Antitumor-Promoting Constituents from Dioscorea bulbifera L. in JB6 Mouse Epidermal Cells

• Published in: Biological & pharmaceutical bulletin 2002, Vol.25(9), pp.1241-1243
• Main Authors: Gao, Huiyuan, Kuroyanagi, Masanori, Wu, Lijun, Kawahara, Nobuo, Yasuno, Takeaki, Nakamura, Yoshiyuki
• Format: Article
• Language: English
• Subjects: Animals; Antineoplastic Agents - chemistry; Antineoplastic Agents - isolation & purification; Antineoplastic Agents - pharmacology; antitumor-promoting activity; Biological and medical sciences; Dioscorea - chemistry; Dioscorea bulbifera L; Drug Screening Assays, Antitumor - methods; Drugs, Chinese Herbal - chemistry; Drugs, Chinese Herbal - isolation & purification; Drugs, Chinese Herbal - pharmacology; Epidermal Cells; Epidermis - drug effects; flavonoid glycoside; General pharmacology; JB6 cell; Medical sciences; Mice; Pharmacognosy. Homeopathy. Health food; Pharmacology. Drug treatments; Rhizome - chemistry; soft agar colony formation method; Tumor Cells, Cultured
• ISSN: 0918-6158; 1347-5215
• DOI: 10.1248/bpb.25.1241

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.