Antiproliferative activity of three methoxylated flavonoids isolated from Zeyheria montana Mart. (Bignoniaceae) leaves.

The present study isolated three major active flavonoids, two flavones named 4',5,7-trimethoxy-luteolin (1) and 6-hydroxy-5,7-dimethoxyflavone (2) and the flavanone 5-hydroxy-6,7-dimethoxyflavanone (3) from Zeyheria montana dichloromethane leaf extract. Isolation and purification were conducted with the application of column chromatography and structures were assigned by spectral analysis. All compounds were evaluated for cytotoxic activities against human tumor cell lines UACC-62 (melanoma), MCF-7 (breast), NCI-ADR/RES (breast expressing phenotype multiple drug resistance), 786-0 (renal), NCI-H460 (lung, non-small cells), PC-3 (prostate), OVCAR-3 (ovarian), HT-29 (colon) and K562 (leukemia) in vitro. All compounds were active in different degrees on several tumor cell lines and flavanone 3 showed cytotoxicity against almost all cell lines, particularly against human NCI-ADR/RES and K562 cell lines. In conclusion, three antiproliferative compounds were isolated for the first time from Zeyheria montana and its leaves were characterized as an important source of methoxylated flavones and flavanone as potential antitumor compounds.