Paraconfuranones A–H, eight new furanone analogs from the insect‐associated fungus Paraconiothyrium brasiliense MZ‐1

Abstract

Paraconfuranones A–H were obtained from fermentation extract of fungus Paraconiothyrium brasiliense inhabiting the Acrida cinerea. Their structures were elucidated on the basis of 1D and 2D NMR spectroscopy.

Structural elucidation and NMR spectral assignments of paraconfuranones I-M from the insect-associated fungus Paraconiothyrium brasiliense

“…Although 1 had been isolated previously from the endophytic fungus Microdiplodia sp. KS 75‐1, its absolute configuration remained unassigned, so we determined the absolute configuration of 1 to be 2 R by comparing the circular dichroism (CD) data with those of paraconfuranone C that we had reported in the previous paper for the first time (Figs and ). Furthermore, the absolute configuration at C‐2 of 2 was also deduced from data.…”

“…Furthermore, the absolute configuration at C‐2 of 2 was also deduced from data. A positive cotton effect at 302 nm and a negative cotton effect at 270 nm were observed in the CD data of 2 , which were consistent with paraconfuranone A; therefore, the absolute configuration at C‐2 of 2 was also determined to be R .…”

“…And the HMBC correlations from H‐4 to C‐2, C‐3 and C‐5, and from H‐12 to C‐2, C‐3 and C‐6. Meanwhile, HMBC cross peaks from H‐13 to C‐4 and C‐5, together with the chemical shift values of C‐2 ( δ 88.7), C‐3 ( δ 201.9), C‐4 ( δ 99.6) and C‐5 ( δ 182.0) revealed the presence of the same 2‐methylfuran‐3(2 H )‐one ring, as in 1 . However, the major differences observed in the 1 H and 13 C‐NMR spectra were that the lack of signal of hydroxymethyl in 1 and the presence of a carbonyl group in 3 .…”

“…In the previous paper, we reported the isolation and structural elucidation of paraconfuranones A–H from the insect‐associated fungus P . brasiliense . During the continual screening for bioactive furanone analogs, another five new furanones, paraconfuranones I–M ( 3–7 ), together with two known furanones ( 1–2 ) were obtained from the genus under different fermentation conditions.…”

Considerations of the chemical biology of microbial natural products provide an effective drug discovery strategy

“…Chemical investigations of culture extracts of this fungus resulted in the discovery of dalesconols A (8) and B, which possessed an unprecedented carbon framework (Zhang et al 2008). The findings of other relevant investigations include: the production of new cytotoxic furanone analogues, paraconfuranones A (9)-H by a fungal strain belonging to Paraconiothyrium brasiliense isolated from the gut of the grasshopper, Acrida cinerea (Liu et al 2015); the production of a series of new epipolythiodioxopiperazines, boydines A (10)-D, and structurally novel sesquiterpenes, boydenes A and B (11) by a symbiotic fungus Pseudallescheria boydii, in the gut of the coleopteran larva of the beetle Holotrichia parallela (boydine B displayed significant inhibitory activity against clinically-relevant bacterial strains Bifidobacterium sp., Veillonella parvula, Anaerosterptococcus sp., Bacteroides vulgatus and Peptostreptococcus sp.) (Wu et al 2014); and the production of a new polyketide glycoside, bionectriol A (12) by a fungal strain belonging to Bionectra sp.…”