3. Synthesis and evaluation of analgesic and anti-inflammatory activities of a novel series of 3-(4, 5-dihydropyrazolyl)-indoles

In this study, synthesis and pharmacological screening of various derivatives of 3-(4, 5-dihydropyrazolyl)-indoles viz 2-(4-substitutedphenyl)-3-(5-(4-substitutedphenyl)-1-phenyl-4, 5-dihydro-1H-pyrazol-3-yl)-1H-indole (4a-4r) is reported. The compounds (4a-4r) were synthesized by cyclization of chalcones (3-(4-substitutedphenyl)-1-(2-(4-substitutedphenyl)-1Hindol-3-yl) prop-2-en-1-one) of indole with phenyl hydrazine in presence of base NaOH. The structures of the new compounds are supported by FT IR, 1H NMR and elemental analysis. These compounds were tested in vivo for their analgesic, inflammatory and ulcerogenic activities. All the compounds tested (4a-4r) showed analgesic and inflammatory activities. Seven compounds (4d, e, h, j, k, p, q) out of 18 compounds showed very good anti-inflammatory activity comparable to the standard drug indomethacin with very less ulcerogenic action. Compounds 4j and 4k showed 86.38 and 88.31% inhibition in paw edema, 79.42 and 73.68 % protection against acetic acid induced writhings and 1.16 and 1.13 of severity index respectively compared to 92.73 %, 78.46 % and 2.16 values of indomethacin. The results showed that the incorporation of appropriately substituted pyrazoline ring in indole nucleus can afford good analgesic and anti-inflammatory activities with reduced gastric irritation to the compounds.