Novel antimitotic dibenzocyclo-octadiene lignan constituents of the stem bark of Steganotaenia araliacea

By means of activity-directed chromatographic fractionation using cultured astrocytoma (ASK) cells, six dibenzocyclo-octadiene Lignans were isolated from Steganotaenia araliacea stem bark. In addition to the most abundant analogue, steganangin [1], two Other known compounds, steganacin [3] and steganolide A [6], and three new compounds, episteganangin [2], steganoate A [4], and steganoate B [5], were obtained. Episteganangin [2] was chemically correlated with the known ketone steganone [7]. All of these compounds demonstrated cytotoxic activity when tested against a panel of eleven human tumor cell lines, with the exception of steganoate A [4]. The magnitude of this activity tended to correlate with antimitotic activity observed with the ASK assay and in vitro inhibition of microtubule assembly. Steganacin [3] was less cytotoxic than colchicine, but more active in these latter two assay systems.