From an ent-Estrane, through a nat-Androstane, to the Total Synthesis of the Marine-Derived Δ8,9-Pregnene (+)-03219A.

The total synthesis of (+)-03219A, a rare Δ8,9-pregnene isolated from the marine-derived Streptomyces sp. SCSIO 03219, is described that is based on a series of transformations that enable progression from epichlorohydrin to an ent-estrane, then conversion to a nat-androstane, and finally establishment of the natural product target. Key to the success of these studies was implementation of two rearrangement processes to formally invert the quaternary center at C13 and establish the C10 quaternary center.

A novel pregnene analogs: synthesis, cytotoxicity on prostate cancer of PC-3 and LNCPa-AI cells and in silico molecular docking study.

New pregnene analogs of N-hydroxamic acid 6, imino-propane hydrazides 7 and 8 as well as the aryl amides 9-11, oxadiazole, pyrazole and sulfinyl analogs 13-15, via the hydrazide analog 5 of methyl ((5-pregnen-3ß,17ß-diol-15α-yl)thio)propanoate (4) were synthesized. The in vitro cytotoxic activities of selected synthesized steroids against two human prostate cancer cell lines (PC-3, and LNCaP-AI) were evaluated by MTT assay. Compound 10 was the most active cytotoxic agent among these steroids against PC-3 and LNCaP-AI cell lines with inhibition of 96.2%, and 93.6% at concentration levels of 10.0 µM and 91.8%, and of 79.8% at concentration of 1.0 µM, respectively. Molecular docking study of 10 showed a hydrogen bonding with the amino acid Asn705 residue of the receptor 1E3G, together with hydrophobic interactions. Therefore, compound 10 can be considered as a promising anticancer agent due to its potent cytotoxic activity.

New Δ8,9-pregnene steroids isolated from the extremophile fungus Exophiala oligosperma.

Three pregnene steroids, two of them new, were isolated from ethyl-acetate partition of liquid-cultivation of the extremophyle fungus Exophiala oligosperma, found in a pH 1.5 hydrochloric acid aqueous solution. Spectroscopic studies using NMR and HRMS, allowed the identification of the molecular structures of both Δ8,9-pregnenes, still not described in the literature.

A Dual Role Reductase from Phytosterols Catabolism Enables the Efficient Production of Valuable Steroid Precursors.

4-Androstenedione (4-AD) and progesterone (PG) are two of the most important precursors for synthesis of steroid drugs, however their current manufacturing processes suffer from low efficiency and severe environmental issues. In this study, we decipher a dual-role reductase (mnOpccR) in the phytosterols catabolism, which engages in two different metabolic branches to produce the key intermediate 20-hydroxymethyl pregn-4-ene-3-one (4-HBC) through a 4-e reduction of 3-oxo-4-pregnene-20-carboxyl-CoA (3-OPC-CoA) and 2-e reduction of 3-oxo-4-pregnene-20-carboxyl aldehyde (3-OPA), respectively. Inactivation or overexpression of mnOpccR in the Mycobacterium neoaurum can achieve exclusive production of either 4-AD or 4-HBC from phytosterols. By utilizing a two-step synthesis, 4-HBC can be efficiently converted into PG in a scalable manner (100 gram scale). This study deciphers a pivotal biosynthetic mechanism of phytosterol catabolism and provides very efficient production routes of 4-AD and PG.

Discovery and optimization of withangulatin A derivatives as novel glutaminase 1 inhibitors for the treatment of triple-negative breast cancer.

To develop novel GLS1 inhibitors as effective therapeutic agents for triple-negative breast cancer (TNBC), 25 derivatives were synthesized from the natural inhibitor withangulatin A (IC50 = 18.2 µM). Bioassay optimization identified a novel and selective GLS1 inhibitor 7 (IC50 = 1.08 µM). In MDA-MB-231 cells, 7 diminished cellular glutamate levels by blocking glutaminolysis pathway, further triggering the generation of reactive oxygen species to induce caspase-dependent apoptosis. Molecular docking indicated that 7 interacted with a new reacting site of allosteric binding pocket by forming various interactions in GLS1. The intraperitoneal administration of 7 at a dose of 50 mg/kg exhibited remarkable therapeutic effects and no apparent toxicity in the MDA-MB-231 xenograft model, indicating its potential as a novel GLS1 inhibitor for treatment of TNBC.

Design and SAR of Withangulatin A Analogues that Act as Covalent TrxR Inhibitors through the Michael Addition Reaction Showing Potential in Cancer Treatment.

The thioredoxin system plays an important role in cancer cells. Inhibiting thioredoxin reductase (TrxR) has emerged as an effective strategy to selectively target cancer cells. Withangulatin A (WA), a natural product extracted from the whole herb of Physalis angulata L. (Solanaceae), exhibits potent anticancer activity and other diverse pharmacological activities. To improve activity and targeting, we designed and prepared 41 semisynthetic analogues of WA. Biological evaluation indicated that the most promising compound 13a displayed the most significant effect on HT-29 cells (human colon cancer cells) (IC50 = 0.08 µM). A structure-activity relationship study indicated that α,ß-unsaturated ketones and ester are necessary groups, allowing 13a to undergo Michael addition reactions with mercaptan and selenol. Liquid chromatography-mass spectrometry (LC-MS) analysis confirmed that 13a modified selenocysteine 498 (U) residues in the redox centers of TrxR, resulting in enzyme inhibition. Therefore, compound 13a acts as a novel TrxR inhibitor and may be a promising candidate for cancer intervention.

Refining androstenedione and bisnorcholenaldehyde from mother liquor of phytosterol fermentation using macroporous resin column chromatography followed by crystallization.

Androstenedione is an androgen and intermediate in the biosynthesis of most adrenocortical, anabolic, sex and synthetic steroids, such as canrenone, eplerenone, norethindrone and spironolactone. Bisnorcholenaldehyde is an important intermediate in the synthesis of progesterone. This study established an androstenedione and bisnorcholenaldehyde separation method that used a macroporous adsorption resin and an ethanol-water mixture as eluent. The adsorption properties of 12 non-polar or weakly polar macroporous adsorption resins were compared, and three resins exhibited a high adsorption capacity and high desorption rate for both androstenedione and bisnorcholenaldehyde. The three resins were then compared using column chromatography, and one resin was selected and parameters (flow rate, resin size, ethanol concentration and volume) of chromatography were optimized to obtain high purity and recovery. Chromatography eluate was concentrated, dissolved in suitable solvent and crystallized at an optimal temperature to obtain a high purity of both androstenedione and bisnorcholenaldehyde from the same starting material. The levels of androstenedione and bisnorcholenaldehyde in the raw material were 39.78% and 19.15%, respectively. After preparative separation and enrichment by resin column chromatography and crystallization, the purity of androstenedione and bisnorcholenaldehyde was 94.3% and 98.6%, respectively, with their recovery yields of 66.8% and 57.9%, respectively. In addition, the resin maintained over 90% separation efficiency for 5 cycles of adsorption. These results indicated that the combination of macroporous resin chromatography followed by crystallization provide a simple, effective, environmentally friendly and low-cost method for the simultaneous purification of androstenedione and bisnorcholenaldehyde.

Characterization of an Aldolase Involved in Cholesterol Side Chain Degradation in Mycobacterium tuberculosis.

The heteromeric acyl coenzyme A (acyl-CoA) dehydrogenase FadE28-FadE29 and the enoyl-CoA hydratase ChsH1-ChsH2, encoded by genes within the intracellular growth (igr) operon of Mycobacterium tuberculosis, catalyze the dehydrogenation of the cholesterol metabolite 3-oxo-4-pregnene-20-carboxyl-CoA (3-OPC-CoA), with a 3-carbon side chain, and subsequent hydration of the product 3-oxo-4,17-pregnadiene-20-carboxyl-CoA (3-OPDC-CoA) to form 17-hydroxy-3-oxo-4-pregnene-20-carboxyl-CoA (17-HOPC-CoA). The gene downstream of chsH2, i.e., ltp2, was expressed in recombinant Rhodococcus jostii RHA1 in combination with other genes within the igr operon. His-tagged Ltp2 copurified with untagged ChsH1-ChsH2, ChsH2, or the C-terminal domain of ChsH2, which contains a domain of unknown function (DUF35). Ltp2 in association with ChsH1-ChsH2 or just the DUF35 domain of ChsH2 was shown to catalyze the retroaldol cleavage of 17-HOPC-CoA to form androst-4-ene-3,17-dione and propionyl-CoA. Steady-state kinetic analysis using the Ltp2-DUF35 complex showed that the aldolase had optimal activity at pH 7.5, with a Km of 6.54 ± 0.90 µM and a kcat of 159 ± 8.50 s-1 ChsH1-ChsH2 could hydrate only about 30% of 3-OPDC-CoA, but this unfavorable equilibrium could be overcome when the aldolase was present to remove the hydrated product, providing a rationale for the close association of the aldolase with the hydratase. Homologs of ChsH1, ChsH2, and Ltp2 are found in steroid-degrading Gram-positive and Gram-negative bacteria, suggesting that side chains of diverse steroids may be cleaved by aldolases in the bacteria.IMPORTANCE The C-C bond cleavage of the D-ring side chain of cholesterol was shown to be catalyzed by an aldolase. The aldolase associates with the hydratase that catalyzes the preceding reaction in the cholesterol side chain degradation pathway. These enzymes are encoded by genes within the intracellular growth (igr) operon of M. tuberculosis, and the operon was demonstrated previously to be linked to the pathogenicity and persistence of the bacteria in macrophages and in mice.

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-ß-D-oleandropyranosyl-(1→4)-ß-D-cymaropyranosyl-(1→4)-ß-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.

[A new C21 steroidal saponins from Periplocae Cortex].

To study the chemical constituents of Periplocae Cortex, the separation and purification of 70% alcohol extract were carried out by column chromatographies on AB-8 macroporous resin, silica gel and preparative HPLC. The structure of the compounds were identified by NMR and TOF-MS. A new compound was isolated and identified as 21-O-methyl-Δ5-pregnene-3ß, 14ß, 17ß, 21-tetraol-20-one-3-O-ß-D-oleandropyranosyl(1-->4)-ß-D-cymaropyranosyl-(1-->4)-ß-D-cymaropyranosyl (1), named as periplocoside P.

Complete NMR assignments of undegraded asterosaponins from Asterias amurensis.

Four asterosaponins, thornasteroside A (1), versicoside A (2), anasteroside B (3), and asteronylpentaglycoside sulfate (4), were isolated from the predatory starfish Asterias amurensis Lütken. Unlike previous studies focusing on structure elucidation by degradation of the complex saponin molecules, complete nuclear magnetic resonance (NMR) assignment for the intact molecules was accomplished using 600 MHz high magnetic field NMR. The complete set of NMR assignments can help in the structure elucidation of asterosaponins isolated in low yields without resorting to chemical degradation. Furthermore, this approach can be extended to other complex steroidal saponins, which may accelerate the discovery of bioactive secondary metabolites from this invasive starfish species.

Synthesis and antimetastatic effects of E-salignone amide derivatives.

The preparation of novel E-salignone derivatives and their biological evaluation as potential antimetastatic agents is described. The E-salignone amide derivatives were prepared from epiandrosterone and androsterone, and characterized by analytical (1) H NMR, (13) C NMR, and mass spectrometry. The derivatives were evaluated for antimetastatic activity in MDA-MB-231 cells by using a transwell assay. Comparing with the positive control, LY294002, compounds 19b, 19d, and 19e exhibited significant inhibitory effects on the EGF-induced invasion of MB-MDA-231 cells. Moreover, compound 19b also had antimigration effects in wound-healing assay. Compound 19b may represent a novel antimetastatic agent for treating breast cancer.

Mass spectrometry combinations for structural characterization of sulfated-steroid metabolites.

Steroid conjugates, which often occur as metabolites, are challenging to characterize. One application is female-mouse urine, where steroid conjugates serve as important ligands for the pheromone-sensing neurons. Although the two with the highest abundance in mouse urine were previously characterized with mass spectrometry (MS) and NMR to be sulfated steroids, many more exist but remain structurally unresolved. Given that their physical and chemical properties are similar, they are likely to have a sulfated steroid ring structure. Because these compounds occur in trace amounts in mouse urine and elsewhere, their characterization by NMR will be difficult. Thus, MS methods become the primary approach for determining structure. Here, we show that a combination of MS tools is effective for determining the structures of sulfated steroids. Using 4-pregnene analogs, we explored high-resolving power MS (HR-MS) to determine chemical formulae; HD exchange MS (HDX-MS) to determine number of active, exchangeable hydrogens (e.g., OH groups); methoxyamine hydrochloride (MOX) derivatization MS, or reactive desorption electrospray ionization with hydroxylamine to determine the number of carbonyl groups; and tandem MS (MS(n)), high-resolution tandem MS (HRMS/MS), and GC-MS to obtain structural details of the steroid ring. From the fragmentation studies, we deduced three major fragmentation rules for this class of sulfated steroids. We also show that a combined MS approach is effective for determining structure of steroid metabolites, with important implications for targeted metabolomics in general and for the study of mouse social communication in particular.

Biotransformation of 17α-ethynyl substituted steroidal drugs with microbial and plant cell cultures: a review.

Structural modification of steroids through whole-cell biocatalysis is an invaluable procedure for the production of active pharmaceutical ingredients (APIs) and key intermediates. Modifications could be carried out with regio- and stereospecificity at positions hardly available for chemical agents. Much attention has been focused recently on the biotransformation of 17α-ethynyl substituted steroidal drugs using fungi, bacteria and plant cell cultures in order to obtained novel biologically active compounds with diverse structure features. Present article includes studies on biotransformation on 17α-ethynyl substituted steroidal drugs using microorganisms and plant cell cultures. Various experimental and structural elucidation methods used in biotransformational processes are also highlighted.

03219A, a new Δ(8,9)-pregnene isolated from Streptomyces sp. SCSIO 03219 obtained from a South China Sea sediment.

03219A (1), a new pregnene steroid possessing a rare Δ(8,9)-double bond in the skeleton, together with the known naphthoquinone antibiotic (+)-cryptosporin (2) have been isolated from the fermentation broth of Streptomyces sp. SCSIO 03219, which was isolated from a marine sediment collected in the South China Sea. The structure of 03219A was elucidated using a combination of NMR, MS and X-ray crystallographic methods.

Steroids excreted in urine by neonates with 21-hydroxylase deficiency. 4. Characterization, using GC-MS and GC-MS/MS, of 11oxo-pregnanes and 11oxo-pregnenes.

In 21-hydroxylase deficiency, urinary metabolites of 21-deoxycortisol, mainly derived from its 11oxo form 21-deoxycortisone, are indicators of intra-adrenal overproduction of 17-hydroxyprogesterone. In affected neonates these metabolites are numerous and most have not been previously described. This work forms the concluding part of a comprehensive study of urinary steroids, aiming to enhance the diagnosis of this disorder and to further elucidate steroid metabolism in neonates. Cortisol metabolites found in untreated patients, similarly almost exclusively present in their 11oxo form in neonates, have been included for completeness. Steroids were analyzed, after extraction and enzymatic conjugate hydrolysis, as methyloxime-trimethylsilyl ether derivatives on gas-chromatographs coupled to quadrupole and ion-trap mass-spectrometers. GC-MS and GC-MS/MS spectra were used together to determine the structure of hitherto undescribed 11oxo-pregnane(enes). Few GC-MS features were associated with the presence of the non-derivatizeable 11oxo group in pregnane(ene)s. GC-MS/MS contributed only to the characterization of structures outside the C-ring, as described in the preceding parts of this study. Parallels were found between the metabolism of 21-deoxycortisone and cortisone. The major metabolic pathway was that of classical 3α,5ß-reduction with a prominent further hydroxylation, predominantly at C6. Oxidation of the 6-hydroxyl was also common. We conclude that further oxygenated metabolites of 21-deoxycortisone have potential as more reliable markers of 21-hydroxylase deficiency in the early neonatal period, because their levels are higher during that period of life than for the classical marker 11oxo-pregnanetriol.

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.

Steroids excreted in urine by neonates with 21-hydroxylase deficiency. 2. Characterization, using GC-MS and GC-MS/MS, of pregnanes and pregnenes with an oxo- group on the A- or B-ring.

Urine from neonates with 21-hydroxylase deficiency contains a large range of metabolites of 17-hydroxyprogesterone, 21-deoxycortisol and androgens but few have been previously described. We present the second part of a comprehensive project to characterize and identify these in order to enhance diagnosis and to further elucidate neonatal steroid metabolism. Steroids were analyzed, after extraction and enzymatic conjugate hydrolysis, as methyloxime-trimethylsilyl ether derivatives on gas-chromatographs coupled to quadrupole and ion-trap mass-spectrometers. GC-MS and GC-MS/MS spectra were used together to determine the structure of the A- and B-rings containing an oxo group. Fragmentations indicating presence of 3-, 6-, and 7-oxo groups and also 1ß-, 2α-, 4ß-, and 6ß-hydroxyls are presented and discussed for the first time. Interpretation was aided by comparison with spectra of available relevant standards, of oxidation products of standards and urinary metabolites and of deuterated derivatives. Endogenous 1-enes and 2(3)-ene artifacts of non-hydrolyzed 3α-sulfates are also reported. D-ring and side chain structure was determined according to our previously published criteria. Likely metabolic relationships were also explored. We conclude that GC-MS combined with GC-MS/MS allows identification of the A- and B-ring structure of pregnane and pregnenes in the presence of an oxo group on one of these rings. Major oxygenations are 1ß, 15ß, 16α and 21-hydroxy and 6- and 7-oxo groups. Minor positions of hydroxylation are those at 2α, 4ß and 6ß. Three major metabolic streams exist in affected neonates in addition to the classical 3α-hydroxy-5ß-pregnane pathway, i.e. these of the 3-oxo-4-enes as well as 3α- and 3ß-hydroxy-5α-anes.

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-3ß,17α,20(S)-triol-20-O-ß-d-digitoxopyranoside (1), cymaropyranurolactone 4-O-ß-d-digitalopyranosyl-(1 â†’ 4)-O-ß-d-cymaropyranosyl-(1 â†’ 4)-O-ß-d-oleandropyranosyl-(1 â†’ 4)-O-ß-d-cymaropyranoside (2), 3ß,17α,20(S)-trihydroxy-5α-pregn-6-ene (3), and 5α-pregn-6-ene-3ß,17α,20(S)-triol-3-O-ß-d-digitalopyranoside (4) by spectroscopic methods.

Transformations of 3-hydroxy steroids with lewis and anhydrous protic acids: the case of pregn-4-en-3ß,17α,20ß-triol.

The acid-catalyzed dehydration is one of the most important processes, which transforms 3-hydroxy steroids into their corresponding unsaturated derivatives. This reaction is of great importance because it can produce molecules that play a key role in the understanding of the natural metabolism of steroids. Sterol dehydration is generally performed with aqueous acidic systems, and the treatment often affords low yields of the desired compounds and/or complex mixtures of by-products. In this paper, we report the results obtained from the study of the structural and stereochemical effects of the acid-induced reaction of pregn-4-en-3ß,17α,20ß-triol in anhydrous systems. In particular, the treatment of this trihydroxy steroid model with Lewis acids leads to the corresponding Δ(3,5) -steradiene as the only product and in very high yields. With Lewis acids, no modifications of the 1,2-diol function on the D-ring are observed, even when the reactions are performed at high temperatures. Protic acid catalysis in non-aqueous organic solvents causes the formation of an epimeric mixture of the corresponding Δ(3,5) -steradiene derivatives by a partial stereochemical inversion of the asymmetric C-17. The reactivity of the 17α,20ß-diolic residue is also evaluated by exposing pregn-4-en-3ß,17α,20ß-triol and the corresponding Δ(3,5) -steradiene to the prolonged action of anhydrous protic acid systems under thermal conditions.