Preparative isolation and dual column high-performance liquid chromatography of ginkgolic acids from Ginkgo biloba.
A chromatographic procedure for the preparative isolation of six different 6-alkylsalicylic acids (syn. ginkgolic acids) with as alkyl substituents C13:0, C15:0, C15:1, C17:1, C17:2 and, tentatively C17:3 from Ginkgo biloba leaves was developed. The procedure consisted of a combination of normal-phase, reversed-phase and argentation chromatography. The compounds were characterised by means of UV, 1H-NMR and 13C-NMR spectroscopy, and mass spectrometry after silylation. A 15 cm C18 RP-HPLC column connected in series with a 20 cm silver(I) loaded cation exchanger HPLC column in combination with the solvent methanol-water (93:7) acidified with 0.1% formic acid was capable of separating the ginkgolic acids C13:0, C15:1, C17:2, C15:0 and C17:1 within 21 min on an analytical scale. The separation is based on a combination of reversed-phase mechanisms and double bond complexation. Detection took place by UV at 311 nm. The separation is a good starting point for the development of a quantitative procedure for the five major ginkgolic acids in Ginkgo leaves and standardised extracts.
van Beek
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Laboratory of Organic Chemistry, Phytochemical Section, Wageningen University, The Netherlands. teris.vanbeek@bio.oc.wau.nl
Wintermans
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MS
D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D002852:Chromatography, Ion Exchange / Q000379:methods; D020441:Ginkgo biloba / Q000737:chemistry*; D012459:Salicylates / Q000302:isolation & purification*; D013057:Spectrum Analysis
D012459:Salicylates; C112485:ginkgolic acid