The absolute configuration of franganine (1), a cyclopeptide alkaloid isolated from the methanol root bark extract of Discaria americana, was established on the basis of detailed NMR spectroscopic data and X-ray diffraction analysis of its salt (2).
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http://dx.doi.org/10.1021/np300206x | DOI Listing |
Spectrochim Acta A Mol Biomol Spectrosc
December 2024
Department of Chemistry, University of Virginia, Charlottesville, VA 22904, United States. Electronic address:
Amino acids play important roles in human pathology and physiology and the qualitative and quantitative determination of chiral amino acids in humans and mammals also has important impacts on the life sciences. Therefore, the introduction of artificial probes to assess the concentrations and enantiomeric compositions [ee = ([D] - [L])/([D] + [L])] of amino acids in aqueous solution is necessary in understanding certain biological processes and diagnosing and treating diseases. Herein, a bifunctional achiral coumarin probe (Br-Coumarin) is reported to determine the absolute configuration, ee value, and concentration of 16 amino acids in THF/HO = 1/4 solution at micromolar concentrations.
View Article and Find Full Text PDFSci Rep
December 2024
Department of Geosciences, Geotechnology, and Materials Engineering for Resources, Graduate School of International Resource Sciences, Akita University, Akita, Japan.
The present investigation employs relevance vector machine (RVM) and long short-term memory (LSTM) models to predict the time-dependent bearing capacity of concrete piles. Each RVM model (SRVM) is configured by each linear, polynomial, gaussian, sigmoid, laplacian, and exponential kernel function. Each SRVM model has been optimized by each genetic (GA_SRVM) and particle swarm optimization (PSO_RVM) algorithm.
View Article and Find Full Text PDFBiosci Biotechnol Biochem
December 2024
Faculty of Science and Technology, Keio University, Yokohama, Japan.
Most actinomycetes and fungi have a multitude of silent biosynthetic genes whose activation could lead to the production of new natural products. Our group recently designed and used a co-culture method to isolate new natural products, based on the idea that pathogens might produce immune suppressors to avoid attack by immune cells. Here, we searched for compounds produced by the co-culture of immune cells with pathogenic fungi isolated from clinical specimens.
View Article and Find Full Text PDFAppl Sci (Basel)
January 2024
Department of Microbiology and Medical Zoology, University of Puerto Rico School of Medicine, San Juan 00921, Puerto Rico.
Gracilioether M () and 11,12-dihydrogracilioether M (), two polyketides with a [2(5H)-furanylidene]ethanoate moiety, along with known plakortone G () and its new naturally occurring derivative 9,10-dihydroplakortone G (), were isolated from the Caribbean marine sponge . The structures and absolute configuration of , , and were characterized by analysis of HRESIMS and NMR spectroscopic data, chemical derivatization, and side-by-side comparisons with published NMR data of related analogs. Compounds and and a mixture of and were evaluated for cytotoxicity against MCF-7 human breast cancer cells.
View Article and Find Full Text PDFJ Org Chem
December 2024
Department of Pharmacy, The First Affiliated Hospital, Jinan University, Guangzhou 510630, China.
Nine new structurally diverse filicinic acid-based meroterpenoids (-) with four kinds of carbon skeletons were isolated from the rhizomes of . Their structures, including the absolute configurations, were elucidated by comprehensive analysis of spectroscopic data, quantum chemical calculations, and single-crystal X-ray diffraction. Structurally, compounds - feature an unprecedented 6/6/5/6/6/6 hexacyclic system with a rare oxaspiro[4.
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