[Aromatization of C-19 steroid in human fetal liver tissue]

In this study we examined whether or not human fetal liver has the ability to aromatize various C-19 steroids to estrone, estradiol and estriol. The human fetal liver homogenate (1g in 10ml of 0.1 M-phosphate buffer) was incubated with the labelled C-19 steroids ([7-3H]-DHEA,-DHEAS, -A:10 microCi, [4-14C]-A:3 microCi) and NADPH at 37 degrees C for 2h in air. [14C]-E1,-E2,-E3 or [3H]-E1,-E2,-E3 (1 x 10(4)dpm, 250 micrograms) were added as tracers after the addition of 3 volumes of ethanol, respectively. E1,E2 and E3 produced were decided by submission to extraction with ethyl acetate, Bio-Rad AG1-X2 resin column chromatography, thin layer chromatography and then co-crystallization to constant specific activity and the 3H/14C ratio. The yield of isolated E1,E2 and E3 were calculated from the 3H/14C ratio of the final crystal. Consequently, DHEA was transformed to 0.78 pmol E1/h/g, 0.14 pmol E2/h/g and 0.18 pmol E3/h/g in human fetal liver, respectively. E1,E2 and E3 were converted from DHEAS to 0.04 pmol/h/g, under 1 fmol/h/g and 0.04 pmol/h/g, respectively. A was transformed to 17.5 pmol E1/h/g, 26.6 pmol E2/h/g and under 1 fmol E3/h/g, respectively. These results indicate that human fetal liver is able to aromatize C-19 steroid to estrogens.