Isolation, Identification and Cytotoxic Activity of Triterpenes and Flavonoids from Green Walnut (Juglans regia L.) Pericarps

摘要

Three a -amyrine type triterpenes ( 1-3 ) in addition to oleanolic acid ( 4 ) and six known flavonoids, namely apigenin ( 5 ) and its 7-O- b -D-glucuronide ( 9 ), 5,6,4 ￠ -trihydroxy-7,3 ￠ -dimethoxy-flavone ( 6 ), cirsilineol ( 7 ) , sudachitin ( 8 ) and cilicione-b ( 10 ) were isolated from the dichloromethane extract of the pericarps of Juglans regia . The structures of the compounds were established on the basis of spectroscopic analyses (UV, IR, HRESIMS and 1D & 2D NMR). Compounds 2 , 3 and 6 - 10 were isolated from J. regia for the first time . To the best of our knowledge, compound 3 is a new natural product. All isolated compounds, as well as the dichloromethane extract were evaluated for their cytotoxic activity against the human cancer cell lines, MCF-7, HCT-116, HeLa, Κ562, Raji and THP-1. Compounds ( 1 ) and ( 5 ) showed the most potent anticancer activity against the cancer cells assessed. Interestingly, the concentration of compound ( 5 ) that was cytotoxic to cancer cells did not induce human peripheral blood mononuclear cell apoptosis. These results suggest that the structure of compound ( 5 ) may eventually serve as a lead for developing novel anticancer drugs with limited side effects against normal cells.