Identification of CB1 Ligands among Drugs, Phytochemicals and Natural-Like Compounds: Virtual Screening and In Vitro Verification

Cannabidiol-A friend or a foe?

Cannabidiol (CBD), one of the main actives from Cannabis sativa has been perpetually explored lately for its therapeutic effects. Its main attributes, such as anti-inflammatory and antioxidant effects, snowball into pain management, epilepsy and seizure alleviation, anxiety relief, as well as numerous other implications through the entire metabolism. However, conventional administration routes challenge its therapeutic potential, with reported poor water solubility, hepatic degradation, gastric instability and erratic bioavailability observed in oral administration. As a result, the transdermal delivery systems have emerged as a promising alternative to oral or inhaled routes, offering improved bioavailability and targeted effects. The medical use of CBD throughout Europe, UK, USA or Australia is extensive and usually represented by pharmaceutical preparations recommended after conventional treatment routs fail. The non-medical use is limited by each country's own legislation, a wider range of products being available, but the irregular regulatory landscape coupled with the growing market of cannabinoid-infused products, emphasizes the need for standardized formulations and further clinical research. The present work critically examines the transdermal administration of cannabidiol, explores the skin's potential as a route and the strategies involved in using it for systemic targeting. We highlighted key challenges and provided insights into CBD`s variable bioavailability based on different administration routes and methods, thus compiling a literature-based absorption, distribution, metabolism, and excretion (ADME) study. We also explore the role of the endocannabinoid system, its function in various medical conditions, and the therapeutic effects associated with CBD, particularly in light of the varying legislation across countries. While the breadth of potential benefits is compelling, it is essential to emphasize the ongoing nature of CBD research as individual responses to it can vary significantly.

Identification and structural characterization of CB1 receptor antagonists: A comprehensive virtual screening and molecular dynamics study of arachidin-2

The cannabinoid receptor 1 (CB1) is an essential component of the endocannabinoid system, responsible for regulating various physiological processes such as pain, mood, and appetite. Despite increasing interest in the therapeutic potential of CB1 modulators, the precise mechanisms by which small molecules modulate receptor activity-particularly without fully transitioning between active and inactive states-remain partially understood. In this study, the complexity of CB1-ligand interactions was evaluated for the inactive CB1 state. A comprehensive pipeline, integrating ligand-based similarity search, 2D fingerprint-based reverse virtual screening and molecular dynamics (MD) simulations, identified compounds with core scaffolds commonly found in bioactive natural products, such as stilbenoids and polyphenolic compounds. Arachidin-2 (AR2) and a polyphenolic derivative were subjected to extended MD simulations, revealing their ability to stabilize the inactive CB1 state across key helices. The distinct stability differences observed in the helices HI, HIV, and HVI of the active CB1 state further highlighted ligand-specific conformational dynamics. A comparative analysis with co-crystallized synthetic ligands AM6538 and AM841 demonstrated the distinct binding behaviors of natural and synthetic ligands. AR2 showed more favorable binding to the inactive form (-22.0 kcal/mol) than to the active state. Similarly, the polyphenolic compound exhibited a greater binding difference (∼6 kcal/mol) between the inactive and active states. Notably, AM6538 and AM841 demonstrated the strongest binding (∼30 kcal/mol) to the inactive and active state, respectively. Key residues stabilizing the identified compounds in CB1-inactive state included PHE102, GLY166, PHE170, VAL196, LEU359, SER383, and CIS386. These findings underscore the utility of computational methods in the discovery and development of novel CB1 modulators for potential biomedical applications.

Computational and Experimental Drug Repurposing of FDA-Approved Compounds Targeting the Cannabinoid Receptor CB1

The cannabinoid receptor 1 (CB1R) plays a pivotal role in regulating various physiopathological processes, thus positioning itself as a promising and sought-after therapeutic target. However, the search for specific and effective CB1R ligands has been challenging, prompting the exploration of drug repurposing (DR) strategies. In this study, we present an innovative DR approach that combines computational screening and experimental validation to identify potential Food and Drug Administration (FDA)-approved compounds that can interact with the CB1R. Initially, a large-scale virtual screening was conducted using molecular docking simulations, where a library of FDA-approved drugs was screened against the CB1R's three-dimensional structures. This in silico analysis allowed us to prioritize compounds based on their binding affinity through two different filters. Subsequently, the shortlisted compounds were subjected to in vitro assays using cellular and biochemical models to validate their interaction with the CB1R and determine their functional impact. Our results reveal FDA-approved compounds that exhibit promising interactions with the CB1R. These findings open up exciting opportunities for DR in various disorders where CB1R signaling is implicated. In conclusion, our integrated computational and experimental approach demonstrates the feasibility of DR for discovering CB1R modulators from existing FDA-approved compounds. By leveraging the wealth of existing pharmacological data, this strategy accelerates the identification of potential therapeutics while reducing development costs and timelines. The findings from this study hold the potential to advance novel treatments for a range of CB1R -associated diseases, presenting a significant step forward in drug discovery research.

Goods and Bads of the Endocannabinoid System as a Therapeutic Target: Lessons Learned after 30 Years

The cannabis derivative marijuana is the most widely used recreational drug in the Western world and is consumed by an estimated 83 million individuals (∼3% of the world population). In recent years, there has been a marked transformation in society regarding the risk perception of cannabis, driven by its legalization and medical use in many states in the United States and worldwide. Compelling research evidence and the Food and Drug Administration cannabis-derived cannabidiol approval for severe childhood epilepsy have confirmed the large therapeutic potential of cannabidiol itself, Δ9-tetrahydrocannabinol and other plant-derived cannabinoids (phytocannabinoids). Of note, our body has a complex endocannabinoid system (ECS)-made of receptors, metabolic enzymes, and transporters-that is also regulated by phytocannabinoids. The first endocannabinoid to be discovered 30 years ago was anandamide (N-arachidonoyl-ethanolamine); since then, distinct elements of the ECS have been the target of drug design programs aimed at curing (or at least slowing down) a number of human diseases, both in the central nervous system and at the periphery. Here a critical review of our knowledge of the goods and bads of the ECS as a therapeutic target is presented to define the benefits of ECS-active phytocannabinoids and ECS-oriented synthetic drugs for human health. SIGNIFICANCE STATEMENT: The endocannabinoid system plays important roles virtually everywhere in our body and is either involved in mediating key processes of central and peripheral diseases or represents a therapeutic target for treatment. Therefore, understanding the structure, function, and pharmacology of the components of this complex system, and in particular of key receptors (like cannabinoid receptors 1 and 2) and metabolic enzymes (like fatty acid amide hydrolase and monoacylglycerol lipase), will advance our understanding of endocannabinoid signaling and activity at molecular, cellular, and system levels, providing new opportunities to treat patients.

Identification of Novel CB2 Ligands through Virtual Screening and In Vitro Evaluation

Cannabinoid receptor type 2 (CB2) is a very promising therapeutic target for a variety of potential indications. However, despite the existence of multiple high affinity CB2 ligands, none have yet been approved as a drug. Therefore, it would be beneficial to explore new chemotypes of CB2 ligands. The recent elucidation of CB2 tertiary structure allows for rational hit identification with structure-based (SB) methods. In this study, we established a virtual screening workflow based on SB techniques augmented with ligand-based ones, including molecular docking, MM-GBSA binding energy calculations, pharmacophore screening, and QSAR. We screened nearly 7 million drug-like, commercially available compounds. We selected 16 molecules for in vitro evaluation and identified two novel, selective CB2 antagonists with K_i values of 65 and 210 nM. Both compounds are structurally diverse from CB2 ligands known to date. The established virtual screening protocol may prove useful for hit identification for CB2 and similar molecular targets. The two novel CB2 ligands provide a desired starting point for future optimization and development of potential drugs.