title: Labdanes and isopimaranes from Platycladus orientalis and their effects on erythrocyte membrane and on Plasmodium falciparum growth in the erythrocyte host cells.
abstract: Six labdanes (1-6) and four isopimaranes (7-10), including three new natural products (7, 9, and 10), were isolated from Platycladus orientalis, and their structures determined using 1D and 2D NMR methods, ion-cyclotron resonance HRMS, and optical rotation data. Relative configurations of all chiral centers in the isopimaranes were determined using NOESY experiments at 600 and 800 MHz. Specific optical rotation data were used to correlate absolute configurations. Compounds 1-9 and aframodial (11) were tested for their in vitro antiplasmodial activity and for their ability to induce changes of erythrocyte shape in order to obtain data about possible correlation between the two effects. All compounds tested exhibited weak (IC(50) > 25 microM) in vitro antiplasmodial effects against Plasmodium falciparum strain 3D7. At the same time, the compounds caused echinocytic or stomatocytic changes of the erythrocyte membrane curvature, indicative of their incorporation into the lipid bilayer, in the concentration region where the antiplasmodial activity was observed. The antiplasmodial effect of these compounds thus appears to be an indirect effect on the erythrocyte host cell. Weak or moderate antiplasmodial activity observed with many other apolar natural products, in particular those with amphiphilic structures, is also likely to be an indirect effect.
authors.affiliation: Department of Medicinal Chemistry, The Danish University of Pharmaceutical Sciences, Universitetsparken 2, DK-2100 Copenhagen, Denmark.
authors.forename: Javad
authors.initials: J
authors.lastname: Asili
authors.forename: Maja
authors.initials: M
authors.lastname: Lambert
authors.forename: Hanne L
authors.initials: HL
authors.lastname: Ziegler
authors.forename: Dan
authors.initials: D
authors.lastname: Staerk
authors.forename: Majid
authors.initials: M
authors.lastname: Sairafianpour
authors.forename: Matthias
authors.initials: M
authors.lastname: Witt
authors.forename: Gholamreza
authors.initials: G
authors.lastname: Asghari
authors.forename: Ismaiel S
authors.initials: IS
authors.lastname: Ibrahimi
authors.forename: Jerzy W
authors.initials: JW
authors.lastname: Jaroszewski
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000187:drug effects; D029779:Cupressaceae / Q000737:chemistry*; D004224:Diterpenes / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D004912:Erythrocytes / Q000187:drug effects; D007492:Iran; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D018515:Plant Leaves / Q000737:chemistry; D010946:Plants, Medicinal / Q000737:chemistry*; D010963:Plasmodium falciparum / Q000187:drug effects*
chemical_list: D004224:Diterpenes