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Bioactivity-Guided Metabolite Profiling of Feijoa (Acca sellowiana) Cultivars Identifies 4-Cyclopentene-1,3-dione as a Potent Antifungal Inhibitor of Chitin Synthesis
- Mokhtari, Mona, Jackson, Michael D., Brown, Alistair S., Ackerley, David F., Ritson, Nigel J., Keyzers, Robert A., Munkacsi, Andrew B.
- Journal of agricultural and food chemistry 2018 v.66 no.22 pp. 5531-5539
- Acca sellowiana, Candida, agricultural wastes, antibacterial properties, antifungal agents, antifungal properties, chitin, cultivars, fluorescence microscopy, fungi, gas chromatography-mass spectrometry, inhibitory concentration 50, metabolites, multivariate analysis
- Pathogenic fungi continue to develop resistance against current antifungal drugs. To explore the potential of agricultural waste products as a source of novel antifungal compounds, we obtained an unbiased GC-MS profile of 151 compounds from 16 commercial and experimental cultivars of feijoa peels. Multivariate analysis correlated 93% of the compound profiles with antifungal bioactivities. Of the 18 compounds that significantly correlated with antifungal activity, 5 had not previously been described from feijoa. Two novel cultivars were the most bioactive, and the compound 4-cyclopentene-1,3-dione, detected in these cultivars, was potently antifungal (IC₅₀ = 1–2 μM) against human-pathogenic Candida species. Haploinsufficiency and fluorescence microscopy analyses determined that the synthesis of chitin, a fungal-cell-wall polysaccharide, was the target of 4-cyclopentene-1,3-dione. This fungal-specific mechanism was consistent with a 22–70-fold reduction in antibacterial activity. Overall, we identified the agricultural waste product of specific cultivars of feijoa peels as a source of potential high-value antifungal compounds.