A new high-speed counter-current chromatography method for semi-preparative separation and purification of alkaloids from embryo of the seed of Nelumbo nucifera Gaertn was developed by using pH-gradient elution mode. Diethyl ether was used as the stationary phase of the two-phase solvent system and Na2HPO4/NaH2PO4 buffer solution with pH values of 7.5 and 7.2 in gradient mode as the mobile phase. Consequently, 33 mg of liensinine, 42 mg of isoliensinine, and 67 mg of neferine were obtained from 200 mg of crude extracts. The purities of them were all over 98% as determined by HPLC area normalization method, and the structures were identified by 1H-NMR and 13C-NMR.
A preparative high-speed counter-current chromatography method for isolation and purification of flavonoid compounds from Oroxylum indicum was successfully established by using ionic liquids as the modifier of the two-phase solvent system. Two flavonoid compounds including baicalein-7-O-diglucoside and baicalein-7-O-glucoside were purified from the crude extract of O. indicum by using ethyl acetate–water–[C4mim][PF6] (5:5:0.2, v/v) as two-phase solvent system. 36.4 mg of baicalein-7-O-diglucoside and 60.5 mg of baicalein-7-O-glucoside were obtained from 120 mg of the crude extract. Their purities were 98.7 and 99.1%, respectively, as determined by HPLC area normalization method. The chemical structures of the isolated compounds were identified by 1H-NMR and 13C-NMR.
A preparative high-speed countercurrent chromatography method for isolation and purification of neomangiferin and mangiferin from Rhizoma anemarrhenae was successfully established by using ionic liquids as the modifier of the two-phase solvent system. Neomangiferin and mangiferin were purified from the crude extract of R. anemarrhenae by using ethyl acetate-water-[C4mim][PF6] (5:5:0.2 v/v) as two-phase solvent system. In total, 22.5 mg of neomangiferin and 70.6 mg of mangiferin were obtained from 150 mg of the crude extract. The purities of neomangiferin and mangiferin were 97.2 and 98.1%, respectively, as determined by HPLC. The chemical structures of the isolated compounds were identified by 1H-NMR and 13C-NMR.
A chromatographic method for isolation and purification of chemical constituents from the well-known traditional Chinese drug Da-huang (roots of Rheum officinale Baill.) was established by using 12% cross-linked agarose gel, Superose 12, as the separation media. A two-step separation procedure is employed. Sixty five percent methanol was used as the eluent for separation of cinnamic acid, rhein, physcion and emodin form Da-huang crude extract. The fraction containing aloe-emodin and chrysophanol was then separated by using 55% methanol containing 0.5% acetic acid as the eluent. As a result, cinnamic acid and five kinds of hydroxyanthraquinones including rhein, aloe-emodin, chrysophanol, physcion and emodin were obtained. The retention behavior of hydroxyanthraquinones on Superose 12 was also studied. The retention of hydroxyanthraquinones on Superose 12 is based on a mixture of hydrogen bonding and hydrophobic interactions between the hydroxyl groups of the hydroxyanthraquinones and the residues of the cross-linking reagents used in the manufacturing process of Superose 12.
A chromatographic method using 12% cross-linked agarose gel Superose 12 as the separation medium was developed for isolation and purification of the chemical constituents from the pericarp of Sophora japonica L. The mobile phase used for the separation was 2% acetic acid and 7% acetic acid in gradient elution. As a result, eight compounds including four kinds of flavonoids and four kinds of isoflavonoids were obtained in a one-step separation. A straightforward explanation of the separation mechanism of flavonoids and isoflavonoids on Superose 12 is also given. The flavonoids and isoflavonoids are retained on Superose 12 by a combination of hydrogen bonding and hydrophobic interactions between the hydroxyl groups of aglycone and the residues of the cross-linking reagents used in the manufacture of Superose 12.