Structure Elucidation and Complete NMR Spectral Assignments of New Sesquiterpenes Isolated From Marine Derived Fungus Aspergillus sydowii‐HB

Six sesquiterpene derivative compounds ( 1 – 6 ), including one new 7 R ‐sydowic acid ( 1 ) and five known compounds ( 2 – 6 ) were isolated from the secondary metabolites of Aspergillus sydowii ‐HB. The structures were determined by NMR spectroscopy and ESI‐MS analysis, and the configuration of compound 1 was confirmed through DP4 + calculation and NMR chemical shift. All the isolated compounds ( 1 – 6 ) were tested for their cytotoxic activities. The possible biosynthetic pathways for compounds ( 1 – 6 ) were also postulated.