RESUMO
Chemical investigations of a microfungus Xylaria sp. isolated from the Australian rainforest tree Glochidion ferdinandi have afforded two new natural products, 2-hydroxy-6-methyl-8-methoxy-9-oxo-9H-xanthene-1-carboxylic acid (1) and 2-hydroxy-6-hydroxymethyl-8-methoxy-9-oxo-9H-xanthene-1-carboxylic acid (2). Compound 1 has previously been synthesised but only partially characterised. Methylation of 1 using diazomethane afforded the crystalline compound 2,8-dimethoxy-6-methyl-9-oxo-9H-xanthene-1-carboxylic acid methyl ester (3), whose structure was determined by single crystal X-ray analysis. This paper reports the full spectroscopic characterisation of compounds 1-3 by NMR, UV, IR and MS data. All compounds were inactive in a brine shrimp lethality assay and several antimicrobial screens.
Assuntos
Ascomicetos/química , Plantas Medicinais/química , Xantonas/isolamento & purificação , Dose Letal Mediana , Espectroscopia de Ressonância Magnética , Espectrometria de Massas , Metilação , Testes de Sensibilidade Microbiana , Microscopia Ultravioleta , Estrutura Molecular , Espectrofotometria Infravermelho , Árvores/microbiologia , Xantonas/químicaRESUMO
A new antibiotic polyene tetramic acid, ravenic acid (2), has been isolated from the mycelia of a cultured fungus, Penicillium sp. The structure of ravenic acid was determined by detailed spectroscopic analysis and the major isomer identified as possessing (3Z, 7E, 9E, 11E, 13E) stereochemistry.
