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Yu Zong, Xiuyun Sun, Hongying Gao, Kirsten J Meyer, Kim Lewis, Yu Rao
Teixobactin, targeting lipid II, represents a new class of antibiotics with novel structures and has excellent activity against Gram-positive pathogens. We developed a new convergent method to synthesize a series of teixobactin analogues and explored structure-activity relationships. We obtained equipotent and simplified teixobactin analogues, replacing the l- allo-enduracididine with lysine, substituting oxygen to nitrogen on threonine, and adding a phenyl group on the d-phenylalanine. On the basis of the antibacterial activities that resulted from corresponding modifications of the d-phenylalanine, we propose a hydrophobic interaction between lipid II and the N-terminal of teixobactin analogues, which we map out with our analogue 35...
April 13, 2018: Journal of Medicinal Chemistry
Roberto Biondi, Stefano Brancorsini, Giulia Poli, Maria Giulia Egidi, Enrico Capodicasa, Livio Bottiglieri, Sandro Gerli, Eleonora Brillo, Gian Carlo Di Renzo, Dragos Cretoiu, Romeo Micu, Nicolae Suciu
Hydroxyl radical (.OH) is highly reactive, and therefore very short-lived. Finding new means to accurately detect .OH, and testing the ability of known .OH scavengers to neutralize them in human biological fluids would leverage our ability to more effectively counter oxidative (.OH) stress-mediated damage in human diseases. To achieve this, we pursued the evaluation of secondary products resulting from .OH attack, using a detection system based on Fenton reaction-mediated D-phenylalanine (D-Phe) hydroxylation...
May 1, 2018: Talanta
Shin-Hong Ou, Liang-Siou Pan, Jiin-Jiang Jow, Ho-Rei Chen, Tzong-Rong Ling
In this study, electrochemical sensors for the enantioselective recognition of d and l phenylalanine were prepared using a molecular imprinting technique in which the electro-polymerization of pyrrole was carried out by Chronopotentiometry(CP) with the target molecules being present on a Ag screen printed electrode's (SPE) surface. The sensing performance was evaluated by multi-potential steps at 0 and 2V(vs. Ag/AgCl) held for 1s and 2s, respectively, for 20 cycles (with the two enantiomers being present at the same concentration)...
May 15, 2018: Biosensors & Bioelectronics
Ting-Jian Zhang, Song-Ye Li, Wei-Yan Yuan, Yi Zhang, Fan-Hao Meng
A series of N-(9,10-anthraquinone-2-carbonyl)amino acid derivatives (1a-j) was designed and synthesized as novel xanthine oxidase inhibitors. Among them, the L/D-phenylalanine derivatives (1d and 1i) and the L/D-tryptophan derivatives (1e and 1j) were effective with micromolar level potency. In particular, the L-phenylalanine derivative 1d (IC50  = 3.0 μm) and the D-phenylalanine derivative 1i (IC50  = 2.9 μm) presented the highest potency and were both more potent than the positive control allopurinol (IC50  = 8...
April 2018: Chemical Biology & Drug Design
Yosuke Sumida, Sachio Iwai, Yoshiaki Nishiya, Shinya Kumagai, Toshihide Yamada, Masayuki Azuma
d-Amino acids are important building blocks for various compounds, such as pharmaceuticals and agrochemicals. A more cost-effective enzymatic method for d-amino acid production is needed in the industry. We improved a one-pot enzymatic method for d-amino acid production by the dynamic kinetic resolution of N-succinyl amino acids using two enzymes: d-succinylase (DSA) from Cupriavidus sp. P4-10-C, which hydrolyzes N-succinyl-d-amino acids enantioselectively to their corresponding d-amino acid, and N-succinyl amino acid racemase (NSAR, EC...
November 15, 2017: Journal of Bioscience and Bioengineering
Yuhuan Sun, Chuanqi Zhao, Nan Gao, Jinsong Ren, Xiaogang Qu
Stereoselectivity towards substrates is one of the most important characteristics of enzymes. Amino acids, as cofactors of many enzymes, play important roles in stereochemistry. Herein, chiral nanozymes were constructed by grafting a series of d- or l-amino acids onto the surfaces of ceria (cerium oxide) nanoparticles. We selected the most commonly used drug for combating Parkinson's disease, that is, 3,4-dihydroxyphenylalanine (DOPA) enantiomers, as examples for chiral catalysis. Through detailed kinetic studies of cerium oxide nanoparticles (CeNPs) modified with different eight amino acids, we found that phenylalanine-modified CeNP was optimal for the DOPA oxidation reaction and showed excellent stereoselectivity towards its enantiomers...
December 22, 2017: Chemistry: a European Journal
Tarsila G Castro, Nuno M Micaêlo, Manuel Melle-Franco
Antiamoebin I (AAM-I) and zervamicin II (Zrv-IIB) are peptaibols that exert antibiotic activity through the insertion/disruption of cell membranes. In this study, we investigated how the folding of these peptaibols are affected when some of their native residues are replaced with proline analogues and asymmetrical D-α,α-dialkyl glycines (two classes of noncanonical amino acids). Systematic substitutions of native Aib, Pro, Hyp, and Iva residues were performed to elucidate the folding properties of the modified peptaibols incorporating noncanonical residues...
October 16, 2017: Journal of Molecular Modeling
Ru Jia, Yingchao Li, Hussain H Al-Mahamedh, Tingyue Gu
Different species of microbes form mixed-culture biofilms in cooling water systems. They cause microbiologically influenced corrosion (MIC) and biofouling, leading to increased operational and maintenance costs. In this work, two D-amino acid mixtures were found to enhance two non-oxidizing biocides [tetrakis hydroxymethyl phosphonium sulfate (THPS) and NALCO 7330 (isothiazoline derivatives)] and one oxidizing biocide [bleach (NaClO)] against a biofilm consortium from a water cooling tower in lab tests. Fifty ppm (w/w) of an equimass mixture of D-methionine, D-leucine, D-tyrosine, D-tryptophan, D-serine, D-threonine, D-phenylalanine, and D-valine (D8) enhanced 15 ppm THPS and 15 ppm NALCO 7330 with similar efficacies achieved by the 30 ppm THPS alone treatment and the 30 ppm NALCO 7330 alone treatment, respectively in the single-batch 3-h biofilm removal test...
2017: Frontiers in Microbiology
Mohini M Konai, Utsarga Adhikary, Jayanta Haldar
Designing selective antibacterial molecules remains an unmet goal in the field of membrane-targeting agents. Herein, we report the rational design and synthesis of a new class of lipopeptides, which possess highly selective bacterial killing over mammalian cells. The selective interaction with bacterial over mammalian membranes was established through various spectroscopic, as well as microscopic experiments, including biophysical studies with the model membranes. A detailed antibacterial structure-activity relationship was delineated after preparing a series of molecules consisting of the peptide moieties with varied sequence of amino acids, such as d-phenylalanine, d-leucine, and d-lysine...
September 18, 2017: Chemistry: a European Journal
Xiong Liu, Wenqi Zhou, Longqi Xu
A type of resin-anchored CuPF6 -(S)-BINAP was synthesized and identified. The PS-CuPF6 -(S)-BINAP resin was used to adsorb the phenylalanine enantiomers. The results showed that the adsorption capacity of PS-CuPF6 -(S)-BINAP resin toward L-phenylalanine was higher than that of resin toward D-phenylalanine. PS-CuPF6 -(S)-BINAP resin exhibited good enantioselectivity toward L-phenylalanine and D-phenylalanine. The influence of phenylalanine concentration, pH, adsorption time, and temperature on the enantioselectivity of the resin were investigated...
September 2017: Chirality
Junru Wu, Shu Feng, Wenchao Liu, Feng Gao, Yanzuo Chen
A major challenge in cancer photodynamic therapy (PDT) is the poor tumor selectivity of the photosensitizer. Therefore, temoporfin (mTHPC)-loaded nanoparticles, based on vitamin-E-succinate-grafted chitosan oligosaccharide and cyclic (arginine-glycine-aspartic acid-d-phenylalanine-lysine) (c[RGDfK])-modified d-α-tocopheryl polyethylene glycol 1000 succinate, were prepared (RGD-NPs) and were expected to enhance the accumulation of mTHPC in integrin-rich U87MG tumors. The RGD-NPs generated were 144.9nm in diameter and uniformly spherical...
August 7, 2017: International Journal of Pharmaceutics
Ranran Meng, Jingwu Kang
Because of the bioactivity against the human topoisomerase II, the stereoisomeric impurities of sitafloxacin should be controlled in the process of manufactory. In the present work, a capillary electrophoresis (CE) method was developed and validated for simultaneous determination of three stereoisomeric impurities of sitafloxacin. The separation with high resolution not only for the separation of enantiomers, but also for the separation of diastereoisomers was achieved by using a background electrolyte composed of dual chiral selectors, namely γ-cyclodextrin (γ-CD) and Cu(2+)-d-phenylalanine (D-Phe) complex...
July 14, 2017: Journal of Chromatography. A
Jin Wang, Pan Li, Bi Gong, Shuying Li, Huiling Ma
BACKGROUND: The effects of modified atmosphere packaging (MAP) on phenol metabolism and preservation of fresh in-hull walnuts have been investigated. Fruit was packaged under MAP1 (film thickness, 30 μm), MAP2 (45 μm) and MAP3 (50 μm) and stored at -0.5 to 1.0 °C for up to 60 days. RESULTS: Firmness, soluble solid concentration, total phenols, total flavonoids and total antioxidant activity of the green hull were maintained at higher levels under the MAP conditions, whereas decay incidence was lower compared to the control during storage...
December 2017: Journal of the Science of Food and Agriculture
Shabi Abbas Zaidi
This work demonstrates the facile and efficient preparation protocol of β-Cyclodextrin-reduced graphene oxide modified glassy carbon electrode (β-CD/RGO/GCE) sensor for an impressive chiral selectivity analysis for phenylalanine enantiomers. In this work, the immobilization of β-CD over graphene sheets allows the excellent enantiomer recognition due to the large surface area and high conductivity of graphene sheets and extraordinary supramolecular (host-guest interaction) property of β-CD. The proposed sensor was well characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and electrochemical impedance spectroscopy (EIS) techniques...
August 15, 2017: Biosensors & Bioelectronics
Junji Hayashi, Tomonari Seto, Hironaga Akita, Masahiro Watanabe, Tamotsu Hoshino, Kazunari Yoneda, Toshihisa Ohshima, Haruhiko Sakuraba
A stable NADP+ -dependent d-amino acid dehydrogenase (DAADH) was recently created from Ureibacillus thermosphaericus meso -diaminopimelate dehydrogenase through site-directed mutagenesis. To produce a novel DAADH mutant with different substrate specificity, the crystal structure of apo-DAADH was determined at a resolution of 1.78 Å, and the amino acid residues responsible for the substrate specificity were evaluated using additional site-directed mutagenesis. By introducing a single D94A mutation, the enzyme's substrate specificity was dramatically altered; the mutant utilized d-phenylalanine as the most preferable substrate for oxidative deamination and had a specific activity of 5...
June 1, 2017: Applied and Environmental Microbiology
S Nagarjun, Shivsharan B Dhadde, Veeresh P Veerapur, B S Thippeswamy, Baburao N Chandakavathe
Present study was designed to evaluate the effect of chromium-d-phenylalanine complex (Cr (d-phe)3 ) on indomethacin-induced inflammatory bowel disease (IBD) in rats. Adult Wistar rats were pretreated with vehicle/Cr (d-phe)3 (30, 60 and 90μg/kg, p.o.) for 11days. On day 8 and 9, after one h of the above mentioned treatment, indomethacin (7.5mg/kg/day,s.c.) was administered to induce IBD. On day 12, blood samples were collected from animals for lactate dehydrogenase (LDH) estimation and ileum was isolated for macroscopic scoring, biochemical estimation (lipid peroxidation, reduced glutathione and myeloperoxidase activity) and histopathological study...
May 2017: Biomedicine & Pharmacotherapy, Biomédecine & Pharmacothérapie
Lucas Canto de Souza, Gustavo Provensi, Daniela Vullo, Fabrizio Carta, Andrea Scozzafava, Alessia Costa, Scheila Daiane Schmidt, Maria Beatrice Passani, Claudiu T Supuran, Patrizio Blandina
Rats injected with by d-phenylalanine, a carbonic anhydrase (CA) activator, enhanced spatial learning, whereas rats given acetazolamide, a CA inhibitor, exhibited impairments of fear memory consolidation. However, the related mechanisms are unclear. We investigated if CAs are involved in a non-spatial recognition memory task assessed using the object recognition test (ORT). Systemic administration of acetazolamide to male CD1 mice caused amnesia in the ORT and reduced CA activity in brain homogenates, while treatment with d-phenylalanine enhanced memory and increased CA activity...
May 15, 2017: Neuropharmacology
Valentin Sereda, Nicole M Ralbovsky, Milana C Vasudev, Rajesh R Naik, Igor K Lednev
Self-assembly of short peptides into nanostructures has become an important strategy for the bottom-up fabrication of nanomaterials. Significant interest to such peptide-based building blocks is due to the opportunity to control the structure and properties of well-structured nanotubes, nanofibrils, and hydrogels. X-ray crystallography and solution NMR, two major tools of structural biology, have significant limitations when applied to peptide nanotubes because of their non-crystalline structure and large weight...
September 2016: Journal of Raman Spectroscopy: JRS
Ee Li, Jiajia Wu, Peng Wang, Dun Zhang
D-amino acids have been reported to be able to inhibit biofilm formation or disperse existing biofilms of many microbes, in some cases, it is due to growth inhibition as an unspecific effect. In this work, six different D-amino acids were tested for their inhibitory effects on biofilm development and bacteria growth of Pseudoalteromonas sp. SC2014, a marine microbe involving in microbiologically influenced corrosion (MIC). Experimental results indicated that D-phenylalanine (D-Phe) inhibited biofilm formation effectively at concentrations that did not affect cell growth, whereas, the other D-amino acids either showed little effect or inhibited biofilm formation when inhibited bacteria growth...
September 22, 2016: FEMS Microbiology Letters
Jaime A Valderrama, Virginia Delgado, Sandra Sepúlveda, Julio Benites, Cristina Theoduloz, Pedro Buc Calderon, Giulio G Muccioli
A variety of aminoisoquinoline-5,8-quinones bearing α-amino acids moieties were synthesized from 3-methyl-4-methoxycarbonylisoquinoline-5,8-quinone and diverse l- and d-α-amino acid methyl esters. The members of the series were evaluated for their cytotoxic activity against normal and cancer cell lines by using the (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) (MTT) assay. From the current investigation, structure-activity relationships demonstrate that the location and structure of the amino acid fragment plays a significant role in the cytotoxic effects...
September 8, 2016: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
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