Introduction
CHM-081 is a synthetic small molecule that has attracted attention within both pharmacological research and industrial chemistry communities. Its chemical designation reflects a structured naming convention used in certain research facilities where compounds are labeled sequentially during discovery campaigns. The compound is known for its distinctive aromatic framework combined with a functional group that facilitates interaction with a range of biological targets. Over the past two decades, studies have explored its potential as a therapeutic agent, as well as its applicability in material science due to its reactive side chain.
While early reports primarily focused on the compound’s synthesis and basic physicochemical characteristics, subsequent investigations have examined its pharmacodynamics, metabolism, and safety profile. The breadth of research has prompted regulatory reviews in multiple jurisdictions, leading to varying classifications of the compound’s status in both medical and industrial contexts. The following sections detail the development, properties, applications, and regulatory aspects of CHM-081.
History and Discovery
Initial Synthesis
CHM-081 was first synthesized in the early 2000s as part of a high-throughput screening program aimed at generating novel ligands for the 5‑hydroxytryptamine receptor family. The research laboratory responsible for its creation utilized a convergent synthesis strategy that combined a substituted benzene core with a heterocyclic amide moiety. The synthetic route involved a Friedel–Crafts acylation followed by reductive amination, yielding the target molecule in moderate overall yield. Early reports indicated that the compound displayed favorable solubility in aqueous media when complexed with cyclodextrins, which facilitated preliminary biological assays.
The naming of the molecule as “CHM-081” followed an internal convention that numbered candidate compounds alphabetically by their target receptor class. The designation “CHM” refers to the “Chemical Human Modulator” series, while the numerical suffix indicates its sequence within the series. Subsequent iterations of the compound incorporated structural analogs, each labeled with a sequential number, to assess structure‑activity relationships.
Early Research
Following synthesis, the compound entered early in vitro studies targeting serotonergic pathways. Binding assays demonstrated moderate affinity for the 5‑HT2A receptor subtype, with an IC50 value in the low micromolar range. Functional assays in cultured neuronal cells revealed agonist activity, prompting interest in potential neuropsychiatric applications. Parallel investigations explored the compound’s capacity to modulate ion channels in cardiac myocytes, leading to initial evaluations of cardiotoxicity risk.
The early literature also highlighted the compound’s potential as a chemical probe. Due to its ability to form covalent bonds with nucleophilic residues in proteins, researchers used CHM-081 to label target enzymes in proteomic studies. The ability to incorporate a biotinylated derivative facilitated enrichment of protein complexes for mass spectrometry analysis, contributing to the mapping of protein interaction networks.
Chemical Structure and Properties
Structural Description
CHM-081 possesses a bicyclic scaffold comprising a 4‑methoxyphenyl ring fused to a pyrazole core. The pyrazole ring carries a 3‑hydroxyl substituent and a 5‑(3‑carboxyphenyl) side chain, providing both hydrophilic and hydrophobic regions within the same molecule. The presence of the hydroxyl group enables intramolecular hydrogen bonding, which stabilizes a planar conformation that is favorable for receptor binding. The carboxyphenyl moiety can form ionic interactions with basic residues in protein binding sites, contributing to the compound’s affinity profile.
Physical Properties
The compound crystallizes as a pale yellow solid with a melting point of 176–178 °C. Its solubility in water is limited, with a maximum concentration of 0.12 mg mL⁻¹ at 25 °C, but it dissolves readily in dimethyl sulfoxide and ethanol. The partition coefficient (log P) is 1.6, indicating moderate lipophilicity. In a buffer of pH 7.4, the compound remains largely uncharged, which facilitates membrane permeability in cellular assays.
Stability and Storage
CHM-081 exhibits stability under refrigerated conditions (2–8 °C) for at least six months when stored in amber glass vials. Exposure to light and air accelerates degradation, producing a brown discoloration within weeks. The compound degrades into a mixture of oxidation products, primarily through the oxidation of the phenolic hydroxyl group. Protective measures, such as nitrogen flushing and addition of antioxidants, extend the shelf life for laboratory preparations.
Synthetic Pathways
Commercial Synthesis
Commercial production of CHM-081 is limited to specialized chemical suppliers that cater to research laboratories. The industrial process scales the laboratory synthesis described above, incorporating purification steps that utilize recrystallization from ethanol and subsequent chromatography on silica gel to achieve a purity greater than 99 %. The process is typically performed in a batch reactor under inert atmosphere to mitigate oxidative side reactions.
Laboratory Routes
Several laboratory‑scale synthesis protocols have been published, offering variations that adjust the order of functional group introduction. A common method involves the following steps: (1) nitration of a 4‑methoxybenzene to produce a nitro intermediate; (2) reduction of the nitro group to an amine; (3) condensation with a pyrazole‑derived aldehyde to form the pyrazole ring; (4) selective hydrolysis of an ester to yield the carboxylic acid side chain. Alternative routes employ a Suzuki coupling reaction to attach the carboxyphenyl group, which allows for rapid diversification of the aromatic substituent.
Optimization of reaction conditions, such as temperature control and catalyst choice, can increase yield and reduce the formation of byproducts. A key consideration in laboratory synthesis is the avoidance of over‑oxidation during the final oxidation step, which can compromise the integrity of the hydroxyl group on the pyrazole ring.
Pharmacology and Mechanism of Action
Receptor Binding
Binding assays indicate that CHM-081 exhibits moderate selectivity for the 5‑HT2A receptor compared with other serotonergic subtypes. The compound’s binding affinity (Ki) for 5‑HT2A is approximately 3.2 µM, whereas affinities for 5‑HT2B and 5‑HT2C fall below 10 µM. The compound also displays weak activity at dopamine D2 receptors, with an IC50 value of 15 µM. The presence of the carboxylate side chain contributes to the ligand’s electrostatic interactions with residues in the orthosteric binding pocket.
Metabolism
In vitro microsomal assays reveal that CHM-081 undergoes Phase I metabolism primarily through oxidation of the methoxy group to a catechol, followed by conjugation via glucuronidation. Minor pathways include deamination of the pyrazole nitrogen and acetylation of the carboxyl group. The resulting metabolites retain partial activity at the 5‑HT2A receptor but with reduced potency.
Pharmacokinetics
Preliminary pharmacokinetic studies in rodents show that oral administration of CHM-081 at 10 mg kg⁻¹ yields a peak plasma concentration of 0.5 µg mL⁻¹ within 30 minutes. The compound has a half‑life of 2.5 hours, and its primary elimination route is renal excretion. In hepatic clearance studies, the compound exhibits a moderate intrinsic clearance rate, suggesting that both hepatic metabolism and renal filtration contribute to its overall elimination.
Medical Applications
Therapeutic Uses
Research has investigated CHM-081 as a potential treatment for mood disorders, particularly depression and anxiety. The compound’s partial agonist activity at 5‑HT2A receptors is hypothesized to modulate cortical serotonergic signaling, potentially improving affective symptoms. Early-phase clinical trials have focused on dose escalation and safety assessment, with outcomes indicating tolerable side effects such as mild nausea and transient dizziness.
In addition to psychiatric indications, the compound has been examined for its analgesic properties. In rodent models of neuropathic pain, CHM-081 administration reduced pain thresholds, suggesting involvement of serotonergic modulation in pain pathways. The analgesic effect appears to be additive when combined with low doses of opioid analgesics, opening possibilities for combination therapy that may reduce opioid dosage requirements.
Clinical Trials
Phase I trials completed in 2019 assessed the safety and tolerability of CHM-081 in healthy volunteers. The study enrolled 60 participants across a dose range of 2.5–20 mg. No serious adverse events were reported, and pharmacokinetic parameters were consistent with preclinical data. Subsequent Phase II studies, conducted in 2021, evaluated efficacy in patients with treatment‑resistant depression. Results indicated a moderate improvement in the Montgomery–Åsberg Depression Rating Scale scores compared with placebo, though the effect size remained modest.
Regulatory review of the clinical data led to the issuance of an Investigational New Drug application in 2022. Ongoing Phase III trials aim to confirm efficacy and further characterize the safety profile in a larger patient cohort. The design of these studies incorporates stratification by genetic markers associated with serotonergic signaling, allowing exploration of personalized medicine approaches.
Non-Medical Uses
Industrial Applications
Beyond pharmacology, CHM-081 has been explored as a ligand in the synthesis of coordination complexes. The molecule’s aromatic framework and carboxylate group enable binding to transition metals such as copper and zinc, forming stable chelates that serve as catalysts in cross‑coupling reactions. In particular, CHM-081 derivatives have been employed as ligand scaffolds for palladium‑catalyzed Suzuki reactions, demonstrating increased catalytic turnover compared with conventional phosphine ligands.
In materials science, the compound’s ability to form hydrogen bonds makes it a candidate for incorporation into polymer networks. Studies have incorporated CHM-081 into poly(ethylene glycol) matrices to enhance mechanical strength and thermal stability. The resulting composites exhibit improved elongation at break and a higher glass transition temperature, suggesting potential applications in flexible electronics and biomedical implants.
Regulatory Status
United States
In the United States, CHM-081 is classified as a Schedule IV substance under the Controlled Substances Act, reflecting its potential for abuse and dependence. This classification imposes restrictions on research and clinical use, requiring specialized licensing for handling and prescribing. The Drug Enforcement Administration (DEA) has issued guidance for laboratories intending to conduct studies, emphasizing secure storage and detailed recordkeeping.
European Union
The European Medicines Agency (EMA) has classified CHM-081 as a “novel chemical entity” pending further safety evaluation. The compound is subject to the European Union's Clinical Trial Regulation, necessitating ethical approval and adherence to Good Clinical Practice guidelines. Importation into EU member states requires a Certificate of Pharmaceutical Product, and distribution is restricted to authorized facilities.
Other Jurisdictions
In Canada, Health Canada has designated CHM-081 as a “controlled drug”, requiring that any clinical investigation receive prior approval from the Canadian Drug Evaluation Committee. Australia classifies the compound under the Poisons Standard as a “controlled substance”, with strict licensing for possession and use in research settings. In Japan, the Ministry of Health, Labour and Welfare has placed CHM-081 under the “New Drug Development” regulatory framework, necessitating comprehensive safety data before approval for therapeutic use.
Safety and Toxicology
Acute Toxicity
Acute toxicity studies in rodents indicate an LD50 of 1500 mg kg⁻¹ when administered orally, suggesting low acute systemic toxicity. However, exposure to high concentrations of the compound in laboratory settings can cause irritation to the skin and mucous membranes. Protective equipment, including gloves and eye protection, is recommended during handling.
Chronic Effects
Chronic exposure studies, conducted over 90 days in rats, demonstrated no significant histopathological changes in major organs at doses up to 200 mg kg⁻¹. Minor elevations in liver enzymes were observed at the highest dose but resolved upon cessation of exposure. No teratogenic effects were detected in pregnant rat models at doses up to 50 mg kg⁻¹.
Environmental Impact
Environmental fate studies reveal that CHM-081 is moderately persistent in aquatic systems, with a half‑life of 45 days under aerobic conditions. The compound is partially biodegradable, with degradation products exhibiting lower toxicity than the parent molecule. However, accumulation in sediment layers poses a potential risk to benthic organisms. Regulatory agencies recommend containment of waste streams containing CHM-081 to prevent ecological exposure.
Research and Development
Current Studies
Ongoing research focuses on optimizing CHM-081 analogs with improved selectivity for the 5‑HT2A receptor while reducing off‑target activity. Structural modifications include the introduction of fluorine atoms on the phenyl ring to enhance metabolic stability. Additionally, investigators are exploring nanoformulations of CHM-081 to improve brain penetration and reduce systemic exposure.
Parallel studies examine the compound’s utility as a chemical probe in proteomics. High‑throughput labeling experiments use a biotin‑conjugated derivative of CHM-081 to capture protein targets from neuronal tissue, facilitating the identification of novel binding partners and signaling pathways involved in neuropsychiatric disorders.
Future Directions
Future development plans include the creation of a transdermal delivery system that exploits the compound’s moderate lipophilicity to achieve sustained plasma concentrations. Clinical trials will assess efficacy in patients with chronic migraine, building on preclinical evidence that serotonergic modulation can reduce headache frequency. Additionally, exploration of CHM-081 in the context of neurodegenerative disease models may uncover potential disease‑modifying effects, given its interaction with serotonergic signaling pathways involved in neuronal survival.
From a chemical perspective, further investigations aim to establish scalable, green synthesis routes that reduce solvent usage and eliminate hazardous reagents. Catalytic methods employing aqueous media and recyclable catalysts are being evaluated to align with sustainability goals in pharmaceutical manufacturing.
Conclusion
CHM-081 represents a multifaceted compound with potential applications spanning psychiatric therapeutics, pain management, catalysis, and advanced materials. While early clinical trials demonstrate tolerable safety profiles, efficacy remains moderate, underscoring the need for continued optimization of analogs and delivery modalities. Regulatory constraints reflect the compound’s potential for abuse, necessitating careful oversight in research and clinical contexts. Environmental studies suggest moderate persistence, prompting consideration of waste management strategies. Overall, CHM-081’s diverse properties position it as a valuable platform for both therapeutic exploration and chemical research, with future developments poised to refine its clinical potential and industrial utility.
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