Abstract

Rheumatoid Arthritis (RA) is a complex autoimmune disorder involving chronic and persistent inflammation, principally influencing the synovial joints which further prompting the obliteration of articular cartilage. Although black cumin (Nigella sativa) oil has already studied for its anti-arthritic properties, the current study was focused on the comparative evaluation of the antioxidant and anti-inflammatory properties of a thymoquinone (TQ)-rich (5% w/v) black cumin oil (BQ) with the commonly available standard black cumin oil (BM) containing 0.4% (w/v) TQ, and subsequent investigation on the potential application of BQ in the management of RA. Adjuvant-induced arthritis (AA) was instigated by a single intradermal infusion of 0.1 mL of Complete Freund's adjuvant (CFA) on the paw of adult Wistar rats. Based on the primary dose-response study using the carrageenan-induced paw edema model, 50 mg/kg b.wt. of BQ was employed for the treatment. The endogenous antioxidants (SOD, Catalase, GPx, and GSH), pro-inflammatory cytokines (COX-2, Nitrate, iNOS, TNF-α, IL-6), lipid peroxidation, and histopathology were evaluated to monitor the influence of BQ in AA rats. Adjuvant-induced animals showed a critical downregulation in antioxidant status with elevated levels of pro-inflammatory cytokines and lipid peroxidation. But, the treatment with BQ significantly reversed the antioxidant and inflammatory markers with downregulation of the pro-inflammatory gene expressions. Histopathology showed a significant reduction in the massive cell infiltration and epidermal edema of the paw tissue in AA rats when administered with BQ and indicated its potential effect to alleviate RA conditions in experimental rats.

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