This thesis describes the isolation and structure elucidation of secondary metabolites formed in static culture from a number of endophytic Xylariaceous fungi. Four Xylaria endophytes isolated from a palm tree in Thailand were surface cultured on an aqueous malt extract-glucose medium. They all produced cytochalasin D, coriloxin, (S)-mellein and (3R,4R)-4-hydroxymellein as the main secondary metabolites suggesting that the four endophytes could be the same species. The endophytic fungus A116 produced cytochalasin D as the main secondary metabolite. Another non-endophytic fungus B315, produced cytochalasin D, (R)-mellein, a mixture of two isomers of 4-hydroxymellein and phloroglucinol. X.62, an endophytic fungus, produced 19,20-epoxycytochalasin C from the mycelium as the main secondary metabolite. The fungus Engleromyces sinensis produced engleromycin acetate as the main secondary metabolite. Fungus X. polymorpha produced (3E)-4-(3¿-acetyl-2¿,6¿-dihydroxy-5¿-methylphenyl)-2-methoxybut-3-enoic acid. / Ministry of Higher Education; Kingdom of Saudi Arabia.

This thesis describes the isolation and structure elucidation of secondary metabolites formed in static culture from a number of endophytic Xylariaceous fungi. Four Xylaria endophytes isolated from a palm tree in Thailand were surface cultured on an aqueous malt extract-glucose medium. They all produced cytochalasin D, coriloxin, (S)-mellein and (3R,4R)-4-hydroxymellein as the main secondary metabolites suggesting that the four endophytes could be the same species. The endophytic fungus A116 produced cytochalasin D as the main secondary metabolite. Another non-endophytic fungus B315, produced cytochalasin D, (R)-mellein, a mixture of two isomers of 4-hydroxymellein and phloroglucinol. X.62, an endophytic fungus, produced 19,20-epoxycytochalasin C from the mycelium as the main secondary metabolite. The fungus Engleromyces sinensis produced engleromycin acetate as the main secondary metabolite. Fungus X. polymorpha produced (3E)-4-(3'-acetyl-2',6'-dihydroxy-5'-methylphenyl)-2-methoxybut-3-enoic acid.