This dissertation describes the phytochemical investigations on the two medicinally important plant, namely Buxus hildebrandtii of Ethiopian origin and B. Sempervirens of Turkish origin. Phytochemical investigations on the leaves of B. hildebrandtii have yielded four new steroidal alkaloids (+)-02-buxafuranamine (75), (+)-6-hydroxy-02–buxafuranamine (76), ( - ) 010 –buxafuranamine (77) and (-)-6-dehydroxy-010 –buxafuranamine (78), along with the known steroidal alkaloids. (+)-irehine (79), (+)-cyclovirobuxine-D (80), (-)cyclosuffro-buxinine-M (81). (-)-E-Buxenone (82) and (-)-Z-buxenone (83), (+)-16a-acetoxybuxabenzamidienine (84) and (+)-benzoylbuxidienine (85), isolated for the first time from the leaves of B. hildebrandtii.
Chemical studies on the roots of Buxus sempervirens have yielded seven new steroidal alkaloids, (+)-16a,31-diacetylbuxadine (86), (+)-semperviraminol (87), (+)-papillotrienine (88), (+)-Nb-demethylpapillo-trienine (89), (+)-buxamine-F (90), (+)-buxaminol-C (91) and (+)-17-oxocycloprotobuxine (92), along with the known steroidal alkaloids, (+)-papilamine (93), (-)-cyclobuxophylline-K (94), (+)-buxaquamarine (95), (+)-buxoxybenzamine (96) and (+)-buxapapilinine (97).Compounds 86, 87, 90, 96 and 97 have shown anti-bacterial and anti-fungal activities, while compounds 86,96 and 97 have also shown phytotoxic activity. Structures of these new and known steroidal alkaloids were established on the basis of extensive spectroscopic studies including one and two-dimensional, and inverse two-dimensional (HMQC and HMBC) NMR experiments.