Exploring the Antiproliferative Activity of Flavolignans From the Leaves of <i>Casearia arborea</i> (Salicaceae)

The Casearia genus (Salicaceae) is well known as a source of natural antitumor prototypes, as described for clerodane diterpenes. In this way, the dichloromethane phase from leaves of Casearia arborea was phytochemically evaluated in liquid chromatography coupled to high-resolution mass spectrometry, furnishing flavonoid, flavolignan, and phenylpropanoid derivatives, and apocarotenoid terpenoids according to Global Natural Products Social Molecular Networking (GNPS) dereplication. The flavolignans were chemically monitored by liquid chromatography using a UV-Vis detector and purified by a semi-preparative liquid chromatographic system, furnishing tricin, tricin-4″-O-(threo-guaiacylglyceryl) ether (salcolin A), and tricin-4″-O-(erythro-guaiacylglyceryl) ether (salcolin B). Additionally, it was observed that tricin was able to reduce live cells and increase apoptotic cell lines of papillary thyroid cancer and induced only necrosis in this HTH83 cell line, whereas salcolins A and B induced cell death in anaplastic thyroid cancer, increasing cell necrosis. Still, there is no significant induction of apoptotic cell death or necrosis in papillary thyroid cancer cells.