Humans perceive thousands of compounds as bitter. In sharp contrast, only approximately 25 taste 2 receptors (TAS2R) bitter taste receptors have been identified, raising the question as to how the vast array of bitter compounds can be detected by such a limited number of sensors. To address this issue, we have challenged 25 human taste 2 receptors (hTAS2Rs) with 104 natural or synthetic bitter chemicals in a heterologous expression system. Thirteen cognate bitter compounds for 5 orphan receptors and 64 new compounds for previously identified receptors were discovered. Whereas some receptors recognized only few agonists, others displayed moderate or extreme tuning broadness. Thus, 3 hTAS2Rs together were able to detect approximately 50% of the substances used. Conversely, though 63 bitter substances activated only 1-3 receptors, 19 compounds stimulated up to 15 hTAS2Rs. Our data suggest that the detection of the numerous bitter chemicals is related to the molecular receptive ranges of hTAS2Rs.

Covering up to January 2016Cannabis sativa L. is a prolific, but not exclusive, producer of a diverse group of isoprenylated resorcinyl polyketides collectively known as phytocannabinoids. The modular nature of the pathways that merge into the phytocannabinoid chemotype translates in differences in the nature of the resorcinyl side-chain and the degree of oligomerization of the isoprenyl residue, making the definition of phytocannabinoid elusive from a structural standpoint. A biogenetic definition is therefore proposed, splitting the phytocannabinoid chemotype into an alkyl- and a β-aralklyl version, and discussing the relationships between phytocannabinoids from different sources (higher plants, liverworts, fungi). The startling diversity of cannabis phytocannabinoids might be, at least in part, the result of non-enzymatic transformations induced by heat, light, and atmospheric oxygen on a limited set of major constituents (CBG, CBD, Δ-THC and CBC and their corresponding acidic versions), whose degradation is detailed to emphasize this possibility. The diversity of metabotropic (cannabinoid receptors), ionotropic (thermos-TRPs), and transcription factors (PPARs) targeted by phytocannabinoids is discussed. The integrated inventory of these compounds and their biological macromolecular end-points highlights the opportunities that phytocannabinoids offer to access desirable drug-like space beyond the one associated to the narcotic target CB.

Marijuana (Cannabis sativa) has long been known to contain antibacterial cannabinoids, whose potential to address antibiotic resistance has not yet been investigated. All five major cannabinoids (cannabidiol (1b), cannabichromene (2), cannabigerol (3b), Δ9-tetrahydrocannabinol (4b), and cannabinol (5)) showed potent activity against a variety of methicillin-resistant Staphylococcus aureus (MRSA) strains of current clinical relevance. Activity was remarkably tolerant to the nature of the prenyl moiety, to its relative position compared to the n-pentyl moiety (abnormal cannabinoids), and to carboxylation of the resorcinyl moiety (pre-cannabinoids). Conversely, methylation and acetylation of the phenolic hydroxyls, esterification of the carboxylic group of pre-cannabinoids, and introduction of a second prenyl moiety were all detrimental for antibacterial activity. Taken together, these observations suggest that the prenyl moiety of cannabinoids serves mainly as a modulator of lipid affinity for the olivetol core, a per se poorly active antibacterial pharmacophore, while their high potency definitely suggests a specific, but yet elusive, mechanism of activity.

Depending on their primary structure, the 28 mammalian transient receptor potential (TRP)

The Transient Receptor Potential Ankyrin 1 channel (TRPA1), is a member of the large TRP family of ion channels, and functions as a Ca(2+) permeable non-selective cation channel in many different cell processes, ranging from sensory to homeostatic tasks. TRPA1 is highly conserved across the animal kingdom. The only mammalian TRPA subfamily member, TRPA1, is widely expressed in neuronal (e.g. sensory dorsal root and trigeminal ganglia neurons)- and in non-neuronal cells (e.g. epithelial cells, hair cells). It exhibits 14-19 amino-(N-)terminal ankyrin repeats, an unusual structural feature. The TRPA1 channel is activated by noxious cold (<17 °C) as well as by a plethora of chemical compounds that includes not only electrophilic compounds and oxidants that can modify, in an alkylative or oxidative fashion, nucleophilic cysteine residues in the channel's N-terminus, but also compounds that do not covalently bind to the channel proteins (e.g. menthol, nifedipin). Based on localization and functional properties, TRPA1 is considered a key player in acute and chronic (neuropathic) pain and inflammation. Moreover, its role in the (patho)physiology of nearly all organ systems is anticipated, and will be discussed along with the potential of TRPA1 as a drug target for the management of various pathological conditions.

Background .The pharmacology, toxicology and pharmacokinetics of bioactive preparations derived from natural sources has become a flourishing field of research. However, researching complex extracts and natural products faces numerous challenges. More broadly in recent years the critique of pharmacological research, and specifically its design, the methods used and reporting has intensified.. Aims: This consensus document provides a perspective on what constitutes best practice in pharmacological research on bioactive preparations derived from natural sources, providing a perspective of what the leading specialist journals in the field consider as the core characteristics of good research. Approach ('Methods'). The editors in chief of seven journals developed this best practice statement in an iterative process. A first draft of the guidelines (prepared by MH) was then discussed and amended by the other authors. Outcomes. Core to this contribution is a table which provides detailed advice including simple points like a use of appropriate controls and the full taxonomic validity of the material under investigation (see also below), to the relevance of the model for the question being researched (e.g. can specific in silico or in vitro models really say s.th. about the species antiinflammatory activity?). Therefore, obviously, researchers must pay detailed attention to reporting and discussing such studies. This information must be discussed critically (as much as it is possible based on the published papers) in terms of their scientific quality and validity. While these points are obvious, as editors we are aware that they are often not properly implemented. Conclusion. We call for an approach which incorporates a careful design, meticulous execution and a detailed reporting of studies focusing on the pharmacology / bioactivity of bioactive preparations. Clearly testable research questions must be developed and investigated experimentally. As the founder of pharmacology Claude Bernard put it already in 1865: '…. either the experimenter's hypothesis will be disproved or it will be proved by experiment. When experiment disproves its preconceived ideas, the experimenter must discard or modify it.'

The relative absorption of a standardized curcuminoid mixture and its corresponding lecithin formulation (Meriva) was investigated in a randomized, double-blind, crossover human study. Clinically validated dosages were used for both products, and plasma levels of all three major curcuminoids [curcumin (1a), demethoxycurcumin (1b), and bisdemethoxycurcumin (1c)] were evaluated. Total curcuminoid absorption was about 29-fold higher for Meriva than for its corresponding unformulated curcuminoid mixture, but only phase-2 metabolites could be detected, and plasma concentrations were still significantly lower than those required for the inhibition of most anti-inflammatory targets of curcumin. Remarkably, phospholipid formulation increased the absorption of demethoxylated curcuminoids much more than that of curcumin (1a), with significant differences in plasma curcuminoid profile between Meriva and its corresponding unformulated curcuminoid mixture. Thus, the major plasma curcuminoid after administration of Meriva was not curcumin (1a), but demethoxycurcumin (1b), a more potent analogue in many in vitro anti-inflammatory assays. The improved absorption, and possibly also a better plasma curcuminoid profile, might underlie the clinical efficacy of Meriva at doses significantly lower than unformulated curcuminoid mixtures.

N-Arachidonoyldopamine (NADA) was recently identified as an endogenous ligand for the vanilloid type 1 receptor (VR1). Further analysis of the bovine striatal extract from which NADA was isolated indicated the existence of substances corresponding in molecular mass to N-oleoyldopamine (OLDA), N-palmitoyldopamine (PALDA), and N-stearoyldopamine (STEARDA). Quadrupole time-of-flight mass spectrometric analysis of bovine striatal extracts revealed the existence of OLDA, PALDA, and STEARDA as endogenous compounds in the mammalian brain. PALDA and STEARDA failed to affect calcium influx in VR1-transfected human embryonic kidney (HEK) 293 cells or paw withdrawal latencies from a radiant heat source, and there was no evidence of spontaneous pain behavior. By contrast, OLDA induced calcium influx (EC 50 ‫؍‬ 36 nM), reduced the latency of paw withdrawal from a radiant heat source in a dose-dependent manner (EC 50 ‫؍‬ 0.72 g), and produced nocifensive behavior. These effects were blocked by co-administration of the VR1 antagonist iodo-resiniferatoxin (10 nM for HEK cells and 1 g/50 l for pain behavior). These findings demonstrate the existence of an endogenous compound in the brain that is similar to capsaicin and NADA in its chemical structure and activity on VR1. Unlike NADA, OLDA was only a weak ligand for rat CB1 receptors; but like NADA, it was recognized by the anandamide membrane transporter while being a poor substrate for fatty-acid amide hydrolase. Analysis of the activity of six additional synthetic and potentially endogenous N-acyldopamine indicated the requirement of a long unsaturated fatty acid chain for an optimal functional interaction with VR1 receptors.We recently identified N-arachidonoyldopamine (NADA) 1 as an endogenous compound that possesses nanomolar potency for vanilloid type 1 (VR1) and cannabinoid CB1 receptors (1-3). Following injection into skin, NADA produces VR1-mediated thermal hyperalgesia, with an EC 50 of 1.5 g. Previous studies indicated that anandamide and the lipoxygenase product 12(S)-hydroperoxyeicosatetraenoic acid also possess affinity for VR1 (4, 5). However, whereas NADA is similar in potency to capsaicin in a variety of assays of VR1 activity, anandamide and 12(S)-hydroperoxyeicosatetraenoic acid are at least 20-fold less potent than capsaicin (4).All of the putative endovanilloids identified to date are products of arachidonic acid, an unsaturated long chain fatty acid with a primary role in inflammation and pain. Research on the structure-activity relationship for VR1 has shown that a vanillylamine moiety and a long unsaturated acyl chain are required for optimal interaction with the receptor (6, 7). Although anandamide and lipoxygenase products contain the long unsaturated acyl chain, they lack the vanillyl group, which probably accounts for their decreased affinity for and efficacy on VR1 compared with NADA. Because dopamine is a naturally occurring aromatic amine structurally similar to vanillylamine, it was hypothesized that certain unsaturated N-acyldopamines may exist i...