Seven new meroditerpenoids, from the marine sponge Strongylophora strongylata, that inhibited the maturation of starfish oocytes

Seven new meroditerpenoids, strongylophorines 13 - 19 ( 1 - 7), have been isolated together with the four known strongylophorines 2 ( 8), 3 ( 9), 4 ( 10), and 8 ( 11) by a screening method using oocytes of the starfish Asterina pectinifera from a marine sponge Strongylophora strongylata collected at Iriomote Island, Okinawa, Japan. The structures were assigned according to their spectral data. Ten strongylophorines inhibited the maturation of starfish oocytes in the range 1.1 - 37.6 mu M (IC50), while strongylophorine 4 ( 10) was not active at 250 mu M.