title: Structures of steroidal saponins from the tubers of Brodiaea californica and their inhibitory activity on tumor promoter-induced phospholipid metabolism.
abstract: Phytochemical examination of the fresh tubers of Brodiaea californica resulted in the isolation of four new steroidal saponins. Their structures were determined, by extensive spectral analysis including two-dimensional (2D) NMR spectroscopy and acid-catalyzed hydrolysis, to be (25S)-spirost-5-ene-1 beta,3 beta-diol [(25S)-ryscogenin] 1-O-[O-beta-D-glucopyranosyl-(1-->3)-O-alpha-L-rhamnopyranosyl-(1-->2)- beta-D-glucopyranoside] (1), (25S)-ruscogenin 1-O-[O-beta-D-glucopyranosyl-(1-->3)-O-alpha-L-rhamnopyranosyl-(1-->2)-O -[beta-D-xylopyranosyl-(1-->3)]-beta-D-glucopyranoside] (2), the C-20 and C-22 isomer of 2 (3) and the 6'-O-acetyl derivative of 2 (4), respectively. The conformations of the tetrasaccharide moiety of 2 and 4 were inspected through molecular mechanics and molecular dynamics calculation studies, showing that the acetyl group attached to C-6 of the inner glucose was near the C-21 methyl of the aglycon in the calculated preferred conformation of 4, which must cause the downfield shift of 21-Me by 0.07 ppm in comparing the 1H-NMR of 4 with that of 2. The inhibitory activity of the isolated saponins on 12-O-tetradecanoylphorbor-13-acetate (TPA)-stimulated 32P-incorporation into phospholipids of HeLa cells was evaluated to identify new antitumor-promoter compounds.
authors.affiliation: School of Pharmacy, Tokyo University of Pharmacy and Life Science, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Mimaki
authors.forename: O
authors.initials: O
authors.lastname: Nakamura
authors.forename: Y
authors.initials: Y
authors.lastname: Sashida
authors.forename: K
authors.initials: K
authors.lastname: Koike
authors.forename: T
authors.initials: T
authors.lastname: Nikaido
authors.forename: T
authors.initials: T
authors.lastname: Ohmoto
authors.forename: A
authors.initials: A
authors.lastname: Nishino
authors.forename: Y
authors.initials: Y
authors.lastname: Satomi
authors.forename: H
authors.initials: H
authors.lastname: Nishino
mesh_terms: D016588:Anticarcinogenic Agents / Q000494:pharmacology*; D002240:Carbohydrate Sequence; D006367:HeLa Cells; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D008969:Molecular Sequence Data; D010743:Phospholipids / Q000378:metabolism*; D018517:Plant Roots / Q000737:chemistry*; D010946:Plants, Medicinal / Q000737:chemistry*; D012503:Saponins / Q000737:chemistry* / Q000494:pharmacology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
chemical_list: D016588:Anticarcinogenic Agents; D010743:Phospholipids; D012503:Saponins; D013755:Tetradecanoylphorbol Acetate