Which component of sulfasalazine is responsible for the therapeutic effect in rheumatoid ahritis

Sulfasalazine:- It is a compound of sulfapyridine and 5-amino salicylic acid (5-ASA); exes antiinflammatory activity and is useful in ulcerative colitis, RA patients. mechanism of action:- Sulfapyridine split off in the colon by bacterial action and absorbed systemically appears to be the active moiety (contrast ulcerative colitis, in which 5-ASA acting locally in the colon is the active component). Generation of superoxide radicals and cytokine elaboration by inflammatory cells may be suppressed. Ref:- kd tripathi; pg num:-211