title: Cancer chemopreventive effects of cycloartane-type and related triterpenoids in in vitro and in vivo models.
abstract: Forty-eight natural and semisynthetic cycloartane-type and related triterpenoids have been evaluated for their inhibitory effects on Epstein-Barr virus early antigen (EBV-EA) activation induced by the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) in Raji cells as a primary screening test for anti-tumor promoters. In addition, these triterpenoids have been tested for their inhibitory effects on activation of (+/-)-(E)-methtyl-2-[(E)-hydroxyimino]-5-nitro-6-methoxy-3-hexemide (NOR 1), a nitric oxide (NO) donor, as a primary screening test for anti-tumor initiators. All of the compounds tested exhibited inhibitory effects on both EBV-EA and NOR 1 activation. Six of these compounds having a C-24 hydroxylated side chain, viz., (24R)-cycloart-25-ene-3beta,24-diol (9), (24R)-cycloartane-3beta,24,25-triol (11), (24S)-cycloartane-3beta,24,25-triol (12), (24xi)-24-methylcycloartane-3beta,24,241-triol (14), (24xi)-241-methoxy-24-methylcycloartane-3beta,24-diol (15), and (24xi)-24,25-dihydroxycycloartan-3-one (27), showed higher inhibitory effects than the others tested on both EBV-EA (IC50 values of 6.1-7.4 nM) and NOR 1 activation. Furthermore, compounds 14 and 15 exhibited inhibitory effects on skin tumor promotion in an in vivo two-stage mouse skin carcinogenesis test using 7,12-dimethylbenz[a]anthracene (DMBA) as an initiator and TPA as a promoter.
authors.affiliation: College of Science and Technology, Nihon University, 1-8 Kanda Surugdai, Chiyoda-ku, Tokyo 101-8308, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Kikuchi
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Akihisa
authors.forename: Harukuni
authors.initials: H
authors.lastname: Tokuda
authors.forename: Motohiko
authors.initials: M
authors.lastname: Ukiya
authors.forename: Kenji
authors.initials: K
authors.lastname: Watanabe
authors.forename: Hoyoku
authors.initials: H
authors.lastname: Nishino
mesh_terms: D000465:Algorithms; D000818:Animals; D016588:Anticarcinogenic Agents / Q000737:chemistry* / Q000494:pharmacology*; D000956:Antigens, Viral / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D051379:Mice; D008954:Models, Biological; D015394:Molecular Structure; D012867:Skin / Q000187:drug effects; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013997:Time Factors; D014315:Triterpenes / Q000737:chemistry* / Q000494:pharmacology*
chemical_list: D016588:Anticarcinogenic Agents; D000956:Antigens, Viral; C033305:Epstein-Barr virus early antigen; D014315:Triterpenes; C085352:cycloartane; D013755:Tetradecanoylphorbol Acetate