.

New oxypropanol alpha- and beta-adrenoceptor blocking agents, analogs of labetalol, were synthesised and studied in vitro in left atria and aorta for alpha and beta activity.