|De Lucca Ii, Anthony|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 4/4/2004
Publication Date: 9/11/2004
Citation: De Lucca II, A.J., Boue, S.M., Bland, J.M., Wartelle, L.H., Selitrennikoff, C., Renault, S., Cushion, M., Cleveland, T.E., Walsh, T. 2004. CAY-1, a plant-produced saponin active against phytopathogenic and medical pathogenic fungi. In: Proceedings of World Conference on Magic Bullets (Celebrating Paul Ehrlich's 150th Birthday). Abstract 119. p. 19.
Technical Abstract: Background: Plants must produce potent antimicrobials to survive in their environment. Our program involves the discovery of novel, plant-produced fungicides. The first plant material explored was cayenne pepper. Methods: pepper was aqueously extracted. Sequential HPLC/MS separations were performed with parallel bioassays until the active fungicide was purified. NMR analysis confirmed the chemical structure of the pure compound, CAY-1. Experiments were performed to determine CAY-1 fungicidal properties, activity under different pH values (3-9), time course of activity, mode of action, binding with fungal membrane sterols, and in vitro cytotoxicity to mammalian cells. Two precursor molecules were purified and their fungicidal properties determined. Bioassay data was analyzed statistically by ANOVA or Dunn's method. Results: CAY-1 (mol. mass: 1243) was a novel steroidal saponin with 5 sugars (4 glucose and 1 galactose). It was significantly lethal (p is less than 0.05, 3-20 uM) to germinating conidia of five Aspergillus species and Pneumocystis carinii. CAY-1 inhibits Cryptococcus neoformans (90 percent at 1 ug ml**1) and five Candida species (90 percent at 8-16 ug ml**1) growth. No loss of fungicidal activity occurred over a wide pH (3-9) range. CAY-1 bound to fungal membrane sterols and caused leakage of cytoplasmic ions. CAY-1 acted rapidly and was significantly lethal at 10 uM in 5 min to germinating conidia of A. flavus. CAY-1 (is less than or equal to 100 ug ml**1) did not exhibit significant toxicity when tested against 55 mammalian cell lines. CAY-1 precursors with one and two less glucose moieties had significant reduction or elimination of fungicidal properties, respectively. Conclusions: (1) CAY-1 was a potent fungicide at concentrations not lethal, in vitro, against mammalian cells, which acts rapidly under a wide pH range. (2) Loss of even one glucose moiety greatly reduced CAY-1 fungicidal properties. CAY-1 data and our current research with novel, plant-produced fungicides show that plants are an excellent source of potent fungicides with potential utility to combat medically and agriculturally important fungi.