The Aporphine and Isoquinolinedienone Alkaloids of Ocotea glaziovii

Alcaloides aporfínicos con actividad antituberculosa aislados de Ocotea discolor Kunth (Lauraceae)

La tuberculosis causa miles de muertes a nivel mundial y que, actualmente, los fármacos usados no son suficientes y en ocasiones son obsoletos para su tratamiento, se hace necesaria la búsqueda de nuevos compuestos que ayuden a combatirla. Por tanto, se evaluó la actividad antituberculosis de los alcaloides ocoxilonina (1), ocoteina (2), dicentrina (3) y 1,2-metilendioxi-3, 10,11-trimetoxiaporfina (4), aislados de la madera de Ocotea discolor. Las estructuras fueron identificadas por medio del análisis de los datos espectroscópicos de resonancia magnética nuclear (NMR 1D – 1H, 13C, 2D – COSY, HSQC y HMBC), espectros de masas y comparación con datos de la literatura. Todos los compuestos aislados demostraron actividad antituberculosa, con un rango de variación en la concentración mínima inhibitoria entre 140 y 310 μM, siendo la ocoteina (2) la más activo contra la cepa virulenta de Mycobacterium tuberculosis H37Rv.

Alkaloids from Peumus boldus and their Acetylcholinesterase, Butyrylcholinesterase and Prolyl Oligopeptidase Inhibition Activity

Eleven isoquinoline alkaloids (1–11) were isolated from dried leaves of Peumus boldus Mol. by standard chromatographic methods. The chemical structures were elucidated by MS, and 1D and 2D NMR spectroscopic analysis, and by comparison with literature data. Compounds isolated in sufficient amount were evaluated for their acetylcholinesterase, and butyrylcholinesterase inhibition activity using Ellman's method. In the prolyl oligopeptidase assay, Z-Gly-Pro- p-nitroanilide was used as substrate. Promising butyrylcholinesterase inhibition activities were demonstrated by two benzylisoquinoline alkaloids, reticuline (8) and N-methylcoclaurine (9), with IC50 values of 33.6 ± 3.0 μM and 15.0 ± 1.4 μM, respectively. Important prolyl oligopeptidase inhibition activities were shown by N-methyllaurotetanine (6) and sinoacutine (4) with IC50 values of 135.4 ± 23.2 μM and 143.1 ± 25.4 μM, respectively. Other tested compounds were considered inactive.

A novel carbamoyl radical based dearomatizing spiroacylation process

An easy access to novel spirodienonamides based on a dearomatizing spiroacylation process is described for the first time.

Lauraceae alkaloids

Lauraceae is one of the most representative botanical families, presenting 67 genera, with over 2500 species and more than 300 different alkaloids reported, mainly isoquinolines.

Syntheses of Aporphine and Homoaporphine Alkaloids by Intramolecularortho-Arylation of Phenols with Aryl Halides via SRN1 Reactions in Liquid Ammonia

The photostimulated intramolecular ortho-arylation reactions of bromoarenes linked with pendant phenoxy containing N-substituted tetrahydroisoquinolines in liquid ammonia afforded aporphine (54-82% yield) alkaloid derivatives via SRN1 reactions. This strategy was extended for the first time to the synthesis of a homoaporphine derivative (40% yield). Tetrahydroisoquinoline precursors that contained electron-withdrawing groups on nitrogen (i.e., amides, sulfonamides, and carbamates) gave cyclized products, whereas precursors with basic nitrogens (i.e., NH or NMe) either failed to yield cyclized products or gave aporphines in only low yield.

Isolation and biochemical characterization of a new topoisomerase I inhibitor from Ocotea leucoxylon

In a continuation of our search for potential tumor inhibitors from plants, we found that a crude extract from Ocotea leucoxylon showed selective activity typical of inhibitors of the enzyme topoisomerase I in a yeast assay for DNA-damaging agents. Using a bioassay-directed fractionation approach, the major bioactive compound was isolated and identified as the known aporphine alkaloid dicentrinone (4); the inactive alkaloid dicentrine (3) was also isolated. Compound 4 showed selective bioactivity against the rad52 repair-deficient yeast strain RS322 (IC(12) 49 microg/mL) and was inactive against the rad52- and topo1-deficient strain RS321 (IC(12) > 2000 microg/mL) and against the repair-proficient strain RJ03 (IC(12) > 2000 microg/mL). Biochemical studies with recombinant human topoisomerase I indicated that dicentrinone (4) is an inhibitor of the human enzyme. Colony formation studies suggest that it is weakly cytotoxic, but that its mechanism of toxicity differs from that of camptothecin and its derivatives.

Costaricine, a new antiplasmodial bisbenzylisoquinoline alkaloid from Nectandra salicifolia trunk bark

A MeOH extract of Nectandra salicifolia trunk bark, obtained during a diversity-based plant collection in a lower montane rainforest in Costa Rica, showed activity in an in vitro antiplasmodial assay measuring incorporation of [3H]-labeled hypoxanthie by Plasmodium falciparum. In addition to 15 known alkaloids isolated from samples of trunk bark, roots, and leaves/twigs of this species, a new bisbenzylisoquinoline alkaloid (+)-costaricine [(+)-12-O-methyllindoldhamine] (1) was isolated from bark (0.038% yield) and from roots (0.001%). (+)-Costaricine was active in the antiplasmodial assay, with IC50 values of 50 ng/mL vs. the chloroquine-sensitive D6 clone and 294 ng/mL vs. the chloroquine-resistant W2 clone of P. falciparum.