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Cochliotoxin, a Dihydropyranopyran-4,5-dione, and Its Analogues Produced by Cochliobolus australiensis Display Phytotoxic Activity against Buffelgrass (Cenchrus ciliaris)

TitleCochliotoxin, a Dihydropyranopyran-4,5-dione, and Its Analogues Produced by Cochliobolus australiensis Display Phytotoxic Activity against Buffelgrass (Cenchrus ciliaris)
Publication TypeArticolo su Rivista peer-reviewed
Year of Publication2017
AuthorsMasi, M., Meyer S., Clement S., Cimmino A., Cristofaro M., and Evidente A.
JournalJournal of Natural Products
Volume80
Pagination1241-1247
ISSN01633864
Keywords3 epi radicinin, 3-b)pyran-4, 3-dihydropyrano(4, 3-epi-radicinin, 3-hydroxy-2-methyl-7-(3-methyloxiranyl)-2, 5-dione, Arizona, article, Ascomycetes, Ascomycota, Bioassay, Cenchrus, Cenchrus ciliaris, chemical structure, chemistry, Cochliobolus, Cochliobolus australiensis, cochliotoxin, coleoptile, concentration (parameters), controlled study, Deuteromycetes, Digitaria, Digitaria californica, epimer, Esterification, fungus isolation, herbicide, Herbicides, hydroxyl group, Integrated pest management, isolation and purification, Liquid culture, Mitosporic Fungi, Molecular Structure, Mycotoxin, mycotoxins, nonhuman, phytotoxicity, plant leaf, Plant leaves, plant toxin, Poaceae, proton nuclear magnetic resonance, pyrone derivative, Pyrones, radicinin, radicinol, Spectroscopy, Stereochemistry, unclassified drug, Weed
Abstract

Buffelgrass (Pennisetum ciliare or Cenchrus ciliaris) is a perennial grass that has become highly invasive in the Sonoran Desert of southern Arizona. In the search for novel control strategies against this weed, strains of the foliar fungal pathogen Cochliobolus australiensis from buffelgrass have been screened for their ability to produce phytotoxic metabolites that could potentially be used as natural herbicides in an integrated pest management strategy. A new phytotoxin, named cochliotoxin, was isolated from liquid culture of this fungus together with radicinin, radicinol, and their 3-epimers. Cochliotoxin was characterized, essentially by spectroscopic methods, as 3-hydroxy-2-methyl-7-(3-methyloxiranyl)-2,3-dihydropyrano[4,3-b]pyran-4,5-dione. Its relative stereochemistry was assigned by 1H NMR techniques, while the absolute configuration (2S,3S) was determined applying the advanced Mosher's method by esterification of its hydroxy group at C-3. When bioassayed in a buffelgrass coleoptile elongation test and by leaf puncture bioassay against the host weed and two nontarget grasses, cochliotoxin showed strong phytotoxicity. In the same tests, radicinin and 3-epi-radicinin also showed phytotoxic activity, while radicinol and 3-epi-radicinol were largely inactive. All five compounds were more active in leaf puncture bioassays on buffelgrass than on the nontarget grass tanglehead (Heteropogon contortus), while the nontarget grass Arizona cottontop (Digitaria californica) was more sensitive to radicinin and 3-epi-radicinin. Cochliotoxin at low concentration was significantly more active on buffelgrass than on either native grass, but the difference was small. © 2017 The American Chemical Society and American Society of Pharmacognosy.

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URLhttps://www.scopus.com/inward/record.uri?eid=2-s2.0-85019700054&doi=10.1021%2facs.jnatprod.6b00696&partnerID=40&md5=347dbba7cd56c6d4a549b26a0d905d86
DOI10.1021/acs.jnatprod.6b00696
Citation KeyMasi20171241