Isolation of indole alkaloids from Catharanthus roseus by centrifugal partition chromatography in the pH-zone refining mode.

Centrifugal partition chromatography (CPC) in the pH-zone refining mode allowed a preparative and efficient isolation of vindoline, vindolinine, catharanthine and vincaleukoblastine from a crude mixture of Catharanthus roseus alkaloids. The separation protocol was tested with a synthetic mixture of vindoline, catharanthine and vincaleukoblastine. The fraction content was analyzed and the results compared with theoretical chromatograms obtained by numerical simulation.

Saponins from the stem bark of Filicium decipiens.

Four new saponins have been isolated from the stem bark of Filicium decipiens and identified as 3-O-{beta-D-glucopyranosyl(1-->2)-beta- D-glucopyranosyl}-28-O-{[alpha-L-arabinopyranosyl(1-->2)-beta- D-xylopyranosyl (1-->6)]. [4-O-angeloyloxy-alpha-L-arabinopyranosyl(1-->2)-alpha-L- rhamnopyranosyl(1-->2)]}-beta-D-glucopyranosyl gypsogenic acid, 3-O-{beta-D-glucopyranosyl(1-->2)-beta-D- glucopyranosyl}-28-O-{[alpha-L-arabinopyranosyl(1-->2)- beta-D-xylopyranosyl(1-->6)] [4-O-angeloyloxy-alpha-L- arabinopyranosyl(1-->2)-alpha-L-rhamnopyranosyl(1-->2)]}-beta-D- glucopyranosyl medicagenic acid, 3-O-{beta-D-glucopyranosyl(1-->2)-beta-D- glucopyranosyl}-28-O-{[alpha-L-arabinopyranosyl(1-->2)] [beta-D-xylopyranosyl(1-->4)]alpha-L-rhamnopyranosyl(1-->2)-4-O-[3'- hydroxy-2'-methyl-butyroyloxy)-3-hydroxy-2-methyl-butyroyloxy++ +]-beta-D- fucopyranosyl} medicagenic acid and 3-O-beta-D-glucopyranosyl-28-O- {[alpha-L-arabinopyranosyl(1-->2)] [beta-D-xylopyranosyl(1-->4)] alpha-L-rhamnopyranosyl(1-->2)-4- O-[(3'-hydroxy-2'-methyl-butyroyloxy)-3-hydroxy-2-methyl-butyro yloxy]-beta- D-fucopyranosyl} zanhic acid. These structures were elucidated by analysis of 2D-NMR spectra and of electrospray ionization mass spectra.

Dammarane saponins from Zizyphus lotus.

Four dammarane-type saponins were isolated by means of centrifugal partition chromatography from the root bark of Zizyphus lotus. Their structures were elucidated using a combination of 1D and 2D 1H and 13C NMR spectra and mass spectroscopy. One of these glycosides is the known jujuboside A.

Flow Thermolysis Rearrangements in the Indole Alkaloid Series: Strictamine and Akuammicine Derivatives. The Absolute Configurations of Ngouniensine and epi-Ngouniensine.

Flow thermolysis of strictamine (1) generated two of the predictable rearrangement products, resulting from [1,5]-sigmatropic shifts: akuammicine (2) and indolenine 9. Besides formation of these two compounds, a quite different pathway gave rise to a novel rearrangement leading to indole 6, with the framework of the natural alkaloid ngouniensine (19). Rearrangement to the ngouniensine skeleton became the major pathway when the akuammicine derivatives 10, 12, and 17 were submitted to thermolysis, generating compounds 11, 13 + 15, and 18, respectively.

Alkaloids from Aspidosperma species from Bolivia.

Two Bolivian Aspidosperma species were investigated. The seed and stem bark of Aspidosperma macrocarpon Mart. contain six known alkaloids: (-)-vincadifformine, ervinceine, kopsanone, kopsinine, kopsanol in the seed, and kopsanone, kopsinine, kopsanol, 18-epikopsanol in the stem bark.