Bioassay directed fractionation of the methyl ethyl ketone extract of Chiloscyphus rivularis yielded eight sesquiterpenoids, and detailed spectroscopic interpretation led to the assignment of their structures as 12-hydroxychiloscyphone, chiloscypha-2,7-dione, 12-hydroxychiloscypha-2,7-dione, chiloscypha-2,7,9-trione, rivulalactone, 4-hydroxy oppositant-7-one, chiloscyphone, and intermedeol. The structure and stereochemistry of rivulalactone, a novel trinorsesquiterpenoid, was confirmed by its synthesis starting from chiloscyphone. 12-Hydroxychiloscyphone, chiloscypha-2,7-dione, 12-hydroxychiloscypha-2,7-dione, chiloscypha-2,7,9-trione, rivulalactone are new. 12-Hydroxychiloscyphone showed selective bioactivity towards DNA repair-deficient yeast mutants and cytotoxicity to human lung carcinoma cells. In order to improve the activity of cytotoxic furanonaphthoquinones by affixing a hydroxyamino side chain, 2-methyl-2-[2'-(4',9'-dihydronaphtho[2',3'-b]furan-4',9'-dionyl methyl)amino]-1,3-propanediol and its analogs have been synthesized. Bioassay data showed they act by a different mechanism of action than their parental furanonaphthoquinone derivatives. / Ph. D.

As a part of search for bioactive natural products from the plants in collaboration with the Natural Products Discovery Institute (NPDI), ten plant extracts were investigated for their antiplasmodial activity against Plasmodium falciparum Dd2 strain. Twenty-eight compounds were isolated, and twelve of them were new compounds. The structures of all these compounds were determined by analysis of their mass spectrometric, 1D and 2D NMR, and ECD spectrum. Among these natural products, there were three compounds with good antiplasmodial activity, trichospirolide A with an IC50 value of 1.5 μM, malleastrumolide A with an IC50 value of 2.7 μM, and (+)-lariciresinol with an IC50 value of 3.7 μM. In addition to the studies of drug delivery of bioactive natural product, doxorubicin, a novel thiolated doxorubicin analog were designed and synthesized. Its analogs and PEG stabilizing ligands were then conjugated to gold nanoparticles and the resulting Au-Dox constructs were evaluated by TEM. The release of native drug can be achieved by the action of reducing agents, and that reductive drug release gave the cleanest drug release. / Ph. D.