Structural identification of compounds from Toona sinensis leaves with antioxidant and anticancer activities

The aim of this study was to isolate key active compounds from Toona sinensis leaves (TSL) with antioxidant and anticancer activities. Four compounds, quercetin-3-O-α-L-rhamnopyranoside (QLR), kaempferol-3-O-α-L-rhamnopyranoside (KLR), 1,2,3,4,6-penta-O-galloyl-β-D-glucopyranose (PGG) and ethyl gallate (EG), were purified from the ethyl acetate fraction of TSL by column chromatography. Their structures were identified by mass spectrometry (MS) and nuclear magnetic resonance (NMR) spectrometry analyses. All four compounds exhibited strong antioxidant activities (including ABTS radical scavenging activities and ORAC values). PGG showed the strongest antioxidant activity. KLR showed the strongest anticancer activities against human hepatoma HepG2 and human breast cancer MCF-7 cells. QLR, PGG, and EG showed relatively weak anticancer activities. These results suggest that four compounds are key chemical compositions valuable for preparing functional foods in the food industry.