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At least 145 records · Page 8Linked to original sources
PubMed1996

Sensitive high-performance liquid chromatographic fluorescence assay for the quantitation of topotecan (SKF 104864-A) and its lactone ring-opened product (hydroxy acid) in human plasma and urine.

A sensitive reversed-phase high-performance liquid chromatographic fluorescence method is described for the simultaneous determination of topotecan (I) and the hydrolysed lactone ring-opened product hydroxy acid (II) in plasma and for the determination of I in urine. To 250 microliters of plasma, a 750-microliters volume of cold methanol was added to stabilize the pH-dependent conversion of I into II. In plasma, the lower limit of quantitation (LLQ) for both compounds was 0.10 ng/ml. The between-day variation for I at the LLQ was 7.1% and for II was 5.5%. Prior to injection, urine samples were acidified with orthophosphoric acid and diluted with phosphate-buffered saline (PBS). In urine, the calibration curve for I was linear in the range of 10 to 250 ng/ml and the LLQ was 10 ng/ml. The assay was developed to enable pharmacological analysis of I, in on-going phase I and II studies, in patients with solid tumors.

Camptothecin↗
PubMed1976

Ultrastructural localization of catalase and L-alpha-hydroxy acid oxidase in microperoxisomes of Hydra.

The ultrastructural localization of catalase and L-alpha-hydroxy acid oxidase (LalphaHAO) was studied in two species of Hydra. Diaminobenzidine reaction product of catalase activity was present in small round or elongated bodies resembling microperoxisomes in the epitheliomuscular, digestive and gland cells. They were closely related to the endoplasmic reticulum, and were often found in proximity to deposits of lipid and glycogen. Reaction product of LalphaHAO activity was also associated with the microperoxisomes. With rapidly oxidized substrates, such as L-lactic acid, reaction product diffused into the cytoplasm around the microperoxisomes. With slowly oxidized substrates, such as DL-alpha-hydroxyisovaleric acid, reaction product was restricted to the matrix of the microperoxisomes. No reaction product was present in the microperoxisomes in the absence of substrate or with D-lactic acid. The rate of substrate oxidation measured biochemically roughly paralleled the amount of cytochemical reaction product deposited with different substrates. Microperoxisome-like bodies reactive for LalphaHAO were also found in the epidermal cnidoblasts; however, catalase could not be demonstrated in them. This study provides the first cytochemical evidence for the presence of an H2O2-producing oxidase in microperoxisomes.

Alcohol Oxidoreductases↗
PubMed2003

Diastereoselective conjugate addition to chiral alpha,beta-unsaturated carbonyl systems in aqueous media: an enantioselective entry to alpha- and gamma-hydroxy acids and alpha-amino acids.

The stereoselectivity of the ultrasonically induced zinc--copper conjugate addition of iodides to chiral alpha,beta-unsaturated carbonyl systems under aqueous conditions was studied. Alkyl iodides add diastereoselectively to methylenedioxolanone 1 and methyleneoxazolidinone 2 to afford the 1,4-addition products in good yields (38-95 %) and with high diastereomeric excess (44-90 % de). The 1,4-addition to chiral gamma,delta-dioxolanyl-alpha,beta-unsaturated esters 3-5 also proceeds with good yields (51-99 %). The diastereoselectivity is dependent on the geometry of the olefin: the Z isomer 3 gives high diastereoselectivity, while the reactions with the E isomer 4 are nonstereoselective. The reaction proceeds with excellent chemoselectivity and allows the use of iodides bearing ester, hydroxy, and amino groups. Since the 1,4-addition products can be readily hydrolyzed, this methodology constitutes a novel entry for the enantioselective synthesis of alpha- and gamma-hydroxy acids and alpha-amino acids in aqueous media. The results obtained support the radical mechanism proposed by Luche, and represent one of the few examples of a radical stereoselective conjugate addition in aqueous medium.

Amino Acids↗
PubMed1981

The inflammatory effects of hydroperoxy and hydroxy acid products of arachidonate lipoxygenase in rabbit skin.

1. The inflammatory effects of hydroperoxy (HPETE) and hydroxy (HETE) acids, synthesized by arachidonic acid lipoxygenases, have been investigated in rabbit skin. 2. High doses (10-20 micrograms) of 5-, 12- or 15-HPETE or the 5,12-di-hydroxy acid, leukotriene B4 (0.1-1 micrograms), caused small but significant increases in plasma exudation following intra-dermal injection. 3. Leukotriene B4 was equipotent with prostaglandin E2 and prostacyclin in potentiating bradykinin-induced plasma exudation, and was 100 times more active in this property than any other lipoxygenase product tested. 4. Leukotriene B4-induced plasma exudation was enhanced by prostaglandin E2. 5. The mono-HETEs were relatively inactive in causing or enhancing plasma exudation. 6. Leukotriene B4 (0.1 microgram) or prostaglandin E1 (1.0 micrograms) significantly elevated leukocyte accumulation in rabbit skin, whereas PGE2, 5-HPETE, 5-HETE, 12-HPETE or 12-HETE were inactive at doses up to 1 microgram.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
PubMed1997

Cosmetic use of alpha-hydroxy acids.

Frequent and daily use of cosmetic and skin-care products that contain alpha-hydroxy acids (AHAs) moisturizes the skin and produces smoother, less-wrinkled skin surfaces. The cosmetic products developed as astringents and exfoliants diminish skin scales and remove excess skin oil. New studies suggest that photodamaged skin improves with AHA treatment.

Beauty Culture↗
PubMed1984

Hyperkeratinization, corneocyte cohesion, and alpha hydroxy acids.

Hyperkeratinization is a primary or fundamental event in a majority of today's skin disorders. Hyperkeratinization is usually the result of decreased desquamation due to increased corneocyte cohesion. Strength of corneocyte cohesion is determined by strength of intercellular bonding. Intercellular bonding is weakened by water and diminished by retinoids and alpha hydroxy acids (AHAs). Conversely, bonding is strengthened or enhanced by dehydration, vitamin A deficiency, and some alpha acetoxy acids (AAAs). Agents that control or modify keratinization can be useful in treatment of many skin disorders.

Animals↗
PubMed2000

Application of ligand-exchange capillary electrophoresis to the chiral separation of alpha-hydroxy acids and beta-blockers.

The application of the principle of ligand-exchange capillary electrophoresis to two substance classes is described. As chiral selector N-(2-hydroxyoctyl)-L-4-hydroxyproline-copper(II) complex was used. This principle was applied to the chiral separation of alpha-hydroxy acids and drugs containing amino alcohol structure such as beta-blockers. The enantioselectivity was found to be strongly dependent on pH corresponding to the optimal conditions for complex formation for each structure class.

Adrenergic beta-Antagonists↗
PubMed1983

Microbial Resolution of alpha-Hydroxy Acids by Enantiospecifically Dehydrogenating Bacteria from Soil.

Thirty-three bacterial strains were isolated from soil, utilizing optically asymmetric degradation of dl-2-hydroxy-4-methylpentanoic acid (dl-HMPA) as the screening probe. Those strains were distributed in the following group and genera: Coryneform and Bacillus, Pseudomonas, and Streptomyces. Among them, the most potent strains, Bacillus freudenreichii NRS-137KH20B and Brevibacterium albidum NRS-130KH20B, could perform the resolution of more than 30 g of dl-HMPA per liter within 4 to 5 days of fermentation. Optically pure l- and d-HMPA enantiomers were obtained in more than 80% theoretical yield, whereas the transformed enantiomer was almost quantitatively recovered as 2-oxo-4-methyl-pentanoic acid in the culture broth. The enantiospecific dehydrogenation responsible for this resolution reaction had a rather wide substrate specificity on straight or branched aliphatic C(4) to C(16) 2-hydroxy acids, exhibiting the optima at chain lengths of either C(7) or C(5), although the enantiospecificity was not changed by chain length. The process was thus successfully extended to the preparation of optically pure C(5) to C(9) 2-hydroxy acids.

Journal Article↗
PubMed1965

Alpha-hydroxy acid oxidase: localization in renal microbodies.

Differential and density equilibrium centrifugation have established the presence of alpha-hydroxy acid oxidase in microbodies of the kidney of the rat. The enzyme has been demonstrated in cells of the distal convoluted tubule by a microscopic cytochemical method. This enzyme, like certain others in microbodies, produces hydrogen peroxide.

Acid Phosphatase↗
PubMed1996

An alpha hydroxy acid derivative suitable for sensitive skin.

BACKGROUND: Individuals with sensitive skin may not tolerate some products formulated with alpha hydroxy acids (AHAs) due to unacceptable levels of stinging and irritation. OBJECTIVE: To develop a neutral molecule that is well tolerated by individuals with sensitive skin without stinging or irritation, yet retains the beneficial effects of AHAs. METHODS: A neutral amide derivative, methoxypropylgluconamide (MPG), was invented. Formulations containing MPG (15%) were tested by cummulative irritation, repeat insult patch testing, and lactic acid stinging assay. Bilateral comparison clinical and histological studies of xerosis and photoaging assessments were performed. RESULTS: MPG was nonirritating and nonsensitizing. Clinically significant improvements in xerosis and photoaging including uneven pigmentation were seen. Improvement in the morphology of the stratum corneum epidermis and in the amount of glycosaminoglycans in the epidermis and dermis were seen histologically. CONCLUSIONS: A molecule was invented (MPG) that could be formulated in a neutral vehicle to avoid skin irritation and produced improvements in xerosis and photoaging.

Biopsy↗
PubMed1978

Effects of dihydroxy bile acids and hydroxy fatty acids on the absorption of oleic acid in the human jejunum.

Perfusion studies of the normal human jejunum were performed to test whether dihydroxy bile acids and hydroxy fatty acids inhibit the absorption of oleic acid, since previous reports documented their inhibitory effects on the absorption of several other organic solutes. 3 mM deoxycholate and 7 mM glycodeoxycholate inhibited the absorption of 3 mM oleic acid in isotonic micellar solutions while inducing net fluid secretion. Similarly, fractional absorption of oleic acid decreased in the presence of hydroxy fatty acids. However, only the changes induced by 2 mM ricinoleic acid could be distinguished from changes induced by an increase in total fatty acid concentration. Under all experimental conditions, close linear relationships existed between net water movement and fractional absorption of glucose, xylose, and fatty acids, as well as between the absorption rates of these solutes. In contrast, net fluid secretion induced by hypertonic D-mannitol (450 mosmol/liter) had no effect on solute absorption. Our data and observations in the literature do not allow formulation of a hypothesis which would adequately define all effects of dihydroxy bile acids and fatty acids on intestinal transport processes. The observations help explain the malabsorption of fat and other nutrients in patients with the blind loop syndrome.

Adult↗
PubMed1978

Genetics and physiological expression of beta-hydroxy acid dehydrogenase in Drosophila.

A mutant Hadnl was induced in Drosophila melanogaster and found to be deficient in beta-hydroxy acid dehydrogenase. This mutation was utilized to study the genetics and physiological expression of Had+ . Had+ was mapped to the X chromosome at 54.4 and seems to be the structural gene for the enzyme. Enzyme activity in male and female flies indicates that the gene shows both dosage compensation independent from dose effect and differential activity during ontogeny. Electrophoretic mobility data indicate that the enzyme is a dimer which forms by random association of subunits. The fact that the mutant shows no detrimental effect implies that the enzyme is dispensable, at least under laboratory conditions. The biological and technical implications of this gene--enzyme system are discussed.

Animals↗
PubMed1999

The effects of an alpha hydroxy acid (glycolic acid) on hairless guinea pig skin permeability.

The barrier integrity of hairless guinea pig skin after treatment with an alpha hydroxy acid was assessed through in vivo topical application of an oil-in-water emulsion containing 5 or 10% glycolic acid at pH 3.0. The control was a commercial moisturizing lotion, pH 7.8. A dosing regimen for the glycolic acid formulations that was tolerated by the hairless guinea pigs and significantly decreased stratum corneum turnover time was determined using the dansyl chloride staining technique. Once-daily dosing of hairless guinea pig skin for 3 weeks with the glycolic acid formulations resulted in approximately a 36-39% decrease in stratum corneum turnover time compared with the control lotion. After this treatment, hairless guinea pigs were sacrificed for the in vitro measurement of the percutaneous absorption of [14C]hydroquinone and [14C]musk xylol. No significant differences in the 24-hour absorption of either test compound were found for skin treated with the control lotion or the glycolic acid formulations. There were also no significant differences found in the absorption of [3H]water through skin from the different treatment groups. Although no increase in skin penetration occurred after treatment with the glycolic acid formulations, histology revealed approximately a twofold increase in epidermal thickness. Also the number of nucleated cell layers nearly doubled in skin treated with 5% and 10% glycolic acid compared with the control lotion and untreated skin. These studies demonstrate that substantial changes in the structure of hairless guinea pig epidermis can occur without significant effect on skin permeability of two model compounds.

Administration, Topical↗
PubMed1984

Metabolism of monoterpenes: lactonization of (+)-camphor and conversion of the corresponding hydroxy acid to the glucoside-glucose ester in sage (Salvia officinalis).

The bicyclic monoterpene ketone (+)-camphor is a major constituent (up to 26%) of the volatile oil of immature sage (Salvia officinalis L.) leaves; however, as the plant matures the content of this ketone declines in the fully expanded leaves (to about 65% of maximum) as does the overall yield of oil (to roughly 60% of maximum). Examination of the metabolism of (+)-[G-3H]camphor in discs prepared from mature leaves of flowering sage plants revealed that this ketone was converted to a water-soluble metabolite which on chromatographic analysis proved to be considerably more polar than a simple monoterpenyl glycoside. Mass spectral analysis of several derivatives of the terpenoid moiety of the metabolite obtained from large-scale incubations allowed identification of the aglycone, while degradative studies and detailed radiochromatographic analyses indicated that the metabolite contained two glucose residues; one glycosidically linked and the other in ester linkage. All of the evidence was consistent with the initial lactonization of camphor to 1,2-campholide followed by conversion to the beta-D-glucoside-6-O-glucose ester of the corresponding hydroxy acid (1-carboxymethyl-3-hydroxy-2,2,3-trimethyl cyclopentane). Direct evidence for the intermediacy of 1,2-campholide was also obtained through isotopic dilution experiments and by direct testing of the labeled lactone. The lactonization of camphor in sage resembles a similar step in the catabolism of camphor by microorganisms, but appears to be the first report of this reaction type in higher plants.

Camphor↗
PubMed1996

Poly(alpha-hydroxy acids): carriers for bone morphogenetic proteins.

A broad spectrum of cells and cell products is associated with bone homeostasis and the renewal of bone following injury. The coupled interactions among cells provide the power behind sculpting of bone, sustaining form, and ensuring functionality. Local and systemic regulatory molecules (e.g. growth factors, hormones) direct cellular interactions through autocrine, paracrine, and hormonal pathways. Recently, genes for a class of osteogenic regulatory molecules have been cloned, and gene product expression has enabled investigators to assess safety and efficacy in animal studies. The molecules are known as bone morphogenetic proteins (BMPs). Therapeutic applications of BMPs depend on a carrier system. A carrier could spatially and temporally localize BMP for regional needs and be custom-tailored for acute craniofacial applications or for recalcitrant extremity non-unions. The poly(alpha-hydroxy acids) (PHAs) may be suitable for these applications. Therefore, the purposes of this paper are (i) to mention, briefly, basic concepts of the bone wound continuum and the possible therapeutic roles of BMPs; (ii) to outline several properties of selected PHAs relevant to bone regeneration dynamics; and (iii) to review selected preclinical studies with PHAs.

Animals↗
PubMed1997

Surface characterization of poly(alpha-hydroxy acid) microspheres prepared by a solvent evaporation/extraction process.

This work constitutes the first attempt to characterize the wettability of poly(alpha-hydroxy acid) (PAHA) microspheres in situ, prepared according to a complex process involving emulsification, solvent evaporation, washing and freeze-drying. The analysis of the flotation profile of the microspheres has allowed us to determine both advancing and receding contact angles at the microsphere/air/water interface and furnished information on the organization of poly(vinyl alcohol) (PVA) and bovine serum albumin (BSA) at the surface of the PAHA coating. By the comparison of contact angles measured from model surfaces obtained by sampling pure PAHA, PVA, BSA and mixed PVA/PAHA monolayers on glass and poly(methyl methacrylate) (PMMA) substrates, it was concluded that the emulsifier (PVA or BSA) was strongly anchored to the surfaces of the microspheres. The use of BSA to formulate the microspheres from a single oil-in-water emulsion led to dry particles having a hydrophobic surface. The unfolding of the hydrophilic segments of the BSA embedded at the surface of the microspheres, following immersion in water, increased the wettability of the microspheres by water. The same qualitative results were obtained when PVA was used to stabilize single emulsions. On the other hand, microspheres formulated from a double water-in-oil-in-water emulsion displayed no modifications of their wettability when immersed in water. This can be explained by the absence of mobility of the hydrophilic segments of the emulsifier which are blocked in the surface or at the subsurface of the polymer matrix.

Biocompatible Materials↗
PubMed2005

Novel 3-amino-2-hydroxy acids containing protease inhibitors. Part 1: Synthesis and kinetic characterization as aminopeptidase P inhibitors.

Novel, potent inhibitors of aminopeptidase P, containing a 3-amino-2-hydroxy acid and a proline or a proline analogues, have been prepared. One part of the bestatin-derived inhibitors was found to inhibit APP from Escherichia coli and from rat intestine according to a mixed-type mechanism, with Ki values up to 1.26 microM. The other compounds, 3-amino-2-hydroxy acyl prolines of a different configuration, inhibit APP competitively, according to a slow-binding mechanism, with Ki values in the nanomolar up to the micromolar range.

Amino Acids↗