RESUMO
An ultra-selective 1D NMR experiment - GEMSTONE-ROESY - enables clear, unambiguous assignment of ROE signals in the not uncommon situation that traditional selective methods fail. Its usefulness is demonstrated in the analysis of the natural products cyclosporin and lacto-N-difucohexaose I, providing detailed insight into the structures and conformations of these molecules.
RESUMO
Exposure of the phenol, (5-bromo-2-hydroxyphenyl)(2,4,5-trimethoxyphenyl)methanone 18 to ceric ammonium nitrate (CAN) resulted in the formation of 7-bromo-3,4a-dimethoxy-2H-xanthene-2,9(4aH)-dione 19 and 5-bromo-2',5'-dimethoxy-3H-spiro[benzofuran-2,1'-cyclohexa[2,5]diene]-3,4'-dione 20. The brominated spirobenzofuran 20 was then subjected to Suzuki-Miyaura reactions to give six derivatives 22a-f. These compounds, related diones and xanthones displayed mostly noteworthy antimicrobial activity, particularly towards the yeasts Cryptococcus neoformans and Candida albicans. Diones 15 and 30 displayed significant activity (7.8 µg/mL) against C. albicans and C. neoformans, respectively. Furthermore, dione 10 displayed the most significant activity (3.6 µg/mL) against both yeasts.
Assuntos
Benzofuranos/síntese química , Benzofuranos/farmacologia , Candida albicans/efeitos dos fármacos , Cryptococcus neoformans/efeitos dos fármacos , Compostos de Espiro/síntese química , Compostos de Espiro/farmacologia , Xantonas/síntese química , Xantonas/farmacologia , Antibacterianos/síntese química , Antibacterianos/química , Antibacterianos/farmacologia , Antifúngicos/síntese química , Antifúngicos/química , Antifúngicos/farmacologia , Benzofuranos/química , Benzoquinonas/síntese química , Benzoquinonas/química , Benzoquinonas/farmacologia , Estrutura Molecular , Compostos de Espiro/química , Xantonas/químicaRESUMO
Reaction of (2,4,5-trimethoxyphenyl)(2-hydroxyphenyl)methanone with ceric ammonium nitrate furnished the xanthone, 2,3-dimethoxy-9H-xanthen-9-one. Under the same conditions the related (1,4-dimethoxynaphthalen-2-yl)(2-hydroxyphenyl)methanone resulted in the formation of 12a-methoxy-5H-benzo[c]xanthenes 5,7(12aH)-dione. Other examples of this novel transformation are also outlined.
Assuntos
Cério/química , Naftalenos/síntese química , Xantonas/síntese química , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Naftalenos/química , Oxirredução , Xantonas/químicaRESUMO
BACKGROUND: The availability of a suitable matrix reference material is essential for standardization of the immunoassays used to measure serum proteins. The earlier serum protein reference material ERM-DA470 (previously called CRM470), certified in 1993, has led to a high degree of harmonization of the measurement results. A new serum protein material has now been prepared and its suitability in term of homogeneity and stability has been verified; after characterization, the material has been certified as ERM-DA470k/IFCC. METHODS: We characterized the candidate reference material for 14 proteins by applying a protocol that is considered to be a reference measurement procedure, by use of optimized immunoassays. ERM-DA470 was used as a calibrant. RESULTS: For 12 proteins [α(2) macroglobulin (A2M), α(1) acid glycoprotein (orosomucoid, AAG), α(1) antitrypsin (α(1)-protease inhibitor, AAT), albumin (ALB), complement 3c (C3c), complement 4 (C4), haptoglobin (HPT), IgA, IgG, IgM, transferrin (TRF), and transthyretin (TTR)], the results allowed assignment of certified values in ERM-DA470k/IFCC. For CRP, we observed a bias between the lyophilized and liquid frozen materials, and for CER, the distribution of values was too broad. Therefore, these 2 proteins were not certified in the ERM-DA470k/IFCC. Different value transfer procedures were tested (open and closed procedures) and found to provide equivalent results. CONCLUSIONS: A new serum protein reference material has been produced, and values have been successfully assigned for 12 proteins.
