Ascosteroside, a New Antifungal Agent from Ascotricha amphitricha. II. Isolation and Structure Elucidation.

Abstract

The novel antifungal agent ascosteroside (1) was isolated from cultured broth of Ascotricha amphitricha (ATCC74237). The structure based on spectroscopic data was determined to be an a-linked glycoside of a lanostane-type triterpenoid.

Anti-Candida metabolites from endophytic fungi

“…Mycelial crude extract (2.2 g) was processed by chromatography on silica gel; elution with cyclohexane/EtOAc (40:60) yielded 416 mg intermediate product which was separated by HPLC as above, affording 24 mg compound 5 and 62 mg compound 6. Compound 5 was found to identical to ascosteroside previously isolated from the ascomycete Ascotricha amphitricha (Leet et al, 1996) 3436,2922,2874,1693,1652,1458,1381,1202,1148,1069,1033,977,908,785,726,685 and 622 cm À1 . UV (MeOH) k max (e) 202 (13257), 230 (sh, 4498), 280 (77) nm.…”

“…After dereplication studies with common databases (DNP), 1 H and 13 C NMR data (Table 2) revealed the similarity of compound 6 with ascosteroside A (5, Leet et al, 1996). The 13 C NMR spectrum of 6 showed 36 signals.…”

Discovery of Novel Antifungal (1,3)-β- d -Glucan Synthase Inhibitors

“…Exponential-phase C. albicans MY1055 cells in CMS at 10 6 CFU/ml were treated for 30 min at 30°C with increasing concentrations of inhibitors. The treated cells were pulse-labeled for an additional 30 14 C-labeled amino acid per ml. Radiolabeling was quenched by the addition of an equal volume of 10% trichloroacetic acid (TCA).…”

“…1, which inhibit ␤-(1,3)-Dglucan synthase. Two of the compounds, ascosteroside (18,30), also known as L-767812 (8; J. R. Thompson, S. Dreikorn, J. Onishi, M. Meinz, C. Jue, J. Curotto, and M. Kurtz, Conf. Yeast Genet.…”

24-Ethyl,24-methyl-29-nor-lanostanes from Leaves of Freycinetia formosana

“…[4][5][6]9) On the basis of the above evidence as well as the precise spectral comparisons of 1 and analogous nortriterpenes, 10-12) the structure of 1 was concluded to be 24-ethyl,24-methyl-29-nor-5a-lanosta-4(28),7,25-trien-3b-ol. On the basis of the above evidence as well as the precise spectroscopic comparisons of 2 and analogous nortriterpenes, [10][11][12] the structure of 2 was concluded to be 24-ethyl,24-methyl-29-nor-5a-lanosta-4(28),7-dien-3b-ol.…”