Antimicrobial Natural Products from Plant Pathogenic Fungi

Isolates of a variety of fungal plant pathogens ( ICMP 5619, ICMP 15907, ICMP 16789, ICMP 20542, ICMP 16794, and ICMP 16795) were screened for antimicrobial activity against the human pathogenic bacteria , , , , and and were found to have some activity. Investigation of the secondary metabolites of these fungal isolates led to the isolation of ten natural products ( ) of which one was novel, ( )-4,7-dihydroxyoct-2-enoic acid ( ). Structure elucidation of all natural products was achieved by a combination of NMR spectroscopy and mass spectrometry. We also investigated the antimicrobial activity of a number of the isolated natural products. While we did not find ( )-4,7-dihydroxyoct-2-enoic acid ( ) to have any activity against the bacteria and fungi in our assays, we did find that cercosporin ( ) exhibited potent activity against Methicillin resistant (MRSA), dehydro-curvularin ( ) and radicicol ( ) exhibited antimycobacterial activity against , and brefeldin A ( ) and radicicol ( ) exhibited antifungal activity against . Investigation of the cytotoxicity and haemolytic activities of these natural products ( and ) found that only one of the four active compounds, radicicol ( ), was non-cytotoxic and non-haemolytic.