RESEARCH ARTICLE Brazilin isolated from Caes i

is available at the end of the articleBackground Rheumatoid arthritis (RA) is a systemic inflammatory disease of the synovium, cartilage, and bone. RA causes persistent pain, stiffness, swelling, deformities, and loss of joint function [1,2]. Although RA is not inherited, certain human RA susceptible genes may be triggered in response to infection or environmental factors, establishing an autoimmune condition wherein the immune system be-gins to produce substances that attack the joints. Such substances include interleukin-1 (IL-1) and tumor necrosis factor alpha (TNF-α); these factors damage articular cartil-age and bone [3]. Some reports have documented the synthesis of novel cytokines including IL-17, IL-18, and RANK ligand in the synovium, which secretes enzymes degrading proteoglycans and collagen, in turn causing bone loss [4,5]. The worldwide prevalence of RA is 0.5- 1 % [6], an