Study On The Bioactive Chemical Constituents From The Tubers Of Stephania Succifera

Stephania succifera Lo et Y. Tsoong (Menispermaceae) is a species of the genus Stephania, which is usually used in treatments of heat-clearing, relieving pain, antisepsis and anti-inflammation. Domestic and international phytochemical studies on the plants of this genus indicated that the main chemical constituents were isoquinoline alkaloids, which show several pharmacological activities such as antitumor, antimalarial, antihypertensive, et al. It is reported that the main chemical constituents of S. succifera are crebanine and other alkaloids, but there is no more further study on the biological activity and other active constituents of this plant. In an effort to search for more bioactive compounds, chemical constituents from S. succifera were studied under bioassay guidance of antitumor and antimicrobial for the purpose of developing this plant resource, as well as providing evidence for the chemotaxonomy of this genus.Eighteen alkaloids were isolated from the ethanol extract of the tubers of S. succifera by column chromatography, and their structures were indentified by physicochemical properties and spectral data (UV, IR, MS, 1D and 2D NMR) as Cepharanone D (1), N-Formyl-asimilobine (2), N-Formyl-annonain (3), Dehydrocrebanine (4), Crebanine (5), 7-Oxocrebanine (6), AristololactamⅠ(7), Corydalmine (8),4,5-Dioxodehydrocrebanine (9), N-Acetyl-stepharine (10), (-)-N-Formyl-stepharine (11), Dehydrocorydalmine (12), Crebanine N-oxide (13),7-Oxodehydrocaaverine (14), (-)-Sukhodianine (15), Palmatine (16), (-)-Sukhodianine-β-N-oxide (17) and Corynoxidine (18). Among them, compounds 1 and 2 were new alkaloids, and compounds 1-3,9-11,14,15,17 and 18 were isolated from this species for the first time.The cytotoxic activities of 13 alkaloids were tested by MTT assay. Compounds 4 and 5 showed cytotoxic activities against chronic myelogenous leukemia (K562), human gastric carcinoma (SGC-7901), and human hepatoma (SMMC-7721) cell lines. The antimicrobial activities against Staphylococcus aureus and Methicillin-resistant Staphylococcus aureus (MRSA) of all compounds were measured using paper disco diffusion method, among them, compounds 1、3-9、13-17 exhibited antimicrobial activities in different degrees, and compound 5 (Crebanine) showed the strongest inhibitory activity towards the two pathogenic bacteria, while compounds 2、10-12 and 18 exhibited no activities.