title: New dammaranes, esterified with malonic acid, from leaves of Betula pendula.
abstract: Three known and five new dammarane triterpenes, esterified with malonic acid at C-3 with hemolytic activity were identified from the ethanol-water extract of leaves of Betula pendula Roth: 12-O-acetyl-3alpha,12beta,20(S),24(R)-tetrahydroxydammar-25-en-3-yl hydrogen propanedioate, 12-O-acetyl-3alpha,12beta20(S),24(S)-tetrahydroxydammar-25-en-3-yl hydrogen propanedionate, 12-O-acetyl-3alpha,12beta,17alpha,20(S),24(R)-pentahydroxydammar-25-en-3-yl hydrogen propanedioate, [12beta-acetoxy-4,4,8,10,14-pentamethyl-17-(2-methyl-5-oxotetrahydrofuran2(S)-yl)-hexadecahydrocyclopenta[A]phenanthren-3alpha-yl] hydrogen propanedioate, 12- O-acetyl-3alpha,12beta,20(S),25-pentahydroxydammar-23(E)-en-3-yl hydrogen propanedioate, and one which was new for Betula pendula but found in other Betula species: 12-O-acetyl-20,24-epoxy-3alpha,12beta,20(S),24(R),25-pentahydroxydammar-3-yl hydrogen propanedioate. The structures were elucidated by MS, (1)H-NMR, (13)C-NMR, (1)H-(1)H-COSY, DEPT, (1)H-(13)C-NMR (HMQC, HMBC) experiments.
authors.affiliation: Institut für Pharmazeutische Biologie, Universität Bonn, Nussallee 6, D-53115 Bonn, Germany.
authors.forename: U
authors.initials: U
authors.lastname: Hilpisch
authors.forename: R
authors.initials: R
authors.lastname: Hartmann
authors.forename: K W
authors.initials: KW
authors.lastname: Glombitza