Isoxazole derivatives as potent transient receptor potential melastatin type 8 (TRPM8) agonists

• Published in: European journal of medicinal chemistry Vol. 69; pp. 659 - 669
• Main Authors: Ostacolo, Carmine, Ambrosino, Paolo, Russo, Roberto, Lo Monte, Matteo, Soldovieri, Maria Virginia, Laneri, Sonia, Sacchi, Antonia, Vistoli, Giulio, Taglialatela, Maurizio, Calignano, Antonio
• Format: Journal Article
• Language: English
• Published: PARIS Elsevier Masson SAS 01.11.2013; Elsevier
• Subjects: Animals; Calcium imaging; Cells, Cultured; Chemistry, Medicinal; Chronic constriction injury; Dose-Response Relationship, Drug; Humans; Isoxazoles - chemical synthesis; Isoxazoles - chemistry; Isoxazoles - pharmacology; Isoxazolylamine derivatives; Life Sciences & Biomedicine; Male; Mice; Models, Molecular; Molecular Structure; Monte Carlo Method; Pharmacology & Pharmacy; Science & Technology; Structure-Activity Relationship; Transient receptor potential melastatin type-8 channels; TRPM Cation Channels - agonists; Isoxazolylamine derivatives; RT; Transient receptor potential melastatin type-8 channels; SAR; GM; Chronic constriction injury; Calcium imaging; CCI; DM; DMEM; Ca2; FBS; RT-PCR; TRPM8 channels; Structure–activity relationship; ACTIVATION; MECHANISM; COLD ALLODYNIA; SENSORY NEURONS; NEUROPATHIC PAIN; Structure-activity relationship; MENTHOL; CHANNELS; MICE; SENSATION; REVEALS; room temperature; calcium; growth medium; Dulbecco's modified Eagle's medium; differentiation medium; fetal bovine serum; Ca(2+); reverse-transcription PCR
• ISSN: 0223-5234; 1768-3254
• DOI: 10.1016/j.ejmech.2013.08.056

Modulation of the transient receptor potential melastatin type-8 (TRPM8), the receptor for menthol acting as the major sensor for peripheral innocuous cool temperatures, has several important applications in pharmaceutical, food and cosmetic industries. In the present study, we designed 12 isoxazole derivatives and tested their pharmacological properties both in F11 sensory neurons in vitro, and in an in vivo model of cold allodynia. In F11 sensory neurons, single-cell Ca2+-imaging experiments revealed that, when compared to menthol, some newly-synthesized compounds were up to 200-fold more potent, though none of them showed an increased efficacy. Some isoxazole derivatives potentiated allodynic responses elicited by acetone when administered to rats subjected to sciatic nerve ligation; when compared to menthol, these compounds were efficacious at earlier (0–2 min) but not later (7–9 or 14–16 min) time points. Docking experiments performed in a human TRPM8 receptor model revealed that newly-synthesized compounds might adopt two possible conformations, thereby allowing to distinguish “menthol-like” compounds (characterized by high efficacy/low potency), and “icillin-like” compounds (with high potency/low efficacy). Collectively, these data provide rationale structure–activity relationships for isoxazole derivatives acting as TRPM8 agonists, and suggest their potential usefulness for cold-evoked analgesia. [Display omitted] •New isoxazole derivatives as TRPM8 agonists were synthesized.•Their potency and efficacy was tested both in vitro and in vivo.•Derivative with 200-fold greater potency when compared to menthol were identified.•In vivo results showed a time-dependence efficacy different from menthol.•“Menthol like” and “icillin like” compounds were identified by computational studies.