Characterization and purification of proanthocyanidins from cranberry fruits by modern planar chromatography (TLC, AMD, OPLC)

Cranberry fruits (Vaccinium macrocarpon, Ericaceae) have long been the focus of interest for their beneficial in preventing urinary tract infections. Among cranberry compounds, proanthocyanidins (PACs) exhibit bacterial anti-adhesion activity against uropathogenic Escherichia coli [1]. Free anthocyanins (catechin), dimers (PAC A2, PAC B1), and others polymers are characterised by TLC (Eluent: ethyl acetate/dichloromethane/formic acid 60:30:5) derivatization with vanillin-hydrochloric acid reagent [2] to obtain procyanidins fingerprints of different plant extracts, juice and therapeutic forms. In the Optimum Laminar Planar Chromatography (OPLC) semi-preparative mode, the different compounds are purified off-line in about 1mg per plate for catechin, PAC A2 and PAC B1 with a less polar eluent (ethyl acetate/dichloromethane/formic acid 50:30:5, HT Sorb LA 001 0,2mm). In HPTLC or AMD (Automated Multiple Development) it is possible to determine on-line at least five different compounds by scanner densitometry (using the Camag Reprostar System for image analysis) and different extracts can be analysed with regard to PAC A2 quantification as this compound is involved in the biological activity. These three techniques present their own interest according to the objective. For the comparison of different fingerprints and compound determination, the AMD system is the method of choice as it presents the best resolution. OPLC opens up the quick analysis for an important number of samples and this method can be consecutively used in a semi-preparative mode to purify products by direct elution.

References 1. Howell, A.B. (2007) Mol. Nutr. Food Res. 51: 732–72.

2. Wagner, H. (1996) Plant drug analysis. Springer. Heidelberg.