Fagraldehyde, a Secoiridoid Isolated from Fagraea fragrans

in Journal of Natural Products (2008), 71(12), 2038-2040

A secoiridoid aglycone with atypical skeleton, named fagraldehyde (1), together with several known secoiridoids (gentiopicroside (2), sweroside (3) and swertiamarin (4)) were isolated from the bark and ... [more ▼]

A secoiridoid aglycone with atypical skeleton, named fagraldehyde (1), together with several known secoiridoids (gentiopicroside (2), sweroside (3) and swertiamarin (4)) were isolated from the bark and leaves of Fagraea fragrans collected in Cambodia. The conformations of 1 were evaluated on the basis of molecular modeling and NOESY correlations. A hypothetical biogenesis of fagraldehyde was proposed to explain the unusual skeleton. Compound 1 was weakly active in vitro against Plasmodium falciparum. [less ▲]

Antiplasmodial activity of alkaloids from various Strychnos species

in Journal of Natural Products (2002), 65(10), 1381-1386

The in vitro antiplasmodial activities of 69 alkaloids from various Strychnos species were evaluated against chloroquine-resistant and chloroquine-sensitive lines of Plasmodium falciparum. The compounds ... [more ▼]

The in vitro antiplasmodial activities of 69 alkaloids from various Strychnos species were evaluated against chloroquine-resistant and chloroquine-sensitive lines of Plasmodium falciparum. The compounds, comprising mainly indolomonoterpenoid alkaloids, exhibited a wide range of biological potencies in the antiplasmodial assays. The most active alkaloids were also tested for cytotoxicity against HCT-116 colon cancer cells to determine their antiplasmodial selectivity. As a result of these studies, structure-activity relationships for these alkaloids have begun to emerge. Alkaloids presenting four types of bisindole skeleton exhibited potent and selective activities against Plasmodium. They were sungucine-type (IC(50) values ranging from 80 nM to 10 microM), longicaudatine-type (IC(50) values ranging from 0.5 to 10 microM), matopensine-type (IC(50) values ranging from 150 nM to 10 microM), and usambarine-type alkaloids. Within the last structural type, isostrychnopentamine (49) and ochrolifuanine A (46) were found to be active against chloroquine-sensitive and -resistant strains (IC(50) values of 100-150 and 100-500 nM, respectively), and dihydrousambarensine (51) exhibited a 30-fold higher activity against the chloroquine-resistant strain (IC(50) = 32 nM) than against the chloroquine-sensitive one. [less ▲]

Guiaflavine, a New Bisindole Quaternary Alkaloid from the Stem Bark of Strychnos Guianensis

in Journal of Natural Products (1999), 62(6), 898-900

A reinvestigation of Strychnos guianensis resulted in the isolation of a colored quaternary bisindole alkaloid from the stem bark. The structure of this new substance, guiaflavine (1), was defined by ... [more ▼]

A reinvestigation of Strychnos guianensis resulted in the isolation of a colored quaternary bisindole alkaloid from the stem bark. The structure of this new substance, guiaflavine (1), was defined by detailed spectroscopic methods and comparison with model compounds. [less ▲]

Madangolide and Laingolide A, Two Novel Macrolides from Lyngbya bouillonii (Cyanobacteria)

in Journal of Natural Products (1999)

Two new macrolide derivatives, madangolide (2) and laingolide A (3), have been isolated from the cyanobacterium Lyngbya bouillonii, collected in Papua New Guinea. Their structures (without stereochemistry ... [more ▼]

Two new macrolide derivatives, madangolide (2) and laingolide A (3), have been isolated from the cyanobacterium Lyngbya bouillonii, collected in Papua New Guinea. Their structures (without stereochemistry) have been established by detailed high-field 1D and 2D NMR studies and, in the case of 3, by comparison with the spectroscopic data of laingolide (1), previously isolated from the same organism. [less ▲]

12'-Hydroxystrychnobiline, nouvel alcaloïde bisindolinique du Strychnos variabilis

in Journal of Natural Products (1983), 46(5), 638-645

12'-hydroxystrychnobiline, a new unsymmetrical bisindole alkaloid, was isolated from the root barks of Strychnos variabilis. Its structure was established by acid hydrolysis and by spectral analysis ... [more ▼]

12'-hydroxystrychnobiline, a new unsymmetrical bisindole alkaloid, was isolated from the root barks of Strychnos variabilis. Its structure was established by acid hydrolysis and by spectral analysis, especially by 1H-nmr at 360MHz. We compare its absolute stereochemistry with that of other alkaloids that contain an oxazine ring. [less ▲]