Study on the Constituents of Mexican Propolis and Their Cytotoxic Activity against PANC-1 Human Pancreatic Cancer Cells

Three new flavonoids, (2R,3R)-3,5-dihydroxy-7-methoxyflavanone 3-(2-methyl)butyrate (1), (7 '' R)-8-[1-(4'-hydroxy-3'-methoxyphenyl)prop-2-en-l-yl]chrysin (2), and (7 '' R)-8-[1-(4'-hydroxy-3'-methoxyphenyl)prop-2-en-1-yl]galangin (3), together with 41 known compounds (4-44) were isolated from a methanolic extract of Mexican propolis. Compounds 2 and 3 are unique natural flavones containing a 1-phenylallyl moiety. The in vitro preferential cytotoxicity of all the isolates was evaluated against a PANC-1 human pancreatic cell line. Compound 3 displayed the most potent preferential cytotoxicity (PC(50) 4.6 mu M) in the nutrient-deprived medium (NDM) and triggered apoptosis-like morphological changes in PANC-1 cells.