[The inhibitory effect of miconazole on aromatase activity for androstenedione in human placental and ovarian preparations].

The inhibitory effects of miconazole, an antimycotic agent, on aromatase activity for androstenedione in human placenta (105,000 X g pellet fraction) and ovary (800 X g supernatant fraction) were investigated. Various concentrations (0.1-100 microM) of miconazole, aminoglutethimide or delta 1-testololactone were added to the human placental preparation (1 mg protein) and then the mixture was incubated with [1 beta-3 H]-androstenedione (300 pmol) and NADPH (0.5 mg), at 37 degrees C for 30 minutes in air. The reaction was stopped by 10%-trichloroacetic acid (0.8 ml) and the mixture was extracted with chloroform (3 ml). The residual aqueous phase was subjected to Amberlite XAD-II resin-charcoal column chromatography. The amount of 3H2O obtained was regarded as aromatase activity for androstenedione. The effects of miconazole on aromatase activity in human ovarian preparation was also investigated. Aromatase activity in human placenta was suppressed concentration-dependently by miconazole. The inhibition of aromatase activity by miconazole was significantly higher than that by aminoglutethimide and delta 1-testololactone. The I50 values for the inhibition of aromatase activity by miconazole, aminoglutethimide and delta 1-testololactone were 0.60 microM, 15 microM and 34 microM, respectively. The apparent Km value for androstenedione was 320 nM and the apparent Ki value was 120 nM in this assay. The inhibition of aromatase by miconazole in human ovary was also significantly higher than that by aminoglutethimide (I50 value for miconazole = 0.98 microM; I50 value for delta 1-testololactone = 15 microM). These results indicate that miconazole suppresses aromatase activity for androstenedione reversibly in human placenta and ovaries in vitro.