Electronic Theses and Dissertations


Jing Li

Date of Award


Document Type


Degree Name

Ph.D. in Pharmaceutical Sciences

First Advisor

Ikhlas A. Khan

Second Advisor

Marc Slattery

Third Advisor

Jordan K. Zjawiony

Relational Format



for dissertation defense Jing Li Iklas A. Khan, major professor professor of pharmacognosy research professor in the research institute of pharmaceutical sciences assistant director of the national center for natural products research program director of FDA programs two projects are included in the dissertation. The first one is the "Studies of Scutellaria species on the chemical constituents, analytical method, and biological activities". The second one is the "Chemical investigation of Pfaffia paniculata". S. lateriflora was listed in the FDA poisonous plant database and has been classified as an "herb of undefined safety" due to the reports of hepatotoxic reactions. Also, it was reported to be adulterated with germander which is a group of Teucrium species with hepatotoxicity. The primary objective of this project is to explore the chemical constituents of S. lateriflora. Sixteen compounds, including three minor coumarins of which two are new, six flavonoids, four triterpenes, two steroids, and one fatty acid were isolated and identified from this species. In addition seventeen flavonoids have been isolated and identified from S. baicalensis. Based on the chemical constituents, a simple HPLC-PDA fingerprinting method was developed to distinguish S. lateriflora from germander, and to assess the quality of commercial products claiming to contain S. lateriflora. Also, a HPLC/ESI-MSn method was established to identify thirteen flavonoids and one stilbene derivatives. Cytotoxicity of these two extracts and thirteen flavonoids isolated from them were not observed at the highest tested concentrations suggesting that the reports of hepatotoxic reactions on S. lateriflora might very likely be due to germander. The potent PPARs activation of skullcap extracts as well as several characteristic flavonoids was identified that provides some information on possible new application of skullcap, especially S. lateriflora, for the treatment of diabetic-related diseases. Also the potent activity of tested flavonoids on PPARs suggests the potential of these flavonoids as leads for PPAR? and PPAR? agonists. P. paniculata has been commonly used in Brazil for three centuries with the same indications as American and Asian ginseng. More than fifty preparations are available on USA market, but no analytical method(s) existed to assess the quality of the raw materials, and the products claiming to contain P. paniculata. In order to develop an appropriate validated quantitative analytical method for the quality control of this plant material and dosage form the phytochemical investigation of P. paniculata was carried out. Two new nortriterpenoids pfaffine A and B, one new yellow compound pfaffine C, along with eleven known compounds were isolated and identified from the roots of this plant. These compounds will be used as markers for quality control of raw materials of P. paniculata as well as products claiming to contain this species.





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