| Studies of the metabolites produced by the soil fungus Talaromyces flavus (Klocker) Stolk and Samson are presented in this thesis. This fungus is an effective biological control agent for Verticillium wilt of eggplant (Solanum melongena L.), a disease caused by the fungus Verticilliumdahliae Kleb. The first part of this thesis describes the isolation and structure elucidation of the organic soluble metabolites produced when the fungus is grown in liquid still culture. The mycelium extracts afford only the ubiquitous metabolites D-mannitol (1), a fatty acid and its methyl ester (3 and 4), a di- and triglyceride (6 and 5), and ergosterol (7). The fungal broth, however, is a source of a number of metabolites of polyketide origin. These include the previously unreported tetraketides, 4,6-dihydroxy-5-methylphthalide (10) and 4-carboxy-5-hydroxyphthalaldehydic acid methyl ester (15), a hexaketide, 7-hydroxy-2,5-dimethylchromone (13), and a metabolite whose structure is consistent with that of 3-hydroxymethyl-6,8-dimethoxycoumarin (17). 5-Hydroxymethylfurfural (12) has also been isolated; however, it is thought to be an artifact in the broth extract. A number of higher order polyketides have been isolated which arise from a heptaketide precursor. These include the known metabolites altenusin (18) and its ;Biogenetically, metabolites 10, 15, and 23 are formed by a polyketide pathway. (1-... |
