Chemical Structures and Cytotoxic Activities of the Constituents Isolated from Citrus Sphaerocarpa

From the peels of Citrus sphaerocarpa, two new limonoids, sphaerocarpain Ⅰ and Ⅱ were isolated together with five known compounds including methyl deacetylnomilinate and ichangin.The chemical structures of the new compounds were elucidated based on chemical/physicochemical evidence.For sphaerocarpain Ⅰ and Ⅱ, the absolute configuration was established by comparison of experimental and predicted electronic circular dichroism (ECD) data.Among the isolated compounds, sphaerocarpain I, II, methyl deacetylnomilinate and ichangin showed cytotoxic activity against both human neuroblastoma cells (SH-SY5Y) and human glioblastoma cells (U-251 MG).