Anticancer Meroterpenoids from Centrapalus pauciflorus leaves: Chromone- and 2,4-Chromadione-Monoterpene Derivatives

[Image: see text] Eight previously undescribed chromones, named pauciflorins F–M and two 5-methyl-2,4-chromadione derivatives named as pauciflorins N and O, were isolated from the methanol extract of the leaves of Centrapalus pauciflorus (Willd.) H.Rob. together with the known (+)-spiro-ethuliacoumarin. The structures were determined via extensive spectroscopic analyses, including HRESIMS, 1D NMR ((1)H, (13)C JMOD), and 2D NMR (HSQC, HMBC, (1)H–(1)H COSY, and NOESY) experiments. Through an MTT assay, seven isolated compounds were tested for their antiproliferative properties against human adherent breast (MCF-7, MDA-MB-231), cervical (HeLa, SiHa), and ovarian (A2780) cancer cell lines. Pauciflorin F was effective against MCF-7 breast cancer cells, its activity (IC(50) 5.78 μM) was comparable to that of the reference agent cisplatin (IC(50) 5.78 μM).