Immunomodulatory properties of 1,2-dihydro-4-hydroxy-2-oxo-1,8-naphthyridine-3-carboxamide derivative VL15

Activation of CB2R by synthetic CB2R agonist, PM289, improves brain endothelial barrier properties, decreases inflammatory response and enhances endothelial repair

The Cannabinoid 2 Receptor (CB2R) has been found to provide immunological modulation in different cell types. More recently, detection of CB2R in the cerebral endothelium suggests a possible role in the resolution of inflammation at the level of the blood-brain-barrier (BBB). Here, the notion that CB2R upregulation in brain endothelial cells could be exploited to promote vascular protection and BBB integrity was evaluated. Targeting and activation of CB2R was accomplished by a novel and highly specific chromenopyrazole based CB2R agonist, PM289. This study demonstrates that CB2R upregulation is induced as early as 8 h in the cortical vasculature in an experimental mouse model of TBI. Unlike CB2R, CB1R was marginally detected and not significantly induced. In the human brain endothelial cell line, hCMEC/D3 cells, similar induction of CB2R was observed upon stimulation with TNFα. Analysis of transendothelial electrical resistance shows that PM289 markedly prevented the barrier-leakiness induced by TNFα. The BBB is also responsible for maintaining an immunological barrier. The five-fold increase in ICAM1 expression in stimulated endothelial cells was significantly diminished due to CB2R activation. Utilizing wounding assays, results showed that wound repair could be accomplished in nearly half the time when the novel CB2R agonist is present compared to the untreated control. Lastly, mechanistically, the effects of CB2R may be explained by the observed inhibition of the p65 NFκB subunit. Overall, these studies support the notion that targeting and activating CB2R in the brain vasculature could aid in BBB and vascular protection in the context of neuroinflammation.

Novel Cannabinoid Receptor 2 (CB2) Low Lipophilicity Agonists Produce Distinct cAMP and Arrestin Signalling Kinetics without Bias

Cannabinoid Receptor 2 (CB2) is a promising target for treating inflammatory diseases. We designed derivatives of 3-carbamoyl-2-pyridone and 1,8-naphthyridin-2(1H)-one-3-carboxamide CB2-selective agonists with reduced lipophilicity. The new compounds were measured for their affinity (radioligand binding) and ability to elicit cyclic adenosine monophosphate (cAMP) signalling and β-arrestin-2 translocation with temporal resolution (BRET-based biosensors). For the 3-carbamoyl-2-pyridone derivatives, we found that modifying the previously reported compound UOSS77 (also known as S-777469) by appending a PEG2-alcohol via a 3-carbomylcyclohexyl carboxamide (UOSS75) lowered lipophilicity, and preserved binding affinity and signalling profile. The 1,8-naphthyridin-2(1H)-one-3-carboxamide UOMM18, containing a cis configuration at the 3-carboxamide cyclohexyl and with an alcohol on the 4-position of the cyclohexyl, had lower lipophilicity but similar CB2 affinity and biological activity to previously reported compounds of this class. Relative to CP55,940, the new compounds acted as partial agonists and did not exhibit signalling bias. Interestingly, while all compounds shared similar temporal trajectories for maximal efficacy, differing temporal trajectories for potency were observed. Consequently, when applied at sub-maximal concentrations, CP55,940 tended to elicit sustained (cAMP) or increasing (arrestin) responses, whereas responses to the new compounds tended to be transient (cAMP) or sustained (arrestin). In future studies, the compounds characterised here may be useful in elucidating the consequences of differential temporal signalling profiles on CB2-mediated physiological responses.

1,8-naphthyridine derivatives: an updated review on recent advancements of their myriad biological activities

Among all nitrogen-containing heterocycles, the 1,8-naphthyridine scaffold has recently gained an immense amount of curiosity from numerous researchers across fields of medicinal chemistry and drug discovery. This new attention can be ascribed to its versatility of synthesis, its reactiveness and the variety of biological activities it has exhibited. Over the past half-decade, numerous diverse biological evaluations have been conducted on 1,8-naphthyridine and its derivatives in a quest to unravel novel pharmacological facets to this scaffold. Its potency to treat neurodegenerative and immunomodulatory disorders, along with its anti-HIV, antidepressant and antioxidant properties, has enticed researchers to look beyond its broad-spectrum activities, providing further scope for exploration. This review is a consolidated update of previous works on 1,8-naphthyridines and their analogs, focusing on the past 5 years.

Cannabinoids and COVID-19

Since the endocannabinoid system is involved in immune function, the effect of cannabinoid intake on infectious conditions is questioned for several years and is of particular interest in the COVID 19 pandemia. Some data suggest that the immunomodulatory effect of cannabinoids may affect the course and severity of SARS-CoV-2 infection. Given the large number of cannabinoids consumers in the community, this commentary presents the current knowledge on the potential impact of cannabinoids and endocannabinoids on bacterial and viral infection courses namely SARS-CoV-2 disease. Practical recommendations, which can be drawn from the literature, are given.

Polypharmacological profile of 1,2-dihydro-2-oxo-pyridine-3-carboxamides in the endocannabinoid system

The endocannabinoid system (ECS) represents one of the major neuromodulatory systems involved in different physiological and pathological processes. Multi-target compounds exert their activities by acting via multiple mechanisms of action and represent a promising pharmacological modulation of the ECS. In this work we report 4-substituted and 4,5-disubstituted 1,2-dihydro-2-oxo-pyridine-3-carboxamide derivatives with a broad spectrum of affinity and functional activity towards both cannabinoid receptors and additional effects on the main components of the ECS. In particular compound B3 showed high affinity for CB1R (K_i = 23.1 nM, partial agonist) and CB2R (K_i = 6.9 nM, inverse agonist) and also significant inhibitory activity (IC₅₀ = 70 nM) on FAAH with moderate inhibition of ABHD12 (IC₅₀ = 2.5 μΜ). Compounds B4, B5 and B6 that act as full agonists at CB1R and as partial agonists (B5 and B6) or antagonist (B4) at CB2R, exhibited an additional multi-target property by inhibiting anandamide uptake with sub-micromolar IC₅₀ values (0.28-0.62 μΜ). The best derivatives showed cytotoxic activity on U937 lymphoblastoid cells. Finally, molecular docking analysis carried out on the three-dimensional structures of CB1R and CB2R and of FAAH allowed to rationalize the structure-activity relationships of this series of compounds.