Influence of Glutamic Acid Enantiomers on C‐mineralization

Seasonal dynamics in the mineralization of glutamic acid enantiomers in soils from selected ecosystems was determined and subjected to a range of treatments: ambient x elevated CO₂ level and meadow x dense x thinned forest environment. Mineralization of glutamic acid was determined by incubation of the soil with 2 mg L‐ or D‐glutamic acid g^‐1 of dry soil to induce the maximum respiration rate. Mineralization of glutamic acid enantiomers in soils fluctuates over the course of a vegetation season, following a similar trend across a range of ecosystems. Mineralization is affected by environmental changes and management practices, including elevated CO₂ level and thinning intensity. L‐glutamic acid metabolism is more dependent on soil type as compared to metabolism of its D‐enantiomer. The results support the hypothesis that the slower rate of D‐ compared to L‐ amino acid mineralization is due to different roles in anabolism and catabolism of the soil microbial community. Chirality 27:104–108, 2015. © 2014 Wiley Periodicals, Inc.     

Enantioanalysis of Pipecolic Acid with Stochastic and Potentiometric Microsensors

Stochastic and potentiometric microsensors based on porphyrins and polymeric surfactants such as polysodium N‐undecanoyl‐ l ‐leucylvanilate and polysodium 相似文献   

Examination of the active secondary structure of the peptide 101.10, an allosteric modulator of the interleukin‐1 receptor,by positional scanning using β‐amino γ‐lactams

The relationship between the conformation and biological activity of the peptide allosteric modulator of the interleukin‐1 receptor 101.10 (D ‐Arg‐D ‐Tyr‐D ‐Thr‐D ‐Val‐D ‐Glu‐D ‐Leu‐D ‐Ala‐NH₂) has been studied using (R)‐ and (S)‐Bgl residues. Twelve Bgl peptides were synthesized using (R)‐ and (S)‐cyclic sulfamidate reagents derived from L ‐ and D ‐aspartic acid in an optimized Fmoc‐compatible protocol for efficient lactam installment onto the supported peptide resin. Examination of these (R)‐ and (S)‐Bgl 101.10 analogs for their potential to inhibit IL‐1β‐induced thymocyte cell proliferation using a novel fluorescence assay revealed that certain analogs exhibited retained and improved potency relative to the parent peptide 101.10. In light of previous reports that Bgl residues may stabilize type II′β‐turn‐like conformations in peptides, CD spectroscopy was performed on selected compounds to identify secondary structure necessary for peptide biological activity. Results indicate that the presence of a fold about the central residues of the parent peptide may be important for activity. Copyright © 2011 European Peptide Society and John Wiley & Sons, Ltd.     

Chiral Separation of the Clinically Important Compounds Fucose and Pipecolic Acid Using CE: Determination of the Most Effective Chiral Selector

In this study, simple electrophoretic methods were developed for the chiral separation of the clinically important compounds fucose and pipecolic acid. In recent years, these analytes, and particularly their individual enantiomers, have attracted considerable attention due to their role in biological functions and disorders. The detectability and sensitivity of pipecolic acid and fucose were improved by reacting them with fluorenylmethyloxycarbonyl chloride (FMOC‐Cl) and 5‐amino‐2‐naphthalene‐sulfonic acid (ANSA), respectively. The enantioseparation conditions were optimized by initially investigating the type of the chiral selector. Different chiral selectors, such as polymeric surfactants and cyclodextrins, were used and the most effective ones were determined with regard to resolution and analysis time. A 10‐mM β‐cyclodextrin was able to separate the enantiomers of ANSA‐DL‐fucose and the polymeric surfactant poly(sodium N‐undecanoyl‐LL‐leucine‐valinate) was able to separate the enantiomers of FMOC‐DL‐pipecolic acid, with resolution values of 3.45 and 2.78, respectively. Additional parameters, such as the concentration and the pH of the background electrolyte (BGE), the concentration of the chiral selector, and the addition of modifiers were examined in order to optimize the separations. The addition of the chiral ionic liquid D‐alanine tert‐butyl ester lactate into the BGE was also investigated, for the first time, in order to improve resolution of the enantiomers. Chirality 25:556–560, 2013. © 2013 Wiley Periodicals, Inc.     

Natural Occurrence of Enantiomers of Organic Compounds Versus Phytoremediations: Should Research on Phytoremediations Be Revisited? A Mini‐review

Decontamination of polluted soils using plants is based on the ability of plant species (including transgenic plants) to enhance bioavailability of pollutants in the rhizosphere and support growth of pollutant‐degrading microorganisms via root exudation and plant species‐specific composition of the exudates. In this work, we review current knowledge of enantiomers of low‐molecular‐weight (LMW) organic compounds with emphasis on their use in phytoremediation. Many research studies have been performed to search for plants suitable for decontamination of polluted soils. Nevertheless, the natural occurrence of L‐ versus D‐enantiomers of dominant compounds of plant root exudates which play different roles in the complexation of heavy metals, chemoattraction, and support of pollutant‐degrading microorganisms were not included in these studies. D‐enantiomers of aliphatic organic acids and amino acids or L‐enantiomers of carbohydrates occur in high concentrations in root exudates of some plant species, especially under stress, and are less stimulatory for plants to extract heavy metals or for rhizosphere microflora to degrade pollutants compared with L‐enantiomers (organic acids and amino acids) or D‐carbohydrates. Determining the ratio of L‐ versus D‐enantiomers of organic compounds as a criterion of plant suitability for decontamination of polluted soils and development of other types of bioremediation technologies need to be subjects of future research. Chirality 26:1–20, 2013. © 2013 Wiley Periodicals, Inc.     

Self‐assembling organo‐peptide bolaphiles with KLK tripeptide head groups display selective antibacterial activity

In keeping with recent efforts to generate compounds for antibiotic and microbicide development, we focused on the creation of non‐natural organo‐peptide hybrids of antimicrobial peptide amides (KLK(L)_nKLK‐NH₂) derived from sapecin B and a self‐assembling oligoglycine organo‐peptide bolaphile containing an ω‐amino fatty acid residue. The hybrid organo‐peptide bolaphiles with two cationic KLK tripeptide motifs linked with an ω‐amino acid residue (penta‐, octa‐ or undecamethylene chain) maintained the self‐assembling properties of the root oligoglycine bolaphile. Electron microscopy clearly revealed complex supramolecular architectures for both sapecin B‐derived peptides and the hybrid analogues. FT‐IR spectroscopy indicated that the supramolecular structures were composed primarily of β‐sheets. CD revealed that the hybrid bolaphiles did not share the same secondary structures as the sapecin B peptides in solution. However, although secondary structures of antimicrobial peptides are central in the activity, the organo‐peptide bolaphiles also retained the potent antimicrobial activity of the leader sapecin B‐derived peptide against both Gram‐positive and Gram‐negative bacteria. In general, the hybrids were more selective than the sapecin B peptides, as they displayed little or no appreciable haemolytic activity. The results obtained herald a new approach for the design of purpose‐built hybrid organo‐peptide bolaphiles. Copyright © 2013 European Peptide Society and John Wiley & Sons, Ltd.     

Oleanane‐Type Glycosides from Tremastelma palaestinum (L.) Janchen

Three new oleanane‐type glycosides, 1 – 3 , were isolated from the whole plant of Tremastelma palaestinum (L.) Janchen, along with eight known triterpene glycosides. The structures of the new compounds were established as 3‐O‐[β‐d‐ glucopyranosyl‐(1→3)‐α‐l‐ rhamnopyranosyl‐(1→3)‐β‐d‐ glucopyranosyl‐(1→3)‐α‐l‐ rhamnopyranosyl‐(1→2)‐α‐l‐ arabinopyranosyl]hederagenin ( 1 ), 3‐O‐[β‐d‐ glucopyranosyl‐(1→3)‐α‐l‐ rhamnopyranosyl‐(1→3)‐β‐d‐ glucopyranosyl‐(1→3)‐α‐l‐ rhamnopyranosyl‐(1→2)‐α‐l‐ arabinopyranosyl]hederagenin 28‐O‐β‐d‐ glucopyranosyl‐(1→6)‐β‐d‐ glucopyranosyl ester ( 2 ), and 3‐O‐[α‐l‐ rhamnopyranosyl‐(1→3)‐β‐d‐ glucopyranosyl‐(1→3)‐α‐l‐ rhamnopyranosyl‐(1→2)‐α‐l‐ arabinopyranosyl]oleanolic acid 28‐O‐β‐d‐ glucopyranosyl‐(1→6)‐β‐d‐ glucopyranosyl ester ( 3 ) by using 1D‐ and 2D‐NMR techniques and mass spectrometry. This is the first report on the phytochemical investigation of a species belonging to Tremastelma genus.     

Novel 3‐Oxo‐ and 3,24‐Dinor‐2,4‐secooleanane‐Type Triterpenes from Terminalia ivorensis A. Chev.

Two new oleanane‐type triterpenes named ivorengenin A (=3‐oxo‐2α,19α,24‐trihydroxyolean‐12‐en‐28‐oic acid; 1 ) and ivorengenin B (=4‐oxo‐19α‐hydroxy‐3,24‐dinor‐2,4‐secoolean‐12‐ene‐2,28‐dioic acid; 2 ), together with five known compounds, arjungenin, arjunic acid, betulinic acid, sericic acid, and oleanolic acid, were isolated from the barks of Terminalia ivorensis A. Chev . (Combretaceae). Their structures were established on the basis of 1D‐ and 2D‐NMR data, and mass spectrometry. A biogenetic pathway to the formation of these compounds from sericic acid, isolated as the major compound from this plant, was proposed. The antioxidant activities of different compounds were investigated by means of the 2,2‐azinobis(3‐ethylbenzothiazoline‐6‐sulfonic acid) (ABTS) and 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) assays, and IC₅₀ values were calculated and compared with Trolox activity. Antiproliferative activities of the isolated compounds were also evaluated against MDA‐MB‐231, PC3, HCT116, and T98G human cancer cell lines, against which the compounds showed significant cytotoxic activities.     

Aurothiomalate as Preventive and Chain‐Breaking Antioxidant in Radical Degradation of High‐Molar‐Mass Hyaluronan

The potential anti‐ or pro‐oxidative effects of a disease‐modifying antirheumatic drug, aurothiomalate, to protect high‐molar‐mass hyaluronan against radical degradation were investigated along with L ‐glutathione – tested in similar functions. Hyaluronan degradation was induced by the oxidative system Cu^II plus ascorbate known as the Weissberger's oxidative system. The time‐ and dose‐dependent changes of the dynamic viscosity of the hyaluronan solutions were studied by the method of rotational viscometry. Additionally, the antioxidative activity of aurothiomalate expressed as a radical‐scavenging capacity based on a decolorization 2,2′‐azinobis(3‐ethylbenzothiazoline‐6‐sulfonic acid) (ABTS) assay was inspected. At the higher concentrations tested, L ‐glutathione showed excellent scavenging of ^.OH and peroxyl‐type radicals, however, at the lowest concentration applied, its pro‐oxidative effect was revealed. The effects of aurothiomalate on hyaluronan degradation were similar to that of L ‐glutathione, however, at the lowest concentration tested, no significant pro‐oxidant effect was observed.     

Escherichia coli‐based cell free production of flagellin and ordered flagellin display on virus‐like particles

Bacterial flagellin has been explored as a potential vaccine adjuvant for enhancing immune responses. In this article, we describe Escherichia coli‐based cell‐free protein synthesis (CFPS) as a method to rapidly produce soluble phase 1 flagellin (FliC) protein from Salmonella typhimurium. The yield was about 300 µg/mL and the product had much higher affinity for the TLR5 receptor (EC50 = 2.4 ± 1.4 pM) than previously reported. The flagellin coding sequence was first optimized for cell‐free expression. We then found that the D0 domain at the C‐terminus of flagellin was susceptible to proteolytic degradation in the CFPS system. Proteolysis was reduced by protease inhibitors, the use of protease‐deficient cell extracts or deletion of the flagellin D0 domain. A human Toll‐Like Receptor 5 (hTLR5)‐specific bioactivity analysis of purified flagellin demonstrated that, although the D0 domain is far from the TLR5 recognition region, it is important for flagellin bioactivity. We next incorporated a non‐natural amino acid displaying an alkyne moiety into flagellin using the CFPS system and attached flagellin to hepatitis B core virus‐like particles (VLPs) using bioorthogonal azide‐alkyne cycloaddition reactions. The ordered and oriented VLP display of flagellin increased its specific TLR5 stimulation activity by approximately 10‐fold. Biotechnol. Bioeng. 2013; 110: 2073–2085. © 2013 Wiley Periodicals, Inc.     

Multi‐cycle recovery of lactoferrin and lactoperoxidase from crude whey using fimbriated high‐capacity magnetic cation exchangers and a novel “rotor–stator” high‐gradient magnetic separator

Cerium (IV) initiated “graft‐from” polymerization reactions were employed to convert M‐PVA magnetic particles into polyacrylic acid‐fimbriated magnetic cation exchange supports displaying ultra‐high binding capacity for basic target proteins. The modifications, which were performed at 25 mg and 2.5 g scales, delivered maximum binding capacities (Q_max) for hen egg white lysozyme in excess of 320 mg g^?1, combined with sub‐micromolar dissociation constants (0.45–0.69 µm) and “tightness of binding” values greater than 49 L g^?1. Two batches of polyacrylic acid‐fimbriated magnetic cation exchangers were combined to form a 5 g pooled batch exhibiting Q_max values for lysozyme, lactoferrin, and lactoperoxidase of 404, 585, and 685 mg g^?1, respectively. These magnetic cation exchangers were subsequently employed together with a newly designed “rotor–stator” type HGMF rig, in five sequential cycles of recovery of lactoferrin and lactoperoxidase from 2 L batches of a crude sweet bovine whey feedstock. Lactoferrin purification performance was observed to remain relatively constant from one HGMF cycle to the next over the five operating cycles, with yields between 40% and 49% combined with purification and concentration factors of 37‐ to 46‐fold and 1.3‐ to 1.6‐fold, respectively. The far superior multi‐cycle HGMF performance seen here compared to that observed in our earlier studies can be directly attributed to the combined use of improved high capacity adsorbents and superior particle resuspension afforded by the new “rotor–stator” HGMS design. Biotechnol. Bioeng. 2013; 110: 1714–1725. © 2013 Wiley Periodicals, Inc.     

Homo‐C‐nucleoside analogs IV. Synthesis of 4‐(2,5‐anhydro‐D‐altro‐pentitol‐1‐yl)‐2‐phenyl‐2H‐1,2,3‐triazole homo‐C‐nucleoside. CD assignment of the absolute configuration of the carbon bridge

Dehydrative cyclization of 4‐(D‐altro ‐pentitol‐1‐yl)2‐phenyl‐2H ‐1,2,3‐triazole in basic medium with one moler equivalent of p‐toluene sulfonyl chloride in pyridine solution gave the homo‐C‐ nucleoside 4‐(2,5‐anhydro‐D‐altro ‐1‐yl)‐2‐phenyl‐2H ‐1,2,3‐triazole. The structure and anomeric configuration was determined by acylation, nuclear magnetic resonance (NMR), and mass spectroscopy. The stereochemistry at the carbon bridge of homo‐C‐ nucleoside 2‐phenyl‐2H ‐1,2,3‐triazoles was determined by circular dichroism (CD) spectroscopy.     

Application of NMR spectroscopy for assignment of the absolute configuration of 8‐tert‐butyl‐2‐hydroxy‐7‐methoxy‐8‐methyl‐9‐oxa‐6‐azaspiro[4.5]dec‐6‐en‐10‐one

In order to assign the absolute configurations of 8‐tert‐butyl‐2‐hydroxy‐7‐methoxy‐8‐methyl‐9‐oxa‐6‐azaspiro[4.5]dec‐6‐en‐10‐one ( 2a , 2b ), their esters ( 5a , 5b , 5c , 5d ) with (R)‐ or (S)‐2‐methoxyphenylacetic acid ( 4a , 4b ) have been synthesized. The absolute configurations of these compounds have been determined on the basis of NOESY correlations between the protons of the tert‐butyl group and the cyclopentane fragment of the molecules. The crucial part of this analysis was assignment of the absolute configuration at C‐5. Additionally, by calculation of the chemical shift anisotropy, δ^RS, for the relevant protons, it was also possible to confirm the absolute configurations at the C‐2 centres of compounds 2a , 2b and 5a , 5b , 5c , 5d . Chirality, 25:422–426, 2013.© 2013 Wiley Periodicals, Inc.     

Tissue‐specific and light‐dependent regulation of phytochrome gene expression in rice

Phytochromes are red‐ and far red light photoreceptors in higher plants. Rice (Oryza sativa L.) has three phytochromes (phyA, phyB and phyC), which play distinct as well as cooperative roles in light perception. To gain a better understanding of individual phytochrome functions in rice, expression patterns of three phytochrome genes were characterized using promoter‐GUS fusion constructs. The phytochrome genes PHYA and PHYB showed distinct patterns of tissue‐ and developmental stage‐specific expression in rice. The PHYA promoter‐GUS was expressed in all leaf tissues in etiolated seedlings, while its expression was restricted to vascular bundles in expanded leaves of light‐grown seedlings. These observations suggest that light represses the expression of the PHYA gene in all cells except vascular bundle cells in rice seedlings. Red light was effective, but far red light was ineffective in gene repression, and red light‐induced repression was not observed in phyB mutants. These results indicate that phyB is involved in light‐dependent and tissue‐specific repression of the PHYA gene in rice.     

1‐Acetyl‐3‐[(3R)‐hydroxyfatty acyl]glycerols: Lipid Compounds from Euphrasia rostkoviana Hayne and E. tetraquetra (Bréb.) Arrond.

Five homologous acetylated acylglycerols of 3‐hydroxyfatty acids (chain lengths C(14) – C(18)), named euphrasianins A – E, were characterized for the first time in Euphrasia rostkoviana Hayne (Orobanchaceae) by gas chromatography/mass spectrometry (GC/MS) and high‐performance liquid chromatography/atmospheric pressure chemical ionization‐mass spectrometry (HPLC/APCI‐MSⁿ). In addition to mass spectrometric data, structures of euphrasianins were verified via a three‐step total synthesis of one representative homologue (euphrasianin A). The structure of the latter was confirmed by 1D‐ and 2D‐NMR experiments as well as high‐resolution electrospray ionization‐mass spectrometry (HR‐ESI‐MS). The absolute configuration of the 3‐hydroxyfatty acid moiety at C(3) was found to be R in the natural euphrasianins, which was determined by alkaline hydrolysis and methylation of a purified fraction, followed by chiral GC analysis. Furthermore, in extracts of Euphrasia tetraquetra (Bréb .) Arrond . euphrasianins C and E were detected exclusively, indicating that this subclass of lipid constituents is possibly valuable for fingerprinting methods.     

Precolumn o‐Phthalaldehyde‐N‐acetyl‐L‐cysteine Derivatization Followed by RP‐HPLC Separation and Fluorescence Detection of Sitagliptin Enantiomers in Rat Plasma

An indirect reversed‐phase high‐performance liquid chromatographic separation and fluorescence detection of sitagliptin enantiomers in rat plasma was developed and validated. Deproteinized rat plasma containing racemic sitagliptin was derivatized with o‐phthalaldehyde and N‐acetyl‐L‐cysteine under alkaline conditions, converted to diastereomers, and separated on a Lichrospher 100 RP‐18e column using 20 mM phosphate buffer and methanol (45:55 v/v) as a mobile phase under isocratic mode of elution at a flow rate of 1.0 mL/min. Fluorescence detection was performed at 330 and 450 nm as excitation and emission wavelengths, respectively. The method was linear in the range of 50–5000 ng/ mL for both enantiomers. The intra‐ and interday accuracy and precision were within the predefined limits of ≤15% at all concentrations. The method was successfully applied to a pharmacokinetic study of sitagliptin after 5 mg/kg oral administration to Wistar rats. Robustness of the method was evaluated using design of experiments. Chirality 25:883–889, 2013. © 2013 Wiley Periodicals, Inc.     

Synthesis of New exo‐ and endo‐3,8‐Dihydro‐β‐santalols and Other Norbornyl‐Derived Alcohols

Several new and differently functionalized cis‐2,3‐dimethylnorbornane derivatives presenting diverse side‐chain lengths were prepared, the structures of which are related to the natural fragrance β‐santalol. In particular, exo‐ and endo‐3,8‐dihydro‐β‐santalols, with either (E) or (Z) C?C‐bond configuration on the side chain, were synthesized in seven steps and 21–24% overall yields. Several other exo‐ and endo‐norbornyl alcohols with shorter side chains were also prepared in high yields. The olfactory evaluation indicated woody, sandalwood, as well as fruity notes for some of the derivatives.     

An improved synthesis of (2S, 4S)‐ and (2S, 4R)‐2‐amino‐4‐methyldecanoic acids: assignment of the stereochemistry of culicinins

An improved synthesis of (2S, 4S)‐ and (2S, 4R)‐2‐amino‐4‐methyldecanoic acids was accomplished using a glutamate derivative as starting material and Evans' asymmetric alkylation as the decisive step. The NMR data of the two diastereomers were measured and compared with those of the natural product. As a result, the stereochemistry of this novel amino acid unit in culicinins was assigned as (2S, 4R). Copyright © 2011 European Peptide Society and John Wiley & Sons, Ltd.     

Changes in the Proliferation and Differentiation of Neonatal Mouse Pink‐Eyed Dilution Melanocytes in the Presence of Excess Tyrosine

Changes in the proliferation and differentiation of epidermal melanocytes derived from newborn mice wild‐type at the pink‐eyed dilution (p) locus (P/P) and from congenic mice mutant at that locus (p/p) were investigated in serum‐free primary culture, with or without the addition of L‐Tyr. Incubation with added L‐Tyr inhibited the proliferation of P/P melanocytes in a concentration‐dependent manner and inhibition was gradually augmented as the donor mice aged. In contrast, L‐Tyr stimulated the proliferation of p/p melanoblasts–melanocytes derived from 0.5‐day‐old mice, but inhibited their proliferation when derived from 3.5‐ or 7.5‐day‐old mice. L‐Tyr stimulated the differentiation of P/P melanocytes. However, almost all cells were undifferentiated melanoblasts in control cultures derived from 0.5‐, 3.5‐ and 7.5‐day‐old p/p mice, but L‐Tyr induced their differentiation as the age of the donor mice advanced. The content of the eumelanin marker, pyrrole‐2,3,5‐tricarboxylic acid as well as the pheomelanin marker, 4‐amino‐3‐hydroxyphenylalanine in p/p melanocytes was greatly reduced compared with P/P melanocytes. However, the contents of eumelanin and its precursor, 5,6‐dihydroxyindole‐2‐carboxylic acid, as well as the contents of pheomelanin and its precursor, 5‐S‐cysteinyldopa in culture media from p/p melanocytes were similar to those of P/P melanocytes at all ages tested. L‐Tyr increased the content of eumelanin and pheomelanin two‐ to threefold in cultured cells and media derived from 0.5‐, 3.5‐ and 7.5‐day‐old mice. These results suggest that the proliferation of p/p melanoblasts–melanocytes is stimulated by L‐Tyr, and that the differentiation of melanocytes is induced by L‐Tyr as the age of the donor mice advanced, although eumelanin and pheomelanin fail to accumulate in p/p melanocytes and are released from them at all ages of skin development.