ISOLATION OF A NEW BIOLOGICALLY ACTIVE COMPOUND FROM TRICHOIDERMA KONINGII

Rosa T.S. FRIGHETTO & Itarnar S. de MELO.
National Research Center for Monitoring and Environmental Impact Assessment/(CNPMA/EMBRAPA), Caixa Postal 69, 13820-000 Jaguarillna, Sao Paulo, Brazil.

The antagonism existing between some fungi forms the basis of the biological control of plant diseases. The mechanisms suggested to be envolved in hiocolltrol by these fungi are antibiosis, lysis, competition, mycoparasitism and promotion of plant growth.

Sclerotinia sclerotiorum(Lib.) de Bary causes serious diseases in a wide range of plant species. The control of the pathogen with the available fungicides has not been effective(Walker et al, 1986). Because the pathogen can survive in soil for several years in the absence of hosts and as the major structures are sclerotia, attention has focused all the studies of biocontrol agents capable of attacking specifically and kill these structures. Naturally occurring strains of Trichoderma koningii (TSS-3) infecting Sclerotinia sclerotia have been isolated in our laboratory. Fermentation in liquid culture medium (PD broth), and extraction of the culture broth with ethyl acetate gave a yellowish oil, which by column chromatography, employing silica gel eluted with linear gradient of hexane/ethyl acetate, and preparative plate chromatography, has led to thc isolation of a nonvolatile new antibiotic as the major metabolite. The structure of this new compound, 4,8-dihydroxy-2-(1 -hydroxyheptyl)-3,4,5,6,7,8-hexahydro-2H-1-benzopyran- 5-one, has been established by spectroscopic methods, and has inferred that it is diastereoisomer from koninginin D, being epimeric at the C-4 position, previously isolated by Dunlop et al.(1989). Other nonvolatile antibiotics has also been previously isolated from Trichoderma spp.(Cutler et al., 1989: Almassi et. al., 1991; Parker et. al., 1995a and 1995b). This work describes the isolation, structure identification and bioassay against S. sclerotiorum: and discuss the nature and possible ecological relevance of the antibiotic product.

Literature
  1. Walker A., Brown P.A. & Entwistle A.R.: Pesticide Science 17, 183-193 (1986).
  2. Dunlop R.W., Simon A., Sivasithamparam K. & Ghisalberti E.: J. Nat. Prod. 52(1), 67-74 (1989).
  3. Cutler H.G., Himmelsbach D.S., Arrendale R.F., Cole P.D. & Cox R.H.: Agric. Biol. Chem. 53(10), 2605-2611 (1989).
  4. Almassi F., Ghisalberti E., Narbey M.J. & Sivasithamparam K.: J. Nat. Prod. 54(2), 396-402 (1991).
  5. Parker S.R., Cutler H.G. & Schreiner P.R.: Biosci. Biotech. Biochem. 59(6), 1126-1127 (1995a); 59(9), 1747-1749 (1995b).
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