Large-scale separation of baicalin and wogonoside from Scutellaria baicalensis Georgi by the combination of pH-zone-refining and conventional counter-current chromatography

Retention mechanism of pH‐peak‐focusing in countercurrent chromatographic separation of baicalin and wogonoside from Scutellaria baicalensis Georgi

“…The pH‐peak‐focusing mode is a variant of the pH‐zone‐refining mode used for countercurrent chromatography. The pH‐peak‐focusing mode is mainly used for analytical purposes, while the pH‐zone‐refining mode is mainly used for preparative purposes in the separation of ionic components [25,26]. Both of these methods have major characteristics in common—they are mainly applied for the separation of ionic components and they always concentrate the eluted components at sharp pH borders.…”

“…Peak overlap tends to occur for one of the following three reasons: first, overloading of the injected sample; second, using solutes with very similar hydrophobicity and p K a values; or, finally, big difference in hydrophobicity and p K a value between the analytes, but they act in an opposite direction, resulting in an incomplete separation [23]. In our very recent study [26], we tried to use pH‐zone‐refining countercurrent chromatography for the preparative separation of baicalin and wogonoside. However, there was always an area of overlap between the two fractions’ peak zones after full optimization, which indicated that baicalin and wogonoside could not be completely separated by the pH‐zone‐refining mode.…”

“…Conventional countercurrent chromatography has been reported to be able to separate baicalin from S. baicalensis [22–25], but the sample loading quantity in these cases was only around 200 mg, and less than 50 mg of baicalin could be obtained in a single run. In our very recent study [26], pH‐zone‐refining countercurrent chromatography combined with conventional countercurrent chromatography was investigated for its use in the preparative separation of baicalin and wogonoside from the crude exact of S. baicalensis . Although a large sample loading, up to 500 mg, could be injected and more than 180 mg of baicalin with 95.3% HPLC purity could be obtained in a pH‐zone‐refining mode, a mixture of two compounds was always produced.…”

Preparative separation of structural isomeric pentacyclic triterpene oleanolic acid and ursolic acid from natural products by pH-zone-refining countercurrent chromatography

“…The countercurrent chromatographic apparatus used in the present study was a multilayer coil planet centrifuge designed in our laboratory (Zhejiang University of Technology, Hangzhou, China), which has been described in previous research. 34 The apparatus was equipped with multilayer coils. The total capacity of the preparative column was 105 mL.…”

Valeriana rigida Ruiz & Pav. Root Extract: A New Source of Caffeoylquinic Acids with Antioxidant and Aldose Reductase Inhibitory Activities

“…Moreover, as a versatile separation chromatography based on a continuous liquid–liquid partition, high-speed counter-current chromatography (HSCCC) with advantages of support matrix-free, no irreversible adsorption, low risk of sample denaturation, and high sample loading capacity has immense potential in separating natural products [ 32 , 33 ], and it is suitable to couple offline DPPH- and ultrafiltration-HPLC in order to achieve efficient screening and separation of bioactive compounds from natural product extracts [ 34 , 35 , 36 ]. Furthermore, pH-zone-refining counter-current chromatography (CCC), developed from conventional HSCCC, can be particularly used for the preparative separation of ionizable target compounds [ 32 , 37 , 38 ].…”