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61.
62.
Daniel J. Watson Paul R. Meyers Kojo Sekyi Acquah Godwin A. Dziwornu Christopher Bevan Barnett Lubbe Wiesner 《Molecules (Basel, Switzerland)》2021,26(24)
With drug resistance threatening our first line antimalarial treatments, novel chemotherapeutics need to be developed. Ionophores have garnered interest as novel antimalarials due to their theorized ability to target unique systems found in the Plasmodium-infected erythrocyte. In this study, during the bioassay-guided fractionation of the crude extract of Streptomyces strain PR3, a group of cyclodepsipeptides, including valinomycin, and a novel class of cyclic ethers were identified and elucidated. Further study revealed that the ethers were cyclic polypropylene glycol (cPPG) oligomers that had leached into the bacterial culture from an extraction resin. Molecular dynamics analysis suggests that these ethers are able to bind cations such as K+, NH4+ and Na+. Combination studies using the fixed ratio isobologram method revealed that the cPPGs synergistically improved the antiplasmodial activity of valinomycin and reduced its cytotoxicity in vitro. The IC50 of valinomycin against P. falciparum NF54 improved by 4–5-fold when valinomycin was combined with the cPPGs. Precisely, it was improved from 3.75 ± 0.77 ng/mL to 0.90 ± 0.2 ng/mL and 0.75 ± 0.08 ng/mL when dosed in the fixed ratios of 3:2 and 2:3 of valinomycin to cPPGs, respectively. Each fixed ratio combination displayed cytotoxicity (IC50) against the Chinese Hamster Ovary cell line of 57–65 µg/mL, which was lower than that of valinomycin (12.4 µg/mL). These results indicate that combinations with these novel ethers may be useful in repurposing valinomycin into a suitable and effective antimalarial. 相似文献
63.
Dr. Dominique Bruns Dr. Daniel Merk Dr. Karthiga Santhana Kumar PD Dr. Martin Baumgartner Prof. Dr. Gisbert Schneider 《ChemistryOpen》2019,8(10):1303-1308
Constructive machine learning aims to create examples from its learned domain which are likely to exhibit similar properties. Here, a recurrent neural network was trained with the chemical structures of known cell-migration modulators. This machine learning model was used to generate new molecules that mimic the training compounds. Two top-scoring designs were synthesized, and tested for functional activity in a phenotypic spheroid cell migration assay. These computationally generated small molecules significantly increased the migration of medulloblastoma cells. The results further corroborate the applicability of constructive machine learning to the de novo design of druglike molecules with desired properties. 相似文献
64.
Sandra M. Meyers Cornelia Laule Irene M. Vavasour Shannon H. Kolind Burkhard Mädler Roger Tam Anthony L. Traboulsee Jimmy Lee David K.B. Li Alex L. MacKay 《Magnetic resonance imaging》2009
This study compared region of interest (ROI) and voxel-based analysis (VBA) methods to determine the optimal method of myelin water fraction (MWF) analysis. Twenty healthy controls were scanned twice using a multi-echo T2 relaxation sequence and ROIs were drawn in white and grey matter. MWF was defined as the fractional signal from 15 to 40 ms in the T2 distribution. For ROI analysis, the mean intensity of voxels within an ROI was fit using non-negative least squares. For VBA, MWF was obtained for each voxel and the mean and median values within an ROI were calculated. There was a slightly higher correlation between Scan 1 and 2 for the VBA method (R2=0.98) relative to the ROI method (R2=0.95), and the VBA mean square difference between scans was 300% lower, indicating VBA was the most consistent between scans. For the VBA method, mean MWF was found to be more reproducible than median MWF. As the VBA method is more reproducible and gives more options for visualization and analysis of MWF, it is recommended over the ROI method of MWF analysis. 相似文献
65.
Katrin Meier Raul Cardoso‐Gil Ulrich Burkhardt Caroline Curfs Michael Hanfland Yuri Grin PD Dr. Ulrich Schwarz 《无机化学与普通化学杂志》2012,638(10):1446-1451
The rare‐earth metal germanides RE2Ge9 (RE = Nd, Sm) have been prepared by thermal decomposition of the metastable high‐pressure phases REGe5 at ambient pressure. The compounds adopt an orthorhombic unit cell with a = 396.34(4) pm; b = 954.05(8) pm and c = 1238.4(1) pm for Nd2Ge9 and a = 395.46(7) pm; b = 946.4(2) pm and c = 1232.1(3) pm for Sm2Ge9. Crystal structure refinements reveal space group Pmmn (No. 59) for Nd2Ge9. The atomic pattern resembles an ordered defect variety of the pentagermanide motif REGe5 (RE = La; Nd, Sm, Gd, Tb) comprising corrugated germanium layers. These condense into a three‐dimensional network interconnected by eight‐coordinated germanium atoms. The resulting framework channels along [100] enclose the neodymium atoms. With respect to the atomic arrangement of the pentagermanides, half of the interlayer germanium atoms are eliminated in an ordered way so that occupied and empty germanium columns alternate along [001]. The rare‐earth metal atoms of both types of compounds, REGe5 and RE2Ge9, exhibit the electronic states 4f 3 and 4f 5 (oxidation state +3) for neodymium and samarium, respectively, evidencing that the modification of the germanium network leaves the electron configuration of the metal atoms unaffected. 相似文献
66.
67.
Cal Y. Meyers Hisham G. Lutfi Yuqing Hou Paul D. Robinson 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(5):580-581
Treatment of 9‐fluorenyllithium with acetyl chloride produces 9‐acetylfluorene, (I), and several by‐products. Among them is a compound unequivocally identified for the first time as the addition product of (I) with 9‐fluorenyllithium, 1,1‐di(9‐fluorenyl)ethanol, C28H22O, (II). The two fluorene‐ring planes of (II) are essentially perpendicular [89.90 (9)°]. A number of intermolecular non‐bonding distances are well within or close to the sum of their respective van der Waals radii and may be responsible for the rarely observed large bowing of one of the fluorene rings. This bowing apparently arises from two molecules impinging on the convex face of the bowed ring, augmented by hydrogen bonding between the peripheral π electrons of the concave face and the hydroxyl H atom of another molecule adjacent to that face. 相似文献
68.
C. A. Estrada E. A. Meyers R. A. Zingaro D. C. Dufner P. K. Nair M. T. S. Nair 《Heteroatom Chemistry》1995,6(4):349-354
The reaction between thin films of CdSe and aqueous HgCl2 was studied using electron diffraction (ED) powder X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). It was found that α-Hg3Se2Cl2 is formed in the CdSe film following its reaction with 0.01 M HgCl2 for a period of 5 minutes. Upon completion of the reaction of CdSe powder with 0.01 M HgCl2, Hg2Cl2 is present in addition to α-Hg3Se2Cl2 in a molar ratio of 1:3.1. The effect of air annealing on CdSe powder was also studied. Heating in air to 450°C for 1 hour resulted in an XRD pattern corresponding to the hexagonal form of CdSe. 相似文献
69.
Electrochemiluminescence Bioassays with a Water‐Soluble Luminol Derivative Can Outperform Fluorescence Assays
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Michael Mayer Prof. Dr. Shigehiko Takegami Michael Neumeier Simone Rink Prof. Dr. Axel Jacobi von Wangelin Silja Schulte Moritz Vollmer Prof. Dr. Axel G. Griesbeck PD Dr. Axel Duerkop Prof. Dr. Antje J. Baeumner 《Angewandte Chemie (International ed. in English)》2018,57(2):408-411
The most efficient and commonly used electrochemiluminescence (ECL) emitters are luminol, [Ru(bpy)3]2+, and derivatives thereof. Luminol stands out due to its low excitation potential, but applications are limited by its insolubility under physiological conditions. The water‐soluble m‐carboxy luminol was synthesized in 15 % yield and exhibited high solubility under physiological conditions and afforded a four‐fold ECL signal increase (vs. luminol). Entrapment in DNA‐tagged liposomes enabled a DNA assay with a detection limit of 3.2 pmol L?1, which is 150 times lower than the corresponding fluorescence approach. This remarkable sensitivity gain and the low excitation potential establish m‐carboxy luminol as a superior ECL probe with direct relevance to chemiluminescence and enzymatic bioanalytical approaches. 相似文献
70.
Zi Jie Lin Jared Bies Shanina S. Johnson John D. Gorden Jacqueline F. Strickland Monica Frazier Jonathan M. Meyers Kerri L. Shelton 《Journal of heterocyclic chemistry》2019,56(2):533-538
A series of 1,4‐N,N′‐bis‐substituted 1,2,4‐triazolium bromide salts were synthesized and tested for anti‐proliferative activity. 1,4‐Bis(naphthalen‐2‐ylmethyl)‐1,2,4‐triazolium bromide ( 2 ) showed activity against MDA‐MB‐468 breast cancer and PC‐3 prostate cancer cell lines. 相似文献