Scopararanes C-G: new oxygenated pimarane diterpenes from the marine sediment-derived fungus Eutypella scoparia FS26

Abstract

Five new oxygenated pimarane diterpenes, named scopararanes C-G (1-5) were isolated from the culture of a marine sediment-derived fungus Eutypella scoparia FS26 obtained from the South China Sea. The structures of these compounds were established on the basis of extensive spectroscopic analysis. The absolute configurations of compounds 1-5, were determined by CD spectroscopic analysis and comparison with literature data. All isolated compounds (1-5) were evaluated for their cytotoxic activities against MCF-7, NCI-H460, and SF-268 tumor cell lines by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) method.

Keywords: pimarane diterpenes; Eutypella scoparia; South China Sea; cytotoxic activity; marine sediment-derived fungus.

Figure 1

Chemical structures of compounds 1–11.

Figure 2

Key HMBC (arrows) and COSY (bold lines) correlations of compound 1.

Figure 3

Key NOESY correlations of compounds 1 and 4, whose conformation was modeled by using the MM2 minimum energy calculation [15].