Sulfation of "estrogenic" alkylphenols and 17 beta-estradiol by human platelet phenol sulfotransferases

We have investigated the ability of alkylphenols to act as substrates and/o r inhibitors of phenol sulfotransferase enzymes in human platelet cytosolic fractions. Our results indicate: (i) straight chain alkylphenols do not in teract with the monoamine-sulfating phenol sulfotransferase (SULT1A3); (ii) short chain 4-n-alkylphenols (C < 8) are substrates for the phenol-sulfati ng enzymes (SULT1A1/2), which exhibit two activity maxima against substrate s with alkyl chain lengths of C1-2 and C4-5; (iii) long chain 4-n-substitut ed alkylphenols (C greater than or equal to 8) are poor substrates and act as inhibitors of SULT1A1/2; (iv) human platelets contain two activities, of low and high affinity, capable of sulfating 17 beta-estradiol, and 4-n-non ylphenol is a partial mixed inhibitor of the low affinity form of this acti vity. We conclude that by acting either as substrates or inhibitors of SULT 1A1/2, alkylphenols may influence the sulfation, and hence the excretion, o f estrogens and other phenol sulfotransferase substrates in humans.