Background: Penthorum chinense Pursh has a long history as a traditional medicine for the
treatment of liver diseases in China. Despite its common use, investigations on the hepatoprotective
components of P. chinense have not been carried out clearly.
Experiment: Four extraction methods related to reflux, cold-soak, microwave and ultrasonic extraction
were compared for optimum condition, combined with in vitro antioxidant activities and in vivo hepatoprotective
effects to explore the chemical principles responsible for its liver protective effects.
Result: Of four methods, the reflux extraction displayed the highest efficiency, producing the most
abundant flavonoid of 82.36 mg/g (as rutin equivalents). Furthermore, among the 10 flavonoid constituents
identified with their mass spectrometry data, HPLC analysis showed the contents of six major ones
from reflux extraction were significantly higher, namely protocatechuic acid (1), catechin (2), 2,6-
dihydroxyacetophenone-4-O-[4',6'-(S)-hexahydroxydiphenoyl]-β-D-glucose (3), pinocembrin-7-O-[3-
O-galloyl-4'',6''-hexahydroxydiphenoyl]-β-D-glucose (PGHG) (4), quercetin-3-O-α-L-rhamnoside (5)
and thonningianins A (Th A) (6). Compounds 2, 4, 5 and 6 exhibited potent antioxidant activity, while
compounds 4, 5 and 6 remarkably prevented the elevation of alanine aminotransferase in an alcoholic
liver injury mouse model. Hence, PGHG, quercetin rhamnosides and Th A could be considered as key
active biomarkers of P. chinense for the treatment of hepatitis.