Quality relevant compounds in homeopathic mother tinctures – Isolation and characterisation of 3,5- and 4,5-dicaffeoylquinic acid

The quality of homeopathic mother tinctures is determined by the quality of the starting material and the method of preparation. In Germany their production and quality parameters are regulated by the official German Homeopathic Pharmacopoeia and the European Pharmacopoeia. According to these Pharmacopoeias, the majority of homeopathic mother tinctures should be prepared from fresh plant material. However, samples of certain mother tinctures from the European market showed an unexpected variability in their thin layer chromatography patterns, which might be caused by mother tinctures prepared from dried plant material instead of fresh plants. The present study contributes to the identification of quality relevant compounds able to distinguish properly manufactured mother tinctures from non-properly manufactured ones. In preliminary tests mother tinctures prepared both from fresh and dried plant material were tested using TLC. In a number of cases there were spots which occurred exclusively in tinctures from dried material. The isolation of the substances responsible for these spots was carried out using Sambucus nigra L. For isolation dried flowers were extracted with methanol. The dry residue was dissolved in water and successively re-extracted with solvents of increasing polarity. The EtOAc-soluble fraction was separated by preparative RP-HPLC/PDA yielding two substances which can be used as quality relevant compounds: 3',5'-O-dicaffeoylquinic acid and 4',5'-O-dicaffeoylquinic acid. It was the first time that the two acids were isolated from Sambucus nigra and characterized on the basis of UV-, MS- and NMR spectroscopic data. 3',5'-O-dicaffeoylquinic acid had already been identified earlier by LC/MS (dissertation G. Rieger, Graz, in preparation).