Studies On The Chemical Constituents And Quality Standard Of Two Rhododendron Species

This thesis consists of five chapters. The first chapter reviews the advances in the chemical constituents and bioactivities of the genus of Rhododendron. The second and third chapters discuss the phytochemistical studies on Rhododenron molle and R. decorum, respectively. The fourth Chapter presents the quality standard analysis of R. molle. And in the last chapter, conclusion of this dissertation is made.R. molle and R. decorum, well known traditional medicinal plants, have long been used for the treatment of various diseases, such as injury, pain, bronchitis, cough and osteomyelitis in traditional Chinese medicine. In the course of searching for more new natural compounds with biological activities, we further systematically investigated the flowers of these two plants, which led to the isolation of fourty-two compounds and thirty-three of them were identified.Twenty-five compouds were isolated from (70%acetone in water) exctacts of R. molle, and twenty-three ones have been elucidated, including five new diterpenoids. The five new compounds were determined as:rhodomollein F (1*), rhodomollein G (2*), rhodomollein H (3*), rhodomollein C (4*), and rhodomollein D (5*). The known compounds were identified as fourteen grayanane diterpenoids:rhodomollein ⅩⅨ (8), rhodojaponin Ⅱ (9), rhodojaponin Ⅰ (10), rhodojaponin Ⅲ (11), rhodojaponin Ⅴ (12), rhodojaponin Ⅶ (13), rhodomollein Ⅲ (14), rhodomollein ⅩⅥ (15), rhodojaponin Ⅵ (16), rhodojaponin Ⅳ (17), rhodomollein Ⅸ (18), grayanotoxin Ⅲ (19), grayanotoxin Ⅱ (20), rhodomollein Ⅰ (21); one kalmanol diterpenoid, kalmanol (22); one lignan:pinoresinol (23); one coumarin:6,8-Dimethoxy coumarin (24), and one triterpenoid:2a,3β,24-trihydroxyurs-12-en-28-oic acid (25)。Seventeen compounds were isolated from70%acetone exctacts of R. decorum, and eleven of them were identified as:Grayanotoxin Ⅰ (1), Rhodomollein Ⅲ (2), Rhodojaponin Ⅵ (3), Rhodomollein Ⅰ (4), Rhodojaponin Ⅱ (5), Rhodojaponin Ⅰ (6), Rhodojaponin Ⅴ(7), Rhodojaponin Ⅲ (8), a-Amyrin (9), Uvaol (10), and taxifolin (11). All the compounds above are known.Since the active and toxic components of the above two poisonous plants of Rhododendron are both grayanane diterpenoids, it is necessary to carry on quantitative analysis on these plants in order to control the safety of utilization of these plants. This thesis described the content analysis of two main ingredients, rhodojaponin Ⅲ and Ⅵ, which were the major constituents of R. molle, and a quality standard for R. molle was established by HPLC-ELSD method.