[Biological activity of kurilostatin--an unusual alkaloid from sea sponges].

Biological activity of kurilostatin (KS), an unusual alkaloid from the sea sponge was studied. KS was shown to exert a strong cytostatic effect upon tumor cells and activated lymphocytes by mitogen. However it does not display any antitumoral activity in vivo. KS was found to induce release of free [Ca2+] from the above mentioned cells. This process is probably the basis of the cytostatic effect mechanism of KS.