Chemical constituents from aerial parts of Mussaenda saigonensis

The genus Mussaenda, belonging to the family Rubiaceae, comprising approximately 160 species, widely distributed in tropical and subtropical regions including Africa, Asia and Southeast Asia. 27 species were found in Viet Nam and several of them are used in folk medicine. An extensive survey of literature on phytochemicals and biological activities of Mussaenda indicated that most of the studies were on M. pubescens, M. macrophylla, M. frondosa, M. hirsutissima, M. arcuata. There are no reports on the chemical and biological data of the Mussaenda saigonensis. This paper reported the results of the isolation of some compounds from aerial parts of M. saigonensis. The dried powder of M. saigonensis aerial parts was exhaustively extracted with ethanol at room temperature to give the crude extract after evaporation of the solvent. This extract was applied to liquid‒liquid partition procedure and successively afford different polar extracts. Compound isolation was performed using column chromatography on silica gel. Chemical structures were elucidated by 1D, 2D-NMR, MS spectra and compared with the literature published data. Six compounds were isolated, including two triterpenoids, 2,3-dihydroxyurs-12-en-28-oic acid (1), 3,23-dihydroxyurs-12-en-28-oic acid (2), two phenolics, coumaric acid (3), caffeic acid (4) and two anthraquinones, aloe-emodin (5) and 11-O--rhamnopyranosylaloe-emodin (6). All compounds were the first reported for Mussaenda saigonensis.