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DMDP acetic acid [N-carboxymethyl-2,5-dideoxy-2,5-imino-d-mannitol] 5 from Stevia rebaudiana is the first isolated natural amino acid derived from iminosugars bearing an N-alkyl acid side chain; it is clear from GCMS studies that such derivatives with acetic and propionic acids are common in a broad range of plants including mulberry, Baphia, and English bluebells, but that they are very difficult to purify. Reaction of unprotected pyrrolidine iminosugars with aqueous glyoxal gives the corresponding N-acetic acids in very high yield; Michael addition of both pyrrolidine and piperidine iminosugars and that of polyhydroxylated prolines to tert-butyl acrylate give the corresponding N-propionic acids in which the amino group of β-alanine is incorporated into the heterocyclic ring. These easy syntheses allow the identification of this new class of amino acid in plant extracts and provide pure samples for biological evaluation. DMDP N-acetic and propionic acids are potent α-galactosidase inhibitors in contrast to potent β-galactosidase inhibition by DMDP. [ABSTRACT FROM AUTHOR]

This newly designed route assembled a pyrazole ring with an aldehydic functionality over another pyrazole moiety. Further, formyl group was exploited in different routes such as condensation reactions, imidazole and pyrimidone/thione synthesis. The present reactions were performed with glycine, a facile catalyst, and the results were compared well with those of conventional methods. [ABSTRACT FROM AUTHOR]

The first diastereoselective synthesis of the 5-hydroxy-pyrrolidinone amino acid common to eight members of the microsclerodermin family is presented. Our strategy involves formal hydration of an unsaturated precursor via the use of a two-step hydroxybromination-debromination protocol; this procedure provides exclusively the requisite 4,5- cis -pyrrolidinone. Furthermore model studies are presented that indicated the potential viability of this hydration strategy in the context of a synthesis of microsclerodermin B. [ABSTRACT FROM AUTHOR]

Apparent molar properties ( V ∅ and K ∅ , s ) of amino acids (glycine, L -alanine and L -valine) within the concentration range of (0.02–0.20) mol·kg −1 in aqueous (0.005, 0.01 and 0.03) mol·kg −1 Levofloxacin (LVFX) solutions are computed from the experimental density ( ρ ) and ultrasonic speed ( c ) values at T = (288.15, 293.15, 298.15, 303.15 and 308.15) K and P = 0.1 MPa. Derived parameters such as partial molar properties ( V ∅ 0 and K ∅ , s 0 ) and their experimental slopes ( S V and S K ) , transfer partial molar properties ( Δ V ∅ 0 and Δ K ∅ , s 0 ), hydration numbers ( n H ) and Hepler’s constant are computed from the data of apparent molar properties. The pair and triplet interaction coefficients have also been evaluated from transfer parameters. The linear variation of V ∅ 0 with the number of carbon atoms in the alkyl chain of amino acids has been utilized to calculate the contribution of the charged end groups ( NH 3 + , COO - ) , ( CH 2 ) group and other alkyl chains of the amino acids to V ∅ 0 . From the obtained parameters, some information in regard with the solute-solvent interaction in the systems studied was obtained. The co-sphere overlap model was used to interpret the positive transfer properties ( Δ V ∅ 0 and Δ K ∅ , s 0 ). The volume and compression data suggest that there exist strong solute-solvent interactions in these systems, which increase with increase in temperature. It is inferred that amino acids studied act as structure-breaker (chaotropic effect) in aqueous LVFX solutions. [ABSTRACT FROM AUTHOR]

A concise organocatalytic route toward the synthesis of furanose and pyranose substituted glycine and alanine derivatives is reported. These compounds are core structural units of some of the naturally available antibiotics and antifungal agents. Proline-catalyzed asymmetric α-amination of aldehydes derived from sugars is used as the key reaction to synthesize twelve sugar amino acid derivatives. The asymmetric transformations proceeded in good yields and with good to excellent diastereoselectivity. The application of the synthesized amino acids is demonstrated by synthesizing a tripeptide containing one of them. [ABSTRACT FROM AUTHOR]

A straightforward and transition-metal-free approach for the efficient synthesis of α-arylglycine derivatives from aromatic imines and carbon dioxide was enabled by an umpolung carboxylation reaction. Various substituted diphenylmethimines underwent the carboxylation smoothly with carbon dioxide in the presence of potassium tert-butoxide and 18-crown-6 to give the corresponding carboxylated products in good to high yields. Besides the enhancement of the solubility of potassium tert-butoxide in THF, 18-crown-6 also plays key roles in suppressing the reverse protonation or 1, 3-proton shift isomerization as well as by stabilizing the carboxylated intermediate. [ABSTRACT FROM AUTHOR]

A conformationally restricted monofluorinated α-amino acid, (3-fluorobicyclo[1.1.1]pentyl)glycine (F-Bpg), was designed as a label for the structural analysis of membrane-bound peptides by solid-state 19F NMR spectroscopy. The compound was synthesized and validated as a 19F label for replacing natural aliphatic α-amino acids. Calculations suggested that F-Bpg is similar to Leu/Ile in terms of size and lipophilicity. The 19F NMR label was incorporated into the membrane-active antimicrobial peptide PGLa and provided information on the structure of the peptide in a lipid bilayer. [ABSTRACT FROM AUTHOR]

α-Ethynyl glycine derivatives have a high potential for functionalization by derivatization of the amino acid or acetylene moiety, and, as a result, are important intermediates in the construction of biologically active compounds, including natural products. The main methods for the synthesis of ethynyl glycines and glycinols can be divided into six different transformations: (a) homologations of serinal derivatives, (b) nucleophilic alkynylations of α-imino esters/alcohols or their precursors α-halo glycinates, (c) derivatizations of alkynyl imino esters, (d) electrophilic alkynylations of α-nitro esters and azlactones by using hypervalent iodine reagents, (e) intra- and intermolecular aminolysis reactions of epoxides, and (f) propargylic aminations through the cyclization of bis(imidate). This microreview summarizes the methods that were published from 1996 to 2015. [ABSTRACT FROM AUTHOR]

The theophylline-7-acetic acid (7- TAA) scaffold is a promising novel lead compound for antimycobacterial activity. Here, we derive a model for antitubercular activity prediction based on 14 7- TAA derivatives with amino acid moieties and their methyl esters. The model is applied to a combinatorial library, consisting of 40 amino acid and methyl ester derivatives of 7- TAA. The best three predicted compounds are synthesized and tested against Mycobacterium tuberculosis H37 Rv. All of them are stable, non-toxic against human cells and show antimycobacterial activity in the nanomolar range being 60 times more active than ethambutol. [ABSTRACT FROM AUTHOR]

Knowledge of thermodynamic properties of substituted amino acids in aqueous medium can provide valuable information regarding the stabilisation mechanism of proteins. In this study, we report the density and ultrasonic speeds of N-acetyl glycine in (0.03, 0.05, 0.1, 0.15 and 0.2) mol ⋅ kg −1 aqueous solutions of tetraethylammonium iodide (TEAI) at temperatures (288.15, 293.15, 298.15, 303.15 and 308.15) K and at pressures 101 kPa. From these results, the apparent molar volume and acoustical parameters, coefficient of isentropic compression, molal hydration number and apparent molar isentropic compression have been evaluated. The partial molar volume, partial molar isentropic compression, and their corresponding transfer functions were calculated. These results were used to interpret the type of interactions occurring in the ternary mixtures using the co-sphere overlap model. The pair and triplet interaction coefficients have been calculated from both the properties. The concentration and temperature dependence of (solute + solute) and (solute + solvent) interactions in the present study was also discussed. The partial molar volumes were used to obtain the partial molar isobaric expansibilities for N-acetyl glycine to examine the temperature dependence of such interactions. The structure-making/breaking ability of N-acetyl glycine has also been discussed in terms of the sign of ∂ C P , ∅ 0 ∂ P T . [ABSTRACT FROM AUTHOR]

Krafft temperature ( T k ) and thermodynamics of micellization of Hexadecylpyridinium chloride (HPyCl) and Hexadecylpyridinium bromide (HPyBr) were carried out in the absence and in the presence of amino acids-glycine, diglycine and triglycine. Thermodynamic parameters of micellization — Gibbs free energy of micellization, enthalpy, entropy, free energy related with hydrophobic part and surface contribution were calculated from the specific conductance data. Transfer values of Gibbs free energy and enthalpy were also calculated. T k of HPyCl and HPyBr were determined in aqueous as well as in presence of aqueous-glycine, diglycine and triglycine. Effect of polar head group, counter-ions, additives, T k , and micellization parameters on micelle formation of the surfactants are the main points taken into consideration while explaining and interpreting the results to get an insight into the interactions of these additives with the cationic surfactants. [ABSTRACT FROM AUTHOR]

An efficient asymmetric synthesis of D-α-(uracil-5-yl)glycine derivatives using an enzymatic dynamic kinetic resolution of D, L-hydantoin intermediates with an immobilized D-hydantoinase ( D-Hyd-1) is described. In addition, mild conditions for a racemization-free solid-phase peptide synthesis (SPPS) using the Fmoc strategy have been found. [ABSTRACT FROM AUTHOR]

A practical method to prepare enantiopure 4,4,4-trifluoro- allo -threonine was developed by using an easily available fluorinated building block and a chiral auxiliary as starting materials. Trifluoroacetic anhydride was annulated with a ketene, derived from a glycine equivalent bearing a chiral oxazolidinone [(4 S ,5 R )-4,5-diphenyloxazolidin-2-one], and acetone to afford a trifluoromethylated α,β-unsaturated lactone. The asymmetric hydride reduction of the α,β-unsaturated lactone proceeded with excellent stereoselectivity to give the corresponding (2 R ,3 S )-4-oxapentan-5-olide derivative exclusively (diastereopurity, 99%). From the reduced product thus obtained, protecting groups were readily removed by acid treatment and subsequent catalytic hydrogenolysis to afford enantiopure (2 R ,3 S )-4,4,4-trifluoro- allo -threonine in an excellent yield (7 steps, 51% overall yield). [ABSTRACT FROM AUTHOR]

The study was designed to isolate and characterize the collagen from skin, scales and fins of Cyprinus carpio and Hypophthalmichthys molitrix. For this purpose nine fishes of each species of three weight groups were collected and categorized as W1 (250-500 g), W2 (501-750 g) and W3 (751- 1000 g). The maximum skin protein content was recorded as 28.13% and 29.13% in C. carpio and H. molitrix, respectively, from the W[sub 3]. The scales of the W[sub 3] displayed a maximum protein contents as 29.91 and 28.38% for C. carpio and H. molitrix, respectively. The maximum protein contents (19.19% and 21.37% for C. carpio and H. molitrix, respectively) were observed in the W[sub 3] group. Protein characterisation using SDS-PAGE revealed the molecular weights (kDa) of the C. carpio skin, scales, and fins ranged from 126 kDa to 220 kDa, 78 kDa to 211 kDa, and 72 kDa to 141 kDa, respectively. The size of the collagen proteins of the H. molitrix skin, scales and fins ranged from 117 kDa to 208 kDa, 81 kDa to 219 kDa, and 72 kDa to 141 kDa, respectively. Glycine was the most abundant amino acid, whereas, Tryptophan was totally absent in all selected tißues. Significant differences were observed for amino acids within the weight groups and between the two fish species. [ABSTRACT FROM AUTHOR]

A novel synthesis of highly substituted pyrrole-N-acetic derivatives is described through the coupling of 1,4-diketones with amino acids following Paal-Knorr's approach. These pyrrole-N-acetic acid derivatives are found to exhibit potent anti-mycobacterial activity against Mycobacterium smegmatis and Mycobacterium tuberculosis strain H37Rv. In particular, 5n, 5q &5r are found to display excellent anti-mycobacterial activity against M. tuberculosis strain H37Rv with MIC values in the range of 2.97 µM. Conversely, these compounds showed low cytotoxicity (selectivity index: >16.83) against HEK-293T cell line. [ABSTRACT FROM AUTHOR]

Infinite head-to-tail chains of zwitterions present in the crystals of all amino acids are known to be preserved even after structural phase transitions. In order to understand the role of the N-H...O hydrogen bonds linking zwitterions in these chains in structural rearrangements, the crystal structures of the N-methyl derivatives of glycine ( N-methylglycine, or sarcosine, with two donors for hydrogen bonding; two polymorphs of N, N-dimethylglycine, DMG-I and DMG-II, with one donor for hydrogen bond; and N, N, N-trimethylglycine, or betaine, with no hydrogen bonds) were studied at different pressures. Methylation has not only excluded the formation of selected hydrogen bonds, but also introduced bulky mobile fragments into the structure. The effects of pressure on the systems of the series were compared with respect to distorting and switching over hydrogen bonds and inducing reorientation of the methylated fragments. Phase transitions with fragmentation of the single crystals into fine powder were observed for partially methylated N-methyl- and N, N-dimethylglycine, whereas the structural changes in betaine were continuous with some peculiar features in the 1.4-2.9 GPa pressure range and accompanied by splitting of the crystals into several large fragments. Structural rearrangements in sarcosine and betaine were strongly dependent on the rate of pressure variation: the higher the rate of increasing pressure, the lower the pressure at which the phase transition occurred. [ABSTRACT FROM AUTHOR]

A one-step approach was observed to give N-substituted aryl glycine derivatives in good to excellent yields (up to 93 %) from ( ortho-hydroxymethyl)aryl benzoates. A cascade mechanism was proposed for the generation and in situ conjugate addition of the ortho-quinone methides. This mechanism is strongly supported by our subsequent findings that tertiary amines could promote the process. Different functional groups on the ( ortho-hydroxymethyl)aryl benzoates and various amines were investigated to explore the scope of this cascade process. The substituents on the substrates strongly affected the reaction time and yield, and various primary and secondary amines were used as nucleophiles. The addition of tertiary amines enhanced the addition process for less basic nucleophiles. [ABSTRACT FROM AUTHOR]

We describe two attempts to the synthesis of novel constrained L-AP4 analogs of potential antagonist activity. Although the first approach to introduce alkyl substituent on the amino acid carbon using cyclopropyl keton failed, conversion of cyclopropanecarboxylate into corresponding β-ketophosphonate is promising and more general. [ABSTRACT FROM AUTHOR]

Abstract: Since 1980, high-speed counter-current chromatography (HSCCC) has been used for separation and purification of natural and synthetic products in a standard elution mode. In 1991, a novel elution mode called pH-zone refining CCC was introduced from an incidental discovery that an organic acid in the sample solution formed the sharp peak of an acid analyte. The cause of this sharp peak formation was found to be bromoacetic acid present in the sample solution which formed a sharp trailing border to trap the acidic analyte. Further studies on the separation of DNP-amino acids with three spacer acids in the stationary phase revealed that increased sample size resulted in the formation of fused rectangular peaks, each preserving high purity and zone pH with sharp boundaries. The mechanism of this phenomenon was found to be the formation of a sharp trailing border of an acid (retainer) in the column which moves at a lower rate than that of the mobile phase. In order to facilitate the application of the method, a new method was devised using a set of retainer and eluter to form a sharp retainer rear border which moves through the column at a desired rate regardless of the composition of the two-phase solvent system. This was achieved by adding the retainer in the stationary phase and the eluter in the mobile phase at a given molar ratio. Using this new method the hydrodynamics of pH-zone-refining CCC was diagrammatically illustrated by three acidic samples. In this review paper, typical pH-zone-refining CCC separations were presented, including affinity separations with a ligand and a separation of a racemic mixture using a chiral selector in the stationary phase. Major characteristics of pH-zone-refining CCC over conventional HSCCC are as follows: the sample loading capacity is increased over 10 times; fractions are highly concentrated near saturation level; yield is improved by increasing the sample size; minute charged compounds are concentrated and detected at the peak boundaries; and elution peaks are monitored with a pH flow meter for compounds with no chromophore. Since 1994, over 70 research papers on pH-zone-refining CCC have been published with the trends increasing in the recent years. [Copyright &y& Elsevier]

Carbanion of ethyl N-(1,3-dithiolan-2-ylidene)glycinate adds to activated nitroarenes mostly in para position to the nitro group. Subsequent oxidation of the resulting sH adducts with DDQ gave respective a-nitroarylated glycine derivatives in moderate yields. The reaction of esters of chiral alcohols such as (-)-menthol or (-)-8-phenylmenthol proceeds with a moderate or high diastereoselectivity leading to enantiomerically enriched nitroarylglycines. [ABSTRACT FROM AUTHOR]

Several amino acids and their derivatives are prominent additives in the field of protein chemistry. This study reports the use of charged amino acids and glycine ethyl ester as precipitants in protein crystallization, using hen egg-white lysozyme (HEWL) as a model. A discussion of the crystallization of HEWL using these reagents as precipitating agents is given. [ABSTRACT FROM AUTHOR]

A mild and efficient method for the monocarboxymethylation of primary amines that takes place under aqueous conditions at room temperature is described. Treatment of an aqueous solution of a variety of primary amines with two equivalents of glyoxylic acid leads to the N-formyl glycine derivatives. Direct hydrolysis of the crude reaction solution leads to the products of amine mono�carboxymethylation in good to excellent yield. [ABSTRACT FROM AUTHOR]

Abstract: A series of amides were synthesized by condensation of theophylline-7-acetic acid and eight commercially available amino acid methyl ester hydrochlorides. Consecutive hydrolysis of six of the amido-esters resulted in the formation of corresponding amido-acids. The newly synthesized compounds were evaluated for their in vitro activity against Mycobacterium tuberculosis H37Rv. The activity varied depending on the amino acid fragments and in seven cases exerted excellent values with MICs 0.46–0.26μM. Assessment of the cytotoxicity revealed that the compounds were not cytotoxic against the human embryonal kidney cell line HEK-293T. The theophylline-7-acetamides containing amino acid moieties appear to be promising lead compounds for the development of antimycobacterial agents. [Copyright &y& Elsevier]

Target compounds (II) are prepared with excellent enantioselectivity in the presence of a D-hydantoinase. [ABSTRACT FROM AUTHOR]

It provides a new, easy, and highly stereoselective approach to a number of tetrahydroisoquinolinyl glycine derivatives. [ABSTRACT FROM AUTHOR]

A photolytic process is developed for the high yielding regioselective addition of a variety of thiols to N-protected allyl-glycine. [ABSTRACT FROM AUTHOR]