Two new polyphenols, penthorumin C (1) and 2,6-dihydroxyacetophenone-4-O- [4',6'-(S)-hexahydroxydiphenoyl]-β-D-glucose (2), along with four known polyphenolic acids, pinocembrin-7-O-[4",6"-hexahydroxydiphenoyl]-β-D-glucose(3), pinocembrin-7-O-[3"-O- galloyl- 4",6"-hexahydroxydiphenoyl]-β-D-glucose (4), thonningianin A (5), and thonningianin B (6) were isolated from Penthourm chinense. All compounds were evaluated for their anti-proliferative activity in HSC-T6 cells, and 2 and 5 showed significant activity, with IC50 values of 12.7 and 19.2 μM, respectively.