- Structure-activity relationship studies of dipeptide-based hepsin inhibitors with Arg bioisosteres
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Hepsin is a type II transmembrane serine protease (TTSP) associated with cell proliferation and overexpressed in several types of cancer including prostate cancer (PCa). Because of its significant role in cancer progression and metastasis, hepsin is an attractive protein as a potential therapeutic and diagnostic biomarker for PCa. Based on the reported Leu-Arg dipeptide-based hepsin inhibitors, we performed structural modification and determined in vitro hepsin- and matriptase-inhibitory activities. Comprehensive structure-activity relationship studies identified that the p-guanidinophenylalanine-based dipeptide analog 22a exhibited a strong hepsin-inhibitory activity (Ki = 50.5 nM) and 22-fold hepsin selectivity over matriptase. Compound 22a could be a prototype molecule for structural optimization of dipeptide-based hepsin inhibitors.
- Kwon, Hongmok,Ha, Hyunsoo,Jeon, Hayoung,Jang, Jaebong,Son, Sang-Hyun,Lee, Kiho,Park, Song-Kyu,Byun, Youngjoo
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supporting information
(2020/12/25)
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- Bio- And Medicinally Compatible α-Amino-Acid Modification via Merging Photoredox and N-Heterocyclic Carbene Catalysis
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An N-heterocyclic carbene and photoredox cocatalyzed α-amino-acid decarboxylative carbonylation reaction is presented. This method displays good scope generality, providing a direct pathway to access various downstream α-amino ketones under bio- and medicinally compatible conditions. Moreover, this strategy is appealing to chemical biology because it has great potential for the chemical modification of peptides or the late-stage synthesis of keto-peptides.
- Chen, Lei,Du, Ding,Feng, Jie,Gao, Jian,Lu, Tao,Ma, Rui,Shi, Zhihao,Zhang, Kuili
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supporting information
(2020/09/02)
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- Synthesis method of (2S)-2-(acetamino)-4-(methylsulfinyl)butyric acid
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The invention relates to a synthesis method of (2S)-2-(acetamino)-4-(methylsulfinyl)butyric acid and mainly aims to solve the technical problems of high cost, high pollution, numerous by-products andharm to mass production of the existing synthesis method. The method comprises the following steps: (1) dissolving solid L-methionine in a sodium carbonate aqueous solution, dropwise adding liquid acetic anhydride, stirring for reacting, filtering and washing unreacted acetic anhydride in filtrate by using a mixed solution of ethyl acetate and petroleum ether, adding an extraction agent which is ethyl acetate into a water phase, acidizing by using solid citric acid, layering, washing, drying and carrying out reduced-pressure distillation to obtain an intermediate which is Nalpha-acetyl-L-methionine; and (2) dissolving the intermediate which is Nalpha-acetyl-L-methionine in acetic acid, dropwise adding hydrogen peroxide with mass percentage concentration of 30%, stirring for reacting, concentrating an obtained product till the product is dry, adding alcohol and crystallizing to obtain the product which is (2S)-2-(acetamino)-4-(methylsulfinyl)butyric acid. The (2S)-2-(acetamino)-4-(methylsulfinyl) butyric acid is used as a raw material for synthesizing a polypeptide drug.
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Paragraph 0019
(2019/01/08)
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- Synthesis, spectroscopic and X-ray characterization of various pyrazine-bridged platinum(II) complexes:1H NMR comparative study of their catalytic abilities in the hydrolysis of methionine- and histidine-containing dipeptides
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Four pyrazine (pz)-bridged Pt(II) complexes, [{Pt(1,3-pd)Cl}2(μ-pz)]Cl2·LiCl (1) (1,3-pd = 1,3-propylenediamine), [{Pt(2,2-diMe-1,3-pd)Cl}2(μ-pz)]Cl2·2[Li(H2O)4]Cl·2H2O (2) (2,2-diMe-1,3-pd = 2,2-dimethyl-1,3-propylenediamine), [{Pt(1,3-pnd)Cl}2(μ-pz)](ClO4)2·H2O (3) (1,3-pnd = (±)-1,3-pentanediamine) and [{Pt(1,3-pnd)Cl}2(μ-pz)]Cl2·2[Pt(1,3-pnd)Cl2]·2H2O (4) have been synthesized. NMR and UV-Vis spectroscopic characterization has been performed for compounds 1-3, while single-crystal X-ray analysis has been carried out for complexes 2 and 4. Atomic distribution in the crystals of 4 indicated a disorder which could be attributed to the presence at the same crystallographic site of four distinct stereoisomers of the [{Pt(1,3-pnd)Cl}2(μ-pz)]2+complex cation. The presence of four stereoisomeric products was also observed in complex 3 by13C NMR spectroscopy. Complexes 1-3 were converted into the corresponding aqua complexes, [{Pt(X)(H2O)}2(μ-pz)]4+(X is 1,3-pd, 2,2-diMe-1,3-pd and 1,3-pnd, respectively), and1H NMR spectroscopy was applied for comparison of their catalytic activities with those of the analogous mononuclear [Pt(X)(H2O)2]2+and pyrazine-bridged [{Pt(en)(H2O)}2(μ-pz)]4+complexes in the hydrolysis of the N-acetylated l-methionylglycine (Ac-l-Met-Gly) and l-histidylglycine (Ac-l-His-Gly). All reactions were performed in the pH range 2.0-2.5 at 37 °C. It was found that all investigated dinuclear Pt(II)-aqua complexes promote selective cleavage of the amide bond involving carboxylic group of the anchoring amino acid methionine in the Ac-l-Met-Gly or histidine in the Ac-l-His-Gly.1H NMR data indicate that neither the size of the chelated diamine ring (five-membered in ethylenediamine and six-membered in 1,3-propylenediamine) nor the bulky substituents incorporated into the 1,3-propylenediamine ligand have significant influence on the rate of hydrolysis of Ac-l-Met-Gly dipeptide. Meanwhile, the rate of hydrolysis of Ac-l-His-Gly depends on both of these factors and decreases in order en > 1,3-pd > 1,3-pnd > 2,2-diMe-1,3-pd. Moreover, it has been shown that all investigated dinuclear Pt(II)-aqua complexes are better catalytic agents in the hydrolysis of the dipeptides than the analogous mononuclear Pt(II)-aqua complexes. The present findings are expected to play a crucial role in the development of new Pt(II) complexes, which can act as effective catalytic reagents for the selective hydrolysis of peptides containing either methionine or histidine residues.
- Rajkovi?, Sne?ana,?ivkovi?, Marija D.,Warzajtis, Beata,Rychlewska, Urszula,Djuran, Milo? I.
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p. 367 - 376
(2016/07/06)
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- Peptide Tyrosinase Activators
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Peptides that increase melanin synthesis are provided. These peptides include pentapeptides YSSWY, YRSRK, and their variants. The peptides may activate the enzymatic activity of tyrosinase to increase melanin synthesis. The pharmaceutical, cosmetic, and other compositions including the peptides are also provided. The methods of increasing melanin production in epidermis of a subject are provided where the methods include administering compositions comprising an amount of one or more peptides effective to increase the melanin production. The methods also include treating vitiligo or other hypopigmentation disorders with compositions including one or more peptides.
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- A detailed study of antibacterial 3-acyltetramic acids and 3-acylpiperidine-2,4-diones
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Inspired by the core fragment of antibacterial natural products such as streptolydigin, 3-acyltetramic acids and 3-acylpiperidine-2,4-diones have been synthesised from the core heterocycle by direct acylation with the substituted carboxylic acids using a strategy which permits ready access to a structurally diverse compound library. The antibacterial activity of these systems has been established against a panel of Gram-positive and Gram-negative bacteria, with activity mostly against the former, which in some cases is very potent. Data consistent with modes of action against undecaprenylpyrophosphate synthase (UPPS) and/or RNA polymerase (RNAP) for a small subset of the library has been obtained. The most active compounds have been shown to exhibit binding at known binding sites of streptolydigin and myxopyronin at UPPS and RNAP. These systems offer potential for their antibacterial activity, and further demonstrate the use of natural products as biologically validated starting points for drug discovery.
- Jeong, Yong-Chul,Bikadi, Zsolt,Hazai, Eszter,Moloney, Mark G.
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supporting information
p. 1826 - 1837
(2014/08/18)
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- PROCESS FOR PRODUCING N-ACYL AMINO ACIDS
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An object of the present invention is to provide a process for producing an N-acyl amino acid (1) in a good yield. The present invention provides a process for producing an N-acyl amino acid (1) by reacting an aldehyde compound (2), an amide compound (3), and carbon monoxide in the solvent in a reactor in the presence of a cobalt compound and hydrogen, characterized in the aldehyde compound (2), the amide compound (3) and the solvent are supplied to the reactor in which the solvent, the cobalt compound, hydrogen and carbon monoxide have been placed in advance.
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Paragraph 0030
(2013/05/21)
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- An improved racemase/acylase biotransformation for the preparation of enantiomerically pure amino acids
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Using directed evolution, a variant N-acetyl amino acid racemase (NAAAR G291D/F323Y) has been developed with up to 6-fold higher activity than the wild-type on a range of N-acetylated amino acids. The variant has been coupled with an enantiospecific acylase to give a preparative scale dynamic kinetic resolution which allows 98% conversion of N-acetyl-dl-allylglycine into d-allylglycine in 18 h at high substrate concentrations (50 g L-1). This is the first example of NAAAR operating under conditions which would allow it to be successfully used on an industrial scale for the production of enantiomerically pure α-amino acids. X-ray crystal analysis of the improved NAAAR variant allowed a comparison with the wild-type enzyme. We postulate that a network of novel interactions that result from the introduction of the two side chains is the source of improved catalytic performance.
- Baxter, Scott,Royer, Sylvain,Grogan, Gideon,Brown, Fraser,Holt-Tiffin, Karen E.,Taylor, Ian N.,Fotheringham, Ian G.,Campopiano, Dominic J.
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supporting information
p. 19310 - 19313
(2013/02/23)
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- METHOD FOR PRODUCING N-ACYLAMINO ACID
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There is provided a method for producing N-acylamino acid of formula (I): wherein R1, R2 and R3 are the same or different and each independently represents a hydrogen atom, a substituted or unsubstituted hydrocarbyl group, or a substituted or unsubstituted heterocyclic group, which comprises supplying an aldehyde compound of formula (II): wherein R1 is as defined above, an amide compound of formula (III): wherein R2 and R3 are as defined above, and a solvent to a reactor in which a solvent, a palladium compound, a halide compound, and carbon monoxide had been charged.
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Page/Page column 4
(2012/10/08)
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- Synthesis, characterisation, and biological activity of three new amide prodrugs of lamotrigine with reduced hepatotoxicity
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Lamotrigine (LTG) is an antiepileptic drug used for the prevention of convulsions. Except several known side effects, hepatic dysfunction is also reported. Hepatotoxic side effects occur due to the dichlorophenyl moiety which develops an abnormally low level of glutathione. Depletion of glutathione causes oxidative stress and hepatic cell damage. The goal of the present study was to test the action and side effects of the three compounds synthesised and compared to LTG. Three amide prodrugs of LTG were synthesised by its reaction with N-acetylamino acids, viz, glycine, glutamic acid, and methionine. Purified synthesised prodrugs were subjected to thin layer chromatography, melting point, solubility and partition coefficients determination and characterised by UV, FTIR, 1H and 13C NMR spectroscopy. The synthesised prodrugs were subjected to in vitro hydrolysis and to anticonvulsant and hepatotoxic activity studies. Significant reduction in hepatotoxicity and comparable anticonvulsant activities were obtained in all synthesised prodrugs as compared to LTG.
- Sinha, Saurabh K.,Shrivastava, Prabhat K.,Shrivastava, Sushant K.
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experimental part
p. 70 - 76
(2011/12/21)
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- Increasing the synthesis/hydrolysis ratio of aminoacylase 1 by site-directed mutagenesis
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Aminoacylase-1 from pig kidney (pAcy1) catalyzes the highly stereoselective acylation of amino acids, a useful conversion for the preparation of optically pure N-acyl-l-amino acids. The kinetic of this thermodynamically controlled conversion is determined by maximal velocities for synthesis (VmS) and hydrolysis (VmH) of the N-acyl-l-amino acid. To investigate which parameter affects maximal velocities, we focused on?the proton acceptor potential of the catalytic base, E146, and studied the influence of the active site architecture on its contribution to the pKa of residue E146. The modeled structure of pAcy1 identified residue D346 as having the strongest impact on the electrostatic features of the catalytic base. Substitutions of D346 generally decreased enzymatic activities but also altered both the pH-dependency of hydrolytic activity and the VmS/VmH ratio of pAcy1. A reduced theoretical pKa value and a lowered experimental pH optimum of hydrolytic rates for the D346A mutant were associated with a 9-fold increase in VmS/VmH. This?supports the importance of electrostatic contributions of D346 to the acid-base properties of E146 and demonstrates for the first time the possibility of engineering the VmS/VmH ratio of pAcy1.
- Wardenga, Rainer,Lindner, Holger A.,Hollmann, Frank,Thum, Oliver,Bornscheuer, Uwe
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experimental part
p. 102 - 109
(2011/02/22)
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- Lipase activity of Lecitase Ultra: characterization and applications in enantioselective reactions
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The general properties of Lecitase Ultra, a phospholipase manufactured and marketed by Novozymes, Denmark, have been studied after purification by ultrafiltration. The enzyme has a molecular mass of 35 KD, pH-optimum of 8.5, and appears to possess a single active site which exhibits both the lipase and phospholipase activities that increase in the presence of Ca2+ and Mg2+ ions. The enzyme is inhibited by heavy metal ions and surfactants, and does not accept p-nitrophenyl acetate and glycerol triacetate. Substrates, such as glycerol tributyrate and p-nitrophenyl palmitate, esters of N-acetyl-α-amino acids and α-hydroxy acids are readily accepted. Amino acids with aliphatic residues, such as alanine, isoleucine, and methionine, are hydrolyzed with high enantioselectivity for the l-enantiomer (E >100), but amino acids with aromatic residues such as phenylalanine and phenylglycine, and esters of α-hydroxy acids are hydrolyzed with low enantioselectivity (E = 1-5). Immobilization of the enzyme in a gelatin matrix (gelozyme) leads to a marginal improvement in the enantioselectivity for these substrates. However, a dramatic improvement in enantioselectivity is observed for ethyl 2-hydroxy-4-oxo-4-phenylbutyrate (E value increases from 4.5 to 19.5 with S-selectivity). Similarly, glycidate esters, such as ethyl trans-(±)-3-phenyl glycidate and methyl trans-(±)-3-(4-methoxyphenyl) glycidate, are selectively hydrolyzed with a remarkable selectivity towards the (2S,3R)-enantiomer providing unreacted (2R,3S)-glycidate esters (ee >99%, conversion 52-55%) by the immobilized enzyme.
- Mishra, Mithilesh Kumar,Kumaraguru, Thenkrishnan,Sheelu, Gurrala,Fadnavis, Nitin W.
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experimental part
p. 2854 - 2860
(2010/04/05)
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- Method for production of methionine from homoserine
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The invention relates to a method for production of D- and/or L-methionine via D- and/or L-homoserine with subsequent chemical transformation to give methionine.
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Page/Page column 18-19
(2008/06/13)
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- Synergie effect of two metal centers in catalytic hydrolysis of methionine-containing peptides promoted by dinuclear palladium(II) hexaazacyclooctadecane complex
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The species obtained by the reaction of [Pd2([18]aneN 6)Cl2](ClO4)2 (where [18]aneN 6 is 1,4,7,10,13,16-hexaazacyclooctadecane) with AgBF4 have been determined by electrospray ionization mass spectrometry (ESI-MS) to be an equilibrium mixture of three major types of dinuclear Pd(II) complex cations, [Pd2(-O)([18]aneN6)]2+, [Pd 2(μ-OH)-([18]aneN6)]3+ and [Pd 2(H2O)(OH)([18]aneN6)]3+, in aqueous solution. The hydroxo-group-bridged one, [Pd2(μ-OH)-([18] aneN6)]3+, is a dominant species, whose crystal structure has been obtained. The crystal structure of [Pd2(μ-OH)-([18] aneN6)](ClO4)3 shows that each Pd(II) ion in the dinuclear complex is tetra-coordinated by three nitrogen atoms and one hydroxo group bridge in a distorted square configuration. The two Pd(II) ions are 3.09 A apart from each other. The dinuclear Pd(II) complex cations [Pd2(μ-OH)([18]aneN6)]3+ and [Pd 2(H2O)(OH)([18]aneN6)]3+ can efficiently catalyze hydrolysis of the amide bond involving the carbonyl group of methionine in methionine-containing peptides with turnover number of larger than 20. In these hydrolytic reactions, the two Pd(II) ions are synergic; one Pd(II) ion anchors to the side chain of methionine and the other one delivers hydroxo group or aqua ligand to carbonyl carbon of methionine, or acts as a Lewis acid to activate the carbonyl group of methionine, resulting in cleavage of Met-X bond. The binding constant of dinuclear Pd(II) complex cations with AcMet-Gly and AcMet were determined by 1H NMR titration to be 282±2 M-1 and 366±4 M-1, respectively. The relatively low binding constants enable the catalytic cycle and the possible catalytic mechanism is proposed. This is the first artificial mimic of metallopeptidases with two metal active centers. The Royal Society of Chemistry 2005.
- Yang, Gaosheng,Miao, Ren,Li, Yizhi,Hong, Jing,Zhao, Chuenmei,Guo, Zijian,Zhu, Longgen
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p. 1613 - 1619
(2007/10/03)
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- D-aminoacylase mutants
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The present invention provides mutant D-aminoacylases and use thereof. The mutant D-aminoacylases are hard to be inhibited by the substrate and, comprise the amino acid sequences of the D-aminoacylase derived from Alcaligenes denitrificans subsp. xylosoxydans MI-4 strain, wherein amino acid residues at specific sites have been modified. The mutants of the present invention have high reaction specificity as well as resistance to inhibition by the substrate. The present invention enables high-yield production of D-amino acids using higher concentrations of N-acyl-DL-amino acid as the substrate. The mutants of the present invention are useful in producing D-tryptophan in particular.
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- Heat-stable D-aminoacylase
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The present invention provides a novel D-aminoacylase, as well as method for producing a D-amino acid using the same. In order to achieve the above objective, the present inventors have succeeded in purifying heat-stable D-aminoacylase from microorganisms belonging to the genus Streptomyces by combining various purification methods. Furthermore, the present inventors found that the purified heat-stable D-aminoacylase is useful in industrial production of D-amino acids. By utilizing the heat-stable D-aminoacylase, it is possible to readily and efficiently produce the corresponding D-amino acids from N-acetyl-DL-amino acids (for example, N-acetyl-DL-methionine, N-acetyl-DL-valine, N-acetyl-DL-tryptophan, N-acetyl-DL-phenylalanine, N-acetyl-DL-alanine, N-acetyl-DL-leucine, and so on).
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- Role of the distance to the S-donor center in the hydrolysis of amino acid esters, catalyzed by palladacycles
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The hydrolysis of N-acetyl-S-methylcysteine and N-acetylmethionine p-nitrophenyl esters, catalyzed by the dimeric palladacycle [Pd(C6H4-CH2NMe2)Cl]2, is described by the kinetic equation kap = k0 + kcat. The catalytic rate constants kcat are equal to 881 ± 96 and 45 ± 3 1 mol-1 s-1, respectively, for the S-methylcysteine and methionine esters at pH 8.0 (25°C). The equilibrium constant K1 for dissociation of the dimeric catalyst by the action of amino acid esters in chloroform at 25°C are equal to (2.9±0.3) × 103 and (3.0±0.6) × 104 1/mol, respectively. Thus the catalysts in the hydrolysis of N-acetyl-S-methylcysteine p-nitrophenyl ester is by an order of magnitude more effective, and the formation of catalytically active species is by an order of magnitude less effective than in the case of the methionine ester. This finding was explained in terms of intramolecular mechanism of hydrolysis with formation of a six-membered cyclic tetrahedral intermediate.
- Kurzeev,Kazankov,Ryabov
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p. 1330 - 1334
(2007/10/03)
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- Photooxidation of Methionine Derivatives by the 4-Carboxybenzophenone Triplet State in Aqueous Solution. Intracomplex Proton Transfer Involving the Amino Group
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Oxidation of the triplet state of 4-carboxybenzophenone (CB) by a series of five substituted methionines and three methionine-containing dipeptides was monitored under laser flash photolysis conditions in aqueous solution. Spectral resolution techniques were employed to follow the concentration profiles of the intermediates formed from the quenching events. From these concentration profiles, quantum yields for the intermediates were determined. Branching ratios were evaluated for the decay of the charge-transfer complex by the competing processes of back electron transfer, proton transfer and escape of radical ions. The relative prominence of these processes was discussed in terms of the proton-transfer tendencies of the nominal sulfur-radical-cationic species. A systematic decrease was observed in the quantum yields for the escape of radical ions along with a correlated increase in the proton-transfer yields. The enhanced propensity of the sulfur radical cations to deprotonate is due to deprotonation at the carbons adjacent to the sulfur-cationic site and at the unsubstituted amino groups when present. This scheme was supported by an observed decrease in the yields of dimeric sulfur radical cations with an increase in the electron-withdrawing abilities of the substituents, making the radical-cationic species stronger acids. The involvement of protons on the amino groups was implicated by the correlation of the quantum yields of ketyl radical formation in the photo-chemistry experiments with the rate constants for the reaction of the CB radical anion with the sulfur-containing substrates in pulse radiolysis experiments.
- Hug, Gordon L.,Bobrowski, Krzysztof,Kozubek, Halina,Marciniak, Bronislaw
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p. 785 - 796
(2007/10/03)
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- Hydrolysis of acetyl-methionine-containing dipeptides promoted by palladium(II) complexes containing methionine-amino acids as ligands
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The [Pd(N,S-Met-a'a'H)(N,S-AcMet-aaH)] (a'a'H and aaH = amino acids) was characterized by electrospray ionization mass spectrometer(ESI-MS) and 1H NMR, in which Met-a'a'H, as ligand, coordinates to Pd(II) via thioether and terminal amino group, and AcMet-aaH, as substrate, coordinates to Pd(II) via thioether and deprotonated amide nitrogen of methionine. The Met-a'a' bond in ligand is intact, the Met-aa bond in substrate, however, is activated toward hydrolysis The difference in hydrolysis behavior between ligand and substrate may be due to a fused six-membered and five-membered ring formation via thioether, deprotonated amide nitrogen and carbonyl oxygen of methionine residue in substrate.
- Luo, Xuemei,Chen, Xiaohua,Song, Yongcheng,Zhu, Longgen
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p. 1079 - 1080
(2007/10/03)
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- Efficient chemoenzymatic synthesis of enantiomerically pure α-amino acids
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A general two-step chemoenzymatic synthesis for enantiomerically pure natural and nonnatural α-amino acids is presented. In the first step of the sequence, the ubiquitous educts aldehyde, amide and carbon monoxide react by palladium-catalyzed amidocarbonylation to afford the racemic N-acyl amino acids in excellent yields. In the second step, enzymatic enantioselective hydrolysis yields the free optically pure a-amino acid and the other enantiomer as the N-acyl derivative, both in optical purities of 85-99.5% ee. The advantage of the chemoenzymatic process compared to other amino acid synthesis are demonstrated by the preparation of various functionalized (-OR, -Cl, -F, -SR) α-amino acids on a 10-g scale.
- Beller, Matthias,Eckert, Markus,Geissler, Holger,Napierski, Bernd,Rebenstock, Heinz-Peter,Holla, E. Wolfgang
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p. 935 - 941
(2007/10/03)
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- Cosmetic composition
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A composition suitable for topical application to mammalian skin and hair for inducing, maintaining or increasing hair growth comprises a hair growth promoter chosen from glutamine derivatives and salts thereof. The composition preferably also comprises an activity enhancer which may be chosen from hair growth stimulants, penetration enhancers and cationic polymers.
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- Cosmetic composition containing DOPA derivatives
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A composition for topical application to human hair or skin contains a chemical analogue of dihydroxyphenyl alanine (DOPA). This chemical analogue can be absorbed by skin or by a hair follicle and metabolised in-vivo, thus leading to the formation of melanin in skin or to the growth of melanin-pigmented hair. Consequently the composition can give controlled skin darkening to mimic sun-induced tanning or can bring about the growth of dar hair in place of the grey or white hair.
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- Cosmestic composition
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A composition suitable for topical application to mammalian skin and hair for inducing, maintaining or increasing hair growth comprises a hair growth promoter chosen from glutamic acid derivatives and salts thereof. The composition preferably also comprises an activity enhancer which may be chosen from hair growth stimulants, penetration enhancers and cationic polymers.
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- Hair growth composition containing citric acid esters
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Triesters of citric acid are used for inducing, maintaining or increasing hair growth. Compositions for topical application to mammalian hair or scalp comprise an effective amount of from 1% to 99% by weight of an ester of citric acid having the structure (1): where, R1, R2 and R3 each independently represent a branched or unbranched alkyl, alkenyl, aryl, alkylaryl or arylalkyl group, each said group having from 1 to 18 carbon atoms, R4 represents -H, or a branched or unbranched saturated or unsaturated acyl, alkyl, aryl, alkylaryl or aylalkyl group having from 1 to 18 carbon atoms, in the presence of a cosmetically acceptable vehicle for the citric acid ester and in the absence of solid absorbent for the ester;, said effective amount of said ester being sufficient to increase hair growth in the rat, when said composition is applied topically thereto over a period of no more than three months, by at least 10% more than that obtainable using a control composition from which the said ester has been omitted, in accordance with the Rat Hair Growth Test.
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- Acetylation under ultrasonic conditions: Convenient preparation of N-acetylamino acids
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An efficient and simple method of preparation of acetylamino acids from amino acids under ultrasonic conditions is described. The reactions proceed without racemization and the yields are almost quantitative.
- Veera Reddy,Ravindranath
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p. 257 - 264
(2007/10/02)
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- Cosmetic composition
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A composition suitable for topical application to mammalian skin and hair for inducing, maintaining or increasing hair growth comprises a hair growth promoter chosen from N-acylated amino-acids, in which the acyl group has from 2 to 20 carbon atoms, together with a cosmetically acceptable vehicle for the hair growth promoter.
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- Catalysis by β-cyclodextrin in the reaction of p-nitrophenyl acetate with α-amino acids
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The reactions of p-nitrophenyl acetate, 1, with both enantiomers of the following α-amino acids: alanine (2a), methionine (2b), leucine (2c), and tryptophan (2d), were studied in the presence of β-cyclodextrin (β-CD).All the reactions were catalyzed by β-
- Barra, Monica,Rossi, Rita H. de
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p. 1124 - 1130
(2007/10/02)
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- Efficient Asymmetric Hydrogenations of (Z)-2-Acetamidoacrylic Acid Derivatives with the Cationic Rhodium Complex of (2S,4S)-MOD-BPPM
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The preparation of (2S,4S)-MOD-BPPM ((2S,4S)-N-(t-butoxycarbonyl)-4-phosphino>-2-phosphino>methyl>pyrrolidine) and its application to highly effective asymmetric hydrogenations of (Z)-2-acetamidoacrylic acid derivatives are described.
- Takahashi, Hisashi,Achiwa, Kazuo
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p. 305 - 308
(2007/10/02)
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- Method for the N-acylation of aminocarboxylic acids
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A process is disclosed for the prparation of an acylated aminocarboxylic acid which comprises contacting an aminocarboxylic acid, its alkali metal or alkaline earth metal salt with a low alkyl carboxylic acid ester of the formula wherein R1 represents hydrogen or a straight-chain or branched or cyclic hydrocarbon moiety of 1 to 30 carbon atoms, which can be substituted if desired, and wherein R2 represents a straight-chain, branched or cyclic hydrocarbon moiety of 1 to 8 carbon atoms in the presence of an alkali metal or alkaline earth metal alcoholate.
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