Isolation, characterization, and antiproliferative activity of polymethoxy flavones from Mentha dumetorum

Natural products have been used commonly in the pharmaceutical industry as well as traditional medicine due to their bioactive contents. The objective of this study is to isolate the polymethoxy flavones (PMFs) and evaluate the antiproliferative activity. The PMFs were extracted from Mentha dumetorum with boiling hot water and then partitioned with hexane and the extract was subjected to chromatographic techniques such as Sephadex LH-20, silica gel, and preparative TLC, and HPLC to isolate the compounds. The structures of isolated compounds were elucidated by spectroscopic techniques such as 1H-NMR, 13C-NMR, LC-TOF-MS, and UV-Vis. The anti-cancer effects of isolated compounds were evaluated using a real-time cell analyzer–single plate (RTCA-SP) instrument against HeLa and HT29 cell lines. The isolated PMFs were identified as xanthomicrol (1), 5-hydroxy-6,7,8,4'-tetrametoxy flavanone (2), 5-desmetil sinensetin (3), 5-demetil nobiletin (4), gardenin B (5), 5-hydroxy-6,7,8,3',4'-penta methoxy flavanone (6) and 5-hydroxy-6,7,4'-trimethoxy flavone (7). Compounds 2 and 5 were found to be the most active against both cell lines. The isolated compounds as well as the plant extract of Mentha dumetorum could be promising agents for the drug development process, especially drugs for cancer treatment. Moreover, isolation methods were developed for the corresponding compounds.