Isolation and frontier molecular orbital investigation of bioactive quinone-methide triterpenoids from the bark of Salacia petenensis.
Setzer, William N.; Holland, Michael T.; Bozeman, Carey A.; Rozmus, Glenn F.; Setzer, Mary C.; Moriarity, Debra M.; Reeb, Sabine; Vogler, Bernhard; Bates, Robert B.; Haber, William A.
Planta Med. (2001), 67(1), 65-69.

Abstract

The crude dichloromethane bark ext. of Salacia petenensis (Hippocrateaceae) from Monteverde, Costa Rica, shows antibacterial and cytotoxic activity. Bioactivity-directed sepn. led to the isolation of tingenone and netzahualcoyonol as the biol. active materials. Also isolated from the ext. were 3-methoxyfriedel-2-en-1-one (a new natural product) and 29-hydroxyfriedelan-3-one. The structures of these compds. were elucidated on the basis of NMR spectral anal. MO calcns. have been carried out using the semi-empirical PM3 and Hartee-Fock 3-21G ab initio techniques on the quinone-methide nortriterpenoids tingenone and netzahualcoyonol, as well as on the nucleotide bases adenine, guanine, cytosine, and thymine. The MO calcns. suggest that a possible mode of cytotoxic action of quinone-methide triterpenoids involves quasi-intercalative interaction of the compds. with DNA followed by nucleophilic addn. of the DNA base to carbon-6 of the triterpenoid.