Isolation and characterization of bioactive compounds from Lepisorus thunbergianus (Kaulf.)

Lepisorus thunbergianus (Kaulf.) (LET) is an evergreen fern found on rocks and tree trunks that is distributed in East and Southeast Asia. Our previous study showed that the methanol extract from LET had significant anti-oxidant activity, but the active components of LET are still unclear. In the present study, isovitexin, orientin, isoorientin and chlorogenic acid were isolated from LET under the guidance of antioxidant activity. In addition, the structure of isovitexin, orientin, isoorientin and chlorogenic acid was characterized using matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS) and nuclear magnetic resonance spectroscopy (NMR). Orientin and isoorientin presented similar activities toward the DPPH, with half maximal inhibitory concentrations (IC50) of 15–17 μmol, and inhibition of reactive oxygen species (ROS) production by 50% at 100 μmol. Chlorogenic acid significantly inhibited intracellular ROS and nitric oxide (NO) production and had a strong effect toward DPPH. Furthermore, chlorogenic acid demonstrated decreased iNOS, COX-2, IFN-β and TNF-α gene expression. These findings demonstrate the potential anti-inflammatory effects of chlorogenic acid. Isoorientin, at a concentration of 100 μmol, showed 50% inhibition of human liver cancer cells (Huh7 and HepG2). These results suggest that compounds isolated from LET have potential to prevent liver cancer cell lines.