RESUMO
Extracts of the biomasses and fermentation broths of 217 extremophilic microorganisms isolated from a number of locales were screened for antifungal activity using whole-cell and mechanism-based in vitro assays. Importantly, eleven broth extracts had activity against several Candida species and Aspergillus fumigatus in whole-cell in vitro assays. One broth specifically inhibited (1,3)beta-glucan synthase activity and four specifically inhibited ketol-isomerase activity, suggesting a mode of action of the antifungal compound(s) present in these extracts. The extract from one thermophile, a novel species of Pseudomonas, was fractionated, an active compound purified and its structure determined. The compound was identified as pyochelin, a previously identified iron-binding compound with heretofore undescribed antifungal activity. To our knowledge, this is the first report demonstrating that extremophiles synthesize compounds that have antifungal activity.
Assuntos
Antifúngicos/metabolismo , Antifúngicos/farmacologia , Proteínas de Membrana , Proteínas de Schizosaccharomyces pombe , Tiazóis , Candida albicans/efeitos dos fármacos , Quitina Sintase/antagonistas & inibidores , Cromatografia Líquida de Alta Pressão , Avaliação Pré-Clínica de Medicamentos/métodos , Inibidores Enzimáticos/farmacologia , Fermentação , Glucosiltransferases/antagonistas & inibidores , Glutamina-Frutose-6-Fosfato Transaminase (Isomerizante)/antagonistas & inibidores , Testes de Sensibilidade Microbiana , Fenóis/análise , Fenóis/farmacologiaRESUMO
4'-Demethyldeoxypodophyllotoxin was isolated as the sole cytotoxic constituent of a chloroform-soluble extract of the stem bark of AMANOA OBLONGIFOLIA. Also identified from this extract were a number of noncytotoxic isolates that comprised the lignans, (+)-sesamin and paulownin, the triterpenes, friedelin, canophyllol, betulin, betulinic acid, and ursolic acid, and the sterols, beta-sitosterol and daucosterol.
RESUMO
1H-nmr spectra of the natural products cucurbitacins A, B, C, D, E, F, I, L, 23, 24-dihydrocucurbitacin F, and hexanorcucurbitacin F, as well as three acetylated derivatives, were measured at 360 MHz in pyridine-d5. Chemical shifts and coupling constants were tabulated. In addition to all of the ring and side-chain protons, it was possible to assign several of the hydroxy group signals of these compounds. These compiled data should be useful for the structure determination of new compounds in this series.