THE EFFECTS OF AMINOSALICYLIC ACID-DERIVATIVES ON NITRIC-OXIDE IN A CELL-FREE SYSTEM

Aims and Methods: To determine the effect of aminosalicylic acid deriv atives on the concentration of nitric oxide produced in a cell-free sy stem, by the use of a sensitive and specific polarographic meter. Resu lts: The aminosalicylic acid derivatives 3-ASA (IC50 100 mu M), 4-ASA (IC50 350 mu M) and 5-ASA (IC50 5 mu M) all decreased the nitric oxide signal. These drugs had a similar inhibitory effect on the formation in vitro of nitrite from sodium nitroprusside (IC50: 200 mu M, 500 mu M and 100 mu M, respectively). Sulphasalazine (31.1+/-5% decrease in s ignal at 1 mM) was less effective than 5-ASA, but sulphapyridine, N-ac etyl 5-ASA, indomethacin and hydrocortisone produced no decrease in ni tric oxide signal at all. Conclusions: Nitric oxide binding may be par t of the mechanism by which ASA derivatives exert their therapeutic ef fect, and this work suggests that it may be an important factor in the pathogenesis of ulcerative colitis.