New dammaranes, esterified with malonic acid, from leaves of Betula pendula.

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-3α,12β,20(S),24(R)-tetrahydroxydammar-25-en-3-yl hydrogen propanedioate, 12-O-acetyl-3α,12β,20(S),24(S)-tetrahydroxydammar-25-en-3-yl hydrogen propanedionate, 12-O-acetyl-3α,12β,17α,20(S),24(R)-pentahydroxydammar-25-en-3-yl hydrogen propanedioate, [12β-acetoxy-4,4,8,10,14-pentamethyl-17-(2-methyl-5-oxotetrahydrofuran2(s)-yl)-hexadecahydrocydopenta[a]phenanthren-3a-yl] hydrogen propanedioate, 12-O-acetyl-3α,12β,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-3α,12β,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, DE-PT, 1 H- 13 C-NMR (HMQC, HMBC) experiments.