Antifungal and antibacterial naphthoquinones from Newbouldia laevis roots

From a dichloromethane extract of Newbouldia laevis roots, four new (6-hydroxydehydroiso-α-lapachone, 7-hydroxydehydroiso-α-lapachone, 5,7-dihydroxydehydroiso-α-lapachone and 3-hydroxy-5-methoxydehydroiso-α-lapachone) and six known naphthoquinones have been isolated. Their structures were established by spectroscopic methods (UV, EI mass spectrometry, 1H and 13C NMR) and that of 7-hydroxydehydroiso-α-lapachone was confirmed by X-ray crystallography. All naphthoquinones showed antifungal activity against Cladosporium cucumerinum and Candida albicans, and activity against the bacteria Bacillus subtilis and Escherichia coli.