Antiproliferative Flavanoid Dimers Isolated from Brazilian Red Propolis

Herein reported are results of the chemical and biological investigation of red propolis collected at the Brazilian Northeast coastline. New propolones A–D (1–4), with a 3-{3-[(2-phenyl­benzo­furan-3-yl)­methyl]­phenyl}­chromane skeleton; propolonones A–C (5–7), with a 3-[3-(3-benzyl­benzo­furan-2-yl)­phenyl]­chromane skeleton; and propolol A (8), with a 6-(3-benzyl­benzofuran-2-yl)-3-phenyl­chromane skeleton, were isolated as constituents of Brazilian red propolis by cytotoxicity-guided assays and structurally identified by analysis of their spectroscopic data. Propolone B (2) and propolonone A (5) display significant cytotoxic activities against an ovarian cancer cell line expressing a multiple drug resistance phenotype when compared with doxorubicin.