Functionalization of β‑Caryophyllene Generates Novel Polypharmacology in the Endocannabinoid System

The widespread dietary plant sesquiterpene hydrocarbon β-caryophyllene (<b>1</b>) is a CB₂ cannabinoid receptor-specific agonist showing anti-inflammatory and analgesic effects in vivo. Structural insights into the pharmacophore of this hydrocarbon, which lacks functional groups other than double bonds, are missing. A structure–activity study provided evidence for the existence of a well-defined sesquiterpene hydrocarbon binding site in CB₂ receptors, highlighting its exquisite sensitivity to modifications of the strained endocyclic double bond of <b>1</b>. While most changes on this element were detrimental for activity, ring-opening cross metathesis of <b>1</b> with ethyl acrylate followed by amide functionalization generated a series of new monocyclic amides (<b>11a</b>, <b>11b</b>, <b>11c</b>) that not only retained the CB₂ receptor functional agonism of <b>1</b> but also reversibly inhibited fatty acid amide hydrolase (FAAH), the major endocannabinoid degrading enzyme, without affecting monoacylglycerol lipase (MAGL) and α,β hydrolases 6 and 12. Intriguingly, further modification of this monocyclic scaffold generated the FAAH- and endocannabinoid substrate-specific cyclooxygenase-2 (COX-2) dual inhibitors <b>11e</b> and <b>11f</b>, which are probes with a novel pharmacological profile. Our study shows that by removing the conformational constraints induced by the medium-sized ring and by introducing functional groups in the sesquiterpene hydrocarbon <b>1</b>, a new scaffold with pronounced polypharmacological features within the endocannabinoid system could be generated. The structural and functional repertoire of cannabimimetics and their yet poorly understood intrinsic promiscuity may be exploited to generate novel probes and ultimately more effective drugs

Iodine-Promoted Aromatization of <i>p</i>‑Menthane-Type Phytocannabinoids

Treatment with iodine cleanly converts various <i>p</i>-menthane-type phytocannabinoids and their carboxylated precursors into cannabinol (CBN, <b>1a</b>). The reaction is superior to previously reported protocols in terms of simplicity and substrate range, which includes not only tricyclic tetrahydrocannabinols such as Δ⁹-THC (<b>2a</b>) but also bicyclic phytocannabinoids such as cannabidiol (CBD, <b>3a</b>). Lower homologues from the viridin series (<b>2c</b> and <b>3c</b>, respectively) afforded cannabivarin (CBV), a non-narcotic compound that, when investigated against a series of ionotropic (thermo-TRPs) biological end-points of phytocannabinoids, retained the submicromolar TRPA1-activating and TRPM8-inhibiting properties of CBN, while also potently activating TRPV2. Treatment with iodine provides an easy access to CBN (<b>1a</b>) from crude extracts and side-cuts of the purification of Δ⁹-THC and CBD from respectively narcotic <i>Cannabis sativa</i> (marijuana) and fiber hemp, substantially expanding the availability of this compound and, in the case of fiber hemp, dissecting it from narcotic phytocannabinoids

Poly-Electrophilic Sesquiterpene Lactones from <i>Vernonia amygdalina</i>: New Members and Differences in Their Mechanism of Thiol Trapping and in Bioactivity

In addition to known compounds, the leaves of <i>Vernonia amygdalina</i> afforded the new sesquiterpene lactones 14-<i>O</i>-methylvernolide (<b>2</b>), 3′-deoxyvernodalol (<b>6</b>), and vernomygdalin (<b>8</b>). These and related compounds were evaluated for modulation of a series of thiol trapping-sensitive transcription factors (NF-κB, STAT3, and Nrf2), involved in the maintenance of the chronic inflammatory condition typical of human degenerative diseases. Vernolide (<b>1</b>) emerged as a potent inhibitor of STAT3 and NF-κB and showed cytostatic activity toward the prostate cancer cell line DU45, arresting the cell cycle at the S phase. The exomethylene lactones are characterized by multiple Michael acceptor sites, as exemplified by vernolide (<b>1</b>) and vernodalol (<b>5</b>). By using the nuclear magnetic resonance-based cysteamine assay, the most reactive thiophilic site could be identified in both compounds, and competitive experiments qualified vernolide (<b>1</b>) as being more thiophilic than vernodalol (<b>5</b>), in agreement with the results of the pharmacological assays

The Bibenzyl Canniprene Inhibits the Production of Pro-Inflammatory Eicosanoids and Selectively Accumulates in Some <i>Cannabis sativa</i> Strains

Canniprene (<b>1</b>), an isoprenylated bibenzyl unique to <i>Cannabis sativa</i>, can be vaporized and therefore potentially inhaled from marijuana. Canniprene (<b>1</b>) potently inhibited the production of inflammatory eicosanoids via the 5-lipoxygenase pathway (IC₅₀ 0.4 μM) and also affected the generation of prostaglandins via the cyclooxygenase/microsomal prostaglandin E₂ synthase pathway (IC₅₀ 10 μM), while the related spiranoid bibenzyls cannabispiranol (<b>2</b>) and cannabispirenone (<b>3</b>) were almost inactive in these bioassays. The concentration of canniprene (<b>1</b>) was investigated in the leaves of 160 strains of <i>C. sativa</i>, showing wide variations, from traces to >0.2%, but no correlation was found between its accumulation and a specific phytocannabinoid profile

Jatrophanes from <i>Euphorbia squamosa</i> as Potent Inhibitors of <i>Candida albicans</i> Multidrug Transporters

A series of structurally related jatro­phane diterpenoids (<b>1</b>–<b>6</b>), including the new eupho­squamosins A–C (<b>4</b>–<b>6</b>), was purified from the Iranian spurge <i>Euphorbia squamosa</i> and evaluated for its capacity to inhibit drug efflux by multi­drug transporters of <i>Candida albicans</i>. Three of these compounds showed an interesting profile of activity. In particular, deacetyl­serrulatin B (<b>2</b>) and eupho­squamosin C (<b>6</b>) strongly inhibited the drug-efflux activity of the primary ABC-transporter <i>Ca</i>Cdr1p, an effect that translated, in a yeast strain overexpressing this transporter, into an increased sensitivity to flucon­azole. These compounds were transported by <i>Ca</i>Cdr1p, as shown by the observation of an 11–14-fold cross-resistance of yeast growth, and could also inhibit the secondary MFS-transporter <i>Ca</i>Mdr1p. In contrast, eupho­squamosin A (<b>4</b>) was selective for <i>Ca</i>Cdr1p, possibly as a result of a different binding mode. Taken together, these observations suggest jatro­phane diterpenes to be a new class of potent inhibitors of multi­drug transporters critical for drug resistance in pathogenic yeasts

Turmeric Sesquiterpenoids: Expeditious Resolution, Comparative Bioactivity, and a New Bicyclic Turmeronoid

An expeditious strategy to resolve turmerone, the lipophilic anti-inflammatory principle of turmeric (<i>Curcuma longa</i>), into its individual bisabolane constituents (<i>ar</i>-, α-, and β-turmerones, <b>2</b>–<b>4</b>, respectively) was developed. The comparative evaluation of these compounds against a series of anti-inflammatory targets (NF-κB, STAT3, Nrf2, HIF-1α) evidenced surprising differences, providing a possible explanation for the contrasting data on the activity of turmeric oil. Differences were also evidenced in the profile of more polar bisabolanes between the Indian and the Javanese samples used to obtain turmerone, and a novel hydroxylated bicyclobisabolane ketol (bicycloturmeronol, <b>8</b>) was obtained from a Javanese sample of turmeric. Taken together, these data support the view that bisabolane sesquiterpenes represent an important taxonomic marker for turmeric and an interesting class of anti-inflammatory agents, whose strict structure–activity relationships are worth a systematic evaluation

Antimicrobial Phenolics and Unusual Glycerides from <i>Helichrysum italicum</i> subsp. <i>microphyllum</i>

During a large-scale isolation campaign for the heterodimeric phloroglucinyl pyrone arzanol (<b>1a</b>) from <i>Helichrysum italicum</i> subsp. <i>microphyllum</i>, several new phenolics as well as an unusual class of lipids named santinols (<b>5a</b>–<b>c</b>, <b>6</b>–<b>8</b>) have been characterized. Santinols are angeloylated glycerides characterized by the presence of branched acyl- or keto-acyl chains and represent a hitherto unreported class of plant lipids. The antibacterial activity of arzanol and of a selection of <i>Helichrysum</i> phenolics that includes coumarates, benzofurans, pyrones, and heterodimeric phloroglucinols was evaluated, showing that only the heterodimers showed potent antibacterial action against multidrug-resistant <i>Staphylococcus aureus</i> isolates. These observations validate the topical use of <i>Helichrysum</i> extracts to prevent wound infections, a practice firmly established in the traditional medicine of the Mediterranean area

STAT-3 Inhibitory Bisabolanes from <i>Carthamus glaucus</i>

Apart from a large amount (ca. 2.0%) of α-bisabolol β-d-fucopyranoside (<b>2a</b>), the aerial parts of the Mediterranean weed <i>Carthamus glaucus</i> afforded an unusual triglyceride (<i>E</i>-2-crotonyl-1,3-distearolylglycerol, <b>7</b>), two lipophilic flavonoids (<b>6a</b>,<b>b</b>), and a series of bisabolane fucopyranosides variously acylated on the sugar moiety (<b>2b</b>–<b>e</b>) or oxidized on the terpenoid core (<b>3</b>, <b>4a</b>,<b>b</b>, <b>5a</b>,<b>b</b>). The fucopyranoside <b>2a</b> is more soluble in polar media and more versatile in terms of formulation than its aglycone [(−)-α-bisabolol, <b>1</b>], an anti-inflammatory cosmetic ingredient in current short supply in its natural form. A comparative investigation of the activity of α-bisabolol (<b>1a</b>), the fucopyranoside <b>2a</b>, and its senecioate <b>2b</b> on transcription factors involved in inflammation and cancer pathways (NF-κB and STAT-3) showed only marginal activity on NF-κB inhibition for all compounds, while STAT-3 was inhibited potently by the fucoside <b>2a</b> and, to a lesser extent, also by α-bisabolol. These observations qualify <b>2a</b> as an easily available compound, both as an apoptotic lead structure and as a potential alternative to natural α-bisabolol (<b>1</b>) for pharmaceutical and/or cosmetic development

Triterpenoid Hydroxamates as HIF Prolyl Hydrolase Inhibitors

Pentacyclic triterpenoid acids (PCTTAs) are pleiotropic agents that target many macromolecular end-points with low to moderate affinity. To explore the biological space associated with PCTTAs, we have investigated the carboxylate-to-hydroxamate transformation, discovering that it de-emphasizes affinity for the transcription factors targeted by the natural compounds (NF-κB, STAT3, Nrf2, TGR5) and selectively induces inhibitory activity on HIF prolyl hydrolases (PHDs). Activity was reversible, isoform-selective, dependent on the hydroxamate location, and negligible when this group was replaced by other chelating elements or O-alkylated. The hydroxamate of betulinic acid (<b>5b</b>) was selected for further studies, and evaluation of its effect on HIF-1α expression under normal and hypoxic conditions qualified it as a promising lead structure for the discovery of new candidates in the realm of neuroprotection

Additional file 1: of Hypoxia mimetic activity of VCE-004.8, a cannabidiol quinone derivative: implications for multiple sclerosis therapy

Figure S1. VCE-004.8 inhibits COX-2 expression and PGE2 release in LPS-stimulated rat primary microglia cells. (A) PGE2 released was analyzed in the supernatants from primary microglia cells treated as in A. Data represent the mean ± SD (n = 3). *p < 0.05 **p < 0.01, ***p < 0.001 (one-way ANOVA followed Tukey’s test). (B) Primary microglia cells were pre-treated with increasing concentrations of VCE-004.8, then stimulated with LPS for 24 h and the expression of COX-2 analyzed by immunoblot (n = 2). (PPTX 384 kb