Functional Teas from the Stems of Penthorum chinense Pursh.: Phenolic Constituents, Antioxidant and Hepatoprotective Activity.

Penthorum chinense Pursh (PCP), a medicinal and edible plant, is traditionally used for liver protection and treatment of liver diseases. In this study, we compared the differences of composition and activity of flowers, stems and leaves of PCP to select a bioactive part. The stems of PCP with stronger antioxidant activity (6.25-100 μg/mL) and lower cytotoxicity (25-200 μg/mL) than the flowers and leaves were a better bioactive part. Then the chemical composition and hepatoprotective effects of an aqueous extract and an 70% ethanolic extract made with stems of PCP were investigated. We found that the 70% ethanolic extract enriched more polyphenols and flavonoids and possessed significantly stronger hepatoprotective activity than the aqueous extract in the dose range of 25-200 μg/mL, which indicated that 70% ethanol is the better solvent of PCP in extraction technology. Moreover, ethyl acetate extract of stems of PCP (PSE) was used to evaluate the hepatoprotective ability of PCP against oxidative damage using an in vitro model of a normal rat's liver cell (BRL-3A). Besides, 12 phenolic compounds were identified from PSE by ultra-performance liquid chromatography followed by electrospray ionization mass spectrometry (UPLC-ESI-MS). Obtained results strongly support the traditional use of PCP and prove stems of PCP to be an important source of bioactive compounds associated with hepatoprotective activity.