Three new alkaloids, iizukines C-E (1-3), including two aspochalasins (1 and 2), and one brasiliamide derivative (3), along with two known aspochalasins, rosellichalasin (4) and cytochalasin Z17 (5), were isolated from the culture of Aspergillus iizukae. Compound 1 was the first aspochalasin uniquely featuring a 1,2,4-triazole functionality, and 3 showed a pair of NMR signals in CDCl with a ratio of about 2:1 due to the existence of conformational isomers. Their structures were determined by extensive spectroscopic analyses and single-crystal X-ray diffractions.
View Article and Find Full Text PDFThree new diastereomers of polyketides (PKs), raistrickiones A−C (⁻), together with two new analogues, raistrickiones D and E ( and ), were isolated from a highly productive strain of , which was subjected to an experimental thermo-change strategy to tap its potential of producing new secondary metabolites. Metabolites and existed in a diastereomeric mixture in the crystal packing according to the X-ray data, and were laboriously separated by semi-preparative HPLC on a chiral column. The structures of ⁻ were determined on the basis of the detailed analyses of the spectroscopic data (UV, IR, HRESIMS, 1D, and 2D NMR), single-crystal X-ray diffractions, and comparison of the experimental and calculated electronic circular dichroism spectra.
View Article and Find Full Text PDFYao Xue Xue Bao
November 2003
Aim: To study the chemical constituents in the mycelia of Hypomyces sp..
Methods: Silica gel column chromatography was employed for the isolation and purification.
Zhongguo Zhong Yao Za Zhi
September 2002
Objective: To study the chemical constituents of Shiraia bambusicola.
Method: Column chromatography with silica gel was employed for the isolation and purification of constituents. The structures were elucidated by means of chemical and spectroscopic data.