Comparative Proteomic Analysis of the Effect of Periplocoside P from Periploca sepium on Brush Border Membrane Vesicles in Midgut Epithelium of Mythimna separata Larvae

Periplocoside P (PSP), a novel compound isolated from Periploca sepium Bunge, possesses insecticidal activity against some lepidopterans, such as Mythimna separata. In M. separata, the brush border membrane vesicles of the midgut epithelium are the initial site of action of periplocosides. We conducted two-dimensional gel electrophoresis and matrix-assisted laser desorption/ionization time of flight/time of flight mass spectrometry analysis to analyze differentially expressed proteins (DEPs) from periplocoside P (PSP)-treated M. separata. We successfully isolated seven up-regulated and three down-regulated DEPs that have been previously identified, as well as a novel DEP. The DEPs are implicated in protein degradation, transporter, folding, and synthesis, and in juvenile hormone biosynthesis. DEPs involved in the oxidative phosphorylation energy metabolism pathway are enriched. Through real-time polymerase chain reaction assay, we confirmed that vma1 expression is significantly up-regulated expression levels in PSP-treated M. separata larvae. Enzymology validation further indicated that PSP can significantly inhibit V-type ATPase activity in a concentration-dependent manner. Given these results, we speculate that in M. separata, the V-type ATPase A subunit in the midgut epithelium is the putative target binding site of periplocosides. This finding provides preliminary evidence for the mode of action of periplocosides.

Bioactive C21 Steroidal Glycosides from the Roots of Cynanchum otophyllum That Suppress the Seizure-like Locomotor Activity of Zebrafish Caused by Pentylenetetrazole

Six new C21 steroidal glycosides, cynotophyllosides A-F (1-6), together with 16 known compounds, were isolated from the roots of Cynanchum otophyllum. The structures of the new compounds were elucidated by spectroscopic analysis and chemical methods. The three major components, otophylloside F (15), otophylloside B (17), and rostratamine 3-O-β-D-oleandropyranosyl-(1→4)-β-D-cymaropyranosyl-(1→4)-β-D-cymaropyranoside (18), suppressed the seizure-like locomotor activity caused by pentylenetetrazole in zebrafish. Preliminary structure-activity relation studies revealed that a pregnene skeleton with a C-12 ester group (ikemaoyl > cinnamoyl > hydroxy > p-hydroxybenzoyl) and a C-3 sugar chain consisting of three 2,6-dideoxysaccharide units is essential for this suppressive activity.

The guggulsterone derivative GG-52 inhibits NF-κB signaling in bone marrow-derived dendritic cells and attenuates colitis in IL-10 knockout mice

AIMS

We previously demonstrated that the novel guggulsterone derivative guggulsterone-52 (GG-52) inhibited the activation of nuclear factor (NF)-κB signaling in intestinal epithelial cells and had preventive and therapeutic effects on dextran sulfate sodium-induced acute colitis. This study investigates the anti-inflammatory effects of GG-52 on bone marrow-derived dendritic cells (BMDCs) and chronic colitis in IL-10(-/-) mice.

MAIN METHODS

BMDCs were generated from the femurs of C57BL/6 wild-type and IL-10(-/-) mice. BMDCs were stimulated with lipopolysaccharide (LPS) in the presence or absence of GG-52. The effect of GG-52 on NF-κB signaling in BMDCs was examined by real-time RT-PCR for IL-12p40 and TNF-α gene expression, western blotting for IκBα degradation, and electrophoretic mobility shift assay. For in vivo studies, wild-type or IL-10(-/-) mice were treated with or without GG-52. Colitis was quantified by the evaluation of histopathological findings. Double immunofluorescence staining for CD11c and phosphorylated IκB kinase (IKK)-α was performed to detect IKK activation in DCs in colonic tissue.

KEY FINDINGS

GG-52 significantly inhibited LPS-induced IL-12p40 and TNF-α gene expression, IκBα degradation, and NF-κB DNA binding activity in BMDCs. In the IL-10(-/-) mouse model chronic colitis, administration of GG-52 significantly reduced the severity of colitis as assessed by histopathology, and suppressed IKK activation in DCs in colonic tissue.

SIGNIFICANCE

These results indicate that the novel guggulsterone derivative GG-52 blocks NF-κB activation in BMDCs and ameliorates chronic colitis in IL-10(-/-) mice, which suggest that GG-52 is a potential therapeutic agent for inflammatory bowel diseases.

Chemical constituents from the roots of Periploca sepium with insecticidal activity

Five compounds were isolated from the root powder of Periploca sepium. By mainly HR-ESI-MS, (1)H, (13)C, and 2D NMR spectral data, they were characterized as periplocoside X (1), oligasaccharide A (2), periplocoside A (3), periplocoside E (4), and periplocoside N (5), respectively. Compounds 1-5 were found to possess insecticidal activities against the red imported fire ant. Among the compounds, periplocoside X showed significant activity with LD(50) values of 748.99, 116.62, 2169.58, and 3079.33mg/l against soldiers, workers, males, and alate females of red imported fire ant, respectively.

A new pregnane glycoside and oligosaccharide from Parabarium huaitingii

Two new compounds, along with two known compounds, were isolated from the barks of Parabarium huaitingii, and their structures were determined as 5α-pregn-6-ene-3β,17α,20(S)-triol-20-O-β-d-digitoxopyranoside (1), cymaropyranurolactone 4-O-β-d-digitalopyranosyl-(1 → 4)-O-β-d-cymaropyranosyl-(1 → 4)-O-β-d-oleandropyranosyl-(1 → 4)-O-β-d-cymaropyranoside (2), 3β,17α,20(S)-trihydroxy-5α-pregn-6-ene (3), and 5α-pregn-6-ene-3β,17α,20(S)-triol-3-O-β-d-digitalopyranoside (4) by spectroscopic methods.

Neurosteroid analogues. 16. A new explanation for the lack of anesthetic effects of δ(16)-alphaxalone and identification of a δ(17(20)) analogue with potent anesthetic activity

This study addresses the hypothesis that the lack of anesthetic activity for (3α,5α)-3-hydroxypregn-16-ene-11,20-dione (Δ(16)-alphaxalone) is explained by the steroid Δ(16) double bond constraining the steroid 20-carbonyl group to a position that prevents it from favorably interacting with γ-aminobutyric acid type A (GABA(A)) receptors. A series of Δ(16) and Δ(17(20)) analogues of Δ(16)-alphaxalone was prepared to evaluate this hypothesis in binding, electrophysiological, and tadpole anesthesia experiments. The results obtained failed to support the hypothesis. Instead, the results indicate that it is the presence of the C-21 methyl group in Δ(16)-alphaxalone, not the location of the constrained C-20 carbonyl group, that prevents Δ(16)-alphaxalone from interacting strongly with the GABA(A) receptor and having anesthetic activity. Consistent with this conclusion, a Δ(17(20)) analogue of Δ(16)-alphaxalone without a C-21 methyl group was found to be very similar to the anesthetic steroid (3α,5α)-3-hydroxypregnane-11,20-dione (alphaxalone) with regard to time of onset and rate of recovery from anesthesia when administered to mice by tail vein injection.

D-ring substituted 1,2,3-triazolyl 20-keto pregnenanes as potential anticancer agents: Synthesis and biological evaluation

A facile synthesis of 21-triazolyl derivatives of pregnenolone and their potential antitumour activity is reported. The scheme involves the transformation of the starting pregnenolone acetate into pregnenolone, conversion of pregnenolone to 21-bromo pregnenolone and finally the one-pot, two-step in situ conversion of the bromo derivative to the 21-triazolyl pregnenolone using the 'click chemistry' approach. These derivatives were screened for their anticancer activity against seven human cancer cell lines. The compounds especially 5a, 5b, 5c, 5e, 5g and 5h exhibited significant anticancer activity with compound 5e as the most active in this study.

Homo- and heptanor-sterols and tremulane sesquiterpenes from cultures of Phellinus igniarius

Four steroids, a homopregnene (1) and three heptanorergosterane derivatives (2-4), nine tremulane sesquiterpenes (5-13), and 18 known compounds have been isolated from cultures of the fungus Phellinus igniarius. Their structures and absolute configurations were elucidated by spectroscopic data analysis. In preliminary in vitro assays, at 10(-5) M, compounds 8, 9, 13, and 3beta-hydroxy-11,12-O-isopropyldrimene (14) showed significant vascular-relaxing activities against phenylephrine-induced vasoconstriction with relaxing rates of 35.7%, 45.4%, 46.6%, and 32.1%, respectively, as compared with the blank control.

Synthesis and GABAA receptor activity of A-homo analogues of neuroactive steroids

A procedure is described for the preparation of A-homo-5-pregnenes via an acid catalyzed rearrangement of cyclopropylcarbinols assisted by microwave irradiation. 3alpha-Hydroxy and 4alpha-hydroxy-A-homo-5-pregnen-20-one, analogues of the neuroactive steroid allopregnanolone, were obtained by means of a regioselective epoxidation of a double bond in the expanded A-ring, using a fructose-derived chiral ketone as catalyst and oxone as oxidant. Although both these compounds were marginally active in inhibiting TBPS binding to GABA(A) receptors, 3beta-hydroxy-A-homo-5-pregnen-20-one was almost as active as allopregnanolone. Reduction of the double bond of the latter compound resulted in a ten fold loss of activity.

Microwave-enhanced nucleophilic fluorination in the synthesis of fluoropyridyl derivatives of [3,2-c]pyrazolo-corticosteroids, potential glucocorticoid receptor-mediated imaging agents

Fluoropyridyl derivatives of [3,2-c]pyrazolo-corticosteroids have high affinity for the glucocorticoid receptor (GR) and are highly active glucocorticoids. They are thus considered to be excellent candidates for PET imaging of GR containing tissues when labeled with fluorine-18 (t(1/2)=110 min). Previously reported syntheses of these fluorinated glucocorticoids were accomplished by conventional thermal nucleophilic halogen exchange reactions with chloropyridyl precursors. These reactions were found to proceed at rates too slow for feasible application to radiosynthesis using [(18)F]fluoride. We have applied microwave-heating methods to these reactions and found that significant rate enhancements can be realized. Kinetic experiments showed an average relative rate ratio of 3/1 for microwave versus conventional heating and preparative experiments showed an average relative conversion ratio of 4.5/1 during the initial 120 min, a period approximating one half-life of the isotope. The microwave method described was used to prepare previously unreported 2'-(2-fluoro-4-pyridyl)-11beta,17,21-trihydroxy-16alpha-methyl-20-oxo-pregn-4-eno-[3,2-c]-pyrazole, which was evaluated for biological activity.

Periplocoside E inhibits experimental allergic encephalomyelitis by suppressing interleukin 12-dependent CCR5 expression and interferon-gamma-dependent CXCR3 expression in T lymphocytes

Periplocoside E (PSE) was found to inhibit primary T-cell activation in our previous study. Now we examined the effect and mechanisms of PSE on the central nervous system (CNS) demyelination in experimental allergic encephalomyelitis (EAE). C57BL/6 mice immunized with myelin oligodendrocyte glyco-protein (MOG) were treated with PSE following immunization and continued throughout the study. The effect on the progression of EAE and other relevant parameters were assessed. PSE reduced the incidence and severity of EAE. Spinal cord histopathology analysis showed that the therapeutic effect of PSE was associated with reduced mononuclear cell infiltration and CNS inflammation. As reverse transcription-polymerase chain reaction analysis showed, PSE decreased the CD4(+), CD8(+), and CD11b(+) cell infiltration. T cells from lymph nodes of MOG-immunized mice expressed enhanced levels of CCR5 and CXCR3 mRNA compared with T cells from normal mice. However, CCR5 and CXCR3 expressions were suppressed in T cells from PSE-treated mice. In vitro study also showed PSE inhibited interferon (IFN)-gamma-dependent CXCR3 expression in T cells through suppressing T-cell receptor (TCR) ligation-induced IFN-gamma production, whereas it inhibited interleukin (IL)-12-dependent CCR5 expression through suppressing IL-12 reactivity in TCR-triggered T cells. As a result, the initial influx of T cells into CNS was inhibited in PSE-treated mice. The consequent activation of macrophages/microglia cells was inhibited in spinal cord from PSE-treated mice as determination of chemokine expressions (CCL2, CCL3, CCL4, CCL5, CXCL9, and CXCL10). Consistently, the secondary influx of CD4(+), CD8(+), and CD11b(+) cells was decreased in spinal cords from PSE-treated mice. These findings suggest the potential therapeutic effect of PSE on multiple sclerosis.

Periplocoside E, an Effective Compound from Periploca sepium Bge, Inhibited T Cell Activation in Vitro and in Vivo

Periploca sepium Bge, a traditional Chinese herb medicine, is used for treating rheumatoid arthritis in China. Followed the bioactivity-guided isolation, the most potent immunosuppressive compound, periplocoside E (PSE), a pregnane glycoside, had been identified from P. sepium Bge. We investigated the immunosuppressive effects of PSE in vitro and in vivo. The results showed that PSE in a dose-dependent manner significantly inhibited the proliferation of splenocytes induced by concanavalin A and mixed lymphocyte culture reaction at no cytotoxic concentrations (<5 microM). Administration of PSE suppressed a delayed-type hypersensitivity reaction, and ovalbumin (OVA) induced antigen-specific immune responses in mice. In vivo treatment with PSE dose dependently suppressed OVA-induced proliferation and cytokine [interleukin (IL)-2 and interferon (IFN)-gamma] production from splenocytes in vitro. Purified T cells from OVA-immunized mice with PSE treatment showed its low ability for activation by OVA plus normal antigen presenting cell stimulation again in vitro. Further studies showed PSE dose dependently inhibited anti-CD3-induced primary T cell proliferation, activation for IL-2Ralpha (CD25) expression, and cytokine (IFN-gamma and IL-2) production also at the transcriptional level. PSE was highly specific and significantly inhibited the activation of extracellular signal-regulated kinase and Jun N-terminal kinase, whereas activation of p38 was not affected in T cells stimulated with anti-CD3. These results demonstrated that PSE is an immunosuppressive compound in P. sepium Bge, which directly inhibits T cell activation in vitro and in vivo. This study provided evidence to understand the therapeutic effects of P. sepium Bge and indicated that this herb is appropriate for treatment of T cell-mediated disorders, such as autoimmune diseases.

The role of progesterone metabolites in breast cancer: potential for new diagnostics and therapeutics

Proliferative changes in the normal breast are known to be controlled by female sex steroids. However, only a portion of all breast cancer patients respond to current estrogen based endocrine therapy, and with continued treatment nearly all will become unresponsive and experience relapse. Therefore, ultimately for the majority of breast carcinomas, explanations and treatments based on estrogen are inadequate. Recent observations indicate that 5alpha-pregnane and 4-pregnene progesterone metabolites may serve as regulators of estrogen-responsive as well as unresponsive human breast cancers. The conversion of progesterone to the 5alpha-pregnanes is increased while conversion to the 4-pregnenes is decreased in breast carcinoma tissue, as a result of changes in progesterone metabolizing 5alpha-reductase, 3alpha-hydroxysteroid oxidoreductase (3alpha-HSO) and 20alpha-HSO activities and gene expression. The 5alpha-pregnane, 5alpha-pregnane-3,20-dione (5alphaP) stimulates, whereas the 4-pregnene, 3alpha-hydroxy-4-pregnen-20-one (3alphaHP), inhibits cell proliferation and detachment, by modulation of cytoskeletal and adhesion plaque molecules via the MAP kinase pathway and involving separate and specific plasma membrane-based receptors. The promotion of breast cancer appears to be related to changes in in situ concentrations of cancer-inhibiting and cancer-promoting progesterone metabolites. New diagnostic and therapeutic possibilities for breast cancer are suggested.

Antifungal steroidal glycosides from the patagonian starfish anasteriasminuta: structure-activity correlations

Two new sulfated steroidal hexaglycosides, anasterosides A (2) and B (3), along with the known versicoside A (1) have been isolated from the Patagonian starfish Anasterias minuta. Their structures have been elucidated by spectroscopic analysis (NMR and FABMS) and chemical transformations. Compounds 1 and 2 and the synthetic pentaglycoside 1b derived from versicoside A showed antifungal activity against the plant pathogenic fungus Cladosporium cucumerinum. Desulfation of hexaglycoside 1 rendered a totally inactive saponin.

Subunit-specific modulation of glycine receptors by neurosteroids

The effects of pregnene and androstane steroids were studied on recombinant human glycine receptors (GlyRs) by whole-cell voltage-clamp electrophysiology. The 3beta-sulphates of pregnenolone (PREGS) and dehydroepiandrosterone (DHEAS) inhibited GlyR currents with K(I) values of 2-20 microM for different (alpha(1), alpha(2), alpha(4) and beta) GlyR subunits. PREGS resulted in a parallel shift of the response curve of glycine for alpha(1) GlyRs. The inhibitory potencies of DHEAS relative to PREGS were decreased in transition from embryonic alpha(2) towards adult alpha(1)beta GlyRs. A decreased potency of DHEAS for alpha(4) versus alpha(2) GlyRs represents the first pharmacological difference reported between these subunits. A negative charge at C3 is required for GlyR antagonism but androsterone sulphate epimers at C3 inhibited without stereoselectivity. Some point mutations of alpha(1) GlyRs with characteristic functional consequences did not significantly affect the inhibitory potency of PREGS. Progesterone selectively inhibited alpha(2) GlyRs, while PREG and its acetic ester potentiated alpha(1) GlyRs. Coexpression of the alpha subunits with the beta subunit eliminated the enhancing effects of PREG and attenuated the inhibitory potencies of the neurosteroids. Based on these data we propose that neurosteroids might modulate perinatal GlyR activity and thereby influence neuronal development.

Synthesis and in vitro activity of some epimeric 20 alpha-hydroxy, 20-oxime and aziridine pregnene derivatives as inhibitors of human 17 alpha-hydroxylase/C17,20-lyase and 5 alpha-reductase

Some epimeric 20-hydroxy, 20-oxime, 16 alpha, 17 alpha-, 17,20- and 20,21-aziridine derivatives of progesterone were synthesized and evaluated as inhibitors of human 17 alpha-hydroxylase/C17,20-lyase (P450(17) alpha) and 5 alpha-reductase (5 alpha-R). The reduction of 16-dehydropregenolone acetate (3a) was reinvestigated. NaBH4 in the presence of CeCl3 gave better stereo-selectivity for 20 beta-ol [20 alpha/20 beta-OH (4 alpha/4 beta) = 1/2.7] than LTBAH or the Meerwein-Pondroff method reported; reduction with Zn in HOAc formed exclusively 20 alpha-ol (4 alpha b). The 20 alpha- and 20 beta-hydroxy-4,16-pregnadien-3-one (9 alpha) and (9 beta) were synthesized from the alcohols 4 alpha b and 4 beta b. Several 20-oxime pregnadienes and 16 alpha, 17 alpha-, 17,20- and 20,21-aziridinyl-5-pregnene derivatives were also synthesized. LiAlH4 reduction of the 16-en-20-oxime (12b) yielded 20 (R)-(13a) and 20(S)-17 alpha,20-aziridine (13b) and 20(R)-17 beta,20-aziridine (14a). Several compounds inhibited the human P450(17) alpha with greater potency than ketoconzole. The 5 alpha-R enzyme assay showed that while (9 alpha) did not have any activity, (9 beta) and (3b) were potent 5 alpha-reductase (IC50 = 21 and 31 nM) inhibitors with activities similar to finasteride. The 20-oximes (17a) and (17b) were potent dual inhibitors for both 5 alpha-R (IC50 = 63 and 115 nM, compared to 33 nM for finasteride) and P450(17) alpha (IC50 = 43 and 25 nM, compared to 78 nM for ketoconazole).

Stimulatory effects of starfish sapogenins (Asterias amurensis and Lethasterias nanimensis chelifera) on molluscan heart (Spisula sachalinensis)

Sapogenins from the starfish Asterias amurensis and Lethasterias nanimensis chelifera, 5 alpha-pregn-9(11)-ene-3 beta,6 alpha-diol-20-one, 5 alpha-cholest-9(11)-ene-3 beta,6 alpha-diol-23-one, 5 alpha-cholesta-9(11),24(25)-diene-3 beta,6 alpha-diol-23-one, (20E)-5 alpha-cholesta-9(11),20(22)-diene-3 beta,6 alpha-diol-23-one and 24 zeta-methyl-5 alpha-cholesta-9(11),20(22)-diene-3 beta,6 alpha-diol-23-one, stimulated the contractile force of the heart of the mollusk Spisula sachalinensis at concentration of 5 x 10(-5) M. Ouabain, a specific inhibitor of Na+,K(+)-ATPase, at concentration of 5 x 10(-5) M had no effect on this physiological model. Starfish sapogenins of the cholestane series moderately inhibited rat brain cortex Na+,K(+)-ATPase and decreased Ca2+ influx into Ehrlich carcinoma cells. In contrast, pregnane asterogenin asterone did not inhibit Na+,K(+)-ATPase and increased the influx of Ca2+ into cells. These effects were not the result of cell membrane damage, because none of the compounds tested have hemolytic activity.

Structure-activity relationships of gagaminine and its derivatives on the inhibition of hepatic aldehyde oxidase activity and lipid peroxidation

In order to determine the structure-activity relationships for antioxidative effects of gagaminine, a steroidal alkaloid isolated from the roots of Cynanchum wilfordi (Asclepiadaceae), two derivatives identified as sarcostin and penupogenin were prepared from gagaminine by hydrolysis and reduction. These compounds were evaluated for the inhibitory effects on the aldehyde oxidase activity and on lipid peroxidation in vitro. Furthermore, their effects were compared with those of gagaminine and the related compounds, cinnamic acid and nicotinic acid. The results of this study prove that the cinnamoyl group in the structure of gagaminine is critical in inhibition of the aldehyde oxidase activity while the nicotinoyl group may be necessary for anti-lipid peroxidation of the compound.

20-amino and 20,21-aziridinyl pregnene steroids: development of potent inhibitors of 17 alpha-hydroxylase/C17,20-lyase (P450 17)

In the search for potent inhibitors of P450 17, the key enzyme of androgen biosynthesis, the 20,21-aziridinyl- and 20-aminopregnene steroids 1-11 were synthesized and tested toward rat testicular P450 17. Only the aziridinyl-substituted pregnenolones (1 and 2) and progesterones (3 and 4), respectively, showed inhibitory activity, which strongly depends on C20 stereochemistry. The most active compound 1 [20(S)-20,21-aziridinylpregn-5-en-3 beta-ol; IC50 0.21 microM, progesterone 25 microM; Ki = 1.7 nM, K(m) progesterone = 7.0 microM] is the strongest inhibitor of rat P450 17 described so far. Using UV-vis difference spectroscopy, complexation of the aziridinyl nitrogen to the heme iron, Fe3+, of P450 17 was observed, which could not be reversed by high concentrations of substrate. Preincubation of the enzyme with 1 in the absence and presence of NADPH followed by charcoal treatment results in a strong decrease of enzyme activity within 30 s. However, a recovery of enzyme activity was observed: 90 min after charcoal treatment 75% of the activity was restored.

Modulation of 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) activity in the equine placenta by pregnenolone and progesterone metabolites

The purpose of this study was to measure 3beta-HSD activity in the equine placenta and to assess the effect of fetal and maternal blood plasma progestagens on 3beta-HSD activity was measured in 8 late gestation (collected by caesarian section at 250 to 320 days) and 7 term (collected by caesarian section at 250 to 320 days) and 7 term (collected at birth) equine placentae using a tritium release assay with [3alpha-3H] pregnenolone as substrate. Mean +/- s.d. Km(app) and Vmax for term placentae were in general higher than for late gestation placentae (0.129 +/- 0.217 micromol/l and 23.85 +/- 9.1 nmol/mg/h respectively vs. 0.016 +/- 0.048 micromol/l and 17.36 +/- 20.9 nmol/mg/h) but there was no statistical difference between them. Inhibition studies were performed on 3 term placentae and 3 late gestation ones. Steroid concentrations used for inhibition studies were close to blood plasma concentrations (0.5 to 2 micromol/l). 3beta-hydroxy compounds (5alpha-pregnene-3beta, 20alpha-diol and 3beta-hydroxy-5alpha-pregnan-20-one) showed noncompetitive or mixed inhibition. Mean Ki(app) of 0.7 micromol/l. Inhibition was competitive with 20alpha-hydroxy-5alpha-pregnan-3-one with a mean Ki(app) of 0.1 micromol/l.

Integrity of intermediate filaments is associated with the development of acquired thermotolerance in 9L rat brain tumor cells

Withangulatin A (WA), a newly discovered withanolide isolated from an antitumor Chinese herb, has been shown to be a vimentin intermediate filament-targeting drug by using immunofluorescence microscopy. Together with cytochalasin D and colchicine, these drugs were employed to investigate the importance of vimentin intermediate filaments, actin filaments, and microtubules in the development of acquired thermotolerance in 9L rat brain tumor cells treated at 45 degrees C for 15 min (priming heat-shock). Acquired thermotolerance was abrogated in cells incubated with WA before the priming heat-shock but it could be detected in cells treated with WA after the priming heat-shock. In contrast, cytochalasin D and colchicine do not interfere with the development of thermotolerance at all. The intracellular localizations of vimentin and the constitutive heat-shock protein70 (HSC70) in treated cells were examined by using immunofluorescence microscopy and detergent-extractability studies. In cells treated with WA before the priming heat-shock, vimentin IFs were tightly aggregated around the nucleus and unable to return to their normal organization after a recovery under normal growing conditions. In contrast, the IF network in cells treated with WA after the priming heat-shock was able to reorganize into filamentous form after a recovery period, a behavior similar to that of the cells treated with heat-shock only. HSC70 was found to be co-localized with vimentin during these changes. It is suggested that the integrity of intermediate filaments is important for the development of thermotolerance and that HSC70 may be involved in this process by stabilizing the intermediate filaments through direct or indirect binding.

Induction of aggregation and augmentation of protein kinase-mediated phosphorylation of purified vimentin intermediate filaments by withangulatin A

Purified assembly-competent vimentin, an intermediate filament protein, was obtained from bovine lens in this study. The effects of withangulatin A on vimentin assembly with or without phosphorylation were examined by negative-stain electron microscopy. Soluble tetrameric vimentin was assembled into irregular fibrils with lateral associations or short filaments after pretreatment with 50 or 100 microM withangulatin A, respectively. Incubation of assembled vimentin filaments with withangulatin A at 50 or 100 microM resulted in the formation of aggregates, and the degree of aggregation was concentration dependent. The appearance of vimentin filaments was slightly altered after treatment with cAMP-dependent protein kinase or protein kinase C; however, phosphorylation of filamentous vimentin by the protein kinases in the presence of withangulatin A resulted in higher degrees of aggregation of the filaments, compared with those treated only with the drug. Moreover, the level of phosphorylation of filamentous vimentin by the protein kinases was augmented in the presence of withangulatin A. Experimental results indicated that withangulatin A directly and specifically affects the conformation of the vimentin molecules, thereby resulting in alterations in assembly behavior and reactivity toward cAMP-dependent protein kinase and protein kinase C. The data observed further imply that withangulatin A, which directly causes aggregation of vimentin filaments, is a vimentin intermediate filament-targeting drug.

Induction of vimentin modification and vimentin-HSP72 association by withangulatin A in 9L rat brain tumor cells

Withangulatin A induced cell rounding up and the morphological alteration resulted from the reorganization of all of the major cytoskeletal components, i.e., vimentin, tubulin, and actin, as revealed by immunofluorescence techniques. When the withangulatin A-treated cells changed to a round-up morphology, vimentin intermediate filaments were found to be collapsed and clustered around the nucleus. The alteration was accompanied by characteristic changes of vimentin molecules, including augmentation of phosphorylation, retardation of electrophoretic mobility, and decrease in detergent extractability. The levels of vimentin phosphorylation were augmented by 2.5- and 1.8-fold in cells incubated with 50 microM withangulatin A for 1 and 3 h, respectively. The electrophoretic mobility of vimentin was partially retarded in cells treated with withangulatin A for 1 h at 10 microM and a completely upshift mobility was observed after 5 h treatment at 50 microM. In addition, vimentin molecules became less extractable by nonident P-40 after the cells were treated with withangulatin A and this effect was dose dependent. The decrease in solubility of vimentin was accompanied by the redistribution of HSP72 into the detergent nonextractable fraction and these two events were well correlated. Our results suggest that withangulatin A induced the modification of vimentin, which resulted in the alteration of cell morphology and redistribution of intracellular HSP72, an event that may play an important role in the induction of heat-shock response.

Induction of heat-shock response and alterations of protein phosphorylation by a novel topoisomerase II inhibitor, withangulatin A, in 9L rat brain tumor cells

Withangulatin A is a newly identified in vitro topoisomerase II inhibitor isolated from the Chinese antitumor herb Physalis angulata. In vivo, it was found to be cytotoxic, capable of suppressing general protein synthesis and of inducing the synthesis of a small set of proteins including those generated by heat-shock treatment. The 70 kDa protein generated by withangulatin A was unequivocally identified as the heat-shock protein 70 (HSP70) since both proteins migrated to the same position on two-dimensional polyacrylamide gels, could be recognized by a monoclonal antibody to human HSP70, and exhibited identical peptide maps. The induction of protein synthesis by withangulatin A was regulated at the transcriptional level since it was aborted in cells pre-treated with actinomycin D. However, the initiation of this process did not require de novo protein synthesis since it was not affected by cycloheximide. Other cellular effect of withangulatin A was alterations of protein phosphorylation including an enhancement of phosphorylation of a 65 kDa protein which was also detected in the heat-shocked cells. Moreover, this process was observed within 7.5 min after the initial heat treatment which is much faster than the onset of HSP synthesis. Therefore, increased phosphorylation of the 65 kDa protein may represent one of the earliest signals generated by both heat-shock and withangluatin A and may be involved in the upstream regulation of heat-shock response in cells.

Modified acetylenic steroids as potent mechanism-based inhibitors of cytochrome P-450SCC

Synthesized 20-(4-tetrahydropyranyl-1-butynyloxy)-5-pregnen-3 alpha,20 beta- diol [steroid I] and 20-(3-tetrahydropyranyl-1-propargyloxy)-5-pregnen- 3 alpha,20 beta-diol [steroid III] have been found to inactivate purified adrenocortical cytochrome P-450SCC. When incubated with the enzyme under turnover conditions, steroid I inactivated cytochrome P-450SCC by about 85% in 40 min. This is in contrast to the free triol analog, steroid II which inactivated the enzyme by only 45% within the same incubation period. A comparison of steroid III with its free triol analog, steroid IV, also showed that the diol is a more effective inactivator of the enzyme than the triol. The partition ratio was calculated by two different methods. Each of the steroids I-IV bound to the enzyme with spectrophotometric dissociation constant (Ks) in the micromolar range, producing Type II low spin spectra changes during titration of the enzyme. In addition, it was found that the binding of each of the compounds to the enzyme occurred without inactivation of the enzyme and that the inactivation under turnover condition, is not as a result of conversion to the denatured P-420 species. This demonstrated that steroids I and III could correctly be designated as mechanism-based (suicide) inhibitors. The kinetic studies demonstrated that steroids with the tetrahydropyranyl substituent are more potent inhibitors of cytochrome P-450SCC as shown by an initial turnover rate of 0.06 min-1, an inactivation rate constant of 0.05 min-1, and a partition ratio of about 1.0 for steroid I. Based on our finding, possible mechanisms of inactivation of cytochrome P-450SCC by these acetylenic steroids are proposed.

Effects of steroids and human chorionic gonadotrophin on in vitro oocyte final maturation in two marine flatfish: the dab, Limanda limanda, and the plaice, Pleuronectes platessa

This study investigated the role of gonadotrophin and steroids in the induction of in vitro oocyte maturation in dab (Limanda limanda) and plaice (Pleuronectes platessa), two marine flatfish (Pleuronectiformes) in which the oocytes mature and ovulate in groups (or batches). Clusters of folliculated oocytes were incubated for 3 days with a range of doses of either human chorionic gonadotrophin (HCG) or synthetic steroids with a wide range of structures. They were also incubated with extracts from cultures of HCG-stimulated ovaries. Oocytes were always more responsive to HCG than to steroids, and the median efficient doses obtained with HCG were negatively correlated with oocyte diameters. Bioassay sensitivity to steroids was low when compared with other teleosts, and intraassay variability was high, particularly in plaice. Despite the high variability, a common pattern in specificities to steroids was obtained for the two species, which was also similar to other teleost species. Among the most effective steroids found were 17 alpha,20 beta-dihydroxy-4-pregnen-3-one and 17 alpha,20 beta,21-trihydroxy-4-pregnen-3-one. Extracts from incubates were ineffective. The significance of these findings and possible ways to reduce assay variability and improve sensitivity are discussed.

A new compound, withangulatin A, promotes type II DNA topoisomerase-mediated DNA damage

Withangulatin A, a new compound with a known chemical structure and from the antitumor Chinese herb Physalis angulata L, was found to act on topoisomerase II to induce topoisomerase II-mediated DNA damage in vitro. It has two effective dosage ranges of approximate 0.5 and 20 microM, with about one-third the activity of 20 microM VM-26.

Estrogen enhances attachment of Chlamydia trachomatis to human endometrial epithelial cells in vitro

Ultraviolet light-inactivated elementary bodies of Chlamydia trachomatis serovar E were fluorescently tagged with rhodamine isothiocyanate (5 micrograms/ml) and added to primary cultures of human endometrial gland epithelial cells. The elementary bodies, at a multiplicity of infection of 600:1, were allowed to adsorb to the cell monolayers for 1 hour at 35 degrees C in an atmosphere of 5% carbon dioxide. The monolayers were disaggregated by trypsinization and the individual cells were processed in the fluorescent activated cell sorter for chlamydial attachment. This method of analysis revealed attachment of C. trachomatis to approximately 50% of human endometrial gland epithelial cells. Addition of estrogen (10(-10) mol/L) to the culture medium enhanced chlamydial attachment to human endometrial gland epithelial cells to approximately 80% (p less than or equal to 0.005), and progesterone in combination with estrogen reduced chlamydial attachment in a dose-dependent fashion: 1 ng/ml progesterone, approximately 50%; 5 ng/ml, about 30%; 10 ng/ml, about 18%, respectively (p less than or equal to 0.025).

Inhibition of cholesterol side-chain cleavage by intermediates of an alternative steroid biosynthetic pathway

Mitochondrial preparations from endocrine tissues were incubated with radioactive cholesterol and the effect of hydroxylated metabolites of 23,24-dinor-5-cholen-3 beta-ol (23,24-dinor-5-cholene-3 beta,20-diol and 23,24-dinor-5-cholene-3 beta,21-diol) on the production of pregnenolone was measured. These compounds are intermediates in an alternative, sesterterpene pathway for steroid hormone biosynthesis. It was found that these materials, like the analogous side-chain-hydroxylated derivatives of cholesterol (20 alpha-hydroxycholesterol and 22S-hydroxycholesterol), inhibit cholesterol side-chain cleavage. The possibility that there could be a control mechanism whereby metabolites of 23,24-dinor-5-cholen-3 beta-ol inhibit steroidogenesis occurring by the cholesterol pathway is discussed.

22-thio-23,24-bisnor-5-cholen-3 beta-ol: an active site-directed inhibitor of cytochrome P450scc

The title compound (22-Thiol) was prepared from the 22-hydroxy derivative via the isothiouronium salt. Using purified enzyme components from bovine adrenocortical mitochondria, 22-Thiol was found to be a potent, competitive inhibitor (Ki = 0.7 microM) of cholesterol side chain cleavage. Spectral studies showed that binding of 22-Thiol to cytochrome P450scc produces changes characteristic of sulfur coordination to the heme-iron, suggesting that its high affinity arises from a dual interaction with the cholesterol binding site and the heme. Together with previous results obtained with 22-amino and 22-hydroxy analogues, these findings provide support for the proximity of C-22 and the heme-iron of cytochrome P450scc in the enzyme-substrate complex.

Sleep induction by an adrenal steroid in the rat

The ring A reduced metabolites of deoxycorticosterone and progesterone, 3 alpha, 5 alpha-tetrahydrodeoxycorticosterone (THDOC) and 3 alpha-hydroxy-5 alpha-dihydroprogesterone (3 alpha-OH-DHP) have been shown to be potent barbiturate-like ligands of the benzodiazepine receptor complex. The former has also been reported to have anxiolytic effects in mice and rats. In the present study, sleep recordings were obtained on rats given 5 and 10 mg/kg of these steroids alone and in combination with flurazepam. THDOC, but not 3 alpha-OH-DHP, had potent dose-dependent sleep-inducing properties and increased nonREM sleep. Flurazepam had similar hypnotic effects and also reduced REM sleep. There were no significant interactions between THDOC and flurazepam, except in the case of REM latency, which tended to increase when the two compounds were given together. In summary, THDOC, a mineralocorticoid metabolite found in brain, has sedative properties and could conceivably play a role in stress responses.

Active site-directed inhibition of rabbit cytochrome P-450 1 by amino-substituted steroids

A variety of amino-substituted steroids were investigated as inhibitors of the rabbit hepatic, steroid 21-hydroxylase, cytochrome P-450 1. We reasoned that a steroid analog of pregnenolone capable of mimicking the binding of C21-steroids to the enzyme at the active site and bearing an amine moiety on the 17 beta-side chain would be a potent inhibitor if the amine were free to interact with the heme iron. Our studies reveal that 22-amino-23,24-bisnor-5-cholen-3 beta-ol (22-ABC) is a tightly-bound inhibitor of cytochrome P-450 1-catalyzed reactions (Ki less than 1 nM). Spectral differences elicited by 22-ABC indicate that when bound to the enzyme, the amine moiety of 22-ABC is coordinated to the heme iron. In contrast, several other hepatic cytochrome P-450s which mediate distinct regio-specific routes of metabolism for progesterone or pregnenolone remain largely unaffected at concentrations of 22-ABC that exceed by 2 orders of magnitude that required to inhibit cytochrome P-450 1. 22-ABC also inhibited the metabolism of benzo(a)pyrene attributable to cytochrome P-450 1 but did not inhibit that induced by treatment with rifampicin or 2,3,7,8-tetrachlorodibenzo-p-dioxin. Analogs of 22-ABC bearing a hydroxyl group or a methylamine in place of the amine moiety exhibit lower affinities for cytochrome P-450 1. In addition, either increasing or decreasing the number of carbons of the side chain reduced the affinity of the inhibitor for cytochrome P-450 1.

Germinal vesicle breakdown in oocytes of catfish, Mystus vittatus (Bloch): relative in vitro effectiveness of estradiol-17 beta, androgens, corticosteroids, progesterone, and other pregnene derivatives

The relative in vitro effectiveness of estradiol-17 beta, androgen, corticosteroids, progesterone, and other pregnene derivatives on germinal vesicle breakdown (GVBD) using folliculated oocytes of an Indian catfish Mystus vittatus was investigated. 17 alpha,20 beta-Dihydroxyprogesterone was found to be the most effective maturation-inducing steroid (MIS). Estradiol-17 beta and testosterone were not effective but androsterone was found to be fairly effective in final oocyte maturation. Deoxycorticosterone (DOC), hydrocortisone, progesterone, and 17 alpha-hydroxyprogesterone were also effective at their higher concentrations. Among 5 beta-reduced pregnenes, all but 5 beta-pregnene-3 alpha-ol-20-one could induce oocyte maturation. The significance of these findings in relation to the progestagens as natural MIS and the present controversial position of another Indian catfish Heteropneustes fossilis is discussed in the light of available literature.

Discriminatory inhibition of adrenocortical 17 alpha-hydroxylase activity by inhibitors of cholesterol side chain cleavage cytochrome P-450

Two inhibitors of the cholesterol side chain cleavage reaction were tested for their ability to inhibit bovine adrenocortical 17 alpha-hydroxylase and 21-hydroxylase activities. One inhibitor, 22-amino-23,24-bisnor-5-cholen-3 beta-ol (22-ABC), was found to be a potent inhibitor of 17 alpha-hydroxylation of either progesterone or pregnenolone but was inactive on 21-hydroxylase activity. 22-ABC was found to be a competitive inhibitor of 17 alpha-hydroxylase (cytochrome P-45017 alpha) activity, having an apparent inhibitor constant of 29 nM when using pregnenolone as the substrate. Spectral binding studies showed that 22-ABC produces a type II difference spectrum when added to a bovine adrenocortical microsomal preparation, due presumably to a coordination of its amine nitrogen atom to the heme-iron of cytochrome P-45017 alpha. The second cholesterol side chain cleavage inhibitor tested, (20R)-20-phenyl-5-pregnene-3 beta,20-diol (20-PPD), was found not to inhibit either the 21- or 17 alpha-hydroxylase activities. It is proposed that the phenyl group projecting from C-20 of 20-PPD prevents this steroid from binding to cytochrome P-45017 alpha. The discriminatory interaction of these two steroids with adrenocortical cytochromes P-450 provides some insight with respect to possible structural features of the active-site regions of these enzymes.

Mechanisms of spontaneous and induced frameshift mutation in bacteriophage T4

Frequencies of spontaneous and proflavine-induced frameshift mutations increased dramatically as a function of the number of reiterated base pairs at each of two sites in the lysozyme gene of bacteriophage T4. At each site, proflavine induces addition mutations more frequently than deletion mutations. We confirm that the steroidal diamine, irehdiamine A, induces frameshift addition mutations. At sites of reiterated bases, we propose that base pairing is misaligned adjacent to a gap. The misaligned configuration is stabilized by the stacking of mutagen molecules around the extrahelical base, forming a sandwich. Proflavine induces addition mutations efficiently at a site without any reiterated bases. Mutagenesis at such sites may be due to mutagen-induced stuttering of the replication complex.

Relative inhibitory potency of five mineralocorticoid antagonists on aldosterone biosynthesis in vitro

Spirolactones are mineralocorticoid antagonists which bind to aldosterone receptors in the distal nephron. During the last decade, several antimineralocorticoids, which are more potent than spironolactone in competing for mineralocorticoid receptors have been developed. In the present study, we have compared the direct activity of spironolactone and four related compounds: prorénone (SC 23133), SC 19886, SC 26304 and its carboxylic analog SC 27169, on aldosterone biosynthesis. Two of them (SC 26304 and its carboxylic analog SC 27169) had no effect on adrenal steroidogenesis, even at concentrations up to 10(-3)M. Spironolactone and prorenone (SC 23133) induced a marked but reversible inhibition of aldosterone biosynthesis. SC 19886 totally inhibited aldosterone production and the activity of this compound lasted for more than 7 hours. In addition, SC 19886 and prorenone (SC 23133) totally suppressed ACTH and angiotensin II-induced stimulation of aldosterone biosynthesis whereas SC 27169 was unable to block adrenal response to these corticotropic hormones. Our results suggest that compounds such as prorenone (SC 23133), SC 19886 and spironolactone, which are potent inhibitors of aldosterone biosynthesis could be more active in the treatment of primary aldosteronism than those antimineralocorticoids which are devoid of action on aldosterone biosynthesis.

Relative in vitro effectiveness of 17 alpha, 20 beta-dihydroxy-4-pregnen-3-one and other pregnene derivatives on germinal vesicle breakdown in oocytes of ayu (Plecoglossus altivelis), amago salmon (Oncorhynchus rhodurus), rainbow trout (Salmo gairdneri), and goldfish (Carassius auratus)

The relative effectiveness of several pregnene derivatives, which had previously been identified in the ovaries of ayu (Plecoglossus altivelis), on germinal vesicle breakdown (GVBD) was investigated in vitro using folliculated oocytes of four species of teleosts, ayu, amago salmon (Oncorhynchus rhodurus), rainbow trout (Salmo gairdneri), and goldfish (Carassius auratus). Although some species differences existed in the relative effectiveness of each steroid on GVBD, 17 alpha, 20 beta-dihydroxy-4-pregnen-3-one (17 alpha, 20 beta-diOHprog) was consistently the most potent inducer of final oocyte maturation. Both progesterone and 17 alpha-hydroxyprogesterone were effective at relatively high concentrations. Of the 5 beta-reduced metabolites, 17 alpha, 20 beta-dihydroxy-5 beta-pregnan-3-one was almost as effective as 17 alpha, 20 beta-diOHprog in oocytes of amago salmon and rainbow trout, while the other 5 beta-reduced compounds (3 alpha-hydroxy-5 beta-pregnan-20-one, 17 alpha-hydroxy-5 beta-pregnane-3,20-dione, 3 alpha, 17 alpha-dihydroxy-5 beta-pregnan-20-one, 5 beta-pregnane-3 alpha, 17 alpha, 20 beta-triol, and 5 beta-pregnane-3 beta, 17 alpha, 20 beta-triol) were almost or totally ineffective at the concentrations tested (1-0.001 micrograms/ml). These bioassay results, together with previous findings on the capacity of the ovary to produce 17 alpha, 20 beta-diOHprog, indicate that 17 alpha, 20 beta-diOHprog is the natural maturation-inducing steroid hormone common to three species of Salmoniformes, ayu, amago salmon, and rainbow trout. These results, however, only suggest that 17 alpha, 20 beta-diOHprog is involved in maturation of goldfish oocytes, since supportive physiological and biochemical data are lacking. Possible regulatory roles of 5 beta-reduced metabolites on steroid-induced oocyte maturation are discussed.

Inhibition of steroidogenesis in cultured Leydig tumor cells by 22-amino-23,24-bisnor-5-cholen-3 beta-O1 and (20R) 20-phenyl-5-pregnene-3 beta,20-diol

Using the cholesterol side-chain cleavage enzyme purified from bovine adrenals, we have previously shown that 22-amino-23,24-bisnor-5-cholen-3-beta-ol (22-ABC) and (20R) 20-phenyl-5-pregnene-3 beta, 20 diol (20-PPD) are potent competitive inhibitors of this enzyme. The studies presented herein were designed to characterize the effects of these new inhibitors on steroid production by intact cells. Using cultured Leydig tumor cells, we compared the effects of 22-ABC, 20-PPD, and aminoglutethimide (a well-known inhibitor of the cholesterol side-chain cleavage enzyme) on hormone-stimulated steroidogenesis. Our results show that these compounds inhibit steroid production in a dose-dependent manner and that 20-PPD and 22-ABC are about 100 and 4 times more active, respectively, than aminoglutethimide. In these cells, the inhibitory effects of the new compounds seem to be localized exclusively at the conversion of cholesterol to pregnenolone.

Inhibition of adrenocortical cytochrome P-450scc by (20R)-20-phenyl-5-pregnene-3 beta,20-diol

The effects of the cholesterol analogue, (20R)-20-phenyl-5-pregnene-3 beta,20-diol (20-PPD), on the catalytic and spectral properties of purified bovine adrenocortical cytochrome P-450scc were investigated. In contrast to results with cholesterol and (20R)-20-hydroxycholesterol, no conversion of 20-PPD to pregnenolone could be detected; instead, 20-PPD was found to be a potent inhibitor of cytochrome P-450scc. Kinetic analyses showed that the inhibition is reversible and competitive with respect to cholesterol with an apparent Ki = 30nM. Spectral binding studies with ferricytochrome P-450scc showed that 20-PPD formed a 1:1 complex with the enzyme, having an absorption spectrum similar to that produced by (20R)-20-hydroxycholesterol. These results indicate that 20-PPD binds with very high affinity to the substrate site on cytochrome P-450scc. The finding that the phenyl side chain is readily accommodated suggests the presence in this site of an open pocket which may be normally occupied by C-22 to C-27 of the cholesterol side chain.

[Direct action of mineralocorticoid antagonists on biosynthesis of aldosterone: comparative activities of several new compounds]

Spironolactone is a diuretic steroid which is capable of blocking the binding of aldosterone to its cytosol receptor at the distal convoluted tubule. In addition, it has been shown that spironolactone is a strong inhibitor of steroidogenesis. More recently, new aldosterone antagonists have been discovered. Some of these compounds are more active than spironolactone in competing with aldosterone and have higher specificity for mineralocorticoid receptors. In this study we compare the direct activity of new antimineralocorticoids (SC 23133, SC 19886, SC 26304, and SC 27169) on aldosterone biosynthesis. Marked differences were found in the activity of these compounds upon steroidogenesis. SC 23133 gave rise to a strong inhibiting activity (90%). This activity was reversible (recovery of spontaneous production occurs 150 min after the end of the administration of SC 23133). SC 19886 totally inhibited aldosterone biosynthesis (95%) in a lasting mean. Conversely, SC 27169 and SC 26304 presented no or weak inhibiting effect. Further experiments showed that SC 27169 was unable to block the stimulation of aldosterone biosynthesis induced by corticotropic peptides, whereas the administration of SC 23133 and SC 19886 totally suppressed the stimulatory effect of ACTH and angiotensin II. Owing to the important stimulation of the renin-angiotensin system induced by antimineralocorticoid treatment, these results suggest that SC 23133 and SC 19886 will exert a higher antinatriuretic activity than SC 27169.

The molecular structure of (20R)-20-phenyl-5-pregnene-3 beta, 20-diol, an inhibitor of cholesterol conversion to pregnenolone

The crystal and molecular structure of (20R)-20-phenyl-5-pregnene-3 beta, 20-diol hemihydrate has been determined by X-ray analysis in order to establish the configuration and conformation at C(20). Interest in this compound was stimulated by its high affinity inhibitory binding to cytochrome P-450SCC, the enzyme which catalyzes the biosynthesis of pregnenolone (3 beta-hydroxy-5-pregnen-20-one) from cholesterol. The results of the analysis suggest a possible conformation for the cholesterol side chain in the enzyme complex.

A comparison of the biological properties of androst-5-en-3 beta-ol, a series of (20R)-n-alkylpregn-5-en-3 beta-ols and 21-isopentylcholesterol with those of cholesterol

The delta 5-sterol, androst-5-en-3 beta-ol, which has no side chain at C-17, did not permit molting of the insect Heliothis zea, growth of either the protozoan Tetrahymena pyriformis, or the yeast Saccharomyces cerevisiae adapted to anaerobic conditions, nor was the sterol esterified by a mammalian microsomal ACAT preparation. However, the sterol did form a liposome with egg lecithin and, when fed to mice, did inhibit hepatic cholesterol synthesis. 21-Isopentylcholesterol also formed a liposome but neither supported the growth of the yeast nor was metabolized by the protozoan. When sterols, 20(R)-n-alkylpregn-5-en-3 beta-ols, with side chains of varying lengths were added to the medium of the protozoan, maximal esterification with fatty acids occurred with the 20(R)-n-pentyl derivative, and maximal inhibition of tetrahymanol formation occurred with the n-butyl, n-pentyl, and n-hexyl derivatives. In all of the assays cholesterol showed a positive response, either permitting molting or growth, being metabolized, inhibiting sterol or tetrahymanol synthesis, or forming a liposome.

Bioassay of a new aldosterone antagonist and evaluation of a simple method of quantitative comparison

The renal antimineralocorticoid activity of single oral doses of a new aldosterone antagonist OH OPC(ME)-K was compared to that of spironolactone in two studies in healthy men. OH OPC(ME)-K reversed the urinary electrolyte response to fludrocortisone in the period up to 16 hr after treatment, but it was less potent than spironolactone on a weight basis. The best estimate of the relative potency of OH OPC(ME)-K: spironolactone (derived from a simple protocol using equal single doses of the two drugs) was 0.60:1 (95% confidence limits 0.24:1 to 1.42:1), in good agreement with the estimate from a more complex three-dose parallel-line bioassay (0.61:1, 95% confidence limits 0.48:1 to 0.79:1). The results of simple single-dose studies can be used, with certain assumptions, to provide a useful estimate of the relative potency of new aldosterone antagonists at an early stage of development.

Inactivation of herpes simplex virus by a pregnene derivative (TX 3047)

1. Two strains of independently purified Herpes simplex virus type 1 were irreversibly inactivated after incubation with the pregnene derivative methyl-p-toluene sulphonate of diethylamino-3-beta-ethoxy-20-hydroxy-pregn-5-ene (TX 3047) in vitro. 2. RNA and DNA synthesis (both cellular and viral) were studied in the presence of TX 3047. Viral and cellular DNA synthesis but not viral RNA synthesis was reduced. 3. Formation of infectious particles was not affected by TX 3047 if the parental virus was absorbed to the cell before it was incubated with TX 3047. This suggests that TX 3047 acts at the level of the membrane.

Does irehdiamine kink DNA?

We report equilibrium, relaxation kinetic, and transient electric dichroism studies on the complex of the diamino steroid irehdiamine A with DNA. The results are consistent with a beta-kinked structure for the complex at saturation, with a kink in the DNA structure induced by a bound steroid every second base pair. The results that favor this hypothesis include an apparent length decrease of rod-like bacterial DNA molecules when only a small amount of drug is bound, followed by an apparent length increase at saturation. The limiting dichroism amplitude implies a substantial increase in the tilt of the bases relative to the orientation axis; at saturation the base UV transition moments are tilted about 31 degrees from the plane perpendicular to the orientation axis. Because of the direction of polarization of the 260-nm transition moments, the results indicate that the tilt of the bases must be predominantly in the short rather than the long axis of the base pair. The large hyperchroism of the complex is consistent with loss of base stacking, as required by a kinked structure. The kinetic results imply a bimolecular reaction mechanism, with a temperature-dependent association rate constant of roughly 10(8) M(-1) sec(-1), and a dissociation rate constant of about 5 x 10(3) sec(-1), nearly independent of temperature. The association activation energy and apparent reaction enthalpy vary from 12 to 22 kcal mol(-1); heat is absorbed on complex formation as expected for loss of base-stacking interactions. An anomalous result of the experiments is the larger apparent length increase (13%) exhibited by two eukaryotic DNAs, compared to 6% for three prokaryotic DNAs. Differences were also observed in the kinetic properties of the complexes.

Studies on oocyte maturation of the medaka, Oryzias latipes. V. On the structure of steroids that induce maturation in vitro

The response of oocytes within isolated follicles (800-950 micron in diameter) to various steroids was examined with the teleost fish, Oryzias latipes. Continuous exposure of oocytes, which were removed from ovarian investments 17 hours before predicted germinal vesicle breakdown (GVBD), to C19- or C21-steroids brought about maturation in vitro but never triggered ovulation. The steroids effective in inducing maturation have in common a C=0 (or alpha-OH) group at 3C and a beta-OH group at 17C in the C19-steroids, and a C=O (or beta-OH) group at 3C and a C=O (or alpha-OH) group at 20C in the C21-steroids, in addition to an delta4- or delta5-unsaturated for 5alpha-saturated configuration. The orientation of the hydrogen at 5C seems to be critical in determining the ability of a particular steroid to stimulate oocyte maturation. Maturation of oocytes in the ovaries of hypophysectomized females was induced by administering progesterone, but the mature oocytes did not subsequently undergo ovulation. Thus the steroid hormone is capable of inducing oocyte maturation but apparently does not participate directly in the ovulation of Oryzias latipes oocytes.

Synthesis of pregnenoic acid derivatives possessing structural elements of prostaglandins

Pregneoic acid derivative V in which the character of functional groups and distances between them (expressed in terms of C-C bonds) resemble those occurring in prostaglandins has been synthetised. 3beta-Hydroxyandrost-5-en-17-one acetate VII was converted to ethyl 3beta-acetoxypregn-5-en-21-oate XIIa via a Reformatsky reaction followed by dehydration of adduct VIIIa and selective hydrogenation of the diene X. Compound XIIa was then transformed into trienone XIII by oxidation of the 3beta-hydroxy-5-ene XIIc with DDQ. The trienone XIII was subsequently epoxidised with alkaline hydrogen peroxide and m-chloroperbenzoic acid to give diepoxide XV which was reduced with aluminum amalgam to the final product V.