Antiplasmodial activities of homogentisic acid derivative protein kinase inhibitors isolated from a Vanuatu marine sponge Pseudoceratina sp.

As part of our search for new antimalarial drugs in South Pacific marine sponges, we have looked for inhibitors of Pfnek-1, a specific protein kinase of Plasmodium falciparum. On the basis of promising activity in a preliminary screening, the ethanolic crude extract of a new species of Pseudoceratina collected in Vanuatu was selected for further investigation. A bioassay-guided fractionation led to the isolation of a derivative of homogentisic acid [methyl (2,4-dibromo-3,6-dihydroxyphenyl)acetate, 4a] which inhibited Pfnek-1 with an IC(50) around 1.

Antimalarial potential of xestoquinone, a protein kinase inhibitor isolated from a Vanuatu marine sponge Xestospongia sp.

As part of our search for new antimalarial drugs, we have screened for inhibitors of Pfnek-1, a protein kinase of Plasmodium falciparum, in south Pacific marine sponges. On the basis of a preliminary screening, the ethanolic crude extract of a new species of Xestospongia collected in Vanuatu was selected for its promising activity. A bioassay-guided fractionation led us to isolate xestoquinone which inhibits Pfnek-1 with an IC(50) around 1 microM.

Routine use of natural abundance deuterium NMR in a polypeptidic chiral oriented solvent for the determination of the enantiomeric composition of chiral building blocks.

[reaction: see text] Natural abundance deuterium 2D NMR spectroscopy in chiral liquid crystal was successfully used to efficiently analyze the enantiomeric composition of organic chiral building blocks involved in the syntheses of natural and synthetic bioactive products. The results reported here emphasize the high potential of this analytical strategy and prove its applicability for routinely determining enantiomeric excesses.