Two new phenylpropanoid glycosidic compounds (a pair of epimers), named pleionosides K (1) and L (2), were isolated from the pseudobulbs of Pleione bulbocodioides (Franch.) Rolfe. Their structures, including absolute configurations, were elucidated by a combination of MS, NMR data, chemical methods and the comparison of experimental and calculated electronic circular dichroism (ECD). Their possible biosynthetic pathway was discussed in the text. Furthermore, the two compounds exhibited moderate hepatoprotective activity against N-acetyl-p-aminophenol (APAP)-induced HepG2 cell damage in in vitro assays, with cell survival rates of 25.83% and 28.82% at 10 μM, respectively, and antioxidant effect against H2O2-induced toxicity in human SK-N-SH cell, with increasing viability at 10 μM of 24.9% and 34.6%, respectively.
Keywords: Pleione bulbocodioides; antioxidant activity; biosynthetic pathway; hepatoprotective activity; phenylpropanoid glycosides.