The ethyl acetate extract from the Streptomyces sp. isolate B8652 delivered the trioxacarcins A to approximately C (2a to approximately 2c) and additionally three new derivatives designated as trioxacarcins D to approximately F (2d to approximately 2f). All trioxacarcins showed high anti-bacterial and some of them high anti-tumor and anti-malaria activity. The structures of the new antibiotics ...

Two-dimensional (2D) nuclear magnetic resonance (NMR) methods for the investigation of correlation and exchange have been introduced in recent years and have been applied to a range of different systems. Here, we report on the use of 2D NMR diffusion-diffusion correlation spectroscopy for the investigation of diffusion anisotropy in cellular plant tissues and of diffusion-diffusion exchange spe...

This application note demonstrates non-uniform sampling (NUS) acquisition and processing for routine measurement of 2D NMR spectra using tools in Agilent VnmrJ 4 software. It shows that NUS techniques can be applied easily and reliably to small molecule NMR measurements, yielding 2D spectra with comparable digital resolution to those obtained by traditional linear sampling methods, typically wi...

Covariance NMR has attracted considerable interest in recent years and new applications of this technique aimed at paving the way forward to structure elucidation are appearing frequently in the scientific literature. For example, Zhang and coworkers used Covariance TOCSY NMR to improve the resolution of 2D spectra and simplify the task of mixtures analysis.1 The objectives of this technique ar...

This paper provides the full (13) C NMR assignments for the trifluoroacetamides of five potentially appetite-reducing 5-HT2C benzazepine receptor agonists and two open-ring synthetic precursors. These compounds exist in solution as mixtures of two rotamers for each of which the (13) C NMR signals have now been assigned with the assistance of 2D NMR experiments and the carbonyl-induced shifts of...

Purification of the n-BuOH fraction of the aqueous alcoholic extract from the roots of Phytolacca americana resulted in the isolation of two triterpene saponins named esculentoside B (1), and esculentoside A (2). The structures of isolated compounds were characterized on the basis of extensive spectral data (1D and 2D NMR; and MS) and in comparison with their Nuclear Magnetic Resonance (NMR) an...

Ru-based olefin metathesis catalysts containing carbohydrate-derived NHCs from glucose and galactose were synthesized and characterized by NMR spectroscopy. 2D-NMR spectroscopy revealed the presence of Ru-C (benzylidene) rotamers at RT and the rate of rotation was measured using magnetization transfer and VT-NMR spectroscopy. The catalysts were found to be effective at ring-opening metathesis p...

The assignment of resonances in the complex NMR spectrum of a protein is the first step in any study of protein structure, function or dynamics. Prior to 1980, assignment was achieved using 1D NMR, and based, for the most part, on the assumption that the structure of the protein in solution was the same as in the X-ray structure. The introduction of 2D NMR techniques such as COSY and NOESY in t...

The NMR study of the flavonoids 6a,11a-dihydro-9-methoxy-6H-benzofuran[3,2-C] benzopiran-3-ol (1) and (2,3cis-3,4-cis-3,4,5,8-tetramethoxy-[1,2 : 6,7]-furanoflavan (2) is described. In addition to convencional 1D NMR methods, 2D shift-correlated NMR techniques (COSY, HMQC, HMBC and NOESY) were used for the complete H and C resonance assignments. The relative stereochemistry at the asymmetric ce...

A xanthone, 1,3,6,7-tetrahydroxy-xanthone (compound (1)) had been isolated from Garcinia benthami Pierre. The isolation was conducted through the chromatography technique and spectroscopy methods by spectroscophyc: mass spectrometry (LC-MS), infra red (IR), UV, 1H-NMR, 13C-NMR (1D and 2D-NMR). Antioxidant activity test by using DPPH (1,1diphenyl-2-picrylhydrazyl) method from the isolated compou...