Isolation and frontier molecular orbital investigation of bioactive quinone-methide triterpenoids from the bark of Salacia petenensis.
The crude dichloromethane bark extract of Salacia petenensis (Hippocrateaceae) from Monteverde, Costa Rica, shows antibacterial and cytotoxic activity. Bioactivity-directed separation led to the isolation of tingenone and netzahualcoyonol as the biologically active materials. Also isolated from the extract were 3-methoxyfriedel-2-en-1-one (a new natural product) and 29-hydroxyfriedelan-3-one. The structures of these compounds were elucidated on the basis of NMR spectral analysis. Molecular orbital calculations 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 molecular orbital calculations suggest that a possible mode of cytotoxic action of quinone-methide triterpenoids involves quasi-intercalative interaction of the compounds with DNA followed by nucleophilic addition of the DNA base to carbon-6 of the triterpenoid.
Department of Chemistry, University of Alabama in Huntsville, 35899, USA. wsetzer@matsci.uah.edu
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D045563:Indolequinones; D007211:Indoles / Q000737:chemistry / Q000302:isolation & purification*; D008958:Models, Molecular; D015394:Molecular Structure; D011809:Quinones / Q000737:chemistry / Q000302:isolation & purification*; D019685:Rosales / Q000737:chemistry*; D014315:Triterpenes / Q000737:chemistry / Q000302:isolation & purification*
D045563:Indolequinones; D007211:Indoles; D011809:Quinones; D014315:Triterpenes; C068040:quinone methide