Novel hydrazones based on (-)-carvone were synthesized via condensation of terpenoid with 4-R-phenoxyacetic acid hydrazides. The structure of target compounds was established by FT-IR, Raman, 1 H-NMR and 13 C-NMR spectral analysis, FAB/ESI mass spectrometry. (-)-Carvone hydrazones were proven to exist as Z/E geometrical isomers about C=N bond using ion mobility-tandem mass spectrometry (IM-MS/MS). Single crystal X-ray diffraction study was applied to determine molecular and crystal structure of compound 3e. Hydrazones 3a-3e were evaluated as potential anticonvulsant agents after their oral administration against maximal electroshock (MES) and pentylenetetrazole (PTZ)-induced seizures in mice. Analgesic activity of compounds was investigated by topical application on models of capsaicin and AITC-induced pain. The present findings indicate that (-)-carvone derivatives afforded seizure protection both at short (1 h) and long (24 h) time period by blocking electroshock-and chemical-induced convulsions.Hydrazones binding to TRPA1/TRPV1 ion channels was proposed as possible mechanism explaining significant analgesic effect of compounds.

A series of novel (−)-verbenone hydrazones was designed and synthesized via condensation of terpenoid with hydrazides derived from phenoxyacetic acid. The structure of target compounds was confirmed by 1H-NMR and 13C-NMR analysis, Raman and FT-IR spectroscopy, electrospray ionization method and fast atom bombardment (FAB) mass spectrometry. Thermal properties of (−)-verbenone hydrazones 3a–3e were estimated by differential scanning calorimetry and their purity by HPLC coupled to mass spectrometry. Verbenone hydrazones were revealed to exist as Z/E geometrical isomers about C═N bond and cis/trans amide conformers. Verbenone derivatives were estimated as potential anticonvulsant agents after their oral administration against pentylenetetrazole and maximal electroshock-induced seizures in mice. Analgesic effect of hydrazones was studied by topical application on models of allyl isothiocyanate and capsaicin-induced pain. The present findings indicate that verbenone hydrazones contribute to seizure protection both at short (6 h) and long (24 h) time periods by blocking chemical- and electroshock-induced convulsions. Binding of compounds 3a–3e to TRPA1/TRPV1 ion channels was suggested as a feasible mechanism explaining their significant analgesic activity.

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Hydrazones were obtained in 76–78% yield via condensation of (2S,5R)-2-isopropyl-5-methylcyclohexanone with 4-R-phenoxyacetic acid hydrazides in the presence of a catalytic amount of glacial acetic acid. The structure of the target compounds has been established by FTIR-ATR, Raman, 1H-NMR and 13C-NMR spectral analysis and EI/FAB/ESI mass spectrometry. Thermal properties of hydrazones 3a–3e were elucidated by differential scanning calorimetry (DSC) and their purity by HPLC coupled to mass spectrometry. Synthesized compounds were found to exist as Z/E geometrical isomers about C=N bond and cis/trans amide conformers.