A new flavanone isolated from rhizoma Smilacis glabrae and the structural requirements of its derivatives for preventing immunological hepatocyte damage

From the rhizome of Smilax glabra Roxb., a new flavanone was isolated and n amed as smitilbin (1), together with 6 known compounds, engeletin (2), asti lbin (3), dihydroquercetin (4), eurryphin (5), resveratrol (6), and 5-O-caf feoylshikimic acid (7). These compounds were applied to the assay of liver nonparenchymal cells (NPC) against hepatocytes (HC) isolated from mice with an immunological liver injury. Against the NPC-caused elevation of ALT (al anine transaminase) in culture supernatant from HC, the pretreatment of NPC with flavanoids (1-3) dose-dependently blocked the ALT release while 4, th e aglycone of 3, did not. The chromone 5 showed a much stronger inhibition. Compound 6 also showed the activity. However, 1-7 did not show any suppres sion of NPC or CCl4-induced ALT release when they were used to pretreat HC. These results suggest that compounds 1-3, 5, and 6 could protect the hepat ocyte damage from NPC through selectively producing the dysfunction of NPC with an essential requirement of rhamnose, and the chromone part in their s tructures may be critical for exhibiting the activity rather than through p rotecting the hepatocyte membranes.