A C29-triterpene, beccaridiol (1), a dihydrochalcone natural product, 2′,4′-dihydroxy-3-(4-methoxyphenyl)-propiophenone (2), as well as three known compounds, 4′-hydroxy-1′,2′-dihydro-β-ionone, 4′-O-methyldavidigenin (3), and ursolic acid, have been isolated from an EtOAc-soluble extract of the leaves of Diplectria beccariana. Beccaridiol (1) was characterized as an ursane-type 28-nortriterpene possessing an unusual aromatic E-ring by spectroscopic data interpretation. The relative configuration of this unusual isolate was established by analyzing the observed NOESY NMR correlations, and the absolute stereochemistry of 1 was then determined based on the circular dichroism (CD) spectrum of its 2,3-di-p-bromobenzoate (1b) derivative. All isolates were evaluated for their potential cancer chemopreventive properties utilizing a cell culture assay to determine quinone reductase induction.
Bibliographical noteFunding Information:
We thank Dr. K. Fagerquist, Mass Spectrometry Facility, Department of Chemistry, University of Minnesota, Minneapolis, MN, and Drs. J.A. (Art) Anderson and Y. Wang, Research Resources Center (RRC), University of Illinois at Chicago (UIC), for the mass spectral data. We are grateful to the RRC, UIC, for providing spectroscopic equipment, and to Dr. R.A. Kleps of the RRC, UIC, for facilitating the running of the 500 MHz NMR instrument. This research was supported by program project P01 CA48112, funded by the National Cancer Institute, NIH, Bethesda, MD.
Copyright 2008 Elsevier B.V., All rights reserved.
- Circular dichroism
- Diplectria beccariana
- Quinone reductase