ARS | Publication request: FUNGICIDAL PROPERTIES OF CAY-1, A PLANT SAPONIN, FOR EMERGING FUNGAL PATHOGENS

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: November 15, 2005
Publication Date: December 30, 2005
Citation: De Lucca II, A.J., Klich, M.A., Sien, T., Cleveland, T.E., Walsh, T.J. 2005. Fungicidal properties of CAY-1, a plant saponin, for emerging fungal pathogens. 45th Interscience Conference on Antimicrobial Agents and Chemotherapy, December 2005, Washington, D.C. Abstract F-490. p. 180.

Technical Abstract: Fungi once thought harmless to humans have emerged as important causes of morbidity and mortality, especially in immunocompromised patients. These fungi, often resistant to conventional antifungal therapy, include Alternaria sp., Aspergillus (other than A. fumigatus), Cladosporium cladosporioides, Colletotrichum sp., Cuvularia brachyspora, Penicillium thomii, P. sclerotorium and Trichoderma sp. This study determined the in vitro lethality of CAY-1 for these fungi. Methods. CAY-1, a lytic saponin, was purified by HPLC/MS from cayenne pepper. Diseased grapes were surfaced sterilized, placed on potato dextrose agar plates (PDA) and incubated (22°C). Fungal colonies were isolated and identified as Alternaria sp., Aspergillus japonicus, C.cladosporioides, Collectotrichum sp., C. brachyspora, Penicillium sclerotiorum, P. thomii and Trichoderma sp. Isolates were grown (7 days, 22°C) on PDA slants and stored (4°C). Conidia were suspended in 1% potato dextrose broth (PDB), pH 4.86, and diluted to 10**4 conidia/ml. Aliquots (25 ul) of nongerminated and germinating conidia (0 and 8 hr incubation, respectively), and conidia incubated 24 hr (22°C) were added to CAY-1 (final concentrations 0-25 uM in 250 ul PDB). After 30 minute incubation, aliquots (50 ul) were spread on 4 PDA plates/sample. Plates were incubated for two days (22°C) and colonies enumerated. Three replicates/fungal species were performed (n = 12). SigmaStat 9.0 was used for statistical analyses. Results. CAY-1 was significantly (p < 0.05) lethal to the germinating conidia of A. japonicus (equal to or greater than 7.5 uM), Collectotrichum sp. (equal to or greater than 7.5 uM), P. sclerotorium, P. thomii and to 24 hour incubated conidia of Trichoderma sp. (equal to or greater than 10 uM). CAY-1 was inactive against Alternaria and C. brachyspora under the test conditions. Conclusions. CAY-1 showed potent in vitro activity against some of the fungi during their germination phase. Lethality data suggests fungal susceptibility to CAY-1 is related to short term membrane changes during germination.