Novel acetamide derivatives of 2-aminobenzimidazole prevent inflammatory arthritis in rats via suppression of pro-inflammatory mediators.

Benzimidazole ring system is an important pharmacophore with diverse pharmacological activities. In this study, we explored the anti-arthritic effects of newly synthesized acetamide derivatives of 2-aminobenzimidazole (N1 and N2) in rats. FTIR and NMR spectroscopies were used to characterize these compounds. Carrageenan (CRG) induced paw edema model was used to test the acute anti-inflammatory activity of various doses (10, 20 and 30 mg/kg) of N1 and N2 compounds. Based on acute anti-inflammatory effects, the most potent dose of each compound was selected and investigated in complete freund's adjuvant (CFA) induced inflammatory arthritis (RA) model (n = 4 in each group). Histopathological, hematological, radiographic, and RT-qPCR analyses were performed to assess the progression or resolution of inflammatory arthritis. The tested compounds produced a dose-dependent anti-inflammatory activity against CRG induced paw inflammation and similarly reduced edema in CFA induced inflammatory arthritis model. Histopathological and X-ray analyses of ankle joints revealed minimal inflammation and normal joint structures in N1 and N2 treated groups. The tested compounds also reduced the levels of autoantibodies and restored hematological parameters. Interestingly, the tested compounds did not elevate aspartate aminotransferase and alanine transaminase levels and displayed a better safety profile than methotrexate. N1 and N2 compounds also attenuated the transcript levels of IRAK1, NF-kB1, TNF-α, IL-1β, IL17 and MMP1. In addition, N1 displayed a greater inhibition of mRNA levels of COX1, COX2, mPGES1 and PTGDS as compared to N2. Our findings demonstrate that N1 and N2 compounds possess strong anti-arthritic activity which can be attributed to the suppression of pro-inflammatory mediators.