25 Amaryllidaceae alkaloids belonging to different skeletal types were evaluated for their cytotoxic activity against one murine non-tumoral cell line (LMTK) and two human tumoral cell lines (Molt4 and HepG2) according to established protocols. Significant differences of activity related with the type of skeleton of the tested alkaloids could be observed. Pretazettine (22) was among the most active compound among the 25 tested alkaloids on the Molt4 lymphoid cells, but was inactive against HepG2 hepatoma. On the other hand, lycorenine (11) was found to be the most cytotoxic compound against HepG2 hepatoma, even though it appears to be active against Molt4 cells. Almost all of the tested alkaloids showed cytotoxic activity against fibroblastic LMTK cells. Only mesembrenone (25) showed some specificity against Molt4 cells in comparison to LMTK cells.

1-[4-(trimethylamino)phenyl]-6-phenylhexa-1,3,5-triene (TMA-DPH), a membrane fluorescence probe, interacts with living cells by instantaneous partition between the external medium and the plasma membrane, where it becomes fluorescent. The corresponding fluorescence intensity is then proportional to the cell surface. On the other hand, once incorporated into the plasma membrane, TMA-DPH follows this membrane in the constitutive intracellular traffic and behaves as a monitor for endocytosis. Using this tool on L929 synchronized cells, we showed that the endocytosis levels after 30 min uptake of the probe increased from G1 to mitosis, when they abruptly decreased. The cell surface remained constant throughout the cell cycle, except at the beginning of mitosis when it almost doubled.

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were evaluated on cultured tumoral Molt4 lymphoma cell, and on non-tumoral 3T3 and L929 fibroblasts. Furthermore, we tested these saponins for possible immunomodulatory effects on cultured murine spleen lymphocytes. We found that the crude ethanolic bark extract of C. elliptica was strongly cytotoxic on the Molt4 cells and also on the adherent fibroblasts. Compounds I and 2 were only weakly cytotoxic. A third saponin x, the identification of which is in progress, showed a significant cytotoxicity on Molt4 (Fig. 1) and 3T3 cells. This compound also inhibited the mitogenic effects of concanavalln A and lipopolysaccharide on murine splenocytes (Fig. 2).