Analytical and Preparative Separation of Kaoliang and Lac Colors by pH‐Zone‐Refining CCC

Abstract

The natural coloring agents Kaoliang and Lac colors were separated using pH‐zone‐refining countercurrent chromatography (pH‐z‐CCC) on an analytical or preparative scale. The main components of Kaoliang color have been reported to be apigeninidin and luteolinidin, however, the structures of other compounds present in the color have not been elucidated as it is difficult to separate the compounds using conventional chromatographic techniques. Therefore, the separation of this color was done by pH‐z‐CCC that isolated three compounds. LC/MS and ¹H‐NMR analyses were used to determine the structures established as a halogenated phenyl compound, p‐coumaric acid and methylated apigenin. Lac color mainly consists of four anthraquinone derivatives, named laccaic acid A, B, C, and E. These four laccaic acids were separated on a large scale by pH‐z‐CCC. Purified Lac color (1 g) was submitted to pH‐z‐CCC with tridodecylamine as a ligand, and produced 790 mg, 41 mg, 109 mg, and 6 mg of laccaic acid A, B, C, and D, respectively, with a minimum purity of 96%.

Keywords:

• Kaoliang color
• Lac color
• pH‐zone‐refining countercurrent chromatography
• Flavonoids
• Anthraquinone

Acknowledgment

We gratefully acknowledge helpful discussions with Dr. Yoichiro Ito on several points in this study.