Rodolphe Margraff

Preparative separation of anthocyanins by gradient elution centrifugal partition chromatography

Abstract Centrifugal partition chromatography (CPC) allowed purification of anthocyaanins from Champagne vintage by-products (Vitis vinifera) and from blackcurrant (Ribes ni9grum L.). In the first case a 5-1 pilot-CPC used on a preparative multi-gram scale. The biphasic solvent system used was ethyl acetate-1-butanol-water, acidified by TFA (pH 1–3) for both gradient and isocratic normal-phase elutions. Separation selectives which differ for cyanidin and delphinidin glycosides in CPC and cellulose-TLC using the solvent system 1-butanol-acetic acid-water (4:1:5) are discussed.

Partitron 25, a multi-purpose industrial centrifugal partition chromatograph : Rotor design and preliminary results on efficiency and stationary phase retention

Abstract A new preparative chromatograph with a capacity of 25 liters has been designed to meet the most rigorous industrial criteria. All parts contacting liquid phases are made of titanium. The rotor, cast in one piece, can be operated up to 150 bars (2,000 psi). Preliminary results on retention of the liquid stationary phases from non‐aqueous and aqueous–aqueous biphasic solvent systems are presented and commented. A special emphasis is made on the theoretical plate number generated by each individual partition cell. The results highlight the benefit of a new concept of rotor featuring a better mass transfer than that observed in the stacked disk rotors. Finally, the use of neoteric solvents (ionic liquids, supercritical carbon dioxide) is mentioned.

Synthesis of 19-hydroxy docetaxel from a novel baccatin

The synthesis of 19-hydroxy docetaxel is described starting from a new baccatin derivative 4, which was extracted from the needles of Taxus Baccata. This analog exhibits a high level of cytotoxicity in in vitro experimental models.

High-Speed Countercurrent Chromatography : A Promising Method for the Separation of the Annonaceous Acetogenins1

Abstract High-speed countercurrent chromatography (HSCCC) was applied, for the first time, to the separation of Annonaceous acetogenins. The two major acetogenins of the seeds of Annona atemoya, squamocin and rolliniastatin-2, were isolated in one step using a biphasic mixture of heptane/ethyl acetate/methanol/water. In addition, this method yielded four pairs of highly purified acetogenins: squamocin/molvizarin, rolliniastatin-2/asimicin, neoannonin/atemoyin and isodesacetyl uvaricin/desacetyluvaricin. These pairs were further resolved by I-IPLC, leading to a total of eight pure acetogenins in two steps. Isolated acetogenins, which are homologous, position and configurational isomers, have been identified by comparison with standards and by spectroscopic techniques.