V. Černý

On steroids CIII. Molting deficiencies produced by some sterol derivatives in an insect (Pyrrhocoris apterus L.)

Abstract Several sterol derivatives have been found to inhibit the postecdysial hardening and sclerotization of the cuticle in Pyrrhocoris . These compounds are derivatives of cholestane and 24βF-methylcholestane containing 3β-hydroxy and 6-keto groups. It is assumed that these compounds may have ecdysone-antagonistic action.

On steroids CXIII. Sterilizing effect of some 6-ketosteroids on housefly /Musca domestica L./

Abstract The effect of forty seven 6-ketosteroids on the growth and development of ovaries in the housefly was studied. Most of these compounds show a sterilizing activity. The action of some other steroid compounds was also investigated. The syntheseses of some new 6-keto-steroids are described.

Steroids with modified ring A or B: Screening for potential antiandrogenic and synandrogenic activity

Abstract A series of 14 steroids with modified ring A or B (A-homosteroids, B-homosteroids and 3,6-cyclo-A-nor-3,5-seco-6β-androstanes) were tested for potential antiandrogenic activity by binding assays, using prostate cytosol receptor or sex hormone binding globulin as binder, and by the inhibition of 5α-reductase. The results of in vitro screening were compared with in vivo bioassay. The antiandrogenic or synandrogenic activity of these compounds seemed to have an integrated effect on steroid binding to the cytosol receptors, displacement of the endogenous androgens from the binding to sex hormone binding globulin and influence the transformation of testosterone into 5α-dihydrotestosterone.

Polarographie der steroide III. Polarographische reduktion der steroide mit aldehydgruppe in stellung 18

Die polarographische Reduktion der Steroide mit Aldehydgruppe in Stellung 18 und mit verzweigter Kette in Stellung 17 unterscheidet sich von der Reduktion anderer Aldehyde. Die Hohe ihrer Stufen sowie ihre Halbstufenpotentiale verandern sich praktisch nicht mit dem pH-Wert, was durch eine sterische Hinderung der Hydratation erklart wurde. Die umfangreiche axiale 3α-Aminogruppe des Holarrhidins verhindert dessen Adsorption an der Tropfelektrode. Holarrhidin weist keinen Kapazitatseffekt auf und hat eine wesentlich geringere Wirksamkeit auf die Maximaunter- druckung als Verbindungen mit 3β-Dimethylaminogruppe.