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PubMed1989

Hexestrol-linked cytotoxic agents: synthesis and binding affinity for estrogen receptors.

With the erythro-hexestrol derivative 2 as the starting material, a variety of cytotoxic linked hexestrol (HEX) compounds were prepared including the HEX-N-lost derivative 36, the HEX-(chloroethyl)nitrosourea 38, the HEX-cyclophosphamide 44, and the HEX-epoxide 68. Relative binding affinity to estradiol receptors were in the magnitude of 1%, similar to that of comparable diethylstilbestrol compounds. HEX derivatives with long polyether spacers (64, 65, 70, 71) showed no significant decrease in binding affinity in contrast to derivatives with other bulky side chains.

Antineoplastic Agents↗
PubMed1982

Nonsteroidal estrogens: synthesis and estrogen receptor binding affinity of derivatives of (3R*,4S*)-3,4-bis(4-hydroxyphenyl)hexane (hexestrol) and (2R*,3S*)-2,3-bis(4-hydroxyphenyl)pentane (norhexestrol) functionalized on the side chain.

A series of nonsteroidal, side-chain functionalized estrogens based on (3R*,4S*)-3,4-bis(4-hydroxyphenyl)hexane (hexestrol) and (2R*,3S*)-2,3-bis(4-hydroxyphenyl)pentane (norhexestrol) has been prepared; these include amide, diazo ketone, ester, alcohol, ketone, fluoro, bromo, iodo, and saturated hydrocarbon derivatives. Analysis of the binding affinity of these compounds to the uterine estrogen receptor, measured by competitive binding assay, reveals trends that can be related to the steric size, the hydrophobicity, and the hydrogen bond accepting character of the side-chain substituents. Comparison of binding affinities between norhexestrol and hexestrol derivatives indicates that, in general, the norhexestrols show significantly higher receptor binding affinities, making this series of compounds ideally suited as functional probes for the estrogen receptor.

Animals↗
PubMed1984

Synthesis, receptor binding, and target-tissue uptake of carbon-11 labeled carbamate derivatives of estradiol and hexestrol.

The reaction of ethyl chloroformate with amino compounds has been evaluated as a simple route to carbon-11 labeling of steroid hormone-receptor-based imaging agents. Both a 17 beta-amino analogue of estradiol and an aminoethyl derivative of the nonsteroidal estrogen hexestrol with potential affinity for the estrogen receptor were studied. The unlabeled carbamate derivatives of the amino estrogens were prepared by standard methods, and the 11C-labeled analogues were synthesized from [11C]ethyl chloroformate, generated by purging ethanol with [11C]phosgene. Both carbamates showed weak in vitro binding affinity for the estrogen receptor, and only the 11C-labeled hexestrol exhibited a small but significant estrogen-responsive uterus uptake in immature rats.

Animals↗
PubMed1987

Preparation, receptor binding, and fluorescence properties of hexestrol-fluorophore conjugates: evaluation of site of attachment, fluorophore structure, and fluorophore-ligand spacing.

We have undertaken a staged development of certain estrogen-fluorophore conjugates, in order to prepare a fluorescent estrogen suitable for determination of the estrogen receptor content of individual cells. Since non-steroidal estrogens with bulky substituents are often more readily bound by receptor than their steroidal counterparts, we have investigated fluorophore conjugates with derivatives of the non-steroidal estrogen hexestrol [3R*, 4S*)-3,4-bis(4-hydroxyphenyl)hexane). On the basis of the receptor-binding affinity of model compounds, we prepared a prototypical set of three ring- and side-chain-substituted fluorescent hexestrol derivatives, whose binding and fluorescence properties ultimately led to the preparation of a series of side-chain-substituted nitrobenzoxadiazole derivatives. The compounds prepared have binding affinities for the estrogen receptors that range from ca. 1% to 5% that of estradiol, and they have very favorable fluorescence characteristics, similar to those of fluorescein.

Animals↗
PubMed1987

Estrogenic affinity labels: synthesis, irreversible receptor binding, and bioactivity of aziridine-substituted hexestrol derivatives.

To develop an affinity label for the estrogen receptor that would be an estrogen agonist, rather than antagonist, we prepared several aziridine derivatives of the potent nonsteroidal estrogen hexestrol [3R,4S)-3,4-bis(4-hydroxyphenyl)hexane) bearing an aziridine function on the side chain. Three functional groups link the hexestrol ligand and the aziridine: a carbonyl group (ketone or ester), a thioether, or a methylene chain. The apparent competitive binding affinity of these derivatives for the estrogen receptor ranges from 1.8% to 25% that of estradiol, and most of them bind in a time-dependent, irreversible manner with the receptor, although the rate and efficiency of this binding vary widely, often with relatively small changes in structure. This is consistent with the irreversible attachment requiring a precise alignment of activating and reacting residues in the binding site of the receptor. The estrogenic and antiestrogenic activity of these aziridine derivatives was investigated in MCF-7 human breast cancer cells. Most of the compounds are agonists, with one being an antagonist. The derivative (6R,7S)-1-N-aziridinyl-6,7-bis(4-hydroxyphenyl)-5-nonanone (keto-nonestrol aziridine 3) appears to have the most ideal behavior of the estrogenic affinity labeling agents prepared: It is an agonist, and it binds to receptor irreversibly, efficiently, and quite rapidly.

Affinity Labels↗
PubMedDate not supplied

Validation of screening method for residues of diethylstilbestrol, dienestrol, hexestrol, and zeranol in bovine urine using immunoaffinity chromatography and gas chromatography/mass spectrometry.

A method was developed, using commercially available immunoaffinity chromatography cleanup cartridges, followed by detection by gas chromatography/mass spectrometry, to screen for residues of the hormone growth promotants diethylstilbestrol, dienestrol, hexestrol, and zeranol in bovine urine. The single-laboratory, in-house validation included assessment of recoveries, repeatability, linearity of response, detection capability, and specificity (cross-reactivity) with a suite of antibiotics and other hormonal growth promotants. The method was validated for screening at a target concentration of 2.0 microg/L in urine. The detection capabilities for the analytes were diethylstilbestrol, 0.24; dienestrol, 0.15; hexestrol, 0.84; and zeranol, 0.28 microg/L.

Animals↗
PubMed1975

Iodohexestrols. II. Characterization of the binding and estrogenic activity of iodinated hexestrol derivatives, in vitro and in vivo.

The affinity of ortho-iodinated hexestrols for the estrogen binding protein from rat uterus, determined by competitive binding assay, decreases with progressive iodine substitution; 3-iodohexestrol (I-Hex) has a binding affinity 42% that of estradiol. Analysis of [3-H]-I-Hex binding in rat uterine cytosol by sucrose density gradient centrifugation shows both an estrogen-specific binding component (8 S) and a more abundant component (4 S) that is not estrogen specific. Scatchard analysis indicates that this latter binding is of high affinity (Kd equals to 3.7-8.3 times 10- minus-9 M) but is not uterine specific. Polyacrylamide gel electrophoresis shows that most of the [3-H]-I-Hex binding activity in serum and uterine cytosol is distinct from and anodic to the principal protein component (albumin), and that is comigrates with [14-C]thyroxine binding activity. In in vitro incubation of rat uteri, I-Hex can block the specific uptake of [3-H]estradiol into the nuclear fraction; it itself causes a translocation of estrogen-specific binding capacity (as measured by exchange) from cytoplasm to nuclei, and can induce the synthesis of an estrogen-specific uterine protein, all under conditions where it is not metabolically deiodinated to hexestrol. The uterotrophic activities of the iodohexestrols are in most cases comparable to that expected on the basis of their competitive binding affinities. However, selective, estrogen-specific uptake of [3-H]-I-Hex into rat uterus, either in vitro or in vivo, cannot be demonstrated.

Animals↗
PubMed1981

The therapeutic effect of concurrent administration of 5-fluorouracil and allylestrenol or hexestrol in small doses on prostatic carcinoma.

A trial to reduce the dosage of estrogen or to substitute it by other agents was done as a treatment of prostatic carcinoma. Either the combination of 5-FU (200 mg/day) and allylestrenol (50 mg/day), or 5-FU and hexestrol (20 mg/day) was given to 24 cases of prostatic carcinoma, 4 of whom were relapsed hormonal-resistant cases, 14 cases were controlled by large doses of estrogen and 6 were newly treated cases. No progressions were observed following 3 months of therapy. In 5 cases, progression was observed after 6 months. Deteriorated cases increased to 6 cases after 12 months. The effective rate, according to the "vital score," which is proposed as a parameter of the physical condition of patients with prostatic carcinoma, was calculated to be 100% at 3 months, 77% at 6 months, and 71% at 12 months.

Aged↗
PubMed1989

Ultrastructural, physico-chemical and conformational study of the interactions of gentamicin and bis(beta-diethylaminoethylether) hexestrol with negatively-charged phospholipid layers.

Aminoglycoside antibiotics such as gentamicin, which are fully hydrophilic, and cationic amphiphilic drugs such as bis(beta-diethylaminoethylether)hexestrol (DEH), are both known to inhibit lysosomal phospholipases and induce phospholipidosis. This enzymatic inhibition is probably related to the neutralization of the surface negative charges on which the lysosomal phospholipases A1 and A2 are dependent to express fully their activities (Mingeot-Leclerq et al., Biochem Pharmacol 37: 591-599, 1988). Using negatively charged liposomes, we show by 31P NMR spectroscopy that both gentamicin and DEH cause a significant restriction in the phosphate head mobility and, in sonicated vesicles, the appearance of larger bilayer structures. Both DEH and gentamicin increased the apparent size of sonicated negatively charged liposomes (but not of neutral liposomes) as measured by quasi-elastic light scattering spectroscopy. Examination of replicas from freeze-etched samples, however, revealed that gentamicin caused aggregation of liposomes, whereas DEH induced their fusion and the formation of intramembranous roundly shaped structures. Only DEH caused a significant decrease of the fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene, a fluorescent lipid-soluble probe. In addition, DEH, but not gentamicin, interfered with the bilayer to hexagonal phase transition occurring in dioleoyl- and dielaidoylphosphatidylethanolamine liposomes upon warming, and caused the appearance of an isotropic signal suggestive of the formation of inverted micelles. In computer-aided conformational analysis of the molecules at a simulated air-water interface, gentamicin was shown to display a largely-open crescent shape. When surrounded by phosphatidylinositol molecules, it remained as such at the interface which it locally mis-shaped, establishing close contact with the negatively charged phospho groups. In contrast, DEH could be oriented perpendicularly to the interface, with its two cationic groups associated with the phospho groups, and its phenyl- and diethylethandiyl moieties deeply inserted between and interacting with the aliphatic chains. Thus, although both agents cause lysosomal phospholipases inhibition, the differences in their interactions with negatively-charged bilayers is likely to result in a different organization of the phospholipids accumulated in vivo, which could lead to different toxicities.

Fluorescence Polarization↗
PubMed1996

Aminoglycoside antibiotics prevent the formation of non-bilayer structures in negatively-charged membranes. Comparative studies using fusogenic (bis(beta-diethylaminoethylether)hexestrol) and aggregating (spermine) agents.

Aminoglycoside antibiotics cause aggregation but not fusion of negatively-charged liposomes at an extent proportional to their capacity to interact with acidic phospholipids (Van Bambeke et al., 1995, Eur. J. Pharmacol., 289, 321-333). To understand why aggregation is not followed by fusion, we have examined here the influence of two aminoglycosides with markedly different toxic potential (gentamicin > isepamicin) on lipid phase transition in negatively-charged liposomes using 31P-NMR spectroscopy, in comparison with spermine (an aggregating agent) and bis(beta-diethylaminoethylether)hexestrol or DEH (a fusogenic cationic amphiphile). Gentamicin, spermine, and, to a lesser extent, isepamicin inhibit the appearance of the isotropic signal seen upon warming of control liposomes and denoting the presence of mobile structures. This non-bilayer signal appeared most prominently when liposomes were incubated with DEH, a strong fusogenic agent. We conclude that aminoglycosides, like spermine, have the potential to prevent membrane fusion, by inhibiting the development of a critical change in membrane organization, which is associated with fusion. We suggest that this capacity could be a determinant in aminoglycoside toxicity.

Animals↗
PubMed1983

(2R*, 3S*)-1-[18F]fluoro-2,3-bis(4-hydroxyphenyl)pentane [( 18F]fluoronor-hexestrol), a positron-emitting estrogen that shows highly-selective, receptor-mediated uptake by target tissues in vivo.

The positron-emitting, non-steroidal estrogen (2R*, 3S*)-1-[18F]fluoro-2,3-bis(4-hydroxyphenyl)pentane [( 18F]-fluoronor-hexestrol), has been prepared by fluoride ion displacement on a labile trifluoromethanesulfonate (triflate) derivative of a suitably protected precursor, followed by removal of the aryl triflate groups with lithium aluminum hydride and purification by HPLC. In immature female rats, this compound is taken up selectively by the uterus and is retained for prolonged periods, due to its binding to the estrogen receptor. This compound and related 18F-labeled estrogens thus appear to be promising agents for imaging estrogen receptor-positive breast tumors in humans.

Animals↗
PubMed1978

Stable derivatives for the gas chromatographic determination of synthetic anabolic stilbene residues (diethylstilbestrol, dienestrol and hexestrol) in meat and organs of treated cattle in the sub-parts per billion (10(9)) level.

A method for the determination of diethylstilbestrol and the related compounds dienestrol and hexestrol residues in meat and organs of treated cattle is described. After extraction and clean-up, these synthetic estrogens are subjected to reaction with pentafluorobenzoyl chloride, which gives very stable perfluoro esters that are suitable for gas chromatographic determination using an electron-capture detector. With the careful clean-up and the very sensitive response of these derivatives, it is possible to reach a limit of detection in the sub-parts per billion (10(9)) range starting with only 5 g of sample.

Animals↗
PubMedDate not supplied

Hexestrol diazirine photoaffinity labeling reagent for the estrogen receptor.

3-Azibutyl (2R*,3S*)-2,3-bis(4-hydroxyphenyl)pentyl sulfide (1), a photoaffinity labeling reagent for the estrogen receptor (ER), has been prepared in unlabeled and in high specific activity tritium-labeled form (32 Ci/mmol) and has been shown to undergo selective and efficient photocovalent attachment to rat uterine ER. Diazirine 1 demonstrates high binding affinity for ER, as determined by both a competitive binding assay and a direct binding assay (relative binding: estradiol = 100; (1) = 17. Kd: estradiol = 0.19 nM; (1) = 0.98 nM, respectively). It is efficient in site-specific photoinactivation of ER, reaching the level of 31% after 5 min of irradiation at > 315 nm. The tritium-labeled diazirine [3H]-1 undergoes specific photocovalent attachment to ER with an attachment efficiency of 29% and a selectivity of 90%. Both of these values are quite high for a photoaffinity reagent. SDS-polyacrylamide gel electrophoretic analysis of the photolabeled proteins shows specific labeling of a major species at M(r) 65,000, the same species that is labeled by [3H]tamoxifen aziridine, a well-characterized affinity label for ER. Hexestrol diazirine 1 is the first carbene-generating photoaffinity label that covalently labels ER with high efficiency and selectivity, and it should be useful in further studies on the hormone-binding domain of ER.

Affinity Labels↗
PubMed1980

Estrogen receptor based imaging agents. 2. Synthesis and receptor binding affinity of side-chain halogenated hexestrol derivatives.

We have synthesized as potential imaging agents for human breast tumors a series of hexestrol analogues bearing the halogens fluorine, chlorine, bromine, and iodine at the terminus of the hexane chain. The binding affinity of these compounds for the estrogen receptor from uterine tissues forms a monotonically decreasing series, starting at 129% of that of estradiol for the fluoro analogue and decreasing to 60% for the iodo analogue. Such a modest decrease in binding affinity is thought to reflect the preference of the receptor for lipophilic groups and for substituents of moderate steric size at this site, parameters which change in opposite directions in the halogen sequence going from fluorine to iodine. Three estrogenic bis(trifluoromethyl)diphenylethylenes, prepared by DuPont, also showed substantial binding affinities for the estrogen receptor. In terms of ease of radiolabeling and high receptor binding selectivity, the compound that appears to be the most promising candidate for a breast tumor imaging agent in these series is the chain terminal fluorohexestrol.

Animals↗
PubMed1998

Large-scale synthesis of the catechol metabolites of diethylstilbestrol and hexestrol.

Diethylstilbestrol (DES) and hexestrol (HES) are carcinogenic synthetic estrogens. The major metabolites of these compounds are their catechol derivatives, 3'-OH-DES and 3'-OH-HES. Oxidation of these metabolites leads to the electrophilic quinones, which are presumably involved in the tumor-initiating process. A synthetic route based on the McMurry coupling reaction was developed for the synthesis of 3'-OH-DES. Using commercially inexpensive starting materials, this compound was synthesized in four steps, and the cis and trans isomers were separated and identified. Following the same synthetic route, 3'-OH-HES was synthesized in five steps.

Catechols↗
PubMed1998

Metabolic activation and formation of DNA adducts of hexestrol, a synthetic nonsteroidal carcinogenic estrogen.

Hexestrol (HES), a synthetic nonsteroidal estrogen, is carcinogenic in Syrian golden hamsters. The major metabolite of HES is its catechol, 3'-OH-HES, which can be metabolically converted to the electrophilic catechol quinone, HES-3',4'-Q, by peroxidases and cytochrome P450. Standard adducts were synthesized by reacting HES-3',4'-Q with dG and dA to produce the adducts 3'-OH-HES-6'(alpha, beta)-N7Gua and HES-3',4'-Q-6'-N6dA, respectively. When HES-3',4'-Q was reacted with calf thymus DNA, 3'-OH-HES-6'(alpha,beta)-N7Gua was identified by HPLC and tandem mass spectrometry as the depurinating adduct, with minor amounts of stable adducts. 3'-OH-HES was bound to DNA after activation by horseradish peroxidase, lactoperoxidase, or rat liver microsomes. The depurinating adduct 3'-OH-HES-6'(alpha, beta)-N7Gua was identified in these systems at levels of 65, 41, and 11 micromol/mol of DNA-P, respectively. Unidentified stable adducts were observed in much lower amounts and were quantified by the 32P-postlabeling method. Similarly to 3'-OH-HES, the catechol metabolites of the natural steroidal estrogens estrone (E1) and estradiol (E2), namely, 2-OHE1, 4-OHE1, 2-OHE2, and 4-OHE2, can be oxidized to their corresponding quinones by peroxidases and cytochrome P450. The quinones of the carcinogenic 4-OHE1 and 4-OHE2 have chemical and biochemical properties similar to those of HES-3',4'-Q. The results suggest that formation of HES-3',4'-Q may be a critical event in tumor initiation by HES and that HES is an excellent model compound to corroborate the hypothesis that estrogen-3,4-quinones are ultimate carcinogenic metabolites of the natural steroidal estrogens E1 and E2.

Animals↗
PubMed1988

Treatment of postmenopausal breast cancer with bisbromoacetyl hexestrol.

Twenty five cases of advanced postmenopausal breast cancer patients were treated with bisbromoacetyl hexestrol 3 CR and 5 PR were achieved. The response rate was 32%, and the average duration of remission 6 months. Vaginal bleeding was seen in 9 cases, 4 of whom were compelled to discontinue treatment.

Aged↗
PubMed1983

Effect of chloroquine and O,O'-bis(diethylaminoethyl)hexestrol on acidic phospholipid membranes.

The amphiphilic drugs chloroquine and O,O'-bis(diethylaminoethyl)hexestrol are able to form complexes with the acidic-phospholipid 1,2-dipalmitoyl-sn-glycero-3-phosphoglycerol. The dissociation constants of the complexes with chloroquine are independent of pH in the range investigated here (4--7) as well as of temperature (4 degrees C--40 degrees C). The phase transition temperature of phospholipid is markedly reduced by both drugs, the effect is reversible by addition of Ca2.

Calcium↗