Peniphenones A–D from the Mangrove Fungus Penicillium dipodomyicola HN4-3A as Inhibitors of Mycobacterium tuberculosis Phosphatase MptpB

A pair of unusual benzannulated 6,6-spiroketal enantiomers [(−)-1 and (+)-1] and three new biogenetically related compounds (2–4), together with two known related analogues (5 and 6), have been isolated from a mangrove fungus, Penicillium dipodomyicola HN4-3A. Their structures were elucidated on the basis of spectroscopic analysis (1D and 2D NMR data) and X-ray crystallography. The absolute configurations of enantiomers (−)-1 and (+)-1 were determined using quantum chemical calculations of the electronic circular dichroic (ECD) spectra. Compounds 2 and 3 exhibited strong inhibitory activity against Mycobacterium tuberculosis protein tyrosine phosphatase B (MptpB) with IC50 values of 0.16 ± 0.02 and 1.37 ± 0.05 μM, respectively.