High-performance countercurrent chromatography separation of Peucedanum cervaria fruit extract for the isolation of rare coumarin derivatives.

Abstract

For the first time, rare major and minor compounds from fruits of Peucedanum cervaria were isolated. High-performance countercurrent chromatography with two different solvent systems, heptane/ethyl acetate/methanol/water (3:2:3:2 and 2:1:2:1, v/v), was successfully used in the reversed-phase mode. A scale-up process from analytical to semipreparative in a very short time was developed. The structures of isolated compounds were evaluated by high-performance liquid chromatography with diode array detection and electrospray ionization mass spectrometry, gas chromatography with mass spectrometry, and one- and two-dimensional NMR spectroscopy. (8S,9R)-9-(3-Methylbutenoyloxy)-O-acetyl-8,9-dihydrooroselol (compound B), (8S,9R)-9-(2-methyl-Z-butenoyloxy)-O-acetyl-8,9-dihydrooroselol (edultin, compound C), and (8S,9R)-9-acetoxy-O-(2α-methylbutyryl)-8,9-dihydrooroselol (compound D) were obtained using heptane/ethyl acetate/methanol/water (2:1:2:1, v/v) in <40 min. The method yielded 4.6 mg of a mixture of compounds B and C (11:89) and 3.7 mg of compound D. These amounts were obtained from the crude extract (0.5 g) in a single run. Although the compounds are known, their isolation by countercurrent chromatography and the analysis of their relative stereochemistry by two-dimensional NMR spectroscopy have been performed for the first time. Additionally, heptane/ethyl acetate/methanol/water (3:2:3:2, v/v) led to the isolation of oxypeucedanin (1.2 mg; compound A). This is the first time that angular dihydrofuranocoumarin was isolated from plant extract by countercurrent chromatography.