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