Chaetoglobosin V_b from Endophytic Chaetomium Globosum: Absolute Configuration of Chaetoglobosins

Abstract

One new cytochalasan alkaloid, chaetoglobosin V(b) (1), together with two structurally related known compounds, chaetoglobosin V (2) and chaetoglobosin G (3), was isolated from the ethyl acetate extract of a culture of the endophytic fungus Chaetomium globosum, associated with the leaves of Ginkgo biloba tree. The structures of the isolated compounds were elucidated by spectroscopic methods including 1D and 2D NMR and mass spectrometry. The absolute configuration of chaetoglobosin V(b) (1) was established by means of electronic circular dichroism (CD) spectroscopy, on the basis of the comparison between the CD spectrum of (+)-1 with that calculated with time-dependent density functional theory method for a simplified model. The correlation between compounds 1-3 was demonstrated by a biomimetic transformation of chaetoglobosin G (3) under mild conditions in chaetoglobosins V and V(b) (1 and 2). The isolated metabolites were tested against some phytopathogens.

Characterization of Cytochalasins from the Endophytic Xylaria sp. and Their Biological Functions

“…Compound (+)-2 has in fact a CD spectrum very similar to that of (+)-1 ( Figure 3A), and also consistent with that reported for cytochalasin Z 16 . 35 It can therefore be assumed that cytochalasins 1 and 2 have the same absolute configuration of the corresponding chirality centers, as established above for (+)-1. seco-Cytochalasin E, 3, was isolated as colorless oily solid.…”

Bioactive Chaetoglobosins from the Mangrove Endophytic Fungus Penicillium chrysogenum

“…The structures of compounds 3 – 9 were established by comparison with the published data as chaetoglobosin G [26], chaetoglobosin F [6,27], chaetoglobosin C [6], chaetoglobosin A [6], chaetoglobosin E [6], armochaetoglobosin I [28], and cytoglobosin C [29]. …”

“…V11) harbored inside the normal vein attracted our interests due to its antifungal activity exhibited by the methanol extract in vitro. In this study, the chemical investigation of the fungal Penicillium chrysogenum V11 was carried out, and resulted in a novel chaetoglobosin termed Penochalasin I ( 1 ) bearing an unprecedented 6/5/6/5/6/13 six polycyclic system, and a new chaetoglobosin named Penochalasin J ( 2 ), along with seven known chaetoglobosins, chaetoglobosin G ( 3 ) [26], chaetoglobosin F ( 4 ) [6,27], chaetoglobosin C ( 5 ) [6], chaetoglobosin A ( 6 ) [6], chaetoglobosin E ( 7 ) [6], armochaetoglobosin I ( 8 ) [28], and cytoglobosin C ( 9 ) [29] (Figure 1). Details of the isolation, structure characterization, and bioactivity evaluation are reported herein.…”

Endophytic Fungi as a Source of Novel Metabolites

“…Compound 317 did not show antimicrobial activity against a panel of bacteria and fungi at the concentration of 100 μg/mL. Interestingly, its stereoisomer exhibited moderate to weak toxicity against Alternaria solani, Bacillus cereus, and P. aeruginosa [87].…”

“…8.5), isolated from a culture of Chaetomium globosum, an endophytic fungus from the medicinal plant Ginkgo biloba, possesses a very rare fusion into the macrocycle moiety forming a cyclopentenone ring. The absolute stereochemistry of this compound was determined based on CD spectrometry showing that it is a stereoisomer of a known compound (chaetoglobosin V, [87]). Compound 317 did not show antimicrobial activity against a panel of bacteria and fungi at the concentration of 100 μg/mL.…”