Protection by free oxygen radical scavenging enzymes against salicylate-induced embryonic malformations in vitro

Salicylates are among the oldest and most widely used drugs and are known t o lead to foetal death, growth retardation and congenital abnormalities in experimental animals. In this study, the effects of acetyl salicylic acid ( ASA), salicylic acid (SAL) and sodium salicylate (NaSAL) on early organogen esis and the interaction of these molecules with free radicals has been inv estigated. Postimplantation rat embryos were cultured in vitro from day 9.5 of gestation for 48 hr. ASA, SAL and NaSAL were added to whole rat serum a t concentrations between 0.1 and 0.6 mg/ml. Also, the lowest effective conc entration of ASA for all parameters (0.3 mg/ml) and the same concentration of NaSAL and SAL was added to the culture media in the presence of superoxi de dismutase (SOD) (30 U/ml) or glutathione (0.5 mu mol/ml). The growth and development of embryos was compared and each embryo was evaluated for the presence of any malformations. When compared to growth of control embryos, the salicylates decreased all growth and developmental parameters in a conc entration-responsive manner. There was also a concentration-related increas e in overall dysmorphology, including the incidence of haematoma in the yol k sac and neural system, open neural tube, abnormal tail torsion and the ab sence of fore limb bud. When SOD was added in the presence of ASA, growth a nd developmental parameters were improved and there was a significant decre ase in the incidence of malformations. Addition of SOD also decreased the i ncidence of malformations in the presence of SAL, but did not effect the gr owth and developmental parameters of SAL and NaSAL. There was no significan t difference between the embryos grown in the presence of these three molec ules on the addition of glutathione. The effects of salicylates might invol ve free oxygen radicals by the non-enzymatic production of the highly terat ogenic metabolites 2,3- and 2,5-dihydroxybenzoic acid. An enhanced producti on of these metabolites in embryonic tissues may be directly related to the increased risk of congenital malformations. (C) 2000 Published by Elsevier Science Ltd.