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PubMed1991

Isolation of a novel arachidonic acid metabolite 3-hydroxy-5,8,11,14-eicosatetraenoic acid (3-HETE) from the yeast Dipodascopsis uninucleata UOFs-Y128.

When arachidonic acid (AA) is added to the yeast Dipodascopsis uninucleata UOFS Y128, one of the major metabolites isolated and purified with the help of thin layer chromatography (TLC) and high performance liquid chromatography (HPLC) is 3-hydroxy-5,8,11,14-eicosatetraenoic acid (3-HETE). The structure of this new AA metabolite was elucidated mainly by electron impact (EI) mass spectrometry (MS). Strikingly, the formation of this new metabolite was found to be inhibited by aspirin.

Arachidonic Acid↗

PubMed1998

Role of ceramide 1 in the molecular organization of the stratum corneum lipids.

The main barrier of the skin is formed by the lipids in the apical skin layer, the stratum corneum (SC). In SC mainly ceramides (CER), free fatty acids (FFA) and cholesterol (CHOL) are present. The CER are composed of at least six different fractions. CER 1 has an exceptional molecular structure as it contains a linoleic acid linked to a long-chain omega-hydroxy acid (C > 30). The SC lipids are organized in two lamellar phases with periodicities of approximately 6 and 13 nm, respectively. Recent studies revealed that ceramides isolated from pig SC mixed with cholesterol in confined ratios mimic stratum corneum lipid phase behavior closely (Bouwstra, J.A., et al. 1996. J. Lipid Res. 37: 999-1011). In this paper the role of CER 1 for the SC lipid lamellar organization was studied. For this purpose lipid phase behavior of mixtures of CHOL and total ceramide fraction was compared with that of mixtures of CHOL and a ceramide mixture lacking CER 1. These studies showed that in the absence of CER 1 almost no long periodicity phase was formed over a wide CHOL/CER molar ratio. A model is proposed for the molecular arrangement of the two lamellar phases. This model is based on the dominant role CER 1 plays in the formation of the long periodicity phase, electron density distribution calculations, and observations, such as i) the bimodal distribution of the fatty acid chain lengths of the ceramides, ii) the phase separation between long-chain ceramides and short-chain ceramides in a monolayer approach, and iii) the absence of swelling of the lamellae upon increasing the water content organization in SC. In this molecular model the short periodicity phase is composed of only two high electron density regions indicating the presence of only one bilayer, similar to that often found in phospholipid membranes. The molecular arrangement in the long periodicity phase is very exceptional. This phase most probably consists of two broad and one narrow low electron density regions. The two broad regions are formed by partly interdigitating ceramides with long-chain fatty acids of approximately 24-26 C atoms, while the narrow low-electron density region is formed by fully interdigitating ceramides with a short free fatty acid chain of approximately 16 to 18 C atoms.

Animals↗

PubMed2002

Gas chromatography/mass spectrometric assay of endogenous cellular lipid peroxidation products: quantitative analysis of 9- and 10-hydroxystearic acids.

A sensitive, specific, accurate and reproducible gas chromatography/mass spectrometry method was developed for the assay of 9- and 10-hydroxystearic acids in samples obtained as cell extracts. The preparation of the samples required specific procedures to allow the analysis of both the free and the conjugated hydroxy acids as the corresponding methyl esters. The quantification used propyl-paraben as the internal standard and monitoring of a specific fragment of each isomeric hydroxy acid methyl ester, and allowed quantification of the conjugate and the free fractions of both 9- and 10-hydroxystearic acids. This method is suitable for identification and quantification (LOQ 1.8 and 4.4 ng, respectively) of these important metabolites of lipid peroxidation. In particular the development of an assay for the free 9-hydroxystearic acid methyl ester makes the method a reliable analytical tool for investigations of the role of this metabolite in the mechanisms of tumour cell proliferation.

Calibration↗

PubMed1984

Characteristics of leukotriene (LT) and hydroxy eicosatetraenoic acid (HETE) synthesis in human leukocytes in vitro: effect of arachidonic acid concentration.

Suspensions of human blood leukocytes and platelets were stimulated with the ionophore A23187 in the presence of increasing concentrations of arachidonic acid. Nine metabolites of the 5-, 12- and 15-lipoxygenase and the cyclooxygenase pathways were analyzed by high performance liquid chromatography in order to study the rate-limiting steps and other characteristics of their biosynthesis. The data indicate that the LTA4 hydrolase and the LTA4 glutathione transferase activities are respectively the limiting factors in the synthesis of LTB4 and LTC4. At high substrate concentrations (5 X 10(-5)M and above), the 5-lipoxygenase activity was inhibited whereas the synthesis of the 15-HETE (15-lipoxygenase product) increased linearly up to the highest concentration tested (3 X 10(-4)M). The data also indicate that contrary to 5-HETE and LTs, 15-HETE is not formed upon stimulation with the ionophore, but only following incubation with exogenous arachidonic acid (20 microM and above), pointing out major differences in the synthesis of 5- and 15-lipoxygenase products.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗

PubMed1993

Mechanisms of polymer degradation in implantable devices. I. Poly(caprolactone).

Poly(caprolactone) is a biodegradable aliphatic (poly(alpha-hydroxy acid), with important applications in the field of human therapy, due to its biocompatibility and bioresorbability. The degradation of poly(alpha-hydroxy acids) depends on chemical hydrolysis, but there is much interest in the precise mechanisms, including the role of free radicals, especially oxygen free radicals and their role in human disease. The hydrolytic degradation of poly(caprolactone) in aqueous environments was used as the control in a study of the effects of hydroxyl radicals in aqueous solutions. Different methods (GPC, DSC, SEM) were employed to investigate the mechanism of degradation of this semicrystalline physiologically absorbable polymer. The data indicate that hydroxyl radical is likely to be a major factor in the degradation of this polymer.

Biocompatible Materials↗

PubMed1977

Sterol and bile acid metabolism during development: 2. Identification of 3beta-hydroxy-5-cholenoic acid (an intermediate in alternate pathway of bile acid synthesis) in newborn and fetal guinea pig.

3beta-hydroxy-5-cholenoic acid was found in the bile and feces of newborn and fetal guinea pigs. The identity of this compound was confirmed by gas chromatography and mass spectrometry. This finding suggests that the formation of chenodeoxycholic acid through 3beta-hydroxy-5-cholenoic acid is intermediate in the early life of guinea pigs. Thus, it provides a useful model for studying the details of regulatory factors and significance of this pathway. This study also revealed that, unlike the adult guinea pig, the newborn guinea pig has significant amounts of glycine conjugates of bile acid.

Animals↗

PubMed1975

Synthesis and absolute stereochemistry of 5-alkyl-5-(3'-hydroxy-1'-methylbutyl)barbituric acid and 5-alkyl-5-(3'-hydroxy-1'-methylbutyl)-2-thiobarbituric acids.

5-Alkyl-5-(3-hydroxy-1-methylbutyl) barbituric acid (2) and 5-alkyl-5-(3-hydroxy-1-methylbutyl)-2-thiobarbituric acids (3) are matabolites of 5-alkyl-5-(2-pentyl) barbituric acid and 5-alkyl-5-(2-pantyl)-2-thiobarbituric acid, respectively. We have synthesized the four possible optical isomers of 2 and 3 by a procedure which established the absolute stereochemistry of each isomer. The two racemic pairs in each case were also prepared. The properties of these synthetic samples of 2 and 3 of known stereochemistry are compared to the properties of 2 and 3 which have been isolated from metabolism studies.

Barbiturates↗

PubMed1988

Basis of the stereospecific preference of porcine kidney fibroblasts for D-2-hydroxy-4-methylthiobutanoic acid as a source of methionine.

In previous studies we have found that porcine kidney fibroblasts will grow in medium containing D-2-hydroxy-4-methylthiobutanoic acid (D-methionine hydroxy analogue, D-MHA) as the sole source of methionine but not in medium containing the L-isomer (L-MHA) alone. The fibroblasts have been found to have both D-2-hydroxy acid dehydrogenase (EC 1.1.99.6), which uses D-MHA as substrate (Km = 6.0 mM) and L-2-hydroxy acid oxidase (EC 1.1.3.1), which uses L-MHA as substrate (Km = 7.1 mM). These two activities should make it possible for the fibroblasts to grow on either isomer. Only one protein band with L-2-hydroxy acid oxidase activity can be detected with enzyme-specific staining of protein profiles obtained after polyacrylamide gel electrophoresis. The enzyme L-2-hydroxy acid oxidase from porcine kidney has properties that are different from the two porcine isozymes reported previously by others. Passage of DL-[14C]MHA at tracer levels into the porcine kidney fibroblasts in culture is reduced to 31% of control in the presence of 3.75 mM D-MHA, 86% of control with 3.75 mM L-MHA and 65% with 3.75 mM D-lactate but is not affected by up to 3.75 mM L-lactate. It appears that the transport specificity is the basis for the growth promotion of kidney fibroblasts by the D-isomer of MHA as opposed to L-MHA when each is used as the sole source of methionine.

Alcohol Oxidoreductases↗

PubMed1982

A radioimmunoassay for VP16-213 in plasma.

A radioimmunoassay for the semi-synthetic podophyllotoxin VP16-213 has been developed which is suitable for pharmacokinetic studies of the drug. A high titre antiserum was produced in a sheep in response to a VP16-213-BSA conjugate prepared using sodium periodate. Podophyllotoxin does not cross-react with the antiserum and VM26 cross-reacts to only a small extent (less than 0.6%). In the absence of a high specific activity tritium label, a radioiodinated histamine ligand was produced which was only partially displaced from antibody by native drug. VP16-213 can be measured in plasma without prior drug extraction with a theoretical limit of detection of 5-10 micrograms/l. VP16-213 cis (picro) hydroxy acid is recognised by the antiserum to a greater extent than the drug itself. Thus, in order to eliminate any interference from the trans hydroxy acid metabolite chloroform extraction of plasma samples was carried out.

Animals↗

PubMed1990

Designs for a broad substrate specificity keto acid dehydrogenase.

Variations have been made to the structure of the nicotinamide adenine dinucleotide (NAD) dependent L-lactate dehydrogenase from Bacillus stearothermophilus at regions of the enzyme that we believe determine specificity toward different alpha-hydroxy acids (RCHOHCOO-, R = CH3, C2H5, etc.). Two regions of LDH that border the active site (but are not involved in the catalytic reaction) were altered in order to accommodate substrates with hydrophobic side chains larger than that of the naturally preferred substrate, pyruvate (R = CH3). The mutations 102-105GlnLysPro----MetValSer and 236-237AlaAla----GlyGly were made to increase the tolerance for large hydrophobic substrate side chains. The triple and double mutants alone gave little improvement for branched-chain-substituted pyruvates. The five changes together produced a broader substrate specificity alpha-hydroxy acid dehydrogenase, with a 55-fold improved kcat for alpha-ketoisocaproate to a value about 1/14 that of the native enzyme for pyruvate. Rational protein engineering enabled coupled changes in enzyme structure to be obtained with greater probability of success than random mutagenesis.

Amino Acid Sequence↗

PubMed1993

Divinyl ethers and hydroxy fatty acids from three species of Laminaria (brown algae).

Three species of brown algae, Laminaria sinclairii, L. saccharina and L. setchellii, have been investigated for the presence of oxylipins. From one, L. sinclairii, three new divinyl ether fatty acids have been characterized as methyl ester derivatives (methyl 12-[1'(Z),3'(Z)-hexadienyloxy]-6(Z), 9(Z),11(E)-dodecatrienoate, methyl 12-[1'(Z),3'(Z)-hexadienyloxy]-9(Z), 11(E)-dodecadienoate, and methyl 14-[1'(Z),3'(Z)-hexadienyloxy]- 5(Z),8(Z),11(Z),13(E)-tetradecatetraenoate) by a variety of spectroscopic methods. In addition, one new [13(S)-hydroxy-6(Z),9(Z),11(E),15(Z)-octadecatetraenoic acid] and four known monohydroxy polyunsaturated fatty acids have been isolated from all three species as their methyl ester derivatives. The occurrence of these compounds in brown algae strongly suggests that these organisms possess an active lipoxygenase(s) with omega 6 specificity.

Fatty Acids↗

PubMed2004

Chemical peels: their place within the range of resurfacing techniques.

The photoaging index has been developed to determine the level of skin rejuvenation required to reduce the visible signs of aging. Minor photoaging is reversed with free-radical avoidance and peeling with a topical skin care regimen consisting of buffing grains, alpha-hydroxy acid normalizing tonics and vitamin A conditioning lotions. The reversal of moderate photoaging requires the addition of light-to-moderate peels using alpha-hydroxy acids combined with microdermabrasion. For the more advanced case the Jessner/trichloroacetic acid (TCA) combination peel (Monheit peel) is used which can be repeated once to twice a year. Laser resurfacing is especially useful to shrink the collagen and produce a 'face-lift bypass'. The phenol peel remains the standard to reverse heavy lines. A new modified formula (Hetter) is used which contains less phenol and less croton oil. Dermabrasion is helpful for removing multiple actinic keratosis. With this combination of skin care, chemical peels, and dermabrasion it is possible to reverse the photoaging index.

Chemexfoliation↗

PubMed1985

Effects of glutamic acid analogues on identifiable giant neurones, sensitive to beta-hydroxy-L-glutamic acid, of an African giant snail (Achatina fulica Férussac).

The effects of the seven glutamic acid analogues, alpha-kainic acid, alpha-allo-kainic acid, domoic acid, erythro-L-tricholomic acid, DL-ibotenic acid, L-quisqualic acid and allo-gamma-hydroxy-L-glutamic acid were examined on six identifiable giant neurones of an African giant snail (Achatina fulica Férussac). The neurones studied were: PON (periodically oscillating neurone), d-RPLN (dorsal-right parietal large neurone), VIN (visceral intermittently firing neurone), RAPN (right anterior pallial neurone), FAN (frequently autoactive neurone) and v-RCDN (ventral-right cerebral distinct neurone). Of these, d-RPLN and RAPN were excited by the two isomers (erythro- and threo-) of beta-hydroxy-L-glutamic acid (L-BHGA), whereas PON, VIN, FAN and v-RCDN were inhibited. L-Glutamic acid (L-Glu) had virtually no effect on these neurones. alpha-Kainic acid and domoic acid showed marked excitatory effects, similar to those of L-BHGA, on d-RPLN and RAPN. Their effective potency quotients (EPQs), relative to the more effective isomer of L-BHGA were: 0.3 for both substances on d-RPLN, and 1 for alpha-kainic acid and 3-1 for domoic acid on RAPN. alpha-Kainic acid also had excitatory effects on FAN and v-RCDN (EPQ for both: 0.3), which were inhibited by L-BHGA but excited by gamma-aminobutyric acid (GABA). Erythro-L-tricholomic acid showed marked effects, similar to those of L-BHGA, on VIN (EPQ: 0.3) and RAPN (EPQ: 3-1), but produced weaker effects on PON and d-RPLN (EPQ: 0.1). DL-Ibotenic acid produced marked effects, similar to those of L-BHGA, on PON, VIN (EPQ for both: 1) and RAPN (EPQ: 1-0.3), but had weak effects on d-RPLN (EPQ: less than 0.1) and FAN (EPQ: 0.1). It had excitatory effects on v-RCDN (EPQ: 0.1). This neurone was inhibited by L-BHGA but excited by GABA. L-Quisqualic acid showed the same effects as L-BHGA on all of the neurones examined (EPQ range 30-0.1). It was the most potent of the compounds tested on RAPN (EPQ: 30-10), FAN (EPQ: 30) and v-RCDN (EPQ: 3). alpha-Allo-kainic acid and allo-gamma-hydroxy-L-glutamic acid had no obvious effect on any of the neurones examined. As described above, the responses of the neurones examined to these substances varied widely. However, L-quisqualic acid generally had effects on the neurones similar to those of L-BHGA; the L-BHGA-excited neurones were also excited by alpha-kainic acid and domoic acid.

Animals↗

PubMed2006

Some non-equilibrium phenomena in the malic acid/water/Polysorbate 81 system.

Topical formulations undergo radical structural changes after application and the action on the skin is not directly related to the original structure of the formulation. This fact has been well established in the scientific literature. However, and more essential, is the fact that these changes in the formulation structure are not equilibrium ones. Especially so, with the hydroxy acids, which are widely used in cosmetic and dermatological treatment of skin. The article reports the first investigation into the non-equilibrium conditions in a hydroxy acid system. Different phases in the title system, which were not in mutual equilibrium, were brought in contact while avoiding convection. The transfer of substance between them was estimated from the changes in volume of each phase. The results showed, unexpectedly, that the systems were far from equilibrium even after prolonged times in contact. The kinetics of the changes varied to significant degree, from extremely slow, when solid phases were involved to fast for liquid phases. In one case was observed a separated layer, which was not found in the phase diagram under equilibrium conditions.

Chemistry, Pharmaceutical↗

PubMed1982

Catechol O-methyltransferase. 11. Inactivation by 5-hydroxy-3-mercapto-4-methoxybenzoic acid.

5-Hydroxy-3-mercapto-4-methoxybenzoic acid was synthesized as a potential affinity-labeling reagent for catechol O-methyltransferase (COMT, EC 2.1.1.6). This compound was shown to produce noncompetitive inhibition of COMT when assayed in the presence or absence of the reducing agent, dithiothreitol (DTT). If COMT was assayed in the absence of DTT, the compound was shown to be a more potent inhibitor (Kis = 59.9 +/= 15.9 mumol; Kii = 30.2 +/- 5.8 mumol) than if the assays were conducted in the presence of the reducing agent (Kis = 1140 +/- 233 mumol; Kii = 743 +/- 141 mumol). The potent inhibitory effects produced in the absence of DTT could be partially reversed by the addition of DTT to the incubation mixture or by dialysis of the modified enzyme against DTT -containing buffer. These data suggest that in the absence of DTT, 5-hydroxy-3-mercapto-4-methoxybenzoic acid serves as an affinity-labeling reagent for COMT by reaction of the 3-mercapto group of the ligand with an active-site sulfhydryl group. This ligand-protein disulfide bond can be reduced with DTT with subsequent reversal of the inhibitory effects.

Animals↗

PubMed1981

Bile acid synthesis. Metabolism of 3 beta-hydroxy-5-cholenoic acid in the hamster.

Synthesis of 3 beta-hydroxy-5-[1,2-3H]cholenoic acid has permitted a study of its metabolism in bile-fistula hamsters that received the compound by intravenous infusion. Metabolites in bile were identified by reverse isotope dilution after their complete resolution by high pressure liquid chromatography using muPorasil. Recovery of administered radioactivity ranged from 21-60% in three animals. In each study, lithocholic acid (0.8-4.4%) and chenodeoxycholic acid (7.8-11.3%) were identified as metabolites of 3 beta-hydroxy-5-cholenoate and can be considered primary bile acids in the side-chain pathway of bile acid synthesis beginning with the oxidation of cholesterol to 26-hydroxycholesterol.

Animals↗

PubMedDate not supplied

[Cerebrosides and sulfocerebrosides in the brain of the macaque Macaca fascicularis].

The content of cerebrosides and sulfocerebrosides has been determined in the whole brain, in the gray and white matter of the cerebral hemispheres of the macaque. Fatty acid composition and long chain bases of these sphingolipids in the whole brain were also investigated. The species studied belongs to the order of higher primates, the family of lower Old World monkeys. In the whole brain, rather high content of both sphingolipids was found, the cerebral white matter being the richer. Cerebrosides with hydroxy acids predominate in the whole brain, in the white and gray matter. Cerebrosides of the whole brain contain mainly palmitic and stearic acids and relatively small amounts of C24 normal fatty acids. In sulfocerebrosides, the proportion of palmitic and stearic acids is lower and that of C24 normal fatty acids--larger, as compared to cerebrosides. In both sphingolipids, the content of saturated hydroxy acids, mainly cerebronic acid, is rather high. Among the long chain bases, only sphingenine and sphinganine were detected the former being predominant. Sphingolipids from the brain of the macaque were compared to these from the human brain.

Animals↗

PubMed2003

Topical glycolic acid enhances photodamage by ultraviolet light.

BACKGROUND: Alpha-hydroxy acids (AHAs) are widely used as ingredients in cosmetics. Several studies suggest that AHAs can increase the sensitivity of skin to ultraviolet (UV) light. PURPOSE: This study was performed in order to determine whether short-term dermal treatment with glycolic acid, a representative AHA, can enhance the damaging effects of UV light. The duration of the effect of AHAs on the sensitivity of skin to UV light was also examined. METHODS: The backs of 29 Caucasian subjects were treated, once daily, 6 days per week with either 10% glycolic acid (pH 3.5) or placebo in a randomized double-blinded study. At the end of 4 weeks, sites within each treated area were exposed to 1.5 MED of UV light, determined on previously untreated skin. Specimens were obtained for enumeration of sunburn cells (SBCs) in the first group of subjects (n = 16), whereas cyclobutyl pyrimidine dimers (CPDs) in DNA were determined in the second group (n = 13). The minimal erythema dose (MED) in each site was also determined in the first group of subjects. Sunburn cells and MEDs were re-evaluated in the first group 1 week after discontinuing AHA applications. RESULTS: Glycolic acid caused enhanced sensitivity to UV light measured as increased SBC induction and lowered MEDs. Cyclobutyl pyrimidine dimers were elevated but not to a statistically significant level. No differences in SBCs or MEDs were evident after a week of discontinued treatments. CONCLUSION: Short-term application of 10% glycolic acid sensitizes the skin to the damaging effects of UV light. This photosensitivity is reversed within a week of terminating treatments.

Administration, Cutaneous↗