Abstract

EXPLORATION OF 1,2-SUBSTITUTED BENZIMIDAZOLE DERIVATIVES: SYNTHESIS AND IN VITRO ANTHELMINTIC ACTIVITY AGAINST INDIAN EARTHWORMS

Lerissa Princy Mascarenhas and Kumara Prasad S. A.*

Abstract

The present study involves the synthesis and characterization of novel 1,2-substituted benzimidazole derivatives with potential anthelmintic activity. The benzimidazole core was synthesized by the reaction of ophenylenediamine with chloroacetic acid in the presence of 4N hydrochloric acid. Subsequent condensation with 2- ethylphenylhydrazine yielded a series of 1,2-substituted derivatives, which were further converted to their corresponding Mannich bases using various secondary amines. The progress of the reactions was monitored by thin-layer chromatography (TLC), and the crude products were purified by recrystallization. Structural confirmation of the synthesized compounds was carried out using IR and ¹H NMR spectroscopy. The IR spectra (KBr) exhibited characteristic peaks at ~3042 cm⁻¹ (aromatic C–H), 2984 cm⁻¹ (aliphatic C–H), 3323 cm⁻¹ and 3414 cm⁻¹ (N–H stretching), and 1563 cm⁻¹ (C=N stretching). The ¹H NMR spectra (DMSO-d₆) showed signals at δ 7.7 (s, 2H, Ar–CH), 3.76 (s, 2H, CH₂–NH), 4.06 (s, 1H, Ar–NH), 2.2 (s, 1H, N–H), and 1.15 (s, 6H, CH₃). Preliminary in vitro screening of the synthesized compounds revealed promising anthelmintic activity.

Keywords: Benzimidazole derivatives, Mannich bases, Anthelmintic activity, 2- ethylphenylhydrazine.