Ocimum sanctum L water extract: In-situ green synthesis of zinc oxide nanoparticles for treatment of rheumatoid arthritis: Preclinical study

Background and objective: Rheumatoid arthritis is a chronic progressive autoimmune disorder, characterised by destruction of cartilage and under line bones. Though exact etiology of rheumatoid arthritis (RA) remains unknown. It is believed that alteration in control of cellular or molecular responses is involved in the chronic inflammation. Earlier in RA patients it was observed the circulating RA specific biomarkers and immunoglobulin deposits in the synovial joints. Zinc Oxide Nanoparticles (ZnO NPs) is used as an anti-inflammatory and anticancer agent, however there is nil/very less scientific data shows the anti-arthritic activity of green synthesis ZnO nanoparticles (Ocimum sanctum water extract in-situ synthesis of ZnO NPs having active compound Caffeic acid and Rosmerinic acid). Hence, the present activity was planned to assess the anti-arthritic activity of ZnO NPs in CIA rats. Methods: Arthritis in rats were induced by subcutaneous injection of collagen type II (CII) (200 mu l) at the base of tail on day 0 followed by booster dose on day 14. ZnO NPs were given (2 mg/kg b.wt./day) orally for 20 days. At the end of the study serum, joint homogenate was used to assess the level of biomarkers (RF, a-CCP, a-CII and CRP) and inflammatory mediators. In addition, m-RNA expression of various genes such as Nuclear factor-kB (NF-kB), inflammatory mediators like tumour necrosis factor-alpha (TNF-alpha), cyclooxygenase-2 (COX-2) etc. were assayed in joint tissue. Finally all these biochemical and molecular results were confirmed by microscopic study of joint tissue. Results: ZnO NPs, treated rats showed decrease in inflammation and clinical severity. This was related with decrease in the level of biomarkers (like RF, a-CCP and CRP), inflammatory mediators (TNF-alpha, COX-2) and activity of transcription factor NF-kB. All these findings were positively correlated with microscopic analysis of joint tissue that showed reduced inflammation and bone erosion in treated group. Conclusion: This study validates the anti-arthritic activity of ZnO NPs as it mitigates the arthritis related symptoms in CIA rats.