Phytochemicals from the rhizome of Bletilla formosana and their antioxidant, cytoprotective and anti-inflammatory activities

Bletilla formosana (Hayata) Schltr, popularly known as "Xiao Baiji", is commonly consumed as a food ingredient and herbal medicine with the treatment of haemorrhages, chapped skin, colds, and burns in China. The phytochemical investigation of B. formosana rhizomes result in the isolation and identification of 35 chemical compounds, of which biphenyl, phenanthrene and their derivatives are the most abundant structural types. Among the isolated compounds, 12 compounds showed superior antioxidative activities in Ferric reducing/antioxidant power (FRAP), 2,2-diphenyl-1-picryhydrazyl (DPPH), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) scavenging assay. Furthermore, compounds 18-20 (phenanthrenes) and 34 (lignin) had significantly antioxidant capacity and cytoprotective effects through decreasing reactive oxygen species (ROS) content and up-regulating the levels of catalase (CAT), superoxide dismutase (SOD) and glutathione (GSH) in H2O2-induced HepG2 cells. In addition, compounds 8, 10, 16 (dihydrophenanthrenes), 18-20 (phenanthrenes), 27-28 (phenolics), 34-35 (lignin) showed the significant anti-inflammatory by inhibiting productions of interleukin-6 (IL-6), interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) in the lipopolysaccharide (LPS)-induced RAW264.7 macrophage cells. These results confirmed most of isolated compounds displayed significant antioxidant, cytoprotective and anti-inflammatory activities. Among phenanthrenes (18-20) were a prominent type found in the rhizomes of B. formosana. And the more phenolic hydroxyl and methoxy groups of phenanthrene and their derivatives, the better activities. This suggested that Bletilla formosana rhizomes can be used as an edible and medicine homologous plant with antioxidant and anti-inflammatory functions, and can be developed into functional and health nutrition products.