Four New C19 Homolignans, Schiarisanrins A, B, and D and Cytotoxic Schiarisanrin C, from Schizandra arisanensis

Four new C(19) homolignans with a 5,4'-butano-2,4-cyclohexadienone-6-spiro-3'-(2',3'-dihydrobenzo[b]furan) skeleton, schiarisanrin A, schiarisanrin B, schiarisanrin D, and cytotoxic schiarisanrin C, were isolated from Schizandra arisanensis. Their structure and stereochemistry have been established by spectral and single-crystal X-ray analysis. Schiarisanrin C has cytotoxic activity with ED(50) values of 0.36, 7.1, 4.9, and 5.7 &mgr;g/mL, respectively, against KB epidermoid carcinoma of nasopharynx, COLO-205 colon carcinoma, HEPA hepatoma, and HELA cervix tumor cells.