| Summary: | Peanut hulls (<i>Arachis hypogaea</i>, <i>Leguminosae</i>), which are a side stream of global peanut processing, are rich in bioactive flavonoids such as luteolin, eriodictyol, and 5,7-dihydroxychromone. This study aimed to isolate these flavonoid derivatives by liquid-liquid chromatography with as few steps as possible. To this end, luteolin, eriodictyol and 5,7-dihydroxychromone were isolated from peanut hulls using two different techniques, high-performance countercurrent chromatography (HPCCC) and fast-centrifugal partition chromatography (FCPC). The suitability of the biphasic solvent system composed of <i>n</i>-hexane/ethyl acetate/methanol/water (1.0/1.0/1.0/1.5; <i>v</i>/<i>v</i>/<i>v</i>/<i>v</i>) was determined by the <i>Conductor like Screening Model for Real Solvents</i> (<i>COSMO-RS</i>), which allowed the partition ratio <i>K<sub>D</sub></i>-values of the three main flavonoids to be calculated. After a one-step HPCCC separation of ~1000 mg of an ethanolic peanut hull extract, 15 mg of luteolin and 8 mg of eriodictyol were isolated with purities over 96%. Furthermore, 3 mg of 5,7-dihydroxychromone could be isolated after purification by semi-preparative reversed-phase liquid chromatography (semi-prep. HPLC) in purity of over 99%. The compounds were identified by electrospray ionization mass spectrometry (ESI-MS) and nuclear magnetic resonance spectroscopy (NMR).
|
|---|