Biosynthesis of cholestanol: 5-alpha-cholestan-3-one reductase of rat liver

The 3-beta-hydroxysteroid dehydrogenase of rat liver which catalyzes the conversion of 5alpha-cholestan-3-one to 5alpha-cholestan-3beta-ol is localized mainly in the microsomal fraction. The enzyme required NADPH as hydrogen donor and differed from the known 3-beta-hydroxysteroid dehydrogenases of the C(19) series in being inactive in the presence of NADH. The microsomal preparations did not reduce the 3-keto groups of cholest-4-en-3-one, cholest-5-en-3-one, or 5beta-cholestan-3-one to the corresponding 3beta-hydroxy compounds. The conversion of 5alpha-cholestan-3-one to 5alpha-cholestan-3beta-ol was only slightly inhibited by the reaction product or by other monohydroxy steroids, but a strong inhibitory effect was noted with cholest-5-en-3-one, 5alpha-cholestane-3beta, 7alpha-diol and 5alpha-cholestan-7-on-3beta-ol. The microsomes, but not high speed supernatant solution, catalyzed the reverse of the cholestanone reductase reaction, namely the conversion of 5alpha-cholestan-3beta-ol to 5alpha-cholestan-3-one in the presence of oxygen and an NADP-generating system. The action of the microsomal preparations upon 5alpha-cholestan-3-one produced 5alpha-cholestan-3alpha-ol in addition to the 3beta-epimer. The 3-alpha-hydroxysteroid dehydrogenase involved functioned with either NADH or NADPH as hydrogen donor. The ratio of 5alpha-cholestan-3beta-ol to 5alpha-cholestan-3alpha-ol formed from 5alpha-cholestan-3-one was approximately 10:1 and was independent of the sex of the animal from which the microsomes were prepared.     

Syntheses and biologic studies of steroidal methyl sulfides and sulfones.

Reactions of cholest-5-ene (I) and its 3 beta-chloro (II) and 3 beta-acetoxy (III) analogs with trimethylchlorosilane-dimethyl sulfoxide in dry acetonitrile furnish cholest-4-en-6 beta-yl methyl sulfide (IV) and its 3 beta-chloro (V) and 3 beta-acetoxy (VI) analogs. Oxidation of (IV) with m-chloroperbenzoic acid affords cholest-4-en-6 beta-yl methyl sulfone (VII) and 4 alpha, 5-epoxy-5 alpha-cholestan-6 beta-yl methyl sulfone (VIII). Under similar reaction conditions, V furnishes 3 beta-chlorocholest-4-en-6 beta-yl methyl sulfone (IX), while VI gives 3 beta-acetoxycholest-4-en-6 beta-yl methyl sulfone (X) and 3 beta-acetoxy-4 alpha, 5-epoxy-5 alpha-cholestan-6 beta-yl methyl sulfone (XI). The structures of these compounds were established on the basis of analytic and spectral data. Some of these compounds have been evaluated for their possible biologic activities.     

Synthesis of aminosterols and their derivatives

Reactions of steroidal epoxides such as 5,6 alpha-epoxy-5 alpha-cholestane (I) and its 3 beta-chloro (II) and 3 beta-acetoxy (III) analogs with urea in dimethylformamide afforded 6 beta-amino-5 alpha-cholestan-5-ol (IV-VI), 6 beta-amino-N-formyl-5 alpha-cholestan-5-ol (VII-IX), and 6 beta-amino-N-amido-5 alpha-cholestan-5-ol (X-XII), along with the 5 alpha-cholestane-5,6 beta-diol (XIII-XV). In addition to these compounds, the 3 beta-acetoxy analog also afforded the N-carboxyl derivative (XVI).     

Urinary analysis of 16(5alpha)-androsten-3alpha-ol by gas chromatography/combustion/isotope ratio mass spectrometry: implications in anti-doping analysis

We present a method for the analysis of urinary 16(5alpha)-androsten-3alpha-ol together with 5beta-pregnane-3alpha,20alpha-diol and four testosterone metabolites: androsterone (Andro), etiocholanolone (Etio), 5alpha-androstane-3alpha,17beta-diol (5alphaA), 5beta-androstane-3alpha,17beta-diol (5betaA) by means of gas chromatography/combustion/isotopic ratio mass spectrometry (GC/C/IRMS). The within-assay and between-assay precision S.D.s of the investigated steroids were lower than 0.3 and 0.6 per thousand, respectively. A comparative study on a population composed of 20 subjects has shown that the differences of the intra-individual delta(13)C-values for 16(5alpha)-androsten-3alpha-ol and 5beta-pregnane-3alpha,20alpha-diol are less than 0.9 per thousand. Thereafter, the method has been applied in the frame of an excretion study following oral ingestion of 50 mg DHEA initially and oral ingestion of 50mg pregnenolone 48 h later. Our findings show that administration of DHEA does not affect the isotopic ratio values of 16(5alpha)-androsten-3alpha-ol and 5beta-pregnane-3alpha,20alpha-diol, whereas the isotopic ratio values of 5beta-pregnane-3alpha,20alpha-diol vary by more 5 per thousand upon ingestion of pregnenolone. We have observed delta(13)C-value changes lower than 1 per thousand for 16(5alpha)-androsten-3alpha-ol, though pregnenolone is a precursor of the 16-ene steroids. In contrast to 5beta-pregnane-3alpha,20alpha-diol, the 16-ene steroid may be used as an endogenous reference compound when pregnenolone is administered.     

Facile gas-liquid chromatographic resolution of saturated and unsaturated sterols using a polar capillary column

The 5 alpha-stanol-3 beta-ol analogs of cholesterol, campesterol and beta-sitosterol along with many other sterol types were resolved using a Supelcowax 10 (Bonded Carbowax PEG 20M) fused silica capillary column (15 m x 0.25 mm). Unlike non-polar capillary columns, the semi-polar Carbowax liquid phase retains the unsaturated sterols longer than the corresponding saturated sterols, allowing an orderly elution and quantitation. The unnatural epicholestanol (5 alpha-cholestan-3 alpha-ol) was used as internal standard. By this method the stanol content of human plasma and of the unsaponifiable matter of dietary fats and oils is readily determined. Because of low column bleed the Supelcowax 10 liquid phase can be used for combined GC/MS analysis.     

A new triterpenoid from the fern Adiantum lunulatum and evaluation of antibacterial activity

A new triterpenoid, 22,29xi-epoxy-30-norhopane-13beta-ol (1) was isolated together with six known compounds viz., fern-9(11)-en-6alpha-ol. fern-9(11)-ene, fern-9(11)-en-25-oic acid, fern-9(11)-en-28-ol, filicenol-B, adiantone and oxidation product of fern-9(11)-en-6alpha-ol obtained as 6-oxofern-9(11)-ene from the whole plant of Adiantum lunulatum, and their structures were elucidated by means of spectroscopic analysis and antibacterial evaluation of these compounds were conducted.     

Sex pheromone of the tsetse species, Glossina austeni: isolation and identification of natural hydrocarbons, and bioassay of synthesized compounds

Copulatory responses of male Glossina austeni (Newstead) (Diptera: Glossinidae), that were elicited after contact with frozen female tsetse, were not observed after solvent washing of cuticular lipids. Chromatographic analysis of extracts from laboratory-reared and field-collected G. austeni females yielded natural hydrocarbons that were highly stimulatory to males. Most of this activity was produced by compounds in the alkene fraction. Gas chromatograms (GC) contained five natural alkenes; these were separated by preparative GC for bioassays conducted in Tanzania. The two major alkenes were identified using gas chromatography-mass spectrometry (GC-MS) to be 13,17-dimethyltritriacont-1-ene and 13,17-dimethylpentatriacont-1-ene, after the samples had undergone derivatization using dimethyl disulphide and saturation with deuterium. These alkenes and natural alkanes were quantified from G. austeni of both sexes from laboratory and field samples to confirm that their presence was consistent in this species. Trials of synthetic samples resulted in the order of biological activity for the stereoisomers of 13,17-dimethyltritriacont-1-ene as follows: S,R-33:1 > R,S- 33:1 > S,S-33:1 > R,R-33:1. Dose-response data showed an ED(50) at 5 microg per treated, solvent-washed male decoy. Of the four stereoisomers of 13,17-dimethylpentatriacont-1-ene, R,R-35:1 showed the most activity. This is the first report of alkene-induced sexual activity in males of the genus Glossina.     

Crystal structure of 3 beta-benzoyloxy-6 alpha-chloro-5 alpha-cholest-7-ene, a key intermediate in the chemical synthesis of 5 alpha-cholest-8(14)-en-3 beta-ol-15-one

The X-ray crystal structure of 3 beta-benzoyloxy-6 alpha-chloro-5 alpha-cholest-7-ene (IV) was determined by the heavy atom method and refined to R = 0.063 (space group P21, a = 11.364, b = 11.089, c = 12.232, beta = 99.43 degrees, Z = 2). IV was previously shown to be an important intermediate in the acid-catalyzed isomerization of 7-dehydrocholesteryl benzoate. The present work unequivocally establishes the location of the double bond and the configuration of the chlorine of IV, information which is essential to the correct formulation of the mechanism of this reaction.     

Rearrangement of 5S, 12S-dihydroxy-6,8,10,14-(E,Z,E,Z)-eicosatetraenoic acid during gas chromatography: formation of a cyclohexadiene derivative

The 5S, 12S-dihydroxy-6,8,10,14-(E,Z,E,Z,)-eicosatetraenoic acid, a product of double dioxygenation of arachidonic acid by lipoxygenases, undergoes severe decomposition during gas chromatography-mass spectrometric (GC-MS) analysis of the trimethylsilyl ether methyl ester derivative. The decomposition product was studied by GC-MS and identified as a cyclohexadiene derivative of the parent compound formed by ring closure at C6 and C11. Under identical GC conditions, two stereoisomers, i.e. 5S,12R-dihydroxy-6,8,10,14-(Z,E,E,Z)-eicosatetraenoic acid (leukotriene B4), and 6-trans-leukotriene B4 showed excellent chromatographic properties. These data indicated that the 5,12-dihydroxy derivative of arachidonic acid carrying the trans-cis-trans triene unit selectively undergoes cyclization during GC. These studies also provided an explanation to the controversial GC-MS data reported for this lipoxygenase product.     

Characterization of enzymatic processes by rapid mix-quench mass spectrometry: the case of dTDP-glucose 4,6-dehydratase

The single-turnover kinetic mechanism for the reaction catalyzed by dTDP-glucose 4,6-dehydratase (4,6-dehydratase) has been determined by rapid mix-chemical quench mass spectrometry. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) was employed to analyze quenched samples. The results were compatible with the postulated reaction mechanism, in which NAD(+) initially oxidizes glucosyl C4 of dTDP-glucose to NADH and dTDP-4-ketoglucose. Next, water is eliminated between C5 and C6 of dTDP-4-ketoglucose to form dTDP-4-ketoglucose-5,6-ene. Hydride transfer from NADH to C6 of dTDP-4-ketoglucose-5,6-ene regenerates NAD(+) and produces the product dTDP-4-keto-6-deoxyglucose. The single-turnover reaction was quenched at various times on the millisecond scale with a mixture of 6 M guanidine hydrochloride and sodium borohydride, which stopped the reaction and reductively stabilized the intermediates and product. Quantitative MALDI-TOF MS analysis of the quenched samples allowed the simultaneous observation of the disappearance of substrate, transient appearance and disappearance of dTDP-hexopyranose-5,6-ene (the reductively stabilized dTDP-4-ketoglucose-5,6-ene), and the appearance of product. Kinetic modeling of the process allowed rate constants for most of the steps of the reaction of dTDP-glucose-d(7) to be evaluated. The transient formation and reaction of dTDP-4-ketoglucose could not be observed, because this intermediate did not accumulate to detectable concentrations.     

Stereospecific 1,4-addition to an alpha,beta-unsaturated steroidal epoxide: syntheses of new 15-oxygenated sterols

3 beta-Benzoyloxy-14 alpha,15 alpha-epoxy-5 alpha-cholest-7-ene (1) is a key intermediate in the synthesis of C-7 and C-15 oxygenated sterols. Treatment of 1 with benzoyl chloride resulted in the formation of 3 beta,15 alpha-bis-benzoyloxy-7 alpha-chloro-5 alpha-cholest-8(14)-ene (2). Reaction of 2 with LiAlH4 or LiAlD4 resulted in the formation of 5 alpha-cholest-7-ene-3 beta,15 alpha-diol (3a) or [14 alpha-2H]5 alpha-cholest-7-ene-3 beta,15 alpha-diol (3b). Diol 3b was selectively oxidized by Ag2CO3/celite to [14 alpha-2H]5 alpha-cholest-7-en-15 alpha-ol-3-one (4). Treatment of 1 with MeMgI/CuI gave 7 alpha-methyl-5 alpha-cholest-8(14)-ene-3 beta,15 alpha-diol (5). Selective oxidation of 5 with pyridinium chlorochromate (PCC)/pyridine or oxidation with PCC resulted in the formation of 7 alpha-methyl-5 alpha-cholest-8(14)-en-3 beta-ol-15-one (6) and 7 alpha-methyl-5 alpha-cholest-8(14)-ene-3,15-dione, respectively. Reduction of 6 with LiAlH4 yielded 5 and 7 alpha-methyl-5 alpha-cholest-8(14)-ene-3 beta,15 beta-diol (6). Reaction of 1 with benzoic acid/pyridine gave 3 beta,7 alpha-bis-benzoyloxy-5 alpha-cholest-8(14)-en-15 alpha-ol (9). Treatment of 9 with LiAlH4 or ethanolic KOH resulted in the formation of 5 alpha-cholest-8(14)-ene-3 beta,7 alpha,15 alpha-triol (10). Dibenzoate 9, upon brief treatment with mineral acid, gave 3 beta-benzoyloxy-5 alpha-cholest-8(14)-ene-15-one (11). Oxidation of 9 with PCC yielded 3 beta,7 alpha-bis-benzoyloxy-5 alpha-cholest-8(14)-ene-15-one (12). Ketone 12 was also prepared by the selective hydride reduction of 5 alpha-cholest-8(14)-en-7 alpha-ol-3,15-dione (13) to give 5 alpha-cholest-8(14)-ene-3 beta,7 alpha-diol-15-one (14), which was then treated with benzoyl chloride to produce 12.     

Identification of Unknown Impurity of Azelaic Acid in Liposomal Formulation Assessed by HPLC-ELSD,GC-FID,and GC-MS

The identification of new contaminants is critical in the development of new medicinal products. Many impurities, such as pentanedioic acid, hexanedioic acid, heptanedioic acid, octanedioic acid, decanedioic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, and tetradecanedioic acid, have been identified in samples of azelaic acid. The aim of this study was to identify impurities observed during the stability tests of a new liposomal dosage form of azelaic acid that is composed of phosphatidylcholine and a mixture of ethyl alcohol and water, using high-performance liquid chromatography with evaporative light-scattering detector (HPLC-ELSD), gas chromatography–flame ionisation detection (GC-FID), and gas chromatography–mass spectrometry (GC-MS) methods. During the research and development of a new liposomal formulation of azelaic acid, we developed a method for determining the contamination of azelaic acid using HPLC-ELSD. During our analytical tests, we identified a previously unknown impurity of a liposomal preparation of azelaic acid that appeared in the liposomal formulation of azelaic acid during preliminary stability studies. The procedure led to the conclusion that the impurity was caused by the reaction of azelaic acid with one of the excipients that was applied in the product. The impurity was finally identified as an ethyl monoester of azelaic acid. The identification procedure of this compound was carried out in a series of experiments comparing the chromatograms that were obtained via the following chromatographic methods: HPLC-ELSD, GC-FID, and GC-MS. The final identification of the compound was carried out by GC with MS.     

Chlorin e6–cholesterol conjugate and its copper complex. Simple synthesis and entrapping in phospholipid vesicles

Synthesis of 13′[(cholest-5-en)-3β-yloxyethoxycarbamoyl]-chlorin e6 starting from methylpheophorbide and 3β(2-hydroxy)-ethoxycholest-5-ene is presented, as well as the preparation of related copper complex. Both conjugates obtained may be simply incorporated in phosphatidyl choline vesicles.     

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.     

Synthesis and density functional theoretical study of steroidal spiro-triazolidinone

The reaction of 3beta-chloro-5alpha-cholestan-6-one semicarbazone 1 with hydrogen peroxide at 0 degrees C gives 3beta-chloro-5alpha-cholestan-6-spiro-1',2',4'-triazolidine-3'-one 2 as a product. The structural assignment of the product was confirmed on the basis of its elemental, analytical and spectral data. The ab initio calculations were performed by using density functional theory (DFT) at B3LYP/6-31G* basis set in order to describe a free radical reaction mechanism. The reaction proceeds through two radical intermediates formation. The mechanism of the reaction was explained by using frontier molecular orbital (FMO), spin electronic density map, encoded electrostatic potential map and atomic charges. It was found that the localization of frontier orbitals and the flow of atomic charges of all the calculated structures support the present reaction mechanism. The molecular properties like total energy, dipole moment and hardness of each optimized structure, were also explained. Stability of all the optimized structures in this study was supported by their respective fundamental frequencies and energy minima.     

Synthesis of 19-hydroxyaldosterone and the 3 beta-hydroxy-5-ene analog of aldosterone, active mineralocorticoids

19-Hydroxyaldosterone (20) and the 3 beta-hydroxy-5-ene analog of aldosterone (HAA) (8) were synthesized from 21-acetoxy-4-pregnene-3,20-dion-20-ethylene ketal-18, 11 beta-lactone (2) as follows: the double bond was transposed from the 4,5 to the 5,6-position by enol acetylation to 3, followed by sodium borohydride reduction. Further reduction of the resulting lactone 4a with diisobutylaluminum hydride (DIBAH) furnished the 20-ketal of HAA 6, from which free HAA (8) and the 18,21-anhydro compound 7 were obtained by acid treatment. The [1H]NMR spectrum of 8 in CDCl3 showed it to be a mixture of two isomeric forms. Correlation with the known aldosterone-gamma-etiolactone (10) was established by periodate oxidation of HAA to the corresponding etiolactone 9 followed by chromic acid oxidation. The preparation of 20 was next effected in the following manner: the diacetate 4b was converted into the 6 beta, 19-oxido compound 13b by addition of hypobromous acid followed by the hypoiodite reaction of the bromohydrin 11. Mild saponification of 13b lead to the corresponding diol 13a, and was followed by selective oxidation to the 3-one 14, readily dehydrobrominated to 15a. Reductive ring opening furnished a mixture of the 19,21-diol 16a and its 5-ene isomer 16b, which was directly converted to the diketal 17. Reduction with DIBAH gave the hemiacetal 18, and hydrolysis of the latter 19-hydroxyaldosterone (20) as a water-soluble solid, accompanied by the 18,21-anhydro compound 19. 19-Hydroxyaldosterone exists in CHCl3 and water as a mixture of mainly two isomers. Periodate oxidation furnished the etiolactone 21. Preliminary results indicate that HAA and 19-hydroxyaldosterone are active mineralocorticoids in the Kagawa bioassay and short-circuit current measurements.     

An experimental and theoretical approach to 5alpha-cholestan-6-spiro-1',2',4'-triazolidine-3'-one

The 5alpha-cholestan-6-one semicarbazone (1) on reaction with hydrogen peroxide at 0 degrees C affords selectively 5alpha-cholestan-6-spiro-1',2',4'-triazolidine-3'-one. (2) The structural assignment of the product was confirmed on the basis of its elemental, analytical and spectral analysis. The Hartree-Fock method using 6-31G* basis set was employed in order to explore the reaction mechanism. The results of the computational study show that the reaction proceeds through two radical intermediates formation. The different characteristics involved during the reaction were explained, firstly, the lower energy conformation of each molecule using total energy, hardness and dipole moment, and secondly, the explanation of the free radical mechanism, using frontier molecular orbital (FMO) theory, encoded electrostatic potential, spin electronic density and atomic charges. The localization of highest occupied molecular orbital (HOMO) or alpha-HOMO, lowest unoccupied molecular orbital (LUMO) or alpha-LUMO and the flow of atomic charges are in good agreement to support the present mechanism of the reaction. Stability and feasibility of all the optimized structures were supported by their respective fundamental frequencies and energy minima.     

Volatile constituents in the liverwort Tritomaria polita

The essential oil of the liverwort Tritomaria polita, collected in Otztal/Tyrol (Austria), was investigated by chromatographic and spectroscopic methods. Several new compounds were isolated by preparative gas chromatography (GC) and their structures investigated by mass spectrometry (MS) and NMR techniques. In addition to known constituents, the sesquiterpenoids (+)-eudesma-3,11-dien-8-one, (+)-eudesma-3,7(11)-dien-8-one, (+)-6,11-epoxy-eudesmane, (-)-6,7-seco-eudesm-7(11)-en-6-al, (+)-6beta-hydroxy-eudesm-11-ene, (-)-6alpha-hydroxy-eudesm-11-ene, (+)-6,11-epoxy-isodaucane could be identified as natural compounds for the first time.     

Synthesis and cytotoxic analysis of some disodium 3β,6β-dihydroxysterol disulfates

Disodium 3β,6β-dihydroxy-5α-cholestane disulfate (1) was synthesized in 4 steps with a high overall yield from cholesterol. First, cholesterol (4a) was converted to cholest-4-en-3,6-dione (5a) via oxidation with pyridinium chlorochromate (PCC) and then 5a was reduced by NaBH₄ in the presence of NiCl₂ to produce cholest-3β,6β-diol (6a). The reaction of 6a with the triethylamine-sulfur trioxide complex generated diammonium 3β,6β-dihydroxy-5α-cholestane disulfate (7a) and the treatment of 7a by cation exchange resin 732 (sodium form)(Na⁺) yielded the target steroid 1. Disodium 24-ethyl-3β,6β-dihydroxycholest-22-ene disulfate (2) and disodium 24-ethyl-3β,6β-dihydroxycholestane disulfate (3) were synthesized using a similar method. The cytotoxicity of these compounds against Sk-Hep-1 (human liver carcinoma cell line), H-292 (human lung carcinoma cell line), PC-3 (human prostate carcinoma cell line) and Hey-1B (human ovarian carcinoma cell line) cells was investigated. Our results indicate that presence of a cholesterol-type side chain at position 17 is necessary for their biological activity.     

Synthesis of 19-noraldosterone, a potent mineralocorticoid

19-Noraldosterone has been prepared for biological re-evaluation through an extension of a recent synthesis of 19-hydroxyaldosterone: 21-hydroxy-6 beta,19-epoxy-4-pregnene-3,20-dion-20-ethylene ketal-18,11 beta-lactone (1a) was acetylated and then reduced with zinc-acetic acid-isopropanol to the 19-ol 2b. Treatment with sodium acetate transposed the double bond into conjugation, and 2a thus obtained was oxidized with pyridinium chlorochromate to the 19-oxo compound 3. Decarbonylation to the 19-nor lactone 4 was effected by heating with alkali. Protection of the C-3 carbonyl was achieved by ketalization and the resulting mixture of the 5-ene and 5(10)-ene ketals 5 was reduced with DIBAH to the corresponding mixture of the hemiacetals 6. Acid hydrolysis of the latter afforded 19-noraldosterone (7), accompanied by the 18,21-anhydro ketal 8. 19-Noraldosterone in the solid state exists in the cyclic form 7b, which appears to be also the predominant isomer present under conditions of mass spectrometry. [1H]NMR indicates that in chloroform 19-noraldosterone exists mostly as an equilibrium mixture of structures 7a and 7b. Sodium periodate oxidation furnished the gamma-etiolactone 9, confirming the 17 beta configuration in 7.