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.