BACKGROUND: Rheumatoid arthritis (RA) is associated with joint damage. 
Effectiveness of embelin has been established in a wide variety of inflammatory 
disorders, but its utility as a therapeutic agent is limited by its poor 
absorption, rapid metabolism, and fast systemic elimination. To apprehend these 
limitations, we propose to use highly bioavailable embelin-loaded chitosan 
nanoparticles (CS-embelin NPs) for the treatment of RA.
METHODS: The rats were made arthritic using a subcutaneous injection with 0.1 ml 
complete Freund's adjuvant (CFA) into the footpad of the left hind paw. 
CS-embelin NPs (25 and 50 mg/kg) was administered from day 15 to day 28 after 
adjuvant injection. After the experimental period, the animals were sacrificed 
and various biochemical markers were assessed.
RESULTS: Arthritic score and paw swelling were significantly reduced after 
treatment with CS-embelin NPs. Arthritis-induced rats showed a significant 
increase in malondialdehyde (MDA) and nitric oxide (NO) with a concomitant 
reduction of antioxidants in the paw tissue. CS-embelin NPs (25 and 50 mg/kg) 
reduced MDA and NO levels and restored antioxidant levels to normalcy by 
mitigating oxidative stress. The arthritic rats exhibited elevated tumor 
necrosis factor-α (TNF-α), interleukin-6 (IL-6) and interleukin-1beta (IL-1β) 
serum concentrations, upregulated TNF- α and IL-6 protein levels and upregulated 
nuclear factor-kB (NF-kB) mRNA expression in paw tissues. Treatment with 
CS-embelin NPs (25 and 50 mg/kg) significantly reduced serum levels and 
down-regulated inflammatory markers to normalcy, dose-dependently.
CONCLUSION: The results suggest that CS-embelin NPs displayed a protective 
effect against adjuvant-induced arthritis in rats mediated through antioxidant 
and anti-inflammatory effects.