CHARACTERIZATION OF ANTIMITOTIC PRODUCTS FROM MARINE ORGANISMS THAT DISORGANIZE THE MICROTUBULE NETWORK - ECTEINASCIDIN-743, ISOHOMOHALICHONDRIN-B AND LL-15

The effect of selected marine compounds with anti-tumoral activity on the cell microtubule network was tested by immunofluorescence analyses , or by other in vitro analyses involving competition with colchicine or with GTP for tubulin binding and tubulin polymerisation, studies th at were carried out in parallel with other microtubule poisons used as controls. Three compounds were found to disorganise the microtubule n etwork: isohomohalichondrin B, LL-15 and ecsteinascidin 743. The first two compounds prevent microtubule assembly and GTP binding to tubulin . Ecteinascidin 743 disorganises the microtubule network but it does n ot seem to interact directly with tubulin.