As part of an International Cooperative Biodiversity Group (ICBG) program and a collaborative research project with the Natural Products Discovery Institute, twenty plant extracts were investigated for their antiproliferative and antimalarial activities. Bioassay guided fractionation of thirteen extracts led to the identification of three new antiproliferative compounds, ethyl leptaulosides A-C (5.1-5.3), six new antiplasmodial compounds, apoplanesiacarpan A and B (2.4-2.5), (±)-rhodomyrtosone F (3.1), (±)-calliviminone C (3.2), 3α-angeloyloxy-15-hydroxylabda-7,13-dien-16,15-olid-18-oic acid (4.1), 3α-angeloyloxy-15-methoxylabda-7,13-dien-16,15-olid-18-oic acid (4.2), and twenty-six known compounds. The structures of these compounds were elucidated by using a combination of 1D (1H and 13C) and 2D NMR spectroscopy, mass spectrometry, UV, IR, CD, optical rotation, and chemical modifications. Compounds 5.1 and 5.2 showed moderate antiproliferative activity against the A2780 human ovarian cancer cell line assay with IC50 values of 3 uM and 10 uM, respectively. Compound 3.1 showed potent antiplasmodial activity with an IC50 value of 100 nM, while compounds 3.2 and 4.1 showed moderate antiplasmodial activity with IC50 values of 4 uM and 10 uM, respectively. The other compounds had IC50 values larger than 20 ug/mL, and were thus either inactive or only weakly active. / Ph. D. / Plant based natural products have a long history of being used for medicinal purposes and have played an important role in the modern drug discovery program, with the best known examples being paclitaxel as an anticancer drug, and quinine and artemisinin as antimalarial drugs. Despite great progress in fighting malarial and cancer, both diseases remain difficult to combat due to emergence of drug resistance in malarial parasites and hardness to treat various types of cancer. Therefore, it is urgent to discover new antimalarial and anticancer agents to treat these deadly diseases. This research focuses on identifying new antimalarial and anticancer agents from plant extracts. Investigation of twenty plant extracts led to the isolation of three new anticancer, six new antimalarial and twenty-six known compounds. The isolation and structure elucidation of these new bioactive compounds will be discussed in this dissertation.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/72954 |
| Date | 15 September 2016 |
| Creators | Su, Qingxi |
| Contributors | Chemistry, Kingston, David G. I., Carlier, Paul R., Gandour, Richard D., Santos, Webster L. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Detected Language | English |
| Type | Dissertation |
| Format | ETD, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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