Mechanistic insight into inflammatory and oxidative stress ameliorating attributes of Atriplex crassifolia 70% ethanol extract against complete Freund's adjuvant-induced arthritis.

Atriplex crassifolia (AC) has been traditionally used to treat inflammation and arthritis. This study aimed to explore the anti-arthritic effects of Atriplex crassifolia ethanol extract in rat models. FTIR profiling and HPLC techniques were performed for the identification of functional groups and secondary phytochemicals in the 70% ethanol extract of AC (E-AC). Egg albumin protein denaturation assay was performed to evaluate the in vitro anti-inflammatory potential of E-AC. The in vivo anti-inflammatory actions of E-AC were investigated in carrageenan- and histamine-induced acute and complete Freund's adjuvant-induced chronic joint inflammation models. Animals were treated with a three different doses of E-AC (250, 500, and 750 mg/kg) once daily in the acute paw inflammation and for 21 days in the chronic joint inflammation model. Diclofenac sodium (5 mg/kg) and indomethacin (10 mg/kg) were used as standard drugs in the acute and chronic models, respectively. Paw oedema, radiographic scoring, and assessment of various haematological and biochemical parameters were performed to assess the therapeutic efficacy of E-AC. Gene expression studies were conducted to explore the effect of E-AC oral administration on the levels of inflammatory markers. Additionally, ELISA assays were performed to evaluate C-reactive protein and antioxidants concentrations in the serum. Data from the acute paw inflammation models revealed that E-AC 750 mg/kg treatment significantly (p < 0.05) reduced inflammation, possibly through blockage of COX-2-mediated increased prostaglandins (PGs) synthesis. Moreover, E-AC 750 mg/kg treatment significantly inhibited (p < 0.05) histamine-mediated increased regulation of peripheral sensory neurons, resulting in less paw swelling. Data from the chronic joint inflammation model showed that a marked reduction in the arthritic score was noted in rats treated with 750 mg/kg of E-AC. Oral administration of E-AC also normalised all the abnormal haematological markers in the arthritic rats as compared to the untreated arthritic rats. X-ray analysis of arthritic paws further highlighted the curative benefits of the ethanol extract of Atriplex crassifolia. qRT-PCR analysis revealed a significant (p < 0.05) reduction in the mRNA expression of inflammatory cytokines in E-AC and indomethacin-treated rats. Moreover, 750 mg/kg E-AC treatment significantly reduced serum levels of CRP, with a simultaneous up-regulation in the total antioxidant capacity. Serum analysis of E-AC-treated rats also indicated no up-regulation in the levels of AST, ALT, and bilirubin, indicating its relatively non-toxic nature. E-AC also showed nitric oxide scavenging activity in the in vitro assay. Overall, the data from this research highlight the anti-inflammatory potential of Atriplex crassifolia as a complementary treatment for arthritis, thus validating its traditional use in  the joint disorders. Further studies to check the efficacy of ethanol extract of Atriplex crassifolia in combination with low-dose NSAIDs in ameliorating symptoms of various inflammatory disorders are warranted.