Chalinulasterol, a chlorinated steroid disulfate from the Caribbean sponge Chalinula molitba. Evaluation of its role as PXR receptor modulator.

Chalinulasterol (1) a new chlorinated sterol disulfate was isolated from the Caribbean sponge Chalinula molitba. Its structure was elucidated using mass spectrometry and NMR experiments. The possible role of chalinulasterol as modulator of the PXR nuclear receptor was investigated but, in spite of the close structural relationship with the PXR agonist solomonsterol A (2), it showed no activity. The structural requirements for the PXR nuclear receptor activity were discussed.

Disruption of gene expression and induction of apoptosis in prostate cancer cells by a DNA-damaging agent tethered to an androgen receptor ligand.

The goal of our work was the design of DNA-damaging agents that disrupt both DNA repair and signaling pathways in prostate tumor cells. A DNA alkylator (N,N-bis-2-chloroethyl aniline) was linked to a steroid ligand (17beta-hyroxy-estra-Delta(4(5),9(10))-3-one) to produce a complex molecule (11beta-dichloro) that forms DNA adducts that bind the androgen receptor (AR). We speculated that DNA adducts in an AR-DNA adduct complex would be camouflaged from DNA repair proteins that would otherwise remove the adducts in prostate cancer cells. Furthermore, transcription dependent on the AR would be antagonized by AR redistribution to sites distant from AR-driven promoters. The anticancer potential of 11beta-dichloro was demonstrated against prostate cancer cells in vitro and in vivo. 11beta-dichloro induces a unique pattern of gene disruption, induces apoptosis in apoptosis-resistant cells, and shows promising anticancer activity in animals.

Synthesis and biological activity of 17-chloro-16(17) unsaturated D-homo antiprogestins.

An efficient approach to 17-chloro-16(17) unsaturated D-homo antiprogestins is described. The key steps of the synthesis are a ring-expansion via dichlorocarbene addition to a 17-silyl enol ether and a palladium catalyzed coupling of an 11 beta-(4-aryltriflate) with tributyl(1-ethoxyethenyl)stannane or diethyl(3-pyridinyl)-borane. The new progesterone antagonists were tested for their biological activities and compared to those of known antiprogestins.

Selective inactivation of rat liver cytochromes P-450 by 21-chlorinated steroids.

The inactivation by 21-chlorinated steroids of rat liver cytochromes P-450 involved in the hydroxylation of progesterone and androstenedione has been investigated. Preincubation of intact liver microsomes from phenobarbital-treated rats with 21-chloropregnenolone, 21,21-dichloropregnenolone, or 21,21-dichloroprogesterone in the presence of NADPH caused a time-dependent decrease in progesterone 21-hydroxylase and in progesterone or androstenedione 6 beta-hydroxylase activity but had negligible or only minor effects on five other steroid hydroxylases. The compounds differed, however, with regard to the relative rate constants for inactivation of the 21- and 6 beta-hydroxylases. For example, 21,21-dichloroprogesterone and 21,21-dichloropregnenolone inactivated the progesterone 6 beta-hydroxylase at similar rates, but the dichloroprogesterone was a more effective inactivator of the 21-hydroxylase. The results indicate that the introduction of a dichloromethyl group into a substrate bearing a methyl group normally hydroxylated by only one or a few isozymes of cytochrome P-450 may be a rational means of designing isozyme-selective inhibitors but that target and nontarget enzymes may not totally retain the regioselectivity they exhibit towards the underivatized substrate.

Synthesis, properties and reactions of 3 beta-benzoyloxy-7 alpha-15 beta-dichloro-5 alpha-cholest-8(14)-ene.

Treatment of 3 beta-benzoyloxy-14 alpha,15 alpha-epoxy-5 alpha-cholest-7-ene (I) with gaseous HCl in chloroform at -40 degrees C gave, in 87% yield, 3 beta-benzoyloxy-7 alpha,15 beta-dichloro-5 alpha cholest-8(14)-ene (III). Reduction of the latter compound with lithium aluminum hydride in ether at room temperature for 20 min gave, in 86% yield, 7 alpha-15 beta-dichloro-5 alpha-cholest-8(14)-en-3 beta-ol (IV). The latter compound was fully characterized and assignments of the individual carbon peaks in the 13C nuclear magnetic resonance spectra of this sterol have been completed. Reduction of III with excess lithium aluminum hydride in refluxing ether for 4 days gave, in 74% yield, 5 alpha-cholesta-7,14-dien-3 beta-ol (VI). Reduction of the dichloro-steryl benzoate III with lithium triethylborohydride in tetrahydrofuran gave, in 88% yield, 5 alpha-cholest-8(14)-en-3 beta-ol (VII). A similar reduction using lithium triethylborodeuteride led to the formation of [7 beta, 15 xi-2 H2]-VIIa. Treatment of III with concentrated HCl in a mixture of chloroform and methanol gave, in 79% yield, 3 beta-benzoyloxy-5 alpha-cholest-8(14)-en-15-one (II) which was characterized as such and as the corresponding free sterol.

Prepartion of 16alpha-alkoxy and 16alpha-acyloxy derivatives of 21-chloro-17-acyloxy corticosteroids and determination of their vasoconstrictor activities in humans.

A number of number of 16alpha-alkoxy and 16alpha-acyloxy derivatives of 21-chloro-17-acyloxy corticosteroids have been prepared. The synthetic routes used were (a) reaction of the 16alpha,17-disubstituted 21-mesylate with lithium chloride and (b) reaction of the 16alpha-substituted 17,21-cyclic ortho ester with triphenylmethyl chloride. The vasoconstrictor activities in humans exhibited by these compounds were significantly lower than that of a 16beta-methyl analogue.