SYNTHESIS, CHARACTERIZATION AND SCREENING OF PYRAZOLINE DERIVATIVES FOR ANTI-INFLAMMATORY ACTIVITY

Inflammation is a basic way in which the body reacts to infection, irritation or other injury, the key feature being redness, warmth, swelling and pain. There was a need for synthesis of anti-inflammatory agents with increased potency. Pyrazoline (dihydro pyrazole) derivatives exhibit various biological activities. These derivatives are well known for their pronounced anti-inflammatory activity. Therefore such ring systems are of great interest in medicinal chemistry. A series of novel 1, 3, 5 trisubstituted-2-pyrazoline derivatives were synthesized in a series of three steps. Firstly, acetophenone and 4-methoxybenzaldehyde were reacted in presence of sodium hydroxide with ethanol as the solvent leading to the formation of chalcones (1). These chalcones were reacted with hydrazine hydrate which formed the new cyclized product (2). Finally, the cyclized product was reacted with different substituted chlorides in presence of ethanolic solution of sodium hydroxide to give the new 1, 3, 5 trisubstituted-2-pyrazoline derivatives (3a – 3j). All the synthesized compounds were characterized by FTIR spectroscopy, UV spectroscopy and compounds of interest were characterized by (¹H and ¹³C) NMR spectroscopy and LC-MS spectroscopy. These compounds were screened for in-vivo anti-inflammatory activity by using Carrageenan induced rat paw edema method. The compounds were tested at 50 mg/kg dose and diclofenac sodium was used as a reference standard. Compound 3d with acetyl substitution was found to be the most active compound.