Preparative separation of isomeric caffeoylquinic acids from Flos Lonicerae by pH-zone-refining counter-current chromatography

This work concentrates on pH-zone-refining counter-current chromatography of two isomeric dicaffeoylquinic acids, 3,5-dicaffeoylquinic acid and 3,4-dicaffeoylquinic acid along with 3-caffeoylquinic acid, from crude extracts of Flos Lonicerae. The elution sequence of the isomeric dicaffeoylquinic acids, the mixing zone and mechanism of separation are discussed. The separation of 2.136 g of the crude sample from Flos Lonicerae yielded two isomeric compounds: 0.289 g 3,5-dicaffeoylquinic acid and 0.106 g 3,4-dicaffeoylquinic acid plus 0.690 g 3-caffeoylquinic acid at a high purity of over 92.9%, 94.2% and 97.5%, respectively.