Pyrazoles and Pyrazolines as Anti-Inflammatory Agents

• Main Authors: Martha Mantzanidou, Eleni Pontiki, Dimitra Hadjipavlou-Litina
• Format: Article
• Language: English
• Published: MDPI AG 2021-06-01
• Series: Molecules
• Subjects: pyrazolines; pyrazoles; antioxidant activities; anti-inflammatory activities; lipoxygenase inhibition; analgesic activity
• Online Access: https://www.mdpi.com/1420-3049/26/11/3439

The five-membered heterocyclic group of pyrazoles/pyrazolines plays important role in drug discovery. Pyrazoles and pyrazolines present a wide range of biological activities. The synthesis of the pyrazolines and pyrazole derivatives was accomplished <i>via</i> the condensation of the appropriate substituted aldehydes and acetophenones, suitable chalcones and hydrazine hydrate in absolute ethanol in the presence of drops of glacial acetic acid. The compounds are obtained in good yields 68–99% and their structure was confirmed using IR, ¹H-NMR, ¹³C-NMR and elemental analysis. The novel derivatives were studied <i>in vitro</i> for their antioxidant, anti-lipid peroxidation (AAPH) activities and inhibitory activity of lipoxygenase. Both classes strongly inhibit lipid peroxidation. Compound <b>2g</b> was the most potent lipoxygenase inhibitor (IC₅₀ = 80 µM). The inhibition of the carrageenin-induced paw edema (CPE) and nociception was also determined, with compounds <b>2d</b> and <b>2e</b> being the most potent. Compound <b>2e</b> inhibited nociception higher than <b>2d</b>. Pyrazoline <b>2d</b> was found to be active in a preliminary test, for the investigation of anti-adjuvant-induced disease (AID) activity. Pyrazoline derivatives were found to be more potent than pyrazoles. Docking studies of the most potent LOX inhibitor <b>2g</b> highlight hydrophobic interactions with VAL126, PHE143, VAL520 and LYS526 and a halogen bond between the chlorine atom and ARG182.