Isolation of Chlorogenic Acid from <Emphasis Type="Italic">Flaveria bidentis</Emphasis> (L.) Kuntze by CCC and Synthesis of Chlorogenic Acid-Intercalated Layered Double Hydroxide

Preparative counter-current chromatography (CCC) was successfully used for isolation and purification of chlorogenic acid from Flaveria bidentis (L.) Kuntze with a solvent system composed of ethyl acetate–methanol–water at a volume ratio of 50:1:50, v/v. Using a preparative unit of the CCC centrifuge, about 800 mg of the crude extract was separated, yielding 3.2 mg of chlorogenic acid at a purity of 92.0%. The blood pressure lowering and antivirus chlorogenic acid (C₁₆H₁₈O₉) was intercalated into magnesium–aluminum–layered double hydroxides, which was used as host materials for drug-LDH host-guest supermolecular structures by anion exchange under a nitrogen atmosphere. Chlorogenic acid–LDH is a functional and effective drug. The product chlorogenic acid–LDH has been characterized by powder X-ray diffraction (XRD), Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA) and scanning electron micrographs (SEM). The X-ray diffraction patterns of NO₃ ^? form of LDH and chlorogenic acid–LDH were compared, and the basal d spacing value of NO₃ ^?-LDH layer was 8.75 Å (2θ = 10.100°); however, the basal reflection (003) of chlorogenic acid–LDH shifts to lower 2θ (for 003 reflection: 2θ = 5.119°) that is expanded to 17.25 Å, indicating the intercalation of chlorogenic acid into the interlayer of Mg–Al-LDH. Thermogravimetric analysis showed that chlorogenic acid stability had improved, and scanning electron micrographs showed that the morphology of the chlorogenic acid–LDH was irregular masses of distinctly thicker flakes, which was similar to the morphology of NO₃ ^? form of LDH.