Synthesis and biological activities of long chain 2-amino alcohols

This article focuses on the synthesis and the biological activities of long chain amino alcohols. The methods for the synthesis of these sphingosine analogues from various starting materials such as lipidic amino acids, serine, glyceraldehydes, long chain 1,2-diols, are summarized in the first part of the review, followed by a discussion of the biological activities of long chain amino alcohols and the applications for the synthesis of other bioactive compounds.     

Synthesis and biological activities of long chain 2-amino alcohols

Summary This article focuses on the synthesis and the biological activities of long chain amino alcohols. The methods for the synthesis of these sphingosine analogues from various starting materials such as lipidic amino acids, serine, glyceraldehydes, long chain 1,2-diols, are summarized in the first part of the review, followed by a discussion of the biological activities of long chain amino alcohols and the applications for the synthesis of other bioactive compounds.     

Phase transitions in crystals of racemic long chain 2-amino alcohols

Various techniques, namely differential scanning calorimetry, optical microscopy, dielectric and Raman spectroscopy, all covering a wide range of temperatures, were used to study the thermodynamically stable phases and molecular mobility of crystals of long chain 2-amino alcohols. The results showed that two different crystal forms are present in each sample. The temperature behaviour of the phases is studied in details.     

Metabolism of mevalonic acid to long chain fatty alcohols in an insect

A mixture of long chain fatty alcohols (LCFA) with chain lengths of 24 to 30 carbon atoms, as free and esterified components, have been isolated from the aphid, $\text{Schizaphis}\text{graminum}$. Both radiolabelled mevalonic acid and palmitic acid served as effective precursors in the synthesis of LCFA. This is the first time that the $\text{trans}$-methylglutaconate shunt has been shown to be operational for fatty alcohol synthesis and to occur in a lower-evolved animal.     

Preparation and characterization of long alkyl chain methacrylate-based monolithic column for capillary chromatography

This paper describes the fabrication of long alkyl chain methacrylate monolithic materials for using as stationary phases in capillary liquid chromatography. Following deactivation of the capillary surface with 3-(trimethoxysilyl)propyl methacrylate (γ-MAPS), monoliths were formed by co-polymerisation of stearyl methacrylate (SMA) with ethylene glycol dimethacrylate (EDMA) in the presence of the initiator AIBN and a mixture of porogens including iso-amyl alcohol and 1,4-butanediol. The monoliths were prepared in 100 μm i.d. capillaries and the composition of the polymerisation mixtures were optimised in terms of the ratio of SMA/EDMA, the porogen composition and ratio of porogen to monomers. As the porogen weight fraction decreased, the microglobules became smaller and as expected, the total porosity decreased. In order to determine the usability of such materials, the column permeability K was measured by pumping water through the columns at different linear flow rates. Good results were obtained when these capillaries were used to separate mixtures of weak acids, neutral and basic compounds.     

Preparation and characterization of long alkyl chain methacrylate-based monolithic column for capillary chromatography

This paper describes the fabrication of long alkyl chain methacrylate monolithic materials for using as stationary phases in capillary liquid chromatography. Following deactivation of the capillary surface with 3-(trimethoxysilyl)propyl methacrylate (gamma-MAPS), monoliths were formed by co-polymerisation of stearyl methacrylate (SMA) with ethylene glycol dimethacrylate (EDMA) in the presence of the initiator AIBN and a mixture of porogens including iso-amyl alcohol and 1,4-butanediol. The monoliths were prepared in 100 microm i.d. capillaries and the composition of the polymerisation mixtures were optimised in terms of the ratio of SMA/EDMA, the porogen composition and ratio of porogen to monomers. As the porogen weight fraction decreased, the microglobules became smaller and as expected, the total porosity decreased. In order to determine the usability of such materials, the column permeability K was measured by pumping water through the columns at different linear flow rates. Good results were obtained when these capillaries were used to separate mixtures of weak acids, neutral and basic compounds.     

The catabolism of amino acids to long chain and complex alcohols in Saccharomyces cerevisiae

The catabolism of phenylalanine to 2-phenylethanol and of tryptophan to tryptophol were studied by (13)C NMR spectroscopy and gas chromatography-mass spectrometry. Phenylalanine and tryptophan are first deaminated (to 3-phenylpyruvate and 3-indolepyruvate, respectively) and then decarboxylated. This decarboxylation can be effected by any of Pdc1p, Pdc5p, Pdc6p, or Ydr380wp; Ydl080cp has no role in the catabolism of either amino acid. We also report that in leucine catabolism Ydr380wp is the minor decarboxylase. Hence, all amino acid catabolic pathways studied to date use a subtly different spectrum of decarboxylases from the five-membered family that comprises Pdc1p, Pdc5p, Pdc6p, Ydl080cp, and Ydr380wp. Using strains containing all possible combinations of mutations affecting the seven AAD genes (putative aryl alcohol dehydrogenases), five ADH genes, and SFA1, showed that the final step of amino acid catabolism (conversion of an aldehyde to a long chain or complex alcohol) can be accomplished by any one of the ethanol dehydrogenases (Adh1p, Adh2p, Adh3p, Adh4p, Adh5p) or by Sfa1p (formaldehyde dehydrogenase.)     

Transesterification of primary and secondary alcohols using Pseudomonas aeruginosa lipase

Lipases of a newly isolated Pseduomonas aeruginosa MTCC 5113 were assessed for transesterification of benzyl alcohol and vinyl acetate to produce the flavoring agent benzyl acetate. Crude lipase preparations that minimized the cost of the biocatalyst, achieved benzyl alcohol conversion of 89% within 3h at 30 degrees C. In contrast, purified and expensive commercially available lipases of Candida antarctica and porcine pancreas achieved much lower conversions at 80% and 15%, respectively. A well-mixed ( approximately 800 rev.min(-1)) batch reactor having the aqueous phase finely dispersed in heptane was used in these studies. Benzyl alcohol conversion was maximal when the enzyme-containing aqueous phase constituted about 50% of the total reactor volume. Use of solvents such as hexane, benzene, toluene and dimethyl sulfoxide reduced conversion compared with the use of heptane.     

Photoactive amino acid derivatives with long alkyl chains

Summary Azobenzene amphiphiles containing-alanine, L-lysine or-homolysine moieties were synthesized and characterised. Stable monomolecular layers at the air/water interface and LB multilayers has been obtained from some of them. One sample of azobenzenes synthesized has been shown to undergo a reversible trans/cis photoisomerization upon light irradiation in both solution and LB multilayer.Abbreviations DCC N,N-dicyclohexyl carbodiimide - HONSu N-hydroxy succinimide - Boc t-butyloxycarbonyl - Bu^t t-butyl - EtOAc ethyl acetate - THF tetrahydrofuran - TEA triethylamine - HPLC high performance liquid chromatography - TLC thin layer chromatography - Ph phenyl - i-PrOH isopropyl alcohol     

Thermotropic and lyotropic properties of long chain alkyl glycopyranosides. Part II. Disaccharide headgroups

We have investigated the thermotropic and lyotropic properties of some long chain alkyl glycosides with disaccharide headgroups. The thermotropism was measured with polarising microscopy and additionally the lyotropism with the contact preparation method, Fourier-transform Infrared (FTIR) spectroscopy, X-ray diffraction and small angle neutron scattering. A broad thermotropic as well as lyotropic polymorphism was found. The compounds displayed thermotropic S(A) (lamellar) and cubic phases, and the investigation of the lyotropic phase behaviour led to the observation of inverted bicontinuous cubic V(II) phases, lamellar L(alpha) phases, normal bicontinuous cubic V(I) phases, normal columnar H(I) phases, normal discontinuous cubic I(I) phases and lyotropic cholesteric phases. The phases are discussed with respect to the chemical structures that have been varied systematically to derive structure-property relationships.     

Thermotropic and lyotropic properties of long chain alkyl glycopyranosides: part III: pH-sensitive headgroups

As part of a series of papers, the influence of carbohydrate headgroups and aliphatic chains on the mesogenic properties of glycolipids was investigated. Alkyl glycosides with different types of aliphatic chains were synthesised. Neutral glycolipids were oxidized to their uronic acid derivatives, using the well established TEMPO-oxidation. For comparison a 6-deoxy-6-amino alkylglucopyranoside was synthesised. In addition, the thermotropic and lyotropic phase behaviour of the synthesised compounds were investigated. The thermotropism was characterised by polarising microscopy, the lyotropism by the contact preparation method.     

Thermotropic and lyotropic properties of long chain alkyl glycopyranosides. Part I: monosaccharide headgroups

A systematic structure variation of a classical amphiphile (dodecyl-beta-D-glucopyranoside) is performed, demonstrating the influence of anomeric linkage, configuration, ring size and flexibility as well as electric charges on the mesophase behaviour. In addition, we have investigated the thermotropic and lyotropic properties of some long chain alkyl glycosides with monosaccharide headgroups. The thermotropism was measured with polarizing microscopy and differential scanning calorimetry, and additionally the lyotropism with FTIR spectroscopy and X-ray diffraction.     

Enantioselective acetylation of racemic alcohols by Manihot esculenta and Passiflora edulis preparations

Immobilized Manihot esculenta and Passiflora edulis juice preparations have been employed as stereoselective biocatalysts in the enzymatic acetylation of a set of racemic alcohols. Depending on the reaction conditions and the substrate structure, good to excellent enantioselectivities can be achieved in the preparation of the (S)-alcohols and (R)-esters, compounds presenting high interest in organic synthesis.     

Nutritional significance and metabolism of very long chain fatty alcohols and acids from dietary waxes

Very long chain fatty alcohols obtained from plant waxes and beeswax have been reported to lower plasma cholesterol in humans. This review discusses nutritional or regulatory effects produced by wax esters or aliphatic acids and alcohols found in unrefined cereal grains, beeswax, and many plant-derived foods. Reports suggest that 5-20 mg per day of mixed C24-C34 alcohols, including octacosanol and triacontanol, lower low-density lipoprotein (LDL) cholesterol by 21%-29% and raise high-density lipoprotein cholesterol by 8%-15%. Wax esters are hydrolyzed by a bile salt-dependent pancreatic carboxyl esterase, releasing long chain alcohols and fatty acids that are absorbed in the gastrointestinal tract. Studies of fatty alcohol metabolism in fibroblasts suggest that very long chain fatty alcohols, fatty aldehydes, and fatty acids are reversibly inter-converted in a fatty alcohol cycle. The metabolism of these compounds is impaired in several inherited human peroxisomal disorders, including adrenoleukodystrophy and Sj?gren-Larsson syndrome. Reports on dietary management of these diseases confirm that very long chain fatty acids (VLCFA) are normal constituents of the human diet and are synthesized endogenously. Concentrations of VLCFA in blood plasma increase during fasting and when children are placed on ketogenic diets to suppress seizures. Existing data support the hypothesis that VLCFA exert regulatory roles in cholesterol metabolism in the peroxisome and also alter LDL uptake and metabolism.     

Efficient synthesis of a long carbohydrate chain alkyl glycoside catalyzed by cyclodextrin glycosyltransferase (CGTase)

Alkyl glycosides with long carbohydrate groups are surfactants with attractive properties but they are very difficult to synthesize. Here, a method for extension of the carbohydrate group of commercially available dodecyl‐β‐d ‐maltoside (DDM) is presented. DDM was converted to dodecyl‐β‐d ‐maltooctaoside (DDMO) in a single step by using a CGTase as catalyst and α‐cyclodextrin (α‐CD) as glycosyl donor. The coupling reaction is under kinetic control and the maximum yield depends on the selectivity of the enzyme. The Bacillus macerans CGTase favored the coupling reaction while the Thermoanaerobacter enzyme also catalyzed disproportionation reactions leading to a broader product range. A high ratio α‐CD/DDM favored a high yield of DDMO and yields up to 80% were obtained using the B. macerans enzyme as catalyst. Biotechnol. Bioeng. 2009; 104: 854–861. © 2009 Wiley Periodicals, Inc.     

Transesterification of peptide esters and peptidyl resins in methanol-containing calcium acetate

The following crude peptide derivatives obtained by thermolysin catalysis in the presence of calcium acetate, were dissolved in methanol and in methanol-containing calcium acetate to determine the possible occurrence of transesterification: Z-Asn-Leu-Gly-OEt, Boc-Asn-Leu-Gly-OEt, Moz-Asn-Leu-Gly-OBzl, Moz-Asn-Leu-Gly-OtBu, Moz-Gln-Leu-Gly-OEt, Moz-Asn-Ile-Gly-OEt, and Moz-Asn-Leu-Ala-OEt. Only Z-Asn-Leu-Gly-OEt and Moz-Gln-Leu-Gly-OEt were transesterified in methanol, indicating the existence of a peptide derivative-Ca2+ catalytic complex that may favor the reaction. In the presence of calcium acetate, all protected peptide esters except the t-butyl esters were transesterified. The transesterification of several other di- and tripeptide derivatives of different structures in methanol-containing calcium acetate was detected by HPLC and confirmed by the isolation and characterization of some of the protected peptide methyl esters obtained. Boc-Leu-Gly- and Moz-Asn-Leu-Gly-Merrifield resin were also transesterified in these solutions.