Antimicrobial activity of naphthoquinones from fusaria

Twenty-two naphthoquinone compounds isolated or derived synthetically from culture extracts of Fusarium solani and F. oxysporum were examined for antimicrobial activity. Fifteen exhibited antibiotic activity against Staphylococcus aureus, and 12 were active against Streptococcus pyogenes, but none were active at the highest rate of 128 micrograms/ml against Escherichia coli, Klebsiella pneumoniae, Salmonella typhi, Proteus vulgaris, Serratia marcescens, or Pseudomonas aeruginosa. Of 8 plant pathogenic bacteria tested against 11 naphthoquinones, Corynebacterium poinsettiae was inhibited by 6 compounds, and Pseudomonas viridiflava was weakly inhibited by one. Only one of a group of 6 fluorescent soil pseudomonads was inhibited by one naphthoquinone. Antifungal activity of 10 compounds against 8 fungal plant pathogens was limited to inhibition of Phytophthora parasitica by one naphthopyran.