Isolation And Identification Of Effective Constituents From Toona Sinensis Leaves And Their Biological Activities

Toona Sinensis is a kind of perennial deciduous tree commonly found in China. TheToona Sinensis leaves (TSL) were used for a long time as health food and traditional medicineto treat rheumatoid arthritis, cervicitis, urethritis, gastric ulcers, enteritis, cancer and othersignificant pharmacological. As an effective herb, TSL have been widely used in folk, but itsactive constituents are rarely reported. The studies on the chemical constituents and biologicalactivities can provide certain theory basis for making furth full use of this plant resources.The response surface methodology (RSM) was used to optimize ultrasonic-assistedextraction of flavonoids from TSL. The optimal extraction conditions were enthanolconcentration70%(v/v), liquid-solid ratio30:1(v/w), ultrasonic time90min, power320W,and temperature70℃. Under this condition, the yield and ORAC value of flavonoids were51.16mg rutin equivalent (RE)/g and3538μmol trolox equivalents (TE)/g, respectively,which had no significant differences with the predicted values.The antioxidant, antiproliferative and the postprandial glucose suppression effects of thecrude flavonoids of TSL were evaluated. Results showed that the crude flavonoids showedstrong DPPH and ABTS radical scavenging activities, its IC50values were0.24and0.67mg/mL. The crude flavonoids showed high anticancer activities against human hepatomaHepG2and human breast cancer MCF-7cells.The crude flavonoids had significant enzymeinhibitory activities. Its IC50values for the three key enzyme (porcine pancreatic-amylase,rat intestinal sucrase and maltase) activities were0.33,2.08, and3.22mg/mL, respectively.The crude flavonoids were partitioned with different solvents, which yielded petroleumether fraction, chloroform fraction, ethyl acetate fraction, n-butanol fraction, and aqueousfraction, successively. The ethyl acetate fraction showed significantly pharmacologicalactivities than the other fractions. Quercetin-3-O-α-L-rhamopyranoside (QLR),kaempfeml-3-O-α-L-rhamopyranoside (KLR),1,2,3,4,6-penta-O-Galloyl-β-D-glucopyranose(PGG), and ethyl gallate (EG) were seperated from the ethyl acetate fraction using polyamideresin column and semi-preparative HPLC.Four compounds exhibited strong antioxidant activities (including ABTS radicalscavenging activities and ORAC values). PGG showed the strongest antioxidant activity. KLR showed the strongest anticancer activities against human hepatoma HepG2and human breastcancer MCF-7cells. QLR, PGG, and EG showed relatively weak anticancer activities. PGGexhibited significant enzyme inhibitory activity against-amylase with IC50value of0.069mg/mL. The EG had inhibitory effects on sucrase and maltase to some extent. Its IC50valuefor sucrase and maltase were0.82and0.81mg/mL. These results suggest that theaforementioned four compounds are key chemical compositions valuable for preparingfunctional foods in food industry.