title: Antitumor-promoting constituents from Dioscorea bulbifera L. in JB6 mouse epidermal cells.
abstract: An antitumor-promoting effect was found in the extracts/ingredients of a plant used as a traditional medicine in mainland China, using the neoplastic transformation assay of mouse epidermal JB6 cell lines. The ethyl acetate soluble fraction of 75% ethanol extract of the rhizomes of Dioscorea bulbifera L. showed an inhibitory effect against the tumor promotion of JB6 (Cl 22 and Cl 41) cells induced by a promoter, 12-O-tetradecanoylphorbol-13-acetate (TPA). Further investigation on the constituents of the EtOAc fraction from the rhizomes revealed the chemical structure to be kaempferol-3,5-dimethyl ether (1), caryatin (2), (+)-catechin (3), myricetin (4), quercetin-3-O-galactopyranoside (5), myricetin-3-O-galactopyranoside (6), myricetin-3-O-glucopyranoside (7) and diosbulbin B (8). Constituent antitumor-promoting activities were also examined in the same way. Compounds 1-7, characterized as flavonoids with the two hydroxyl groups at C-7 and C-4', showed the most potent inhibitory effect, but there seemed to be differences in the inhibitory effect between flavonol aglycones and flavonol glycosides. Compared with (-)-epicatechin, (+)-catechin exhibited much stronger inhibitory activity which suggested that chemical stereo structures of compounds affect the efficiency of inhibition. Compound 8 showed moderate activity. The constituents with antitumor-promoting activity from this plant are reported for the first time.
authors.affiliation: Department of Traditional Chinese Medicines, Shengyang Pharmaceutical University, China.
authors.forename: Huiyuan
authors.initials: H
authors.lastname: Gao
authors.forename: Masanori
authors.initials: M
authors.lastname: Kuroyanagi
authors.forename: Lijun
authors.initials: L
authors.lastname: Wu
authors.forename: Nobuo
authors.initials: N
authors.lastname: Kawahara
authors.forename: Takeaki
authors.initials: T
authors.lastname: Yasuno
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Nakamura
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D027742:Dioscorea / Q000737:chemistry; D004354:Drug Screening Assays, Antitumor / Q000379:methods; D004365:Drugs, Chinese Herbal / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D000078404:Epidermal Cells; D004817:Epidermis / Q000187:drug effects*; D051379:Mice; D027343:Rhizome / Q000737:chemistry; D014407:Tumor Cells, Cultured
chemical_list: D000970:Antineoplastic Agents; D004365:Drugs, Chinese Herbal