Semi-preparative isolation and purification of phenolic compounds from Achyrocline satureioides (Lam) D.C. by high-performance counter-current chromatography.

Abstract

Phenolic compounds present in Achyrocline satureioides are known to have therapeutic benefits like antioxidant, anti-inflammatory, and antitumour properties. The main polyphenols present in the plant are quercetin (QCT), luteolin (LUT), 3-O-methylquercetin (3OMQ), and achyrobichalcone (ACB). However, the effective isolation and purification of these compounds from A. satureioides inflorescences are not an easy task. To develop an efficient high-performance counter-current chromatography (HPCCC) method for quick separation and purification of naturally occurring phenolic compounds from the extract of A. satureioides. A two-step HPCCC semi-preparative isolation method was developed using a solvent system composed of n-hexane/ethyl acetate/methanol/water (0.8:1.0:0.8:1.0) and dichloromethane/methanol/water (3.5:3.5:2.5). The HPCCC method was used to obtain two fractions. The first fraction (F1 ) contained high levels of ACB, among other constituents, while the second fraction (F2 ) contained mostly QCT, LUT, and 3OMQ. Besides the high ACB content, F1 contained three other flavonoid-aglycones (kaempferol, 97.3%; isokaempferide, 92.4%; and 3,3'-di-O-methylquercetin, 95.2%) identified by an ultra-performance liquid chromatography system coupled to a quadrupole time-of-flight with high-definition mass spectrometry (UPLC-QTOF/HDMS) and nuclear magnetic resonance (NMR) analysis. Purity levels of ACB, 3OMQ, QCT, and LUT were 98.0, 97.0, 97.5, and 90.2%, respectively. This is the first time that high purity ACB and six other flavonoids were obtained from A. satureioides inflorescences by HPCCC. These excellent results reveal the potential and versatility of HPCCC as a technique to produce different types of products from this plant species on a semi-preparative scale: enriched fractions, new metabolites, or high purity compounds.