Gauge including atomic orbitals (GIAO) (1)H NMR chemical shift calculations have been performed for 66 organic compounds at 72 different levels of theory using the multi-standard approach (MSTD) previously developed for (13)C NMR. This straightforward computational technique involves the combination of methanol and benzene as standards. The studied methodology has been shown to predict (1)H NMR chemical shifts efficiently at different levels of theory.
Download full-text PDF |
Source |
---|---|
http://dx.doi.org/10.1021/jo3008447 | DOI Listing |
Anal Chem
December 2024
Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University, Siming South Road 422, Xiamen 361005, China.
Proton (H) NMR spectroscopy presents a powerful tool for biomass mixture studies by revealing the involved chemical compounds with identified ingredients and molecular structures. However, conventional H NMR generally suffers from spectral congestion when measuring biomass mixtures, particularly biomass carbohydrate samples, that contain various physically and chemically similar compounds. In this study, a targeted detection NMR approach, DREAMTIME, is exploited for studying biomass carbohydrate mixtures by spectroscopically targeting the desired compounds in separate 1D NMR spectra.
View Article and Find Full Text PDFBioorg Chem
December 2024
State Key Laboratory of Natural and Biomimetic Drugs, Peking University, Beijing 100191, PR China; Ningbo Institute of Marine Medicine, Peking University, Beijing 100191, PR China. Electronic address:
Prenylated indole diketopiperazines represent a diverse array of alkaloids with complex chemical scaffolds and with a wide range of biological activities. Aiming to discover bioactive metabolites with structural novelty, genomic annotation in association with the MS/MS-based molecular networking demonstrated a deep-sea derived fungus Aspergillus puulaauensis F77 containing a profile of diketopiperazines. Targeted separation of the cultured fungus led to the isolation of 19 undescribed austamide-type diketopiperazines namely versicoines A-S.
View Article and Find Full Text PDFJ Agric Food Chem
December 2024
State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100193, People's Republic of China.
Sativene-related sesquiterpenoids including -sativene analogs are a large member of fungal secondary metabolites with phytotoxic and growth-promoting effects on different plants. In this report, a series of sativene-related sesquiterpenoids with diverse carbon skeletons (-, sativene/isosativene/-sativene/cyclosativene/-isosativene ring systems) were isolated from the plant pathogenic fungus based on a molecular networking strategy. The undescribed structures were elucidated based on NMR spectra, X-ray diffraction analysis, chemical derivation, and calculated electronic circular dichroism calculations.
View Article and Find Full Text PDFJ Funct Biomater
December 2024
Cardiovascular Institute, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115, USA.
Reactive oxygen species (ROS) are generated predominantly during cellular respiration and play a significant role in signaling within the cell and between cells. However, excessive accumulation of ROS can lead to cellular dysfunction, disease progression, and apoptosis that can lead to organ dysfunction. To overcome the short half-life of ROS and the relatively small amount produced, various imaging methods have been developed, using both endogenous and exogenous means to monitor ROS in disease settings.
View Article and Find Full Text PDFMar Drugs
December 2024
CAS Key Laboratory of Tropical Marine Bio-resources and Ecology/Guangdong Key Laboratory of Marine Materia Medica, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China.
Five new metabolites, including three cyclic dipeptide derivatives (-) and two new polyketides (-), together with nine known ones (- and -), were isolated from the mangrove-sediments-derived fungus sp. SCSIO 41431. Their structures were determined using detailed NMR, MS spectroscopic analyses, and quantum chemical calculations.
View Article and Find Full Text PDFEnter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!