Isomeric tropane alkaloids from the aerial parts of Schizanthus tricolor.
Investigation of the aerial parts of Schizanthus tricolor yielded seven isomeric tropane alkaloids: 3alpha-(1-methylitaconyl)-6beta-senecioyloxytropane (1), 3alpha-(1-methylitaconyl)-6beta-angeloyloxytropane (2), 3alpha-(1-methylmesaconyl)-6beta-senecioyloxytropane (3), 3alpha-(1-methylmesaconyl)-6beta-angeloyloxytropane (4), 3alpha-(1-methylmesaconyl)-6beta-tigloyloxytropane (5), 3alpha-(1-methylcitraconyl)-6beta-senecioyloxytropane (6), and 3alpha-(1-methylcitraconyl)-6beta-angeloyloxytropane (7). Their structures were established by NMR including (1)H, (13)C NMR, HSQC, HMBC, COSY, and NOESY experiments, UV, IR, and mass spectrometry. Compounds 1, 6, and 7 are new to the literature. Alkaloids 1, 3, 4, and 5 and a mixture of 3, 4, and 5 were evaluated for in vitro antiplasmodial and cytotoxic activity. Compounds 1, 4, and 5 showed marginal inhibition of Plasmodium falciparum strain K1 with IC(50) values of 22.8, 24.8, and 36.0 microM and displayed no cytotoxicity on MRC-65 cells (CC(50) > 64 microM). Alkaloid 3 was inactive (IC(50) 63.5 microM). The alkaloid mixture exhibited slightly higher activity (IC(50) 17.0 microM) than the pure compounds, indicating some synergy between the different isomers.
Cretton
Sylvian
S
School of Pharmaceutical Sciences, University of Geneva, University of Lausanne, Quai Ernest-Ansermet 30, CH-1211 Geneva 4, Switzerland.
Glauser
Gaetan
G
Humam
Munir
M
Jeannerat
Damien
D
Muñoz
Orlando
O
Maes
Louis
L
Christen
Philippe
P
Hostettmann
Kurt
K
D000470:Alkaloids / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D000962:Antimalarials / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D002677:Chile; D006801:Humans; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D010946:Plants, Medicinal / Q000737:chemistry*; D010963:Plasmodium falciparum / Q000187:drug effects*; D019657:Solanaceae / Q000737:chemistry*; D013237:Stereoisomerism; D014326:Tropanes / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology
D000470:Alkaloids; D000962:Antimalarials; D014326:Tropanes