Chemical constituents of red Mexican propolis.

Chemical investigation of a red-type Mexican propolis sample has led to the isolation of three new compounds, 1-(3′,4′-dihydroxy-2′-methoxyphenyl)-3-(phenyl)propane (1), (Z)-1-(2′-methoxy-4′,5′-dihydroxyphenyl)-2-(3-phenyl)propene (2) and 3-hydroxy-5,6-dimethoxyflavan (3), together with seven known flavanones, isoflavans, and pterocarpans. Structural determination, was accomplished by spectroscopic analysis, particularly 2D NMR and ESI-MS/MS techniques. The present study appears to be the first report on the occurrence of isoflavonoids in Mexican propolis. In addition, the presence of compounds with a 1,3-diarylpropane and 1,3-diarylpropene carbon skeleton were found for the first time in propolis. Isolated compounds 1−10 indicated the possible relation between red Mexican propolis and the genus Dalbergia.