Structure Revision and Protein Tyrosine Phosphatase Inhibitory Activity of Drazepinone.

From the marine-derived fungus Penicillium sumatrense (Trichocomaceae), a pair of enantiomers [(+)- 1 and (-)- 1 ] were isolated with identical 1D NMR data to drazepinone, which was originally reported to have a trisubstituted naphthofuroazepinone skeleton. In this study, we confirmed the structures of the two enantiomers as drazepinone and revised their structures by detailed analysis of extensive 2D NMR data and a comparison of the calculated 13 C chemical shifts, ECD, VCD, and ORD spectra with those of the experiment ones. (+)- 1 and (-)- 1 were evaluated for their PTP inhibitory activity in vitro. (-)- 1 showed selective PTP inhibitory activity against PTP1B and TCPTP with IC 50 values of 1.56 and 12.5 μg/mL, respectively.