Modulation of arachidonic acid metabolism by olsalazine and other aminosalicylates in leukocytes.

We investigated the action of the new aminosalicylate olsalazine (disodium azodisalicylate) on arachidonic acid metabolism in comparison with 5-aminosalicylic acid (5-ASA) and sulphasalazine (SASP) by in vitro incubation of cellular homogenates from human polymorphonuclear (PMNL) and mononuclear (MNL) leukocytes with 14C-labelled arachidonic acid. Olsalazine reduced the synthesis of leukotriene B4 (LTB4), 5-hydroxyeicosatetraenoic acid (5-HETE), 11-HETE, 12-HETE, and 15-HETE in PMNL and MNL slightly less than SASP. 5-ASA was significantly less inhibitory than olsalazine and SASP on the formation of lipoxygenase products in PMNL and on LTB4 synthesis in MNL. In contrast, in MNL the formation of 5-HETE was unaffected, and the production of 11-HETE, 12-HETE, and 15-HETE was even slightly activated by 5-ASA. Total prostaglandin synthesis was dose-dependently reduced by the aminosalicylates (SASP greater than olsalazine greater than 5-ASA), but only SASP markedly altered the prostaglandin (PG) profile, with an increase in PGE2 and PGF2 alpha at the expense of other cyclooxygenase products. It may be concluded that olsalazine resembled SASP with regard to the inhibition of the lipoxygenase but had effects intermediate between the other salicylates on cyclooxygenase. Furthermore, the alteration of the prostaglandin profile by SASP points to an overlying cofactor effect of this drug.