An analysis of phakellin and oroidin structures stimulated by further study of an Agelas sponge

Two new phakellin alkaloids, (-)-7-N-methyldibromophakellin (14) and (-)-7-N-methylmonobromophakellin (15), were isolated from an Agelas sp. sponge, collected near Wewak, Papua New Guinea. Inhibition assays employing both 12- and 15-human lipoxygenase isozymes (12-HLO, 15-HLO) were used to guide the isolation of 14, and LCMS data pointed the way to uncovering 15. The structure elucidations were completed by spectroscopic data analysis and comparisons to the properties of known phakellins. The lipoxygenase IC50 data showed that 14 was modest in its selective inhibition of 12-HLO. The phakellin family is uniquely marine-derived, and comments are offered on the biogenetic insights provided by these new structures.