Synthesis of unsaturated aldehydes by hydroboration of propargyl alcohols and from aldehydo sugar precursors

Propargyl acetates obtained by ethynylation of aldehydo sugar derivatives, followed by acetylation, can be converted by hydroboration with bis(isoamyl)borane and subsequent treatment with hydrogen peroxide into α,β-unsaturated aldehydes; the latter may also be obtained by treating the original aldehydo sugar derivative with formylmethylenetriphenylphosphorane. By these two routes the aldehydo sugars 2,3-O-isopropylidene-aldehydo-D-glyceraldehyde (1), 2,3,4,5-tetra-O-acetyl-aldehydo-D-arabinose (5), and 2,3:4,5-di-O-isopropylidene-aldehydo-D-arabinose (9) have been converted with 2-carbon chain-extension into the corresponding trans-unsaturated aldehydes 3, 7, and 11, respectively. Likewise, by the acetylene route, 1,2:3,4-di-O-isopropylidene-6-aldehydo-α-D-galacto-hexodialdo-1,5-pyranose (13) was converted into the C₈ unsaturated aldehyde 15, although the Wittig route was unsuccessful in this instance, as it was with methyl 2,3-di-O-acetyl-4-deoxy-6-aldehydo-β-L-threo-hex-4-enodialdo-1,5-pyranoside (16).     

Geometric isomers of sex pheromone components do not affect attractancy of Conopomorpha cramerella in cocoa plantations

The cocoa pod borer (CPB), Conopomorpha cramerella (Snellen), sex pheromone was previously identified as a blend of (E,Z,Z)‐ and (E,E,Z)‐4,6,10‐hexadecatrienyl acetates and corresponding alcohols. These pheromone components were synthesized by modification of an existing method and the relative attractiveness of synthetic blends that included different levels of non‐target pheromone components and chemical purities was tested in a cocoa field using Delta traps. Male captures were not significantly different among traps baited with pheromone blends containing 5% to 47% (based on four identified pheromone components) of other geometric acetates [(E,Z,E)‐, (Z,Z,Z)‐, (Z,E,Z)‐ and (Z,E,E)‐4,6,10‐hexadecatrienyl acetates], indicating that C. cramerella males did not discriminate among the pheromone components and other geometric isomers in the blends. Therefore, neither antagonistic nor synergistic effects from other pheromone geometric isomers were observed. The modified synthetic pathway offers the prospect of more economical production of CPB sex pheromone. During 17 weeks when C. cramerella monitoring coincided with the main cocoa pod harvest period in 2013–2014, CPB trap catch data from some blends showed a good correlation with the number of pods with C. cramerella infestation symptoms.     

Isolation of 19,20-dehydroprostaglandins E1 and E2 in human seminal fluid and further studies on 18,19-dehydroprostaglandins E1 and E2

Human seminal fluid was recently found to contain 18,19-dehydroprostaglandins E1 and E2 (E. H. Oliw, H. Sprecher, and M. Hamberg, (1986) J. Biol. Chem. 261, 2675-2683). In the present study, the cis and trans isomers of 18,19-dehydroprostaglandins E1 and E2 were prepared by incubation of microsomes of ram vesicular glands and glutathione with the precursor fatty acids, 8(Z),11(Z),14(Z),18(E/Z)-eicosatetraenoic acids, and 5(Z),8(Z),11(Z),14(Z),18(E/Z)-eicosapentaenoic acids, and used as references to characterize the 18,19-dehydroprostaglandins of human seminal fluid. Based on separation by reversed-phase high-performance liquid chromatography, capillary gas chromatography-mass spectrometry, and ozonolysis of the (-)-menthoxycarbonyl derivatives and on comparison with the authentic compounds, human seminal fluid was found to contain both the cis and trans isomers of 18,19-dehydroprostaglandins E1 and E2. Furthermore, human seminal fluid contained two related compounds, viz. 19,20-dehydroprostaglandins E1 and E2. The structures of these compounds were established by conversion into the corresponding prostaglandin B compounds, by mass spectrometric analysis and by chemical degradation by oxidative ozonolysis, which afforded, inter alia, 2(S)-hydroxy-adipic acid.     

Electroantennogram responses of the European corn borer,Ostrinia nubilalis,to (Z)- and (E)-11-tetradecenyl acetates

Antennal responses of male European corn borer moths, Ostrinia nubilalis, to their two pheromone components, (Z)- and (E)-11-tetradecenyl acetates (tda), were studied. The electroantennogram (EAG) response was highest when the ventral side and lowest when the dorsal side of the antenna faced the air stream carrying the chemical stimulus. Repetitive stimulation with one of the isomers resulted in adaptation which affected the amplitude of response in subsequent tests of both (Z)- and (E)-11-tda. This suggested that the receptors for the two tda isomers are either identical or highly interactive. Mixtures of the two pheromone components did not elicit higher responses than the major component, (Z)-11-tda. A significant difference was observed between London and New York strains of this insect in their relative responses to (Z)- and (E)-11-tda. EAG responses of hybrids of these two strains resembled those for the New York strain.     

Formation of (R)-2,3-dihydrogeranylgeranoic acid from geranylgeraniol in rat thymocytes

In a metabolic study of [1-(14)C]geranylgeranial involving rat thymocytes, the radioactivity was mainly incorporated into two metabolites, Z1 and Z2, the latter moving slower than the former on a silica-gel thin-layer plate. The time course of Z1 and Z2 formation superficially suggested a precursor-product relationship between Z1 and Z2. The two metabolites were chemically converted to their methyl esters on treatment with trimethylsilyl diazomethane. Z1 was cochromatographed with E,E,E-geranylgeranoic acid (GGA). Z2 was prepared in a large quantity from geranylgeranial using thymocytes, and purified by TLC followed by ESI (negative ion mode) or EI mass-spectrometry. The observation of a negative ion at m/z 305 on ESI and a molecular ion at m/z 306 (C(20)H(34)O(2)) with fragments similar to GGA on EI implied that Z2 was dihydroGGA, which has been detected in the urine and serum of patients with Refsum disease. The EI mass spectrum of (R)-2,3-dihydroGGA was identical to that of Z2. The diastereomeric amide synthesized from metabolite Z2 with (R)-1-(1-naphtyl)ethylamine was cochromatographed with (R acid, R) amide, not with (S acid, R) amide, which were similarly synthesized from (R)- and (S)-2,3-dihydroGGAs, respectively. In another metabolic study on [1-(14)C]geranylgeraniol (GGOH), the radioactivity was similarly incorporated into a metabolite corresponding to (R)-2,3-dihydroGGA. (R)-2,3-DihydroGGA induced DNA ladder formation with a maximum at 15 mciroM in thymocytes. However, 2,3-dihydrofarnesoic acid did not induce it at all.     

Synthesis and characterization of 3,13- and 2,13-octadecadienyl compounds for identification of the sex pheromone secreted by a clearwing moth, Nokona pernix

Several geometrical isomers of 3,13- and 2,13-octadecadien-1-ols and their acetates were synthesized starting from 1,8-octanediol or 1,9-nonanediol utilizing acetylene coupling reactions. In addition to commercially available compounds, all geometrical isomers of each dienyl compound were analyzed by NMR and GC-MS to accumulate chemical data for studies of sex pheromones secreted from clearwing moths classified into the family Sesiidae of Lepidoptera. Although acetoxy derivatives of the 3,13- and 2,13-dienes showed almost the same mass spectra, the alcohols were distinguished by comparing the relative intensities of [M-18](+) at m/z 248, indicating direct differentiation of the two positional isomers without derivatization. Furthermore, each geometrical isomer eluted from a high-polar GC column with a different retention time. Base on these data, a pheromone gland extract of a sesiid moth, Nokona pernix, was analyzed by GC-EAD and GC-MS, and two EAG-active components were identified, viz., the (3E,13Z)- and (3Z,13Z)-isomers of 3,13-octadecadien-1-ol in a ratio of 9:1. In the field, the synthetic compounds mixed in 9:1 ratio attracted N. pernix males well, while a single component scarcely attracted the males. The number of attracted males peaked in the middle of June, and a small second peak was observed in August.     

Wound-induced green leaf volatiles cause the release of acetylated derivatives and a terpenoid in maize

Green leaf volatiles (GLVs), generally occurring C6 alcohols, aldehydes and acetates from plants, play an important role in plant-plant communication. These compounds induce intact plants to produce jasmonic acid, and induce defense-related gene expression and the release of volatile compounds. Here, we address wound-induced GLVs cause the release of acetylated derivatives and a terpenoid, (E)-4,8-dimethylnona-1,3,7-triene (DMNT) in intact maize, which may be a type of plant-plant interaction mediated by airborne GLVs. Upon exposure of intact maize seedlings to wound-induced GLVs, (Z)-3-hexenyl acetate was consistently the most abundant compound released. Exogenous application of individual alcohols and aldehydes mostly resulted in the release of corresponding acetate esters. C6-alcohols with a double bond between the second and third, or the third and fourth carbon atoms, C5- or C6-aldehydes, and (Z)-3-hexenyl acetate triggered the release of DMNT. When (Z)-3-hexenyl acetate and hexyl acetate were used to treat maize seedlings, they were recovered from the plants. These data demonstrated that: (1) apart from direct adsorption and re-release of acetate esters, absorption and conversion of exogenous alcohols and aldehydes into acetate esters occurred, and (2) DMNT was induced by a range of aldehydes and unsaturated alcohols.     

Sex pheromone biosynthetic pathway in Spodoptera littoralis and its activation by a neurohormone

Deuterium-labeled fatty acids have been used to elucidate the sex pheromone biosynthetic pathway in Spodoptera littoralis. Label from palmitic acid was incorporated during the scotophase into all the pheromone acetates and their corresponding fatty acyl intermediates. (Z,E)-9,11-tetradecadienyl acetate, the major component of the pheromone blend, is synthesized from palmitic acid via tetradecanoic acid, which, by the action of a specific (E)-11 desaturase and subsequently a (Z)-9 desaturase, is converted into (Z,E)-9,11-tetradecadienoate. By further reduction and acetylation, this compound leads to the dienne acetate. Deuterated precursors applied to the pheromone gland during the photophase were also incorporated into the pheromone. The percentage of labeled (Z,E)-9,11-tetradecadienyl acetate relative to natural compound was significantly higher during the light period. Label incorporation from different intermediates into the pheromone was stimulated by injection of brain-subesophageal ganglion extract during the photophase. The influence of the pheromone biosynthesis-activating neuropeptide on the biosynthetic pathway is discussed.     

Synthesis of two new haptens of 16alpha-hydroxydehydroepiandrosterone (3beta,16alpha-dihydroxyandrost-5-en-17-one)

Synthetic routes leading to 19E and 7Z O-(carboxymethyl)oximes derived from 16alpha-hydroxydehydroepiandrosterone were developed using two independent methods for introduction of the 16alpha-hydroxy group. Firstly, the oxime moiety was built, and then, either epoxidation of the enol acetate followed by the boron trifluoride mediated rearrangement or alkaline hydrolysis of the corresponding alpha-bromide in aqueous N,N-dimethylformamide were employed. The last step in both methods was removal of the protecting groups, which consisted of acid deprotection of the acetates and gentle alkaline hydrolysis of the methyl ester. Final haptens were designed as components for immunoanalytical kits.     

Crystalline 2,3:4,5-di-O-isopropylidene-DL-arabinose diethyl dithioacetal: some reactions of acetal derivatives of arabinose

Acetonation of the diethyl dithioacetals of D- and L-arabinose gives the corresponding 2,3:4,5-diisopropylidene acetals (2a and 2b) as oils having [alpha]D +82 and -81 degrees, respectively; in admixture, the enantiomers form a well crystallized racemate, m.p. 43-45 degrees. The initial product of acetonation is the 4,5-monoisopropylidene acetal. Demercaptalation of 2a with mercury(II) chloride-cadmium carbonate gives 2,3:4,5-di-O-isopropylidene-aldehydo-D-arabinose (5) in high yield, but the literature procedure employing mercury(II) chloride-mercury(II) oxide affords a mixture of 5 and 1,2:3,4-di-O-isopropylidene-beta-D-arabinopyranose (6). A trace of acid readily and completely converts the aldehydo derivative 5 into the cyclic diacetal 6.     

Authentic standards for the reductive-cleavage method. The positional isomers of partially methylated and acetylated or benzoylated 1,5-anhydroribitol

The eight positional isomers of methylated and benzoylated 1,5-anhydroribitol were generated simultaneously from 1,5-anhydroribitol by sequential partial methylation and benzoylation, and the four meso isomers and two enantiomeric pairs of isomers so-formed were isolated in chemically pure form by high-performance liquid chromatography. The corresponding acetates were obtained by debenzoylation of the pure isomers and acetylation. Reported herein are the 1H NMR spectra of the benzoates and the electron-ionization mass spectra of the acetates and the tri-O-methyl derivative. Also reported for the acetates and the tri-O-methyl derivative are their linear temperature-programmed gas-liquid chromatography retention indices on three different capillary columns.     

Conjugated linoleic acid exhibits stimulatory and inhibitory effects on prostanoid production in human endothelial cells and platelets

In addition to their reported antitumorigenic properties, various conjugated linoleic acid (CLA) isomers have also been shown to decrease prostanoid synthesis as a result of inhibiting the cyclooxygenase (COX) enzyme. We have previously reported that several CLA isomers inhibited both platelet aggregation and formation of thromboxane A(2) (TXA(2)), a proaggregatory and vasoconstrictive agent. Since the interaction between platelets and vascular endothelial cells is essential to maintaining vascular homeostasis, we decided to investigate the effects of various CLA isomers on the production of endothelial prostacyclin (PGI(2)), a potent vasodilator and inhibitor of platelet function. Using interleukin 1-beta (IL1-beta)-stimulated human umbilical vein endothelial cells (HUVECs), we initially established that HUVECs of passage #2 should be used since these cells were most responsive to thrombin-induced conversion of endogenous arachidonic acid to PGI(2), as monitored by the formation of its stable, inactive metabolite, 6-ketoPGF(1alpha). In the first part of the study, the effects of CLA isomers in the free fatty acid form were tested. The 10(E), 12(Z)- and 9(Z), 11(E)-CLA isomers inhibited thrombin-induced 6-ketoPGF(1alpha) formation with I(50)'s of 2.6 and 5.5 microM, whereas the 9(Z), 11(Z)- and 9(E), 11(E)-CLA were ineffective at concentrations up to 60 microM. The inhibitory effect of the 10(E), 12(Z)-CLA was irreversible. Next, the effects of CLA incorporation into HUVECs on PGI(2) generation was determined. An average 8-fold stimulation of 6-ketoPGF(1alpha) formation was obtained with quiescent IL1-beta-exposed HUVECs pretreated for 18 h with 25 microM 9(Z), 11(Z)-CLA, whereas cells preincubated with the 10(E), 12(Z) isomer enhanced this eicosanoid 3-fold. Such IL1-beta-treated HUVECs prelabeled with 25 microM 9(Z), 11(Z)-CLA became refractory to thrombin stimulation, as measured by 6-ketoPGF(1alpha) production, whereas a small, statistically insignificant, inhibition was observed upon thrombin treatment of HUVECs prelabeled with the 10(E), 12(Z) isomer. Qualitative similar results were obtained with resting or thrombin-stimulated platelets containing these esterified CLA isomers indicating that these effects occur with cells that contain either the COX-1 or COX-2 isozymes. The results of this in vitro study indicate that the effects of CLA on cellular prostanoid formation in endothelial cells and platelets can be either inhibitory or stimulatory, and this seems to depend not only on the specific CLA isomer and whether or not the CLA is in the free fatty acid form or esterified into cellular lipids, but also whether cells are in the resting or stimulated state. These findings suggest that in vivo, CLA might have multiple, complex effects on vascular homeostasis.     

Biosynthetic pathway for production of a conjugated dienyl sex pheromone of a Plusiinae moth,Thysanoplusia intermixta

Virgin females of Thysanoplusia intermixta (Lepidoptera; Noctuidae; Plusiinae) produce (5E,7Z)-5,7-dodecadienyl acetate as a main sex pheromone component. GC-MS analysis of the pheromone glands, which were treated with deuterated hexadecanoic, (Z)-11-hexadecenoic, and (Z)-7-dodecenoic acids, showed incorporation of the label into the dienyl component. Their incorporation rates confirmed that its biosynthesis proceeds in the following order: Delta11-desaturation of a C(16) acyl intermediate, chain shortening to a C(12) compound by beta-oxidation, Delta5-desaturation to produce a 5,7-dienyl system, reduction of the acyl group, and acetylation. These deuterated precursors also converted into a minor pheromone component, (Z)-7-docecenyl acetate, which might be prepared by the same pathway except for the step of Delta5-desaturation. While deuterium incorporation into the dienyl acetate was not observed in the extracts treated with other labeled dodecenoic acids with (E)-5-, (Z)-6-, and (E)-7-double bonds, the corresponding dodecenyl acetates were produced. This result showed low substrate specificity of the enzymes for reduction and acetylation. Labeled (Z)-10-hexadecenoic acid was not converted into a dodecenyl acetate, indicating the high substrate specificity of the enzyme for beta-oxidation.     

10,20-Methanorhodopsins: (7E,9E,13E)-10,20-methanorhodopsin and (7E,9Z,13Z)-10,20-methanorhodopsin. 11-cis-locked rhodopsin analog pigments with unusual thermal and photo-stability

Synthesis of the retinal analog, 10,20-methanoretinal (R6), where the 11Z conformation is locked in a six-membered ring, yielded four stereoisomers (7E,9E,13E, 7E,9E,13Z, 7E,9Z,13E and 7E,9Z,13Z). These four isomers were separated by straight-phase isocratic HPLC and identified by 1H-NMR and NOE analysis. All isomers smoothly recombined with bovine opsin at a relatively high rate (5-10% of that of the natural chromophore 11Z-retinal). The corresponding 13E and 13Z isomers yielded identical analog pigments, probably due to rapid thermal isomerization around the C13 = C14 double bond. The (7E,9E)-isomers produced a pigment with maximal absorbance at 510 nm, while the pigment produced from the (7E,9Z)-isomers had maximal absorbance at 494 nm. Based upon kinetic considerations, the chromophore structure in the 510-nm-absorbing pigment should be (7E,9E,13E), i.e. equivalent to 11Z-retinal and rhodopsin, while the chromophore structure in the 494-nm-absorbing pigment should be (7E,9Z,13Z), i.e. equivalent to (9Z,11Z,13Z)-rhodopsin, an isorhodopsin analog. In analogy to the 11-cis-locked rhodopsin analogs Rh5 and Rh7, the 510-nm-absorbing pigment, (7E,9E,13E)-10,20-methanorhodopsin, was dubbed Rh6 and the 494-nm-absorbing pigment. (7E,9Z,13Z)-10,20-methanorhodopsin, was dubbed Iso6. The opsin shift of Rh6 (2660 cm-1) is practically identical to that of rhodopsin itself (2650 cm-1). Rh6 and Iso6 are nearly as stable as rhodopsin towards hydroxylamine and solubilization in detergent solution and could be easily purified and reconstituted into proteoliposomes by established procedures. Due to the 11-cis-lock, Rh6 is much less photolabile (bleaching rate less than 1%) than rhodopsin, but it is not completely photostable, probably since photoisomerization around the C7 = C8, C9 = C10 and C13 = C14 bonds is allowed. Illumination of either Rh6 or Iso6 does not generate the common photointermediates but instead produces a complex pattern of photochemical transitions, which during continuous illumination leads to the same final steady state, absorbing at 498 nm. This process is accompanied by a slow but steady loss of pigment, probably due to hydrolytic release of chromophore, which is markedly accelerated in the presence of hydroxylamine. In a physiological assay (light-dependent activation of rod cGMP phosphodiesterase) Rh6 is only marginally active and this probably reflects conformational changes accompanying the above-mentioned photochemical transitions. This supports the concept that normal rhodopsin-based phototransduction requires 11Z to all-E isomerization.(ABSTRACT TRUNCATED AT 400 WORDS)     

Sex attractants for six clearwing and tineid species (Lepidoptera, Sesiidae and Tineidae) from Kazakhstan and Lithuania

Sex attractants for 3 Sesiidae and 3 Tineidae moth species in West-Kazakhstan and Lithuania were discovered by field screening tests of (3Z,13Z)-, (3E,13Z)- and (2E,13Z)-octadecadien-1-ols and their acetates as well as of some binary mixtures of these compounds. Total amount of chemicals was 0.3 mg/dispenser. Males of Synanthedon serica were attracted by a 5:5 mixture of 3E,13Z-18:OAc and 2E,13Z-18:OAc, Chamaesphecia bibioniformis by a 9:1 mixture of 3Z,13Z-18:OAc and 3E,13Z-18:OAc, Paranthrene tabaniformis by a 1:9 mixture of 3Z,13Z-18:OH and 3E,13Z-18:OH, Tinea nonimella by a 1:9 mixture of 3E,13Z-18:OH and 2E,13Z-18:OH, Monopis monachella by a 1:9 mixture of 3Z,13Z-18:OH and 2E,13Z-18:OH, and Nemaxera betulinella by a 9:1 mixture of 2E,13Z-18:OAc and the corresponding alcohol. The periods of attraction to the traps were registered for males of S. serica and Ch. bibioniformis and were found to occur at 15-18 and 15-17 o'clock, local time, respectively.     

Sequential substitution of 1,2-dichloro-ethene: a convenient stereoselective route to (9Z,11E)-, (10E,12Z)- and (10Z,12Z)-

Conjugated linoleic acid (CLA) isomers are present in human foods derived from milk or ruminant meat. To study their metabolism, (9Z,11E)-, (10E,12Z)- and (10Z,12Z)-[1-(14)C]-octadecadienoic acids with high radiochemical and isomeric purities (>98%) were prepared by stereoselective multi-step syntheses involving sequential substitution of 1,2-dichloro-ethene. In the case of the (9Z,11E) isomer, a first metal-catalyzed cross-coupling reaction between (E)-1,2-dichloro-ethene and 2-non-8-ynyloxy-tetrahydro-pyran, obtained from 7-bromo-heptan-1-ol, gave a conjugated chloroenyne. A second coupling reaction with hexylmagnesium bromide provided a heptadecenynyl derivative. Stereoselective reduction of the triple bond and bromination afforded (7E,9Z)-17-bromo-heptadeca-7,9-diene. Formation of the Grignard reagent and carbonation with 14CO(2) gave (9Z,11E)-[1-(14)C]-octadeca-9,11-dienoic acid (overall yield from 7-bromo-heptan-1-ol, 14.4%). (10E,12Z)- and (10Z,12Z)-[1-(14)C]-octadeca-10,12-dienoic acids were synthesized by the same methodology using 1-heptyne, 8-bromo-octan-1-ol and, respectively, (E)-1,2-dichloro-ethene and its (Z) isomer (overall yield from 8-bromo-octan-1-ol, 13.1% (10E,12Z); 17.2% (10Z,12Z)). Impurities (<2% if present) were identified as being (E,E) CLA isomers and were removed by RP-HPLC. Metabolism studies in animal are in progress.     

Depression and excitation induced in mice by two geometric isomers of (+)13,14-didehydro-20-methyl-carboprostacyclin, FCE 22177 and FCE 22176. Comparison with effects on blood pressure and platelet aggregation

Two geometric isomers of a stable derivative of PGI2 (13,14-didehydro-20-methyl-carbo PGI2), FCE 22177 (5E) and FCE 22176 (5Z), have been injected i.v. in mice (5-400 mcg/Kg) to investigate the effects at CNS level (Irwin's test). The synthetic mixture of the two isomers (5E:5Z = 7:3) was also tested. Isomers 5E and 5Z induced opposite effects: 5E (similar to PGI2) was depressive, 5Z induced stimulation. The mixture showed a strong depressive symptomatology. The two isomers and their mixture induced motor incoordination and impaired the performance of mice in the rotarod test (200 mcg/Kg i.v.). Mice were depressed after 5E and mixture; whilst 5Z induced excitation, in accordance with Irwin's test. 5E and 5Z showed analogous effects on mean blood pressure (hypotension) and heart rate (increase) in normotensive rats, but 5E was 7 times more active than 5Z. The two isomers showed analogous inhibitory effect on guinea-pig platelet aggregation in vitro, but 5E was 30 times more active than 5Z. In conclusion, the two geometric isomers have similar effects on blood pressure, heart rate and platelet aggregation, even if differing quantitatively. In contrast, 5E and 5Z have opposite effects at CNS level on motor function and behaviour. The data suggest the presence of two different sites of action for PGI2 in CNS (Ca2+- and adenylate cyclase-linked?). The two geometric isomers, 5E and 5Z, may be useful to study the PGI2 receptor sites in different tissues.     

New analogs of 2-methylene-19-nor-(20S)-1,25-dihydroxyvitamin D3 with conformationally restricted side chains: evaluation of biological activity and structural determination of VDR-bound conformations

We have successfully prepared E- and Z- isomers of 17-20 dehydro analogs of 2-methylene-19-nor-(20S)-1alpha,25-dihydroxyvitamin D3 (2MD). Both isomers bind to the recombinant rat vitamin D receptor (VDR) with high affinity. The Z-isomer (Vit-III 17-20Z) displays activity in vivo and in vitro that is similar to 2MD. The in vitro activity of the E-isomer (Vit-III 17-20E) is comparable to the natural hormone, though in vivo this analog is significantly less calcemic. Crystal structures of the rat VDR ligand binding domain complexed with the analogs demonstrate that the Vit-III 17-20Z analog is oriented almost identically to 2MD, with only minor differences induced by the planar configuration around the C17-C20 double bond. The Vit-III 17-20E analog is oriented in a conformation distinct from both 2MD and the natural hormone. The structural comparisons suggest that the position of C21 in the ligand binding site may be an important determinant of biological activity.     

Synthesis and biological properties of 7alpha-cyano derivatives of the (17alpha,20E/Z)-[125I]iodovinyl- and 16alpha-[125I]iodo-estradiols

The synthesis, receptor binding affinity, estrogenic potency and tissue distribution of the 7alpha-cyano derivatives of the (17alpha,20E/Z)-[125I]iodovinyl-(CIVE) and 16alpha-[125I]iodo-estradiols (CIE) are reported. The iodovinyl derivatives were prepared via the (17alpha,20E/Z)-tri-n-butylstannyl intermediates, derived from the addition of tri-n-butyl tin hydride to the 17alpha-ethynyl group of the 7alpha-cyano-17alpha-ethynylestradiol, using triethylborane as a catalyst. The no-carrier-added [125I]-CIVE isomers were prepared via the same stereospecific reaction. [125I]-CIE was prepared from 7alpha-cyano-16beta-bromoestradiol via halogen exchange with Na125I. Addition of the 7alpha-cyano group to 16alpha-iodoestradiol did not affect estrogen receptor binding affinity (RBA of CIE is 115). However the estrogenic potential of CIE, as measured by the capacity to stimulate the expression of the pS2 gene, was reduced to 1% as compared to that of estradiol. Addition of a 7alpha-cyano group to the (17alpha,20E/Z)-IVE isomers reduced the RBA to 21 and 36, respectively, while the estrogenic potential was reduced to 2-3% of that of estradiol. Uterus uptake in immature rats of the 125I-labeled CIVE 20E-isomer and the 16alpha-iodo CIE peaked at 0.5h post injection while the (17alpha,20Z)-CIVE isomer showed a maximum only past 5h post injection. Uptake of all three 125I-labeled 7alpha-cyanoestrogens was suppressed by the co-injection of non-radioactive estradiol confirming the role of estrogen receptors in the localization process. Uterus retention pattern differ substantially from those of the analogues 7alpha-methylestrogens, which were previously shown to give high maximum 125I-uptake values at 2h post injection. Overall our data indicate that addition of a 7alpha-cyano group to 123I-labeled estrogens does not improve their potential to serve as SPECT agents for the imaging of estrogen receptor densities in breast cancer.