Bioassay-guided separation and identification of anticancer compounds in Tagetes erecta L. flowers

Investigating bioactive components in marigold (Tagetes erecta L.) can provide worthy information for drug development. A rapid and efficient method is needed to obtain available anticancer compounds from the ethanol extract of this plant. Therefore, an offline two-dimensional preparative high performance liquid chromatography method guided by a real time cell analysis system was applied in this study. Syringic acid (1), quercetin (2), 6-hydroxykaempferol (3), protocatechuic acid (4) and quercetagetin (5) with high purities of over 95% were prepared using this method, while 6-hydroxykaempferol was first found in Tagetes erecta L. Compounds 2, 3 and 5 all were flavonoids. The compounds were evaluated for their tumor cell growth inhibitory activities on HEPG2 and A549 cells by using a real-time cell-analyzer. Four compounds were able to inhibit the proliferation of human cancer cells at a concentration of 50 μg mL⁻¹. Compounds 2 and 3 showed significant anticancer activity against A549 and HEPG2 cells. Compounds 4 and 5 were effective against A549 cells. The present study demonstrates that this bioassay-guided offline two-dimensional preparative high performance liquid chromatography method is very conducive to isolating plants rich in flavonoids, leading to the discovery of more worthy natural anticancer compounds.