Estrogenic action of estriol fatty acid esters

Recent studies suggest that, estriol, like estradiol, is biosynthetically esterified with fatty acids. We have synthesized the stearate estriol, at C-16 alpha, C-17 beta and the diester, C-16 alpha,17 beta and tested these D-ring esters for their estrogenic action both in vivo and in vitro, comparing them to estradiol, estriol and estradiol-17-stearate. None of the estriol esters bind to the estrogen receptor. They are only weakly estrogenic in a microtiter plate estrogen bioassay: stimulation of alkaline phosphatase in the Ishikawa endometrial cells. However, both estriol monoesters are extremely potent estrogens when injected subcutaneously (in aqueous alcohol) into ovariectomized mice. Compared to the free steroids, they produced a dramatically increased uterine weight with a greatly prolonged duration of stimulation. The 16 alpha,17 beta-diester also induced a protracted uterotrophic response, but the stimulation of uterine weight was comparatively low. Since the esters of estradiol and estriol do not bind to the estrogen receptor, their estrogenic signal must be generated through the action of esterase enzymes. These naturally occurring esters have the potential of being extremely useful pharmacological agents for long-lived estrogenic stimulation.     

Red blood cell fatty acid ethyl esters: a significant component of fatty acid ethyl esters in the blood

Although alcohol abuse is known to cause an array of ethanol-induced red blood cell (RBC) abnormalities, the underlying molecular mechanisms remain poorly understood. Fatty acid ethyl esters (FAEEs) are toxic, nonoxidative ethanol metabolites that have been found in blood, plasma, and tissues. Because FAEEs have been shown to be incorporated into phospholipid bilayers, we conducted a controlled ethanol intake study to test the hypothesis that FAEEs accumulate and persist within RBCs following ethanol ingestion. We demonstrated that RBC FAEEs account for approximately 5% to 20% of total whole-blood FAEEs, and that the fatty acid composition of FAEEs in RBCs and plasma are different and vary differently over time. These data indicate that a significant percentage of FAEEs in the blood is associated with RBCs and that the metabolism of RBC FAEEs and that of plasma FAEEs (bound to albumin or lipoproteins) are largely independent.     

Two-column gas-liquid chromatography of fatty acid methyl esters

Fatty acid methyl esters were separated into fractions according to chain length on a nonpolar gas-liquid chromatographic column. These fractions were collected and rechromatographed on a polar column. Temperature programming was used in both cases. Data are given for the accuracy of the double procedure applied to a synthetic mixture.     

The anticlastogenic potential of fatty acid methyl esters

To test for possible anticlastogenic effects of fatty acids, the methyl esters of fatty acids--short-chain to long-chain--were examined on busulfan in Chinese hamster bone-marrow cells using the chromosome aberration test. When the experimental animals were treated with fatty acid esters and the mutagen, the chromosome-breaking actions of busulfan were not modulated by the short-chain fatty acids, but the fatty acids from lauric acid (C12) up to nonadecanoic acid (C19) reduced the rate of aberrant metaphases from 9.4 to about 3% at doses of 100 mg/kg and less. Other chemical properties of the fatty acids (saturated or not, number of double bonds, even- or odd-numbered) had no influence on the anticlastogenic effects. The only exceptions to this rule were arachidonic acid, which had no effect, and gamma-linolenic acid, which had no consistent effect on the action of busulfan.     

Growth inhibitory properties of lactose fatty acid esters

Sugar esters are biodegradable, nonionic surfactants which have microbial inhibitory properties. The influence of the fatty acid chain length on the microbial inhibitory properties of lactose esters was investigated in this study. Specifically, lactose monooctanoate (LMO), lactose monodecanoate (LMD), lactose monolaurate (LML) and lactose monomyristate (LMM) were synthesized and dissolved in both dimethyl sulfoxide (DMSO) and ethanol. Minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) were determined in growth media. LML was the most effective ester, exhibiting MIC values of <0.05 to <5 mg/ml for each Gram-positive bacteria tested (Bacillus cereus, Mycobacterium KMS, Streptococcus suis, Listeria monocytogenes, Enterococcus faecalis, and Streptococcus mutans) and MBC values of <3 to <5 mg/ml for B. cereus, M. KMS, S. suis, and L. monocytogenes. LMD showed MIC and MBC values of <1 to <5 mg/ml for B. cereus, M. KMS, S. suis, L. monocytogenes, and E. faecalis, with greater inhibition when dissolved in ethanol. LMM showed MIC and MBC values of <1 to <5 mg/ml for B. cereus, M. KMS, and S. suis. LMO was the least effective showing a MBC value of <5 mg/ml for only B. cereus, though MIC values for S. suis and L. monocytogenes were observed when dissolved in DMSO. B. cereus and S. suis were the most susceptible to the lactose esters tested, while S. mutans and E. faecalis were the most resilient and no esters were effective on Escherichia coli O157:H7. This research showed that lactose esters esterified with decanoic and lauric acids exhibited greater microbial inhibitory properties than lactose esters of octanoate and myristate against Gram-positive bacteria.     

Long-acting estrogenic responses of estradiol fatty acid esters

Estradiol esters at C-17 and C-3 with palmitic, stearic and oleic acids were chemically synthesized and then evaluated for their long-acting estrogenic responses in ovariectomized rats. The duration of the biological effects was measured after a single subcutaneous dose of 0.1 mumol of each ester and compared with those observed with 17 beta-estradiol, estradiol 3-benzoate and estradiol 17-enanthate. Vaginal citology, uterophyc action, serum gonadotropins inhibition and 17 beta-estradiol levels were measured 0, 5, 10, 20, 30 and 60 days after injection. The results disclosed that most of the estradiol derivatives evaluated exhibited a long-acting estrogenic action. However, the monoesters at C-17 showed longer effects that monoesters at C-3, while the estradiol diesters exhibited the shortest effects. In addition as shown by its low serum levels, all estradiol esters with unsaturated fatty acids show a decreased E2 absorption. The overall results indicated that esterification of E2 with long chain fatty acids provided long-acting properties to it, being higher with C-17 esters. Whether some of these compounds could be employed in substitutive endocrine therapy remains to be established.     

Synthesis and properties of fatty acid starch esters

Being completely bio-based, fatty acid starch esters (FASEs) are attractive materials that represent an alternative to crude oil-based plastics. In this study, two synthesis methods were compared in terms of their efficiency, toxicity and, especially, product solubility with starch laurate (C₁₂) as model compound. Laurates (DS > 2) were obtained through transesterification of fatty acid vinylesters in DMSO or reaction with fatty acid chlorides in pyridine. The latter lead to higher DS-values in a shorter reaction time. But due to the much better solubility of the products compared to lauroyl chloride esterified ones, vinylester-transesterification was preferred to optimize reaction parameters, where reaction time could be shortened to 2 h. FASEs C₆–C₁₈ were also successfully prepared via transesterification. To determine the DS of the resulting starch laurates, the efficient ATR-IR method was compared with common methods (elementary analysis, ¹H NMR). Molar masses (M_w) of the highly soluble starch laurates were analyzed using SEC-MALLS (THF). High recovery rates (>80%) attest to the outstanding solubility of products obtained through transesterification, caused by a slight disintegration during synthesis. Particle size distributions (DLS) demonstrated stable dissolutions in CHCl₃ of vinyl laurate esterified – contrary to lauroyl chloride esterified starch. For all highly soluble FASEs (C₆–C₁₈), formation of concentrated solutions (10 wt%) is feasible.     

Lipase-catalysed synthesis of glucose fatty acid esters in tert-butanol

Synthesis of 6-O-acylate--d-glycopyranose from underivatised substrates in anhydrous tert-butanol was achieved using immobilised lipases from Candida antarctica and Mucor miehei. Except for acetic acid, the initial reaction rates with the C. antarctica lipase were independent of acyl donor chain lengths and in a range of 3.9±0.4 mol glucose converted min–1 g enzyme preparation. The catalytic activity of the M. miehei lipase increased with increasing acyl donor chain length with a maximum for stearic acid of 0.45 mol min–1 g. Using maltose as substrate, the catalytic activity decreased by a factor of 48 and 20 with the lipase from C. antarctica and M. miehei, respectively, while with maltotriose no reaction was observed.     

Triterpene fatty acid esters and flavonoids from Inula britannica

Two new triterpene fatty acid esters, 3β,16β-dihydroxylupeol 3-palmitate and 3β,16β-dihydroxylupeol 3-myristate, and a new kaempferol derivativ     

Biocatalytic processes for the production of fatty acid esters

A comparative study of the oleyl oleate production using conventional and enzymatic catalysts has been carried out. The present paper describes the flow diagrams for these processes and compares operation conditions for batch reaction and the downstream proceedings. In addition, continuous and batch processes have been studied. In order to compare the different processes three major points are considered: product properties improvements, operation improvements and improvements on safer and environmental aspects. Experience has shown that biocatalyst is in favour only when most of these issues are far positive for biocatalyst. Enzymatic catalysts involve simpler processes carried out under milder reaction conditions.     

Microwave-assisted synthesis of deuterium labeled estrogen fatty acid esters

Deuterated analogs of estrogen fatty acid esters are needed as internal standards for isotope dilution GC/MS analyses. We have developed a rapid and efficient synthesis for 2,4,16,16-D4-estrone palmitate, stearate, oleate, linoleate, and linolenate and the corresponding 2,4,16,16,17alpha-D5-estradiol fatty acid 17-mono and 3,17-diesters using analogous fatty acid chlorides or fatty acid anhydrides and 4-(dimethylamino)pyridine under microwave irradiation. Chemoselective hydrolysis of fatty acid diesters was carried out by KOH in t-BuOH.     

Occurrence of fatty acid lower-alkyl esters in euonymus fruits

Small amounts of a mixture of fatty acid lower-alkyl esters (FALAEs) were obtained from chloroform extracts of the fruit arils and seeds of four euonymus species (Euonymus sp., Celastraceae). The FALAEs were the products of biosyntheses in the cell rather than experimental artifacts. By using GC-MS, this mixture was shown to contain a total of 19 individual FALAE species comprising four separate fractions, viz. methyl (FAMEs), ethyl (FAEEs), n-propyl, and n-butyl FA esters. Fruit FALAEs included mainly FAEEs and, to a lesser extent, FAMEs, while the n-propyl and n-butyl FA esters, which occurred less frequently, were found here for the first time as the plant products. The FALAE acid components included C₁₄-C₁₈ saturated, mono-, di-, and trienoic FAs with the predominance of ubiquitous linoleic, oleic, palmitic, and, in some cases, also α-linolenic acid. The indices of qualitative and quantitative composition of separate FALAE fractions varied considerably depending on the plant species, fruit part (aril or seed), and the extent of fruit maturity. It can be supposed that, in some euonymus species, FAMEs and FAEEs are formed at the expense of the same FA pool characteristic for a given species. As a whole, euonymus FALAEs and triacylglycerols seem to be synthesized from different FA pools. Discussed is the physiological significance of FALAE biosynthesis in plant metabolism, possible pathways of this biosynthesis, as well as the perspectives of further investigations of FALAEs of plant origin.     

6-d-glucopyranosyl fatty acid esters from Brassica napus pollen

6-d-Glucopyranosyl esters of palmitic, oleic, linoleic and linolenic acids were identified in Brassica napus (rape) pollen. These esters are inactive as plant growth promoters in the bean second-internode bioassay.     

Preparation of fatty acid methyl esters for gas-liquid chromatography

A convenient method using commercial aqueous concentrated HCl (conc. HCl; 35%, w/w) as an acid catalyst was developed for preparation of fatty acid methyl esters (FAMEs) from sterol esters, triacylglycerols, phospholipids, and FFAs for gas-liquid chromatography (GC). An 8% (w/v) solution of HCl in methanol/water (85:15, v/v) was prepared by diluting 9.7 ml of conc. HCl with 41.5 ml of methanol. Toluene (0.2 ml), methanol (1.5 ml), and the 8% HCl solution (0.3 ml) were added sequentially to the lipid sample. The final HCl concentration was 1.2% (w/v). This solution (2 ml) was incubated at 45°C overnight or heated at 100°C for 1–1.5 h. The amount of FFA formed in the presence of water derived from conc. HCl was estimated to be <1.4%. The yields of FAMEs were >96% for the above lipid classes and were the same as or better than those obtained by saponification/methylation or by acid-catalyzed methanolysis/methylation using commercial anhydrous HCl/methanol. The method developed here could be successfully applied to fatty acid analysis of various lipid samples, including fish oils, vegetable oils, and blood lipids by GC.     

Lipase-catalyzed regioselective preparation of fatty acid esters of hydrocortisone

A series of fatty acid derivatives of hydrocortisone has been prepared by an enzymatic methodology. Nine 21-monoacyl products and one 3,11,17-triacetyl derivative, nine of them novel compounds, were obtained in a highly regioselective way through lipase-catalyzed esterification, transesterification and alcoholysis reactions. The influence of various reaction parameters such as acylating agent: substrate ratio, enzyme: substrate ratio, solvent, temperature and nature of acylating agent and alcohol was evaluated. Among the tested lipases, Candida antarctica lipase appeared to be the most appropriate and showed a high efficient behavior especially in a one-pot transesterification. The advantages presented by this methodology, such as mild reaction conditions and low environmental impact, make the biocatalysis a convenient way to prepare acyl derivatives of hydrocortisone. These lipophilic compounds are potential products in the pharmaceutical industry.