Cytosporolides A−C, Antimicrobial Meroterpenoids with a Unique Peroxylactone Skeleton from Cytospora sp.

Abstract

Cytosporolides A-C (1-3), three caryophyllene-derived meroterpenoids with a unique peroxylactone skeleton, were isolated from cultures of the fungus Cytospora sp. Their structures were elucidated by NMR spectroscopy, and the absolute configuration of the 5,6-diol moiety in 1 was assigned using Snatzke's method. Compounds 1-3 showed significant antimicrobial activity against the Gram-positive bacteria Staphylococcus aureus and Streptococcus pneumoniae.

The importance of asking “how and why?” in natural product structure elucidation

“…1) are caryophyllene-derived meroterpenoids isolated in 2010 by Che and colleagues from the fungus Cytospora sp. 6 The carbon framework and oxygenation pattern of the caryophyllenederived moiety was assigned using 1D and 2D NMR spectroscopy, assisted by comparison to the NMR data of known natural products 6-hydroxpunctaporonin B (2) 7 and, the co-isolated, fuscoatrol A (3) (Fig. 2).…”

Peroxy natural products

“…The structures of cytosporolides A-C 355-357 202 have been revised on the basis of synthetic studies and reinterpretation of the NMR data.…”

Punctaporonins N–S, New Caryophyllene Sesquiterpenoids from Cytospora sp.

“…was isolated from a soil sample that was collected at Linzhi, Tibet, China. Our initial investigation of this fungus that was fermented in rice medium at 25°C led to the isolation of three antimicrobial caryophyllene-derived meroterpenoids [ 14 , 15 ] and three cytotoxic caryophyllene sesquiterpenoids [ 16 ]. In the current work, the fungus was refermented in the same solid culture medium at 15°C, and the HPLC chromatogram of the crude extract revealed the presence of additional components.…”