Discovery of novel cannabinoid receptor ligands from diverse marine organisms

Small Molecules from Nature Targeting G-Protein Coupled Cannabinoid Receptors: Potential Leads for Drug Discovery and Development

The cannabinoid molecules are derived from Cannabis sativa plant which acts on the cannabinoid receptors types 1 and 2 (CB1 and CB2) which have been explored as potential therapeutic targets for drug discovery and development. Currently, there are numerous cannabinoid based synthetic drugs used in clinical practice like the popular ones such as nabilone, dronabinol, and Δ(9)-tetrahydrocannabinol mediates its action through CB1/CB2 receptors. However, these synthetic based Cannabis derived compounds are known to exert adverse psychiatric effect and have also been exploited for drug abuse. This encourages us to find out an alternative and safe drug with the least psychiatric adverse effects. In recent years, many phytocannabinoids have been isolated from plants other than Cannabis. Several studies have shown that these phytocannabinoids show affinity, potency, selectivity, and efficacy towards cannabinoid receptors and inhibit endocannabinoid metabolizing enzymes, thus reducing hyperactivity of endocannabinoid systems. Also, these naturally derived molecules possess the least adverse effects opposed to the synthetically derived cannabinoids. Therefore, the plant based cannabinoid molecules proved to be promising and emerging therapeutic alternative. The present review provides an overview of therapeutic potential of ligands and plants modulating cannabinoid receptors that may be of interest to pharmaceutical industry in search of new and safer drug discovery and development for future therapeutics.

Care and feeding of the endocannabinoid system: a systematic review of potential clinical interventions that upregulate the endocannabinoid system

Background

The “classic” endocannabinoid (eCB) system includes the cannabinoid receptors CB₁ and CB₂, the eCB ligands anandamide (AEA) and 2-arachidonoylglycerol (2-AG), and their metabolic enzymes. An emerging literature documents the “eCB deficiency syndrome” as an etiology in migraine, fibromyalgia, irritable bowel syndrome, psychological disorders, and other conditions. We performed a systematic review of clinical interventions that enhance the eCB system—ways to upregulate cannabinoid receptors, increase ligand synthesis, or inhibit ligand degradation.

Methodology/Principal Findings

We searched PubMed for clinical trials, observational studies, and preclinical research. Data synthesis was qualitative. Exclusion criteria limited the results to 184 in vitro studies, 102 in vivo animal studies, and 36 human studies. Evidence indicates that several classes of pharmaceuticals upregulate the eCB system, including analgesics (acetaminophen, non-steroidal anti-inflammatory drugs, opioids, glucocorticoids), antidepressants, antipsychotics, anxiolytics, and anticonvulsants. Clinical interventions characterized as “complementary and alternative medicine” also upregulate the eCB system: massage and manipulation, acupuncture, dietary supplements, and herbal medicines. Lifestyle modification (diet, weight control, exercise, and the use of psychoactive substances—alcohol, tobacco, coffee, cannabis) also modulate the eCB system.

Conclusions/Significance

Few clinical trials have assessed interventions that upregulate the eCB system. Many preclinical studies point to other potential approaches; human trials are needed to explore these promising interventions.

Cannabinomimetic lipid from a marine cyanobacterium

NMR-guided fractionation of two independent collections of the marine cyanobacteria Lyngbya majuscula obtained from Papua New Guinea and Oscillatoria sp. collected in Panama led to the isolation of the new lipids serinolamide A (3) and propenediester (4). Their structures were determined by NMR and MS data analysis. Serinolamide A (3) exhibited a moderate agonist effect and selectivity for the CB1 cannabinoid receptor (Ki=1.3 μM, >5-fold) and represents the newest addition to the known cannabinomimetic natural products of marine origin.

Phylogenomic and chemotaxonomic analysis of the endocannabinoid system

The endocannabinoid system consists of two cannabinoid (CB) receptors, seven ligands, and ligand-catabolizing enzymes such as fatty acid amid hydrolase (FAAH) and monoglyceride lipase (MGL). The system's phylogenetic distribution is poorly known. The ligands cannot be molecularly investigated because they are not polypeptides and their specific synthetic enzymes have not been identified, so no sequences are available. Ligand phylogenetics can be inferred, nonetheless, by their presence in a range of extant organisms. Thus a meta-analysis of ligand extraction studies was performed (chemotaxonomy), and compared to a molecular search for homologs of CB receptors, vanilloid receptors (VR1), FAAH, and MGL in the genomes of sequenced organisms (phylogenomics). Putative homologs underwent functional mapping to ascertain the presence of critical amino acid motifs known to impart protein functionality. From an evolutionary perspective it appears that (1) endocannabinoid ligands evolved before CB receptors; (2) the ligands evolved independently multiple times; (3) CB receptors evolved prior to the metazoan-bilaterian divergence (ie, between extant Hydra and leech), but were secondarily lost in the Ecdysozoa; (4) VR1 may predate CB receptors but its affinity for endocannabinoids is a recent acquisition, appearing after the lower vertebrate-mammal divergence; (5) MGL may be as old as the ligands, whereas FAAH evolved recently, after the appearance of vertebrates. FAAH's emergence correlates with VR1's newly-found affinity for anandamide; this overlap in evolutionary time is recapitulated by complementary distribution patterns of FAAH, VR1, and anandamide in the brain. Linking FAAH, VR1, and anandamide implies a coupling among the remaining "older" parts of the endocannabinoid system, MGL, CB receptors, and 2-AG.