tazettine and hemanthidine

Fifteen Amaryllidaceae alkaloids (1-15) were evaluated for their antiproliferative activities against six distinct cancer cell lines. Several of these natural products were found to have low micromolar antiproliferative potencies. The log P values of these compounds did not influence their observed activity. When active, the compounds displayed cytostatic, not cytotoxic activity, with the exception of pseudolycorine (3), which exhibited cytotoxic profiles. The active compounds showed similar efficacies toward cancer cells irrespective of whether the cell lines were responsive or resistant to proapoptotic stimuli. Altogether, the data from the present study revealed that lycorine (1), amarbellisine (6), haemanthamine (14), and haemanthidine (15) are potentially useful chemical scaffolds to generate further compounds to combat cancers associated with poor prognoses, especially those naturally resistant to apoptosis, such as glioblastoma, melanoma, non-small-cell lung, and metastatic cancers.

Topics: Amaryllidaceae Alkaloids; Antineoplastic Agents, Phytogenic; Apoptosis; Drug Resistance, Neoplasm; Drug Screening Assays, Antitumor; Humans; Molecular Structure; Phenanthridines

Seven alkaloids were isolated from Sprekelia formosissima, and five from Hymenocallis x festalis. Tazettine, lycorine, haemanthidine and haemanthamine were evaluated for antiproliferative and multidrug resistance (mdr) reversing activity on mouse lymphoma cells. Lycorine, haemanthidine and haemanthamine displayed pronounced cell growth inhibitory activities against both drug-sensitive and drug-resistant cell lines, but did not significantly inhibit mdr-1 p-glycoprotein. Thus, the tested alkaloids are apparently not substrates for the mdr efflux pump. Assays for interactions with DNA and RNA revealed that the antiproliferative effects of lycorine and haemanthamine result from their complex formation with RNA.

Topics: Alkaloids; Amaryllidaceae Alkaloids; Aniline Compounds; Animals; Antineoplastic Agents, Phytogenic; Dioxoles; DNA; Drug Resistance, Multiple; Leukemia L5178; Magnoliopsida; Mice; Molecular Structure; Nucleic Acid Denaturation; Phenanthridines; Plant Stems; RNA, Transfer; Tumor Cells, Cultured; Verapamil

[structures: see text] The total syntheses of the amaryllidaceae alkaloids haemanthidine, pretazettine, and tazettine as optically pure enantiomers are reported. Using D-mannose as the starting material, the critical relative stereochemical relationships are established with an intramolecular nitrone-alkene cycloaddition reaction. The synthetic route leads successively to (-)-haemanthidine and then to (+)-pretazettine and (+)-tazettine, taking advantage of the well-established complex relationships among these three alkaloids.

Topics: Alkaloids; Amaryllidaceae Alkaloids; Antineoplastic Agents, Phytogenic; Phenanthridines; Plant Extracts; Stereoisomerism

From the bulbs and leaves of Hymenocallis expansa (Amaryllidaceae), three alkaloid constituents were identified: (+)-tazettine, (+)-hippeastrine, and (-)-haemanthidine. These alkaloids demonstrated significant cytotoxicity when tested against a panel of human and murine tumor cell lines.

Topics: Alkaloids; Amaryllidaceae Alkaloids; Animals; Antineoplastic Agents, Phytogenic; Cell Line; Humans; Mice; Phenanthridines; Plants, Medicinal; Puerto Rico; Tumor Cells, Cultured