Cytotoxic neolignans and butanolides from Machilus obovatifolia

From the chloroform-soluble portion of the stem wood of Machilus obovatifolia, one new neolignan, perseal F (1), four known neolignans, perseal G (2), licarin A, licarin B, acuminatin, two butanolides, linderanolide E and isolinderanolide E, two steroids, beta-sitosterol, beta-sitosterol-beta-D-glucoside, and syringaldehyde were isolated. Perseal F (1) and G (2) are neolignans that have a C-1' formyl side chain instead of a propenyl group. Compound 2 was isolated in a mixture with acuminatin. The structure of 2 was identified by comparison with the product formed by the Lemieux-von Rudloff oxidation of licarin B. Two minor oxidative by-products, 2a and 2b, were also obtained. Linderanolide E showed cytotoxicities against P-388, KB16, A549 and HT-29, 1 against P-388, KB16 and HT-29, and isolinderanolide E against P-388, cancer cell lines, respectively. All structures were identified by means of spectroscopic analyses.