INHIBITION OF SIALYL TRANSFERASE-ACTIVITY BY GOSSYPOL ACETIC-ACID IN HUMAN SEMINAL PLASMA

Seventeen aliquots of 15-mu-l seminal plasma of human origin were incubated with 25-mu-g, 15-mu-g, 5-mu-g and 2.5-mu-g gossypol acetic acid (GAA), dissolved in BWW containing 0.9% sodium chloride and 0.9% benzyl alcohol, at 37-degrees-C for 60 minutes. Following incubation, activity of sialyl transferase (S.T.) was determined by a procedure involving incorporation of radioactive sialic acid into asialofetuin. The activity of S.T., expressed as cpm per hour per 15-mu-l seminal plasma was compared to controls consisting in incubation of sperm in BWW containing 0.9% benzyl alcohol and 0.9% sodium chloride. The activity of S.T. in controls represented 61.3 +/- 8.0% - 67.7 +/- 8.9% of the activity obtained by incubation with BWW only. GAA was found to exert a dose-dependent inhibition of S.T. activity, ranging from 38.3 +/- 20.6% to 53.4 +/- 19.4% (with 25-mu-g) and from 11.3 +/- 14.8% to 21.9 +/- 14.8% (with 2.5-mu-g).