Cannabitwinol, a Dimeric Phytocannabinoid from Hemp, Cannabis sativa L., Is a Selective Thermo-TRP Modulator.

Cannabitwinol (CBDD, 3), the second member of a new class of dimeric phytocannabinoids in which two units are connected by a methylene bridge, was isolated from a hemp (Cannabis sativa L.) industrial extract. The structural characterization of cannabitwinol, complicated by broadening of 1H NMR signals and lack of expected 2D NMR correlations at room temperature, was fully carried out in methanol-d4 at -30 °C. All the attempts to prepare CBDD by reaction of CBD with formaldehyde or its iminium analogue (Eschenmoser salt) failed, suggesting that this sterically congested dimer is the result of enzymatic reactions on the corresponding monomeric acids. Analysis of the cannabitwinol profile of transient receptor potential (TRP) modulation evidenced the impact of dimerization, revealing a selectivity for channels activated by a decrease of temperature (TRPM8 and TRPA1) and the lack of significant affinity for those activated by an increase of temperature (e.g., TRPV1). The putative binding modes of cannabitwinol with TRPA1 and TRPM8 were investigated in detail by a molecular docking study using the homology models of both channels.

Design, Synthesis and In Vitro Experimental Validation of Novel TRPV4 Antagonists Inspired by Labdane Diterpenes.

Labdane diterpenes are widespread classes of natural compounds present in variety of marine and terrestrial organisms and plants. Many of them represents "natural libraries" of compounds with interesting biological activities due to differently functionalized drimane nucleus exploitable for potential pharmacological applications. The transient receptor potential channel subfamily V member 4 (TRPV4) channel has recently emerged as a pharmacological target for several respiratory diseases, including the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Inspired by the labdane-like bicyclic core, a series of homodrimane-derived esters and amides was designed and synthesized by modifying the flexible tail in position 1 of (+)-sclareolide, an oxidized derivative of the bioactive labdane-type diterpene sclareol. The potency and selectivity towards rTRPV4 and hTRPV1 receptors were assessed by calcium influx cellular assays. Molecular determinants critical for eliciting TRPV4 antagonism were identified by structure-activity relationships. Among the selective TRPV4 antagonists identified, compound 6 was the most active with an IC50 of 5.3 µM. This study represents the first report of semisynthetic homodrimane TRPV4 antagonists, selective over TRPV1, and potentially useful as pharmacological tools for the development of novel TRPV4 channel modulators.

Palmitoylethanolamide: A Nutritional Approach to Keep Neuroinflammation within Physiological Boundaries-A Systematic Review.

Neuroinflammation is a physiological response aimed at maintaining the homodynamic balance and providing the body with the fundamental resource of adaptation to endogenous and exogenous stimuli. Although the response is initiated with protective purposes, the effect may be detrimental when not regulated. The physiological control of neuroinflammation is mainly achieved via regulatory mechanisms performed by particular cells of the immune system intimately associated with or within the nervous system and named "non-neuronal cells." In particular, mast cells (within the central nervous system and in the periphery) and microglia (at spinal and supraspinal level) are involved in this control, through a close functional relationship between them and neurons (either centrally, spinal, or peripherally located). Accordingly, neuroinflammation becomes a worsening factor in many disorders whenever the non-neuronal cell supervision is inadequate. It has been shown that the regulation of non-neuronal cells-and therefore the control of neuroinflammation-depends on the local "on demand" synthesis of the endogenous lipid amide Palmitoylethanolamide and related endocannabinoids. When the balance between synthesis and degradation of this bioactive lipid mediator is disrupted in favor of reduced synthesis and/or increased degradation, the behavior of non-neuronal cells may not be appropriately regulated and neuroinflammation exceeds the physiological boundaries. In these conditions, it has been demonstrated that the increase of endogenous Palmitoylethanolamide-either by decreasing its degradation or exogenous administration-is able to keep neuroinflammation within its physiological limits. In this review the large number of studies on the benefits derived from oral administration of micronized and highly bioavailable forms of Palmitoylethanolamide is discussed, with special reference to neuroinflammatory disorders.

Moringin, A Stable Isothiocyanate from Moringa oleifera, Activates the Somatosensory and Pain Receptor TRPA1 Channel In Vitro.

Moringa oleifera Lam. is a tropical plant widely used in traditional medicines and as a food supplement. It is characterized by the presence of glucosinolates and isothiocyanates; the stable isothiocyanate 4-[(α-l-rhamnosyloxy)benzyl]isothiocyanate (moringin) has been widely studied for its bioactivity as hypoglycemic, antimicrobial, anticancer and in particular for its involvement in nociception and neurogenic pain. Moringa extracts and pure moringin were submitted to in vitro assays with the somatosensory TRPA1 ion channel, proving that moringin is a potent and effective agonist of this receptor involved in nociceptive function and pain states. Moringin do not activate or activates very weakly the vanilloids somatosensory channels TRPV1,2,3 and 4, and the melastatin cooling receptor TRPM8. The comparison of moringin's activity with other known agonists of natural origin is also discussed.

Palmitoylethanolamide counteracts substance P-induced mast cell activation in vitro by stimulating diacylglycerol lipase activity.

BACKGROUND: Palmitoylethanolamide (PEA) is a pleiotropic endogenous lipid mediator currently used as a "dietary food for special medical purposes" against neuropathic pain and neuro-inflammatory conditions. Several mechanisms underlie PEA actions, among which the "entourage" effect, consisting of PEA potentiation of endocannabinoid signaling at either cannabinoid receptors or transient receptor potential vanilloid type-1 (TRPV1) channels. Here, we report novel molecular mechanisms through which PEA controls mast cell degranulation and substance P (SP)-induced histamine release in rat basophilic leukemia (RBL-2H3) cells, a mast cell model. METHODS: RBL-2H3 cells stimulated with SP were treated with PEA in the presence and absence of a cannabinoid type-2 (CB2) receptor antagonist (AM630), or a diacylglycerol lipase (DAGL) enzyme inhibitor (OMDM188) to inhibit the biosynthesis of the endocannabinoid 2-arachidonoylglycerol (2-AG). The release of histamine was measured by ELISA and ß-hexosaminidase release and toluidine blue staining were used as indices of degranulation. 2-AG levels were measured by LC-MS. The mRNA expression of proposed PEA targets (Cnr1, Cnr2, Trpv1, Ppara and Gpr55), and of PEA and endocannabinoid biosynthetic (Napepld, Dagla and Daglb) and catabolic (Faah, Naaa and Mgl) enzymes were also measured. The effects of PEA on the activity of DAGL-α or -ß enzymes were assessed in COS-7 cells overexpressing the human recombinant enzyme or in RBL-2H3 cells, respectively. RESULTS: SP increased the number of degranulated RBL-2H3 cells and triggered the release of histamine. PEA counteracted these effects in a manner antagonized by AM630. PEA concomitantly increased the levels of 2-AG in SP-stimulated RBL-2H3 cells, and this effect was reversed by OMDM188. PEA significantly stimulated DAGL-α and -ß activity and, consequently, 2-AG biosynthesis in cell-free systems. Co-treatment with PEA and 2-AG at per se ineffective concentrations downmodulated SP-induced release of histamine and degranulation, and this effect was reversed by OMDM188. CONCLUSIONS: Activation of CB2 underlies the inhibitory effects on SP-induced RBL-2H3 cell degranulation by PEA alone. We demonstrate for the first time that the effects in RBL-2H3 cells of PEA are due to the stimulation of 2-AG biosynthesis by DAGLs.

Isothiocyanates and Glucosinolates from Sisymbrium officinale (L.) Scop. ("the Singers' Plant"): Isolation and in Vitro Assays on the Somatosensory and Pain Receptor TRPA1 Channel.

Sisymbrium officinale (L.) Scop. is a wild common plant of the Brassicaceae family. It is known as "the singers' plant" for its traditional use in treating aphonia and vocal disability. Despite its wide use in herbal preparations, the molecular mechanism of action of S. officinale extracts is not known. The plant is rich in glucosinolates and isothiocyanates, which are supposed to be its active compounds. Some members of this family, in particular allylisothiocyanate, are strong agonists of the transient receptor potential ankyrin 1 (TRPA1) channel, which is involved in the somatosensory perception of pungency as well as in the nociception pathway of inflammatory pain. This study aims to isolate the glucosinolates and isothiocianates from fresh S. officinale to identify the major components and test their activity in in vitro assays with a cloned TRPA1 channel. Samples of cultivated S. officinale have been extracted and the active compounds isolated by column chromatography, HPLC and PTLC. The main components glucoputranjivin, isopropylisothiocyanate and 2-buthylisothiocianate have been tested on TRPA1. The glucosinolates glucoputranjivin and sinigrin turned out to be inactive, while isopropylisothiocyanate and 2-buthylisothiocyanate are potent agonists of TRPA1, with an EC50 in the range of the high potency natural agonists identified so far for this somatosensory channel.

Iodine-mediated cyclization of cannabigerol (CBG) expands the cannabinoid biological and chemical space.

Electrophilic attack to a double bond, the classic trigger of intramolecular isoprenoid cyclizations, is apparently silent in Cannabis and the diversity of the cannabinome can be ultimately traced to the oxidative cyclization of cannabigerolic acid (CBGA, 1a), a process triggered by the generation of an aromatic electrophilic species. To expand the chemical space of the cannabinoid chemotype, we have investigated an oxidative trigger based on the addition of iodine to the terminal isoprenyl double bond of cannabigerol (CBG, 1b), the decarboxylated and thermally stable version of CBGA (1a). Apart from the predictable product of an iodine-induced cascade cyclization (3), also a pair of unprecedented spiranes named spirocannabigerols (4a,b), derived from the formation of an edge-protonated cyclopropyl cation was also formed, along with a product (5) resulting from the incorporation, in a Friedel-Craft fashion, of the reaction solvent (toluene). Biological evaluation of these compounds on six thermo-transient receptor potential channels (TRPs) showed a remodeling of bioactivity compared to GBC, with emphasis on TRPA1 rather than TRPM8.

TRPA1 Modulating C14 Polyacetylenes from the Iranian Endemic Plant Echinophora platyloba.

Phytochemical investigation of the apolar extract obtained from aerial parts of the Iranian endemic plant Echinophora platyloba DC (Apiaceae) resulted in the characterization of the polyacetylene fraction of this plant. This resulted to be composed of the known echinophorins A and B, embedding the very rare α-pyrone terminal, and of the new echinophorin D (3), including also three conjugated triple bonds. The chemical structures of these compounds were secured by detailed inspection of MS and 1D/2D NMR spectra. The isolated polyacteylenes were evaluated for their modulation of six thermo-TRP channels and they revealed a selective activity on TRPA1, an ion channel involved in the mediation of neuropathic and inflammatory pain. This is the first report on the activity of plant polyacetylenes on transient receptor potential (TRP) channels.

Arylboronic acids as dual-action FAAH and TRPV1 ligands.

A series of 31 arylboronic acids designed on the basis of the pharmacophore model for a variety of TRPV1 antagonists was prepared and tested on FAAH and TRPV1 channel. Four of them, that is, compounds 3c, 4a, 5a,b acted as dual FAAH/TRPV1 blockers with IC50 values between 0.56 and 8.11µM whereas ten others (compounds 1c,f-i, 2c-f, 4b) inhibited FAAH and activated/desensitized TRPV1.

Neuroactive and Anti-inflammatory Frankincense Cembranes: A Structure-Activity Study.

An expeditious isolation method for the cembrane diterpene alcohols incensol (1a) and serratol (2) has been developed from respectively African and Indian frankincense. The two native alcohols and a series of semisynthetic derivatives of incensol were evaluated for transient receptor potential vanilloid 3 (TRPV3) activation and the inhibition of NF-κB, the putative molecular targets underlying the psychotropic and anti-inflammatory activities of incensol acetate (IA, 1b). Serratol (2) was the most potent TRPV3 activator, outperforming by 2 orders of magnitude the reference agonist thymol and by 1 order of magnitude incensol acetate (1b). Acylation, epimerization, and oxidation did not significantly improve the affinity of incensol for TRPV3, while NF-κB inhibition, marginal for both natural alcohols, could be improved by esterification of incensol (1a) with lipophilic acids. Interestingly, incensol (1a) but not IA (1b) was a potent inhibitor of STAT3, raising the possibility that hydrolysis to incensol (1a) might be involved in the in vivo biological activity of IA (1b). Serratol was not amenable to chemical modification, but some marine cembranoids related to the frankincense diterpenoids showed a certain degree of TRPV3-activating properties, qualifying the aliphatic macrocyclic cembrane skeleton as a selective chemotype to explore the pharmacology of TRPV3, a thermo-TRP otherwise resistant to modulation by small molecules.

Evaluation of the analgesic effect of 4-anilidopiperidine scaffold containing ureas and carbamates.

Fentanyl is a powerful opiate analgesic typically used for the treatment of severe and chronic pain, but its prescription is strongly limited by the well-documented side-effects. Different approaches have been applied to develop strong analgesic drugs with reduced pharmacologic side-effects. One of the most promising is the design of multitarget drugs. In this paper we report the synthesis, characterization and biological evaluation of twelve new 4-anilidopiperidine (fentanyl analogues). In vivo hot-Plate test, shows a moderate antinociceptive activity for compounds OMDM585 and OMDM586, despite the weak binding affinity on both µ and δ-opioid receptors. A strong inverse agonist activity in the GTP-binding assay was revealed suggesting the involvement of alternative systems in the brain. Fatty acid amide hydrolase inhibition was evaluated, together with binding assays of cannabinoid receptors. We can conclude that compounds OMDM585 and 586 are capable to elicit antinociception due to their multitarget activity on different systems involved in pain modulation.

Inhibitory effect of positively charged triazine antagonists of prokineticin receptors on the transient receptor vanilloid type-1 (TRPV1) channel.

Four positively charged compounds, previously shown to produce analgesic activity by interacting with prokineticin receptor or T-type calcium channels, were tested for their ability to inhibit capsaicin-induced elevation of intracellular Ca(2+) in HEK-293 cells stably transfected with the human recombinant TRPV1, with the goal of identifying novel TRPV1 open-pore inhibitors. KYS-05090 showed the highest potency as a TRPV1 antagonist, even higher than that of the open-pore triazine inhibitor 8aA. The latter showed quite remarkable agonist/desensitizer activity at the rat recombinant TRPM8 channel. The activity of KYS-05090 and the other compounds was selective because none of these compounds was able to modulate the rat TRPA1 channel. Open-pore inhibitors of TRPV1 may be a new class of multi-target analgesics with lesser side effects, such as loss of acute pain sensitivity and hyperthermia, than most TRPV1 antagonists developed so far.

Structure-activity relationships of the prototypical TRPM8 agonist icilin.

A series of structural analogues of the TRPM8 agonist icilin was prepared. The compounds were examined for their ability to exert agonist or antagonist effects in HEK-293 cells expressing the TRPM8 receptor. Most structural modifications of the icilin structure largely met with diminished TRPM8 agonist activity. Cinnamamide 'open-chain' analogs of icilin, however, demonstrated significant antagonistic actions at the TRPM8 receptor. Optimal potency (IC50=73 nM) was observed in the 3-iodo derivative 18l.

Discovery of non-electrophilic capsaicinoid-type TRPA1 ligands.

Replacement of the benzylamide motif of synthetic capsaicin (nonivamide, 1c) with a tetrazole moiety was detrimental for TRPV1 binding, but unexpectedly generated a potent and non-electrophilic TRPA1 agonist (4a). Spurred by this observation and by the relatively small number of non-covalent TRPA1 ligands reported so far, the benzylamide-to-tetrazole swap was investigated in the more lipophilic and powerful vanilloids olvanil (1d), rinvanil (1e), and phenylacetylrinvanil (1f). In all cases, the replacement was detrimental for TRPV1 binding, but a clear modulation of TRPA1 activity was observed. These observations show that the capsaicinoid pharmacophore displays orthogonal structure-activity relationships for TRPV1 and TRPA1 binding, and suggest the possibility of obtaining compounds with dual TRPV1/TRPA1 modulatory properties by exploration of the chemical space around the capsaicin motif.

Effect of acyclic monoterpene alcohols and their derivatives on TRP channels.

A series of thirty-six geraniol, nerol, citronellol, geranylamine, and nerylamine derivatives was synthesized and tested on TRPA1, TRPM8, and TRPV1 channels. Most of them acted as strong modulators of TRPA1 channels with EC50 and/or IC50 values <1 µM. None was able to significantly activate TRPM8 channels, while thirteen of them behaved as 'true' TRPM8 antagonists. Little or no effect was generally observed on TRPV1 channels. Some of the compounds examined, that is, compounds 1d,g,n, 2c,d,h,i,o, 3b,e exhibited an appreciable selectivity for TRPA1 subtype.

Electrophysiological variability in the SH-SY5Y cellular line.

The basic electrophysiological properties of SH-SY5Y tumour cells have been studied by whole cell patch-clamp in voltage clamp configuration. The results shown the existence of a large variability of the response among individual cells in the same experimental conditions. Experiments conducted by using different ionic concentrations of the recording pipette filling solution, yielded a significant variability of peak current amplitude for all the filling solutions used. In addition, variability among groups was detected. The inter-group variability was not dependent on the different ionic components among the groups. Our results confirm earlier findings that this cell line is not constituted of an uniform population of cells. Moreover, from the present results we can conclude that these cells have diverse regulatory patterns of membrane conductance, probably due to both the expression as well as a non precise regulation of the membrane density of the different channels.

Novel pyrrole based CB2 agonists: New insights on CB2 receptor role in regulating neurotransmitters' tone.

The cannabinoid system is one of the most investigated neuromodulatory systems because of its involvement in multiple pathologies such as cancer, inflammation, and psychiatric diseases. Recently, the CB2 receptor has gained increased attention considering its crucial role in modulating neuroinflammation in several pathological conditions like neurodegenerative diseases. Here we describe the rational design of pyrrole-based analogues, which led to a potent and pharmacokinetically suitable CB2 full agonist particularly effective in improving cognitive functions in a scopolamine-induced amnesia murine model. Therefore, we extended our study by investigating the interconnection between CB2 activation and neurotransmission in this experimental paradigm. To this purpose, we performed a MALDI imaging analysis on mice brains, observing that the administration of our lead compound was able to revert the effect of scopolamine on different neurotransmitter tones, such as acetylcholine, serotonin, and GABA, shedding light on important networks not fully explored, so far.

3-Ylidenephthalides as a new class of transient receptor potential channel TRPA1 and TRPM8 modulators.

Following the recent identification of the naturally occurring 3-ylidene-4,5-dihydrophthalide ligustilide and its oxidation product dehydroligustilide as novel TRPA1 modulators, a series of seventeen 3-ylidenephthalides was synthesized and tested on TRPA1 and TRPM8 channels. Most of these compounds acted as strong modulators of the two channel types with EC50 and/or IC50 values distinctly lower than those of the reference compounds.

Mutual Links between the Endocannabinoidome and the Gut Microbiome, with Special Reference to Companion Animals: A Nutritional Viewpoint.

There is growing evidence that perturbation of the gut microbiome, known as "dysbiosis", is associated with the pathogenesis of human and veterinary diseases that are not restricted to the gastrointestinal tract. In this regard, recent studies have demonstrated that dysbiosis is linked to the pathogenesis of central neuroinflammatory disorders, supporting the existence of the so-called microbiome-gut-brain axis. The endocannabinoid system is a recently recognized lipid signaling system and termed endocannabinoidome monitoring a variety of body responses. Accumulating evidence demonstrates that a profound link exists between the gut microbiome and the endocannabinoidome, with mutual interactions controlling intestinal homeostasis, energy metabolism and neuroinflammatory responses during physiological conditions. In the present review, we summarize the latest data on the microbiome-endocannabinoidome mutual link in health and disease, focalizing the attention on gut dysbiosis and/or altered endocannabinoidome tone that may distort the bidirectional crosstalk between these two complex systems, thus leading to gastrointestinal and metabolic diseases (e.g., idiopathic inflammation, chronic enteropathies and obesity) as well as neuroinflammatory disorders (e.g., neuropathic pain and depression). We also briefly discuss the novel possible dietary interventions based not only on probiotics and/or prebiotics, but also, and most importantly, on endocannabinoid-like modulators (e.g., palmitoylethanolamide) for intestinal health and beyond.

First Evidence of the Protective Effects of 2-Pentadecyl-2-Oxazoline (PEA-OXA) in In Vitro Models of Acute Lung Injury.

Acute respiratory distress syndrome (ARDS) is a serious inflammatory lung disorder and a complication of SARS-CoV-2 infection. In patients with severe SARS-CoV-2 infection, the transition to ARDS is principally due to the occurrence of a cytokine storm and an exacerbated inflammatory response. The effectiveness of ultra-micronized palmitoylethanolamide (PEA-um) during the earliest stage of COVID-19 has already been suggested. In this study, we evaluated its protective effects as well as the effectiveness of its congener, 2-pentadecyl-2-oxazoline (PEA-OXA), using in vitro models of acute lung injury. In detail, human lung epithelial cells (A549) activated by polyinosinic-polycytidylic acid (poly-(I:C)) or Transforming Growth Factor-beta (TGF-ß) were treated with PEA-OXA or PEA. The release of IL-6 and the appearance of Epithelial-Mesenchymal Transition (EMT) were measured by ELISA and immunofluorescence assays, respectively. A possible mechanism of action for PEA-OXA and PEA was also investigated. Our results showed that both PEA-OXA and PEA were able to counteract poly-(I:C)-induced IL-6 release, as well as to revert TGF-ß-induced EMT. In addition, PEA was able to produce an "entourage" effect on the levels of the two endocannabinoids AEA and 2-AG, while PEA-OXA only increased PEA endogenous levels, in poly-(I:C)-stimulated A549 cells. These results evidence for the first time the superiority of PEA-OXA over PEA in exerting protective effects and point to PEA-OXA as a new promising candidate in the management of acute lung injury.