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published_or_final_version / Botany / Master / Master of Science

Investigations were made into the trapping biology of the pitchers of Nepenthes rafflesiana (Jack), Family Nepenthaceae, in Brunei, Borneo. The plant produces two distinct pitcher forms, upper and lower, which were found to differ in their prey spectra. Although ants were the most important prey in both forms, the upper form caught more anthophilous insects than the lower. High contrast U/V patterns on the upper pitchers were found to contribute to the attraction of some anthophilous insects, as was the fragrance of upper pitcher fluid. Increased height above ground was also found to increase the numbers of anthophilous insects caught. Upper pitchers possessed features of several pollination syndromes, but may have been mutualistic rather than mimetic, as certain criteria for mimesis were not met. Evidence for mutualism is strongest for ants, in which both pitcher forms were found to be specialising, although the involvement of lower pitcher 'wings' in such a relationship, was discounted. The loss of wings from the upper pitcher form may have occurred to reduce strain on the upper pitcher-tendril attachment. Reduction of fluid volume, and strengthening of the attachment in upper pitchers, support this idea. The possession of upper pitchers was found to allow N.rafflesiana access to populations of anthophilous insects that were not as easily available to the sympatric Nepenthes gracilis (Korth). There was found to be a shift in the prey spectrum of lower N.rafflesiana pitchers, as pitcher size increased. Production of lower pitchers was found to increase when upper pitchers were rendered non-functional. This may allow the plant to regenerate after stem damage. Although covering of pitchers failed to produce a decrease in either male flowering success, or &'37 age of viable seeds produced by female plants, pre-flowering pitcher counts suggested that pitchers were an important factor in reproductive fitness.

The aim of this dissertation was to explore structurally unique secondary metabolites from herb medicinal plants Cornus controversa and Delphinium chrysotrichum. The introduction in the first chapter provides a detailed review about the research progress of chemical constitutents of the genus Cornus. In addition, its pharmacological activities were also summarized in this chapter to provide a framework for understanding the roles of medicinal herbs belong to genus Cornus as anti-diabetes therapeutics and to deliver useful information for further research. In chapter two, seven new compounds, including one iridoid glucoside, cornoside A (59), five iridoid aglycones, cornolactones A – E (60 – 64) and one indenone glucoside, cornoside B (65), together with 10 known compounds have been isolated from the leaves of Cornus controversa. The structures of these compounds were established by interpretation of spectroscopic data. Cornolactone A (61) is the first natural cis-fused tricyclic dilactone iridoid containing both a five- and six-membered lactone ring. Cornoside B (65) is the first alkaloid isolated from the genus Cornus bearing an indole-3-lactic acid-11--D-glucopyranoside skeleton. In chapter three, we described the structure elucidation of three new diterpenoid alkaloids delphatisine D (77), chrysotrichumines A (78) and B (79), as well as 11 known compounds from the whole plants of Delphinium chrysotrichum. Delphatisine D (77) is a rare atisine-type alkaloid from genus Delphinium and is the C-15 epimer of spiramine C which bears an internal carbinolamine ether linkage (NCOC) between C-7 and C-20. Chrysotrichumine A (78) is a rare natural C19-diterpenoid alkaloid possessing a nitrone group between C-17 and C-19. In addition, their cytotoxic activity against human breast cancer cell lines of MCF-7 and MDA-MB-231 were also reported. In chapter four, the detailed extraction and isolation procedures of the new compounds, cornosides A and B, cornolactones A – E, delphatisine D, chrysotrichumine A and B, as well as of all the known compounds were described. In addition, the experimental procedures for the determination of PPARγ and LXR agonistic activities and the MTT cytotoxicity assay were listed in this chapter. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2014. / FAU Electronic Theses and Dissertations Collection