No abstract

Material extracted from hyphae ofFusarium avenaceum, isolated from foliage of balsam fir,Abies balsamea, was toxic to spruce budworm larvae when incorporated into insect diet. The major insecticidal component of the toxic fraction was identified by chemical and spectroscopic methods as enniatin complex, rich in enniatin A/A1. Possible ecological implications of these observations are considered.

A new fungitoxic metabolite, designated scytalidin. was isolated from culture medium which had supported growth of Scytalidium sp., an imperfect fungus. The structure (3) of scytalidin (1 0-butyl-5,9,10,11 -tetrahydro-I 0hydroxy-4-pentyl-4H-cyclonona[1,2-c:5.6-c']difuran-l,3.6,8-tetraone) was established on the basis of spectrometric and chemical investigations. The metabolite is related structurally and biosynthetically to the nonadrides.A SPECIES of Scytalidium, FY strain, was observed by Ricard and his collaboratorsl~~ to be antagonistic to Poria carbonica, a wood-rotting organism responsible, ivcter alia, for heartwood decay in Douglas-fir utility poles in western North America. Metabolites produced by Scytalidium sp. were isolated, and included yellow and red pigments, as well as a colourless compound, m/e 348-42809. Antifungal activity was found to be associated with the crystalline red and colourless substances.1*2 Scytalidium sp., FY strain, has been further investigated in our laboratory. When grown in a synthetic medium in liquid-shake culture, it produced at least two major metabolites which displayed antifungal proper tie^.^ Chemical investigation of one of these, a new compound for which the name scytalidin is proposed, forms the subject of this report.The molecular formula of scytalidin was established as C,,H,,O, by elemental analysis and high resolution mass ~pectrometry.~ 1.r. absorption (CHC1, solution) at 3575 cm-l was attributed to alcohol functionality, further characterized as a single tertiary hydroxy-group on the basis of the following observations. Scytalidin was recovered unchanged after treatment with Jones reagent.5 The metabolite was resistant to acetylation with acetic anhydride-pyridine ; it was, however, readily converted into a monoacetate by the action of acetic anhydride in the presence of zinc chloride.6 Comparison of the n.m.r. spectra of scytalidin and its acetate did not reveal any differences which could be attributed to a proton geminal to the hydroxy-group.' The n.m.r. spectrum of scytalidin in [2H,]dimethyl sulphoxide showed a downfield shift of the OH signal from 6 2.14 to 4-58 p.p.m., and, in accord with the tertiary nature of the hydroxy-function, the signal retained its singlet c h a r a ~t e r . ~~~ Scytalidin displayed i.r. bands (KBr) at 1850, 1827, and 1773 cm-l, and U.V. absorption [ A, , (acetonitrile)]

A growth inhibitor, designated hyalodendrin (C14H16N2O3S2), was isolated from liquid cultures of a species of Hyalodendron, a Hyphomycete. The isolation and production of hyalodendrin and its physical and chemical properties are described. The in vitro antimicrobial activity of this compound against a broad spectrum of fungi associated with decay and deterioration of trees and forest products was examined. Its inhibitory action against these organisms, as well as against others causing diseases in plants and trees, was found to be superior to that of the antifungal agents cryptosporiopsin, nystatin, or scytalidin. Minimum inhibitory concentrations of hyalodendrin were also established for a number of bacteria and fungi pathogenic to humans. Hyalodendrin compared favorably with benomyl in its ability to inhibit in vitro growth of Ceratocystis ulmi, the causal agent of Dutch elm disease. In seed-germination tests, hyalodendrin had a relatively low degree of phytotoxicity. Acute toxicity to mice (LD50) was established at 75 mg/kg.

No abstract

Pungenin was synthesized from 3,4-dihydroxyacetophenone by a short sequence involving manipulation of protecting groups on the 3 and 4 hydroxyl functions. Bioassays indicated that the glucoside is a modest feeding deterrent for sixth-instar spruce budworm larvae, but it does not appear to retard the development of small larvae or lead to increased mortality.

The production and isolation of scytalidin, a recently reported metabolite of Scytalidium sp., are described. The compound was found to be relatively active in vitro against many fungi associated with stain and decay of pulpwood chips in outside storage and decay in the roots and butts of conifers. Other fungi associated with diseases of trees and deterioration of forest products were also found to be sensitive to scytalidin. Seed germination tests indicated relatively low phytotoxicity.

A growth inhibitor with the molecular formula C10H10O4Cl2 was isolated from a medium which had supported growth of a species of Cryptosporiopsis, an imperfect fungus. The compound was named cryptosporiopsin and was characterized on the basis of its physical and chemical properties. Cryptosporiopsin was active in vitro against many wood-rotting basidiomycetes as well as some phycomycetes, ascomycetes, and deuteromycetes. It was more effective than Dithane M-22 or nystatin against the in vitro spore germination of Phytophthora infestans. It was active to varying degrees against six species of bacteria. Cryptosporiopsin was compared with Orbenin and streptomycin against a penicillin-resistant strain of Staphylococcus aureus.