Separation of Four Flavonol Glycosides from Solanum rostratum Dunal Using Solvent Sublation Followed by HSCCC and Low Column Temperature Preparative HPLC

Hyperoside, 3′-O-methylquercetin 3-O-β-D-galactopyranoside, astragalin and 3′-O-methylquercetin 3-O-β-D-glucopyranoside from an invasive weed Solanum rostratum Dunal were separated and purified successfully by high-speed counter-current chromatography (HSCCC) with a solvent system composed of n-hexane-ethyl acetate–methanol–water (1:7:1:7, v/v) and gradient elution mode preparative high-performance liquid chromatography (prep-HPLC) with low column temperature. In the sample pretreatment section, target compounds in aqueous extract of the weed were concentrated using solvent sublation. Two target fractions with purities of 93.75% and 93.68% were obtained from HSCCC. Their chemical structures were identified. The fraction 1 is a pure compound hyperoside and the fraction 2 is the mixture of astragalin, 3′-O-methylquercetin 3-O-β-D-galactopyranoside and 3′-O-methylquercetin 3-O-β-D-glucopyranoside by nuclear magnetic resonance and liquid chromatography-mass spectra. Then, the three flavonol glycosides in the fraction 2 were separated and purified successfully by prep-HPLC with low column temperature.