3-hydroxy-sulfanilamide ( 3-hs ) , a biotransformation product of sulfanilamide , 3-hydroxy-para-aminobenzoic acid ( 3- hpaba ) , a biotransformation product of procaine and para-aminobenzoic acid , as well as 5-aminosalicylic acid ( 5-asa ) , a bacterial split product of salicylazosulfapyridine ( sulfasalazine , salazopyrin ) in the gut , were shown to react spontaneously with and to bind covalently to proteins by simple incubation at alkaline ph .
C0036078
sulfasalazine
C0699547
salazopyrin