Submitted to: Letters in Applied Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/12/2007
Publication Date: 6/15/2007
Citation: Kim, J.H., Campbell, B.C., Mahoney, N.E., Chan, K.L., Molyneux, R.J., May, G.S. 2007. Enhanced activity of strobilurin and fludioxonil by using berberine and phenolic compounds to target fungal antioxidative stress response. Letters in Applied Microbiology. 55:134-141. Interpretive Summary: This research attempted to show if safe, natural compounds could be used to enhance the ability of certain commercial chemicals that are now used to kill fungi that infect crops. The research discovered a number of these natural compounds in a group of chemicals known as phenolics. Using a number of laboratory made genetic mutants of test fungi, we were able to find out what physiological systems of the fungus were affected by the discovered compounds. The most important finding was that we found some safe, natural compounds that could be used to deter the development of resistance of fungi to new fungicides. This is very important from the standpoint of use of fungicides to control mold on agricultural crops.
Technical Abstract: Antifungal activity of strobilurins was tested using berberine hemisulfate and different phenolic compounds. With berberine, the most effective phenolic was veratraldehyde. The sod2delta mutant of Saccharomyces cerevisiae was highly sensitive to berberine and veratraldehyde. Functional complementation analysis verified these compounds target mitochondrial superoxide dismutase (Mn-SOD). Activity of strobilurin (25 to 50 micro mol l-1) was significantly elevated on Aspergillus fumigatus and A. nidulans by co-application with berberine (2 mmol l-1) and/or by veratraldehyde (2-4 mmol l-1) on most aspergilli and Penicillium expansum. These compounds also prevented A. fumigatus MAPK mutants (sakAdelta and mpkCdelta) from escaping toxicity of fludioxonil (a phenylpyrrole fungicide potentiated by the MAPK pathway). Natural products can be used to target cellular stress response systems in fungal pathogens and serve as alternatives/additives to commercial antifungal agents.