Additional cytotoxic neolignans from Persea obovatifolia

Four additional neolignans, comprising obovatifol [(2S,3S)-2,3-dihydro-2- (3,4-dihydroxy-5-methoxyphenyl)-7-methoxy-3-methyl-5-trans-propenyl benzofuran], obovaten [2-(3,4-dihydroxy-5-methoxyphenyl)-7-methoxy-3- methyl-5-trans-propenyl benzofuran], perseal C [(2S,3R)-2,3-dihydro-2-(3,4-methylenedioxyphenyl)-5- formyl-3-hydroxymethyl-7-methoxy benzofuran] and perseal D [2-(3,4-dihydroxy-5-methoxyphenyl)-5-formyl-7- methoxy-3-methyl benzofuran] were isolated in a continuing study of the leaves of Persea obovatifolia. Obovatifol had been reported previously in a mass spectrometric analysis without any other spectroscopic data. Obovaten and perseals C and D are new compounds, bearing a C-1' formyl side-chain, instead of a propenyl group. Their structures were elucidated from spectroscopic data; they showed significant cytotoxic activities against P-388, KB16, A549 and HT-29 cancer cell lines in vitro.