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PubMed1980

Carcinogenicity and hepatotoxicity of cycasin and its aglycone methylazoxymethanol acetate in nonhuman primates.

The carcinogenic potential of cycasin and methylazoxymethanol (MAM) acetate was investigated in nonhuman primates. Old-world monkeys (rhesus, cynomolgus, and African green monkeys) received cycasin and/or MAM acetate by oral or ip routes up to 11 years. Eighteen monkeys survived longer than 2 months after initiation of treatment with cycasin (50-75 mg/kg) or MAM acetate (1.5-3.0 mg/kg) given orally 5 days/week; 9 of the animals were necropsied. Histopathologic examination of a liver tumor from 1 of these monkeys revealed well-differentiated hepatocellular carcinoma. A second monkey had multiple tumors, including hepatocellular carcinoma, intrahepatic bile duct adenocarcinoma, renal carcinoma and adenomas, and adenomatous polyps of the colon. Although liver tumors were not observed in the other monkeys, all but 1 monkey had hepatic lesions such as toxic hepatitis and cirrhosis. These monkeys had received cycasin and/or MAM acetate for an average of 57 months (range, 2-133 mo). A group of 10 monkeys received MAM acetate by weekly ip injections (3-10 mg/kg). Six of these animals developed tumors after receiving an average of 6.14 g (range, 3.58-9.66 g) of MAM acetate for an average of 75 months (range, 50-89 mo). Four of the monkeys developed hepatocellular carcinomas, and 2 had multiple primary tumors including hepatocellular carcinomas, renal carcinomas, squamous cell carcinomas of the esophagus, and adenocarcinomas of the small intestine. Our results showed that long-term administration of cycasin and/or MAM acetate by oral and ip routes was hepatotoxic and carcinogenic in old-world monkeys.

Animals↗
PubMed1981

Adrenocortical suppression in cats given megestrol acetate.

Megestrol acetate was given orally to 8 cats at a dose of 2.5 mg every other day for 2 weeks and to 8 cats at a dose of 5.0 mg every day for 2 weeks. Four cats were designated nontreated controls. Pre-ACTH-stimulated plasma concentrations of cortisol (hydrocortisone) and ACTH-stimulated cortisol and tolerance to large-dose glucose infusion (IV) were determined on each of the 20 cats given megestrol acetate. Cats were restrained with acepromazine maleate and ketamine hydrochloride during blood sample collection and large-dose glucose infusion. Adrenocortical function and tolerance to large-dose glucose infusion were reevaluated for 4 weeks--after 1st and 2nd weeks of megestrol acetate treatment of the treated groups, and after 1st and 2nd weeks when treatment was stopped (ie, experiment weeks 3 and 4). Each week a cat from the control group and 2 cats from the 2 treated groups were selected to determine the changes occurring during the experiment for that week; after collection of plasma samples, each week's 5 selected cats were euthanatized and necropsied. Significant impairment of adrenocortical function and alteration of adrenocortical morphology occurred with both treated groups. The most severe adrenocortical alterations occurred in the cats 1 week after megestrol acetate was no longer given (ie, experiment week 3). Megestrol acetate-induced adrenocortical suppression contributed to the death of 1 cat. It was concluded that if stress occurs to cats on treatment or soon after treatment with megestrol acetate, glucocorticoids should be supplemented. The effects of megestrol acetate on glucose tolerance were overshadowed by the unforeseen intolerance caused by chemical restraint with acepromazine maleate and ketamine hydrochloride.

Adrenal Cortex↗
PubMed1981

Growth hormone, insulin, prolactin and total thyroxine in the plasma of sheep implanted with the anabolic steroid trenbolone acetate alone or with oestradiol.

The mode of action of the anabolic steroid trenbolone acetate (19-norandrost-4,9,11-trien-3-one-17-acetate) was studied through the endogenous hormonal response of castrated male sheep to subcutaneous implantation of 140 mg of trenbolone acetate and 20 mg of oestradiol both separately and in combination. Radioimmunoassay of delta-4,9,11-trienic steroids and oestradiol-17 beta in plasma confirmed that simultaneous administration of trenbolone acetate with oestradiol led to a significantly greater persistence of oestradiol-17 beta residues in plasma (P less than 0.05) than with implantation of oestradiol alone. Oestradiol treatment increased concentrations of growth hormone and insulin (P less than 0.05; P less than 0.001 respectively) in plasma samples collected weekly. Trenbolone acetate by itself had no significant effect and the oestrogenic response was blocked on the simultaneous implantation of trenbolone acetate and oestradiol (despite higher plasma levels of oestradiol-17 beta with this treatment). Plasma total thyroxine was markedly depressed to 45 per cent of its basal level by trenbolone acetate, alone or with oestradiol (P less than 0.001) and depressed to 80 per cent of basal by oestradiol treatment alone (P less than 0.001). Plasma prolactin was unaltered by the above treatments.

Animals↗
PubMed1982

Inhibition of arginine- and hypoglycemia- induced growth hormone release by acetate in dialyzed patients.

We have previously demonstrated that acetate suppresses the basal hypersecretion of growth hormone in diabetic and non-diabetic uremic patients. The present study was designed to clarify the potency and characteristics of the growth hormone suppressive effect of acetate by applying two powerful growth hormone stimuli: arginine infusion and insulin hypoglycemia. In four non-diabetic uremic and three diabetic uremic subjects, arginine infusion caused a rise in plasma growth hormone to 22.8 +/- 3.3 ng/ml and 22.0 +/- 5.6 ng/ml (mean +/- SEM, P less than 0.05). During hemodialysis against acetate buffered dialysis fluid and during a simultaneous acetate infusion, the response to arginine infusion was almost completely inhibited in both groups. In four uremic subjects insulin hypoglycemia elicited an increase in plasma growth hormone to 30.0 +/- 7.0 ng/ml (mean +/- SEM, P less than 0.05). During hemodialysis and acetate infusion the response to insulin hypoglycemia was again almost abolished. The glucagon and insulin responses were unaffected by hemodialysis as well as by acetate infusion. The results demonstrate the high degree of efficiency of the acetate induced growth hormone suppression comparable to that of glucose.

Acetates↗
PubMed1978

Preliminary in vitro and in vivo investigations on methylprednisolone and its acetate.

Sodium fluoride (6--8 mg/ml) inhibits hydrolysis of methylprednisolone acetate to methylprednisolone. An HPLC method for simultaneous determination of hydrocortisone, methylprednisolone and methylprednisolone acetate in plasma is presented. Analysis of plasma samples (containing NaF) for methylprednisolone acetate shows no significant change in concentration over extended periods of storage at -20 degrees C. In vitro hydrolysis of methylprednisolone acetate at 37 degrees C in human whole blood is rapid (average t1/2 = 19 min). In one cat, the bioavailabilities of methylprednisolone acetate rectally was 13% and of methylprednisolone (alcohol) rectally was 26%, relative to intravenous administration of methylprednisolone. In the same cat, the bioavailabilities of methylprednisolone acetate orally was 93% and of methylprednisolone was 82%, relative to intravenous administration of methylprednisolone. All samples collected after oral administration of methylprednisolone acetate to a human subject were found to contain only methylprednisolone (alcohol) indicating hydrolysis of the drug during absorption through the gastrointestinal membrane and/or in the liver. If the ester had the same half-life in blood in vivo as measured in vitro, it would have been measurable in plasma.

Acetates↗
PubMed1993

Plasma acetate levels in a group of obese diabetic, obese normoglycemic, and control subjects and their relationships with other blood parameters.

Acetate is a short-chain fatty acid derived from colonic fermentation of carbohydrate and dietary fiber, and from endogenous glucose and fatty acid metabolism in the liver. An impaired acetate metabolism has been reported in diabetic subjects. The aim of the study was to evaluate plasma acetate levels in a group of obese diabetic subjects, compared with obese normoglycemic subjects and normal control subjects. Eleven noninsulin-dependent diabetic patients taking oral antidiabetic drugs, eight obese normoglycemic subjects, and seven control subjects were studied. Liver, kidney, and gut functions were normal in all subjects. Blood acetate, glucose, insulin, and C-peptide were evaluated in all subjects. Acetate levels were significantly higher in the diabetic subjects than in obese normoglycemic and normal subjects. Significant correlations between HbA1c, glucose, and acetate levels, but not between acetate and C-peptide or insulin, were also observed.

Acetates↗
PubMed1996

Treatment of hypervascular small hepatocellular carcinoma with ultrasound-guided percutaneous acetic acid injection: comparison with segmental transcatheter arterial embolization.

OBJECTIVE: To compare the efficacy of ultrasound-guided percutaneous acetic acid injection and segmental transcatheter arterial embolization for hypervascular small hepatocellular carcinoma. METHODS: The prognosis of 40 patients with one to three angiographically hypervascular hepatocellular carcinoma smaller than 3 cm in diameter treated with either percutaneous acetic acid injection (25 patients) or transcatheter arterial embolization (15 patients) during the past 4.5 yr were analyzed retrospectively. RESULTS: After initial therapy, none of 25 patients treated with percutaneous acetic acid injection developed ascites, whereas 5 of 15 (33%) patients treated with transcatheter arterial embolization developed it (p < 0.01). All tumors became smaller once after each therapy. However, local recurrence (reenlargement of the original tumor) occurred in 1 of 29 (3%) tumors treated with percutaneous acetic acid injection and 11 of 22 (50%) tumors treated with transcatheter arterial embolization (p < 0.005). During the follow-up, 4 of 25 (16%) patients treated with percutaneous acetic acid injection and 10 of 15 (67%) patients treated with transcatheter arterial embolization died. The 1-, 2-, and 3-yr survival rate was 100, 94, and 83%, respectively, in patients treated with percutaneous acetic acid injection and 72, 65, and 39% in patients treated with transcatheter arterial embolization (p < 0.005). The cancer-free survival rate was also significantly better in the former than in the latter group (p < 0.005). CONCLUSIONS: Percutaneous acetic acid injection is superior to segmental transcatheter arterial embolization in the treatment of hypervascular small hepatocellular carcinoma.

Acetic Acid↗
PubMed1997

Imaging of the pancreas and related diseases with PET carbon-11-acetate.

UNLABELLED: The purpose of this study was to evaluate [1-11C]-acetate as a tracer for functional imaging of the pancreas and related diseases using position emission tomography (PET). METHODS: Thirty-three patients underwent 30 min of dynamic attenuation-corrected PET after intravenous administration of 740 MBq (20 mCi) of [1-11C]-acetate. RESULTS: The normal pancreas demonstrates prompt uptake of [1-11C]-acetate and is visualized as early as 2 min post-injection, with maximal activity achieved by 5 min. Subsequent clearance of tracer from the pancreas is slow relative to adjacent organs and background, such that by 10 min post-injection the pancreas is the most prominent organ in the imaging field of view. Pancreatic uptake of [1-11C]-acetate was unaffected by pancreatic endocrine insufficiency, but is absent in chronic pancreatitis complicated by exocrine insufficiency. Moderately reduced [1-11C]-acetate uptake was observed in acute uncomplicated pencreatitis. The level of tracer accumulation was substantially reduced in phlegmatous masses complicating pancreatitis and in chronic mass forming pancreatitis. Adenocarcinoma of the pancreas likewise demonstrated no significant uptake of [1-11C]-acetate. CONCLUSIONS: Accumulation of [1-11C]-acetate by the pancreas allows rapid metabolic imaging using PET, and may be a useful metabolic probe for the study of pancreatic physiology and disease.

Acetates↗
PubMed1998

Megestrol acetate as a biomodulator.

Megestrol acetate is a synthetic analog of progesterone. In general, megestrol acetate exerts its progesterone-like hormonal effect by binding to the progesterone receptor. It has been recognized that megestrol acetate can increase weight and improve some aspects of quality of life in cancer patients and in patients with the acquired immunodeficiency syndrome. This effect occurs in patients with or without concurrent chemotherapy or radiotherapy, through an as yet unknown mechanism. Recently, megestrol acetate has been shown to reverse, at least partially, multidrug resistance to doxorubicin and/or vincristine in cancer cell lines. This potentially beneficial effect has not yet been studied in clinical trials. This biological activity is thought to be mediated through the unique binding of megestrol acetate to p-glycoprotein. At least in vitro megestrol acetate can also enhance the cytotoxic effect of these two chemotherapeutic agents in some MDR-nonexpressing cell lines. These findings suggest that megestrol acetate deserves further preclinical and clinical studies to evaluate its potential role of enhancing cytotoxicity of chemotherapy and improving the quality of life of cancer patients.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2006

Platinum- and gold-catalyzed rearrangement reactions of propargyl acetates: total syntheses of (-)-alpha-cubebene, (-)-cubebol, sesquicarene and related terpenes.

Propargyl acetates, in the presence of catalytic amounts of late transition-metal salts such as PtCl(2) or AuCl(3), represent synthetic equivalents of alpha-diazoketones. This notion is corroborated by a concise approach to various sesquiterpene natural products starting from readily available substrates. Specifically, (+)-carvomenthone (17) is converted into propargyl acetate (S)-26 by a sequence involving Stille cross-coupling of its kinetic enol triflate 18, regioselective hydroboration/oxidation of the resulting 1,3-diene 19, and addition of an alkynyl cerium reagent to aldehyde 21 thus obtained. Since the latter step was found to be unselective, the configuration of the reacting propargyl acetate was unambiguously set by oxidation followed by diastereoselective transfer hydrogenation by using Noyori's catalyst 25. Compound (S)-26, on treatment with PtCl(2) in toluene, converted exclusively to the tricyclic enol acetate 27, which was saponified to give norcubebone 11 in excellent overall yield. The conversion of this compound into the sesquiterpene alcohol (-)-cubebol (6) was best achieved with MeCeCl(2) as the nucleophile, whereas the formation of the parent hydrocarbon (-)-alpha-cubebene (4) was effected in excellent yield by recourse to iron-catalyzed cross coupling methodology developed in this laboratory. Since norketone 11 has previously been transformed into (-)-beta-cubebene (5) as well as (-)-4-epicubebol 8, our approach constitutes formal total syntheses of these additional natural products as well. Along similar lines, the readily available propargyl acetates 1, 33 and 47 were shown to give access to 2-carene 44, sesquicarene 39, and episesquicarene 51 in excellent overall yields. In this series, however, the cycloisomerization reaction was best achieved with catalytic amounts of AuCl(3) in 1,2-dichloroethane as the solvent. In addition to these preparative results, our data provide some insight into the mechanism of these remarkable skeletal rearrangement reactions. Transformations of this type are likely triggered by initial coordination of the alkyne unit of the substrate to the carbophilic transition-metal cation. Formal attack of the alkene moiety onto the resulting pi-complex engenders the formation of an electrophilic cyclopropyl carbene species which subsequently reacts with the adjacent acetate unit to give the final product. The alternative phasing of events, implying initial attack of the acetate (rather than the alkene moiety) onto the metal-alkyne complex, is inconsistent with the stereochemical data obtained during this total synthesis campaign.

Journal Article↗
PubMed2003

Electrochemical deposition of hydroxyapatite with vinyl acetate on titanium implants.

A novel approach to electrochemical processing of hydroxyapatite (HA) coating was explored. Vinyl acetate was added in the electrolytes of calcium and phosphorous in order to improve the adhesion between HA coating and titanium substrate. X-ray powder diffractometer (XRD) spectra indicated that the vinyl acetate did not interfere with the deposition of HA on the surface of titanium cathodes. X-ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM) results revealed that both vinyl acetate and HA were deposited on the titanium cathodes. The vinyl acetate changed the HA crystalline morphology in the deposition layer. The shape and growth direction of the HA crystals in the coating with vinyl acetate differed from those of HA deposition along. The addition of vinyl acetate increased the coating strength considerably, even though further improvement is needed for clinical applications. Moreover, a preliminary study of the bioactivity showed that osteoblastic cells exhibited higher cell proliferation potential on the HA/vinyl acetate coating than on that of pure HA.

Adhesiveness↗
PubMed1995

Farnesyl acetate, a derivative of an isoprenoid of the mevalonate pathway, inhibits DNA replication in hamster and human cells.

Cells treated with compactin, an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, the enzyme which catalyzes the rate-limiting step of the mevalonate pathway, are arrested prior to the DNA synthesis (S) phase of the cell cycle. Identification of a specific pathway product or products with a role in DNA replication, however, has remained elusive. In this report we demonstrate that farnesyl acetate, a derivative of the key isoprenoid pathway intermediate farnesyl pyrophosphate, inhibits DNA replication in both Chinese hamster ovary cells and human (HeLa) cells. This effect is revealed by measurement of DNA content using fluorescence-activated cell sorter analysis and by measurement of [3H]thymidine incorporation. We show that cells treated with farnesyl acetate retain protein synthesis capacity as DNA replication is inhibited and remain intact as viewed with the vital stain propidium iodide. The inhibition of DNA replication by farnesyl acetate occurs in cells treated with high levels of compactin and in cells lacking HMG-CoA reductase. These results indicate that farnesyl acetate action is not dependent on metabolism through the isoprenoid pathway and is not the result of the loss of a metabolite required for replication nor the accumulation of a metabolite which is inhibitory. In addition, cells treated with farnesyl acetate for over 6 h are irreversibly blocked from progressing through S phase, a phenomenon which differs sharply from the results with compactin, removal of which results in synchronous progression through S phase. Farnesyl acetate also blocks protein prenylation in cells, to a degree comparable to a known farnesylation inhibitor, BZA-5B. We propose that farnesyl acetate is acting in a manner quite different from the metabolic block caused by compactin, causing a rapid and irreversible block of DNA replication.

Animals↗
PubMed1985

Metabolism and pharmacokinetics of vinyl acetate.

The hydrolysis of vinyl acetate (formation of acetic acid) has been studied in vitro with rat liver and lung microsomes, rat and human plasma and purified esterases (such as acetylcholine esterase, butyrylcholine esterase, carboxyl esterase). Characterization of the kinetic parameters revealed that rat liver microsomes and purified carboxyl esterase (from porcine liver) displayed the highest activity. In order to establish the rate of metabolism of vinyl acetate in vivo, rats were exposed in closed desiccator jar chambers, and gas uptake kinetics were studied. The decay of vinyl acetate was dose-dependent, indicating possible saturation of metabolic pathway(s). The maximal clearance (at lower concentrations) of vinyl acetate from the system (30 000 ml/h per kg body weight) was similar to the maximal ventilation rate in this species. This indicated that under conditions when metabolic enzymes are not saturated the metabolic rate is mainly determined by pulmonary uptake. The exposure of rats to vinyl acetate resulted in a transient exhalation of significant amounts of acetaldehyde into to the closed exposure system. This indicates the presence of this metabolic intermediate of vinyl acetate in the organism in vivo.

Animals↗
PubMed1990

Model studies on the analysis of pyruvic acid acetal-containing polysaccharides by the reductive-cleavage method.

The 4,6-O-(1-methoxycarbonylethylidene), -(hydroxyisopropylidene), and -(methoxyisopropylidene) acetals of methyl 2,3-di-O-methyl-alpha-D-glucopyranoside were subjected to reductive cleavage in the presence of triethylsilane and trimethylsilyl methanesulfonate-boron trifluoride etherate (Me3SiOMs-BF3.Et2O), BF3.Et2O, or trimethylsilyl trifluoromethanesulfonate (Me3SiOSO2CF3) and the mole fractions of products were determined as a function of reaction time. The 4,6-(1-methoxycarbonylethylidene) acetal was quite stable to reductive-cleavage conditions but isomerization of the initial R,S mixture of diastereomers to the more-stable S diastereoisomer was noted. In addition, a slow, regiospecific, reductive ring-opening of the acetal was observed to give 6-O-[1-(methoxycarbonyl)ethyl] derivatives. The 4,6-(hydroxyisopropylidene) acetal was very unstable under reductive-cleavage conditions. Both Me3SiOMs-BF3.Et2O and Me3SiOSO2CF3 catalyzed complete removal of the group, via the intermediate 6-[1-(hydroxymethyl)ethyl] ether, but BF3.Et2O gave a mixture of products. The 4,6-(methoxyisopropylidene) acetal was also very labile under reductive-cleavage conditions; Me3SiOMs-BF3.Et2O catalyzed complete removal of the acetal, via the intermediate 6-[1-(methoxymethyl)ethyl]ether, but the intermediate ether was quite stable in the presence of either BF3.Et2O or Me3SiOSO2CF3. It is concluded from these studies that polysaccharides bearing 4,6-O-(1-carboxyethylidene) substituents can be analyzed directly by sequential permethylation and reductive cleavage. It is proposed that the identity of the substituted monomer and the positions of substitution of the acetal can be determined by sequential permethylation, ester reduction, and reductive cleavage.

Kinetics↗
PubMed1992

Percutaneous absorption of benzyl acetate through rat skin in vitro. 2. Effect of vehicle and occlusion.

The effect of vehicle and occlusion on the in vitro percutaneous absorption of [methylene-14C]-benzyl acetate (1.7-16.6 mg/cm2) has been studied in diffusion cells using full thickness skin from male Fischer 344 rats. Absorption of neat benzyl acetate through rat skin occluded with parafilm was 49.3 +/- 2.0% (mean +/- SD, n = 4) after 48 hr. When benzyl acetate in ethanol was applied to the skin and the skin was occluded with parafilm, the extent of absorption at 48 hr was not significantly different from that after neat application. However at 6 hr, as the ethanol content of the application mixture was increased, the absorption of benzyl acetate through occluded skin was enhanced proportionally (r = 0.999). When phenylethanol was used as a vehicle, the extent of the benzyl acetate absorption through occluded skin at 48 hr was enhanced (P less than 0.05) compared with that after application neat; with 50% (v/v) phenyl-ethanol, absorption at 48 hr was 56.3 +/- 4.9%. However, this enhanced absorption did not correlate with the proportion of phenylethanol in the application mixture. When dimethylsulphoxide was used as a vehicle, the extent of absorption of benzyl acetate through occluded skin at 48 hr was enhanced (P less than 0.05) compared with that after application neat (absorption was 59.3 +/- 3.7% of the applied dose when 50% (v/v) dimethylsulphoxide was used). As the dimethylsulphoxide content of the application mixture was increased, the absorption of benzyl acetate was enhanced proportionally. Occlusion of the skin surface with parafilm often significantly enhanced absorption (P less than 0.05), although the effect varied with time and vehicle. In general, the degree of any enhanced absorption caused by the use of a vehicle or occlusion of the skin was small, and, in most cases, would be unlikely to be toxicologically significant.

Animals↗
PubMed1986

Enzymatic synthesis of a false cholinergic neurotransmitter: diethylaminoethyl acetate as a muscarinic agonist analog of acetylcholine.

Diethylaminoethyl acetate, an acetylcholine analog, was formed upon the incubation of diethylaminoethanol and acetyl-CoA with bovine brain choline acetyltransferase (acetyl-CoA: choline O-acetyltransferase; EC 2.3.1.6). The new product co-chromatographed with authentic diethylaminoethyl acetate on thin layer plates, and its formation was proportional to the duration of incubation and enzyme concentrations. When tested on guinea-pig ileum, diethylaminoethyl acetate was found to be an agonist with an ED50 of 1.3 X 10(-4) M, compared to an ED50 of 2.0 X 10(-7) M for acetylcholine. The contraction of guinea-pig ileum induced by diethylaminoethyl acetate was blocked by atropine. Moreover, diethylaminoethyl acetate induced a secretion of alpha-amylase from isolated pancreatic acini cells; this effect was also blocked by atropine. It is entirely possible that diethylaminoethyl acetate can be a false cholinergic transmitter generated in vivo when drugs such as aprophen or procaine are administered to animals, since either of these drugs can undergo enzymatic hydrolysis to generate diethylaminoethanol. A method for the synthesis of radioactive diethylamino [1,2-14C]ethyl acetate was also described.

Acetylcholine↗
PubMed1992

The identification of related substances in 9 alpha-fluoroprednisolone-21 acetate by means of high-performance liquid chromatography with diode array detector and mass spectrometry.

A method for the analysis and identification of the principal related substances in 9 alpha-fluoroprednisolone acetate is described. This compound has been chosen as a model for the investigation of related substances which can be originated in the general procedure for introducing a fluorine substituent at position 9 of a corticosteroid molecule. HPLC procedures, both in reversed and in normal phase were used; a rapid scanning UV detector which allows direct spectrophotometric data to be obtained on chromatographic peaks, proved to be a tool of great importance. Thus, after reversed-phase chromatographic separation and observation of the UV spectra and their respective second derivatives, it was possible to characterize some of the principal effective and potential related substances such as 9 alpha-fluorohydrocortisone acetate, 9 alpha-bromoprednisolone acetate, 9 beta, 11 beta-epoxyprednisolone acetate and 9(11)-dehydroprednisolone acetate, emerging as chromatographic peaks. Identification of 9 alpha-bromoprednisolone acetate and of 9 alpha-fluorohydrocortisone acetate which proved to be the most significant impurities, was confirmed by means of an exhaustive study of the mass spectra of these substances conveniently isolated by normal-phase HPLC. The chromatographic, spectrophotometric and mass-spectrometric characteristics of the studied compounds are reported.

Chromatography, High Pressure Liquid↗
PubMed1996

Effect of nomegestrol acetate on estrone-sulfatase and 17beta-hydroxysteroid dehydrogenase activities in human breast cancer cells.

It is well recognized that estradiol (E2) is one of the most important hormones supporting the growth and evolution of breast cancer. Consequently, to block this hormone before it enters the cancer cell or in the cell itself, has been one of the main targets in recent years. In the present study we explored the effect of the progestin, nomegestrol acetate, on the estrone sulfatase and 17beta-hydroxysteroid dehydrogenase (17beta-HSD) activities of MCF-7 and T-47D human breast cancer cells. Using physiological doses of estrone sulfate (E1S: 5 x 10(-9)M), nomegestrol acetate blocked very significantly the conversion of E1S to E2. In the MCF-7 cells, using concentrations of 5 x 10(-6)M and 5 x 10(-5) M of nomegestrol acetate, the decrease of E1S to E2 was, respectively, -43% and -77%. The values were, respectively, -60% and -71% for the T-47D cells. Using E1S at 2 x 10(-6) M and nomegestrol acetate at 10(-5) M, a direct inhibitory effect on the enzyme of -36% and -18% was obtained with the cell homogenate of the MCF-7 and T-47D cells, respectively. In another series of studies, it was observed that after 24 h incubation of a physiological concentration of estrone (E1: 5 x 10(-9)M) this estrogen is converted in a great proportion to E2. Nomegestrol acetate inhibits this transformation by -35% and -85% at 5 x 10(-7)M and 5 x 10(-5)M, respectively in T-47D cells; whereas in the MCF-7 cells the inhibitory effect is only significant, -48%, at 5 x 10(-5)M concentration of nomegestrol acetate. It is concluded that nomegestrol acetate in the hormone-dependent MCF-7 and T-47D breast cancer cells significantly inhibits the estrone sulfatase and 17beta-HSD activities which converts E1S to the biologically active estrogen estradiol. This inhibition provoked by this progestin on the enzymes involved in the biosynthesis of E2 can open new clinical possibilities in breast cancer therapy.

Breast Neoplasms↗