Chaetoconvosins A and B, Alkaloids with New Skeleton from Fungus Chaetomium convolutum

Abstract

Chaetoconvosins A and B (1 and 2), two novel cytochalasan alkaloids with a new 6/6/5/5/7 pentacyclic ring system, were isolated from the solidstate fermented medium of the wheat rhizospheric fungus Chaetomium convolutum cib-100. Their structures were elucidated on the basis of spectroscopic data. The structure of chaetoconvosin A (1) was confirmed by X-ray crystallographic analysis. Chaetoconvosin B (2), the major metabolite, showed remarkable inhibitory ability on root elongation and moderate cytotoxicity against several cancer cell lines.The fungi of the genus Chaetomium are widely distributed in air, soil, plant debris, and endophytic habitats. In the course to study the secondary metabolites of Chaetomium convolutum, two novel cytochalasins, chaetoconvosins A and B (1 and 2), with a new 6/6/5/5/7 penta ring system were isolated, which featured a piperidine-2,6-dione (ring A), a cyclopentanone (ring C), and a 9-oxabicyclo

Analysis of Chaetoconvosins a and B Using Electrospray Ionization Quadrupole Time-of-Flight Mass Spectrometry

“…CD 3 OD was obtained from Cambridge Isotope Laboratories (Andover, MA, USA). Chaetoconvosins A and B were isolated from Chaetomium convolutum [19]. The D-labelling experiment of chaetoconvosin B was carried out by incubation of 0.01 mg chaetoconvosin B in 2 mL CD 3 OD for 24 h. High-resolution experiments were performed on a Bruker micrOTOF-Q mass spectrometer (Bremen, Germany) in positive-ion mode.…”

“…In our laboratory, two novel cytochalasins, chaetoconvosins B and A (1, 2), were isolated from Chaetomium convolutum [19]. The two compounds exhibit moderate cytotoxicity against several cancer cell lines.…”

“…The product ion at m/z 137 resulted from m/z 193 by the loss of two CO molecules. The processes producing the product ion at m/z 203 might go through retro-Diels Alder (RDA) and retro-Michael reaction [24,25], similar to retro-biogenetic pathways [19]. The accurate masses of the major product ions are shown in Table 2.…”

New Orsellinic Acid Esters from Fungus Chaetomium globosporum

“…The fungal seed culture and fermentation process were identical to those reported [14]. The fermented solid rice medium (7 kg) was soaked with AcOEt (13 l …”

Depsidones from an Endophytic Fungus Chaetomium sp. Associated with Zanthoxylum leprieurii

“…Chemical studies of some Chaetomium spp. have afforded more than 250 bioactive metabolites, among them the cytotoxic alkaloid chaetominine [6], antimalarial depsidones [7], azaphilones [8], and the cytotoxic chaetoconvosins [9], which have drawn the attention of both synthetic chemists and pharmacologists.…”