Isolation & Identification of Bioactive Constituents of Plant Pathogenic Fungi and Targeted Synthesis of Isochromanone Analogs

Clausen, Brandon (2017) Isolation & Identification of Bioactive Constituents of Plant Pathogenic Fungi and Targeted Synthesis of Isochromanone Analogs. Undergraduate thesis, under the direction of Kumudini Meepagala from USDA ARS Natural Products Utilization Research, The University of Mississippi.

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Abstract

An unknown fungal species was cultured from necrotic Brachiaria eruciformis leaves found in Oxford, Mississippi. The fungus was identified via molecular techniques as Pyricularia grisea. This fungus was grown on Czapek Dox broth culture medium for 21 days under continuous light at 24 0C. The culture filtrate was extracted with ethyl acetate and concentrated. The major bioactive compound, namely pyrichalasin H, was isolated using TLC-guided fractionation and identified via spectroscopic techniques. The compound was then tested for bioactivity on monocotyledons, dicotyledons and agriculturally important fungal species. Cellular leakage, chlorophyll content and root/shoot length bioassays were also performed to probe the compound’s phytotoxic mechanism of action. In addition to this project, targeted synthesis of structural analogs of a previously-isolated isochromanone compound was carried out in the laboratory. Structures were characterized by spectroscopic techniques and biological activity was evaluated, with significant phytotoxicity observed in monocots.

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