Studies On The Chemical Constituents And Bioactivities Of Hypericum Sampsonii And Hypericum Ascyron

Three chapters were included in the dissertation. In the first and second chapters, the chemical constituents of two plants, H. sampsonii and H. ascyron, were systematic studied. The cytotoxic activities of the new compounds were also evaluated. In addition, the biogenetic pathways of five novel benzoylphloroglucinols with an unprecedented adamantane skeleton was discussed. In the third chapter, natural occurring polycyclic polyprenylated phloroglucinols (PPAPs) to date were summarized.The genus Hypericum belongs to the family Guttiferae, including about400species, was widely distributed throughout the world except the North and South Poles and desert areas. In China, there are about55species and8subspecies, which were mainly distributed in the southwest. As a traditional Chinese medicine distributed from Shaanxi Province to Yangtze River basin in China, H. sampsonii are mainly used for backache, burns, diarrhoea, and swellings. The aerial parts of H. ascyron were used in treatment of headache and hematemesis, and the seeds were used to treat gaseous distention.By means of chromatography and spectroscopic evidences,72compounds were isolated and identified from H. sampsonii, including38new compounds. Several types of PPAPs, steroids, xanthones, and some other compounds were contained. Hyperisampsins A-E (1-5), were new skeletons with an unprecedented rigid caged tetracyclo[6.3.1.13，10.03，7] tridecane-2,11,13-trione adamantyl core with the appendage of a cyclopentane ring. The absolute configuration of2and some other new compounds were determined by ECD and X-ray diffraction, which may provide an alternative method in the determination of the absolute configurations of natural PPAPs.By means of chromatography and spectroscopic evidences,18compounds (9new ones) were isolated and identified from H. ascyron, including14PPAPs with a spirocyclic skeleton,2triterpenoids, and2steroids. Compound15, named3,4-seco-olean-13(18)-ene-12,19-dione-3-oic acid, was the first example of triterpenoid possessing an unusual enedione moiety and3,4-seco-A ring.In addition, some new compounds were evaluated cytotoxic activity and anti-HIV activity in vitro. Most of them showed moderate cytotoxic activity, and compound43showed significant cytotoxicity against HL-60, SMMC-7721, A-549, and MCF-7with IC50values of0.56,0.58,0.53, and0.88μM, respectively. Hyperisampsin A (1) showed obvious anti-HIV activity with EC50and selection index of0.97μM and7.70, respectively.The studies on the chemical constituents of Hypericum sampsonii and Hypericum ascyron from Dabie mountains of Hubei showed similarities of the previous reports and further enriched the skeletons of PPAPs, and will enormously benefit our understanding of the chemical constituents and exploitation of the genus Hypericum.