Extraction and purification of flavanone glycosides and kaemferol glycosides from defatted Camellia oleifera seeds by salting-out using hydrophilic isopropanol

The purpose of this research was to investigate a salting-out procedure for isolating four flavonoid glycosides from defatted Camellia oleifera seeds. The procedure included extraction with 80% methanol, methanol removal and addition of an equal amount of hydrophilic isopropanol and salt to separate the isopropanol fraction from the water layer. Using successive column chromatography, kaemferol-3-O-[2-O-β-d-glucopyranosyl-6-O-α-l-rhamnopyranosyl]-β-d-glucopyranoside (compound 1), kaemferol-3-O-[2-O-β-d-xylopyranosyl-6-O-α-l-rhamnopyranosyl]-β-d-glucopyranoside (compound 2), naringenin-7-O-[β-d-xylopyranosyl(1 → 6)][β-d-glucopyranosyl(1 → 3)-α-l-rhamnopyranosyl(1 → 2)]-β-d-glucopyranoside (compound 3) and naringenin-7-O-β-d-xylopyranosyl(1 → 6)-β-d-glucopyranoside (compound 4) were obtained. The structure of compound 3, a new flavanone glycoside, was analyzed using UV, FT-IR, 1H NMR, 13C NMR and HR-FAB-MS. Quantification using high-performance liquid chromatography (HPLC) demonstrated that defatted C. oleifera seed cake contains 7.92, 17.7, 2.23 and 1.06 mg/g of the four compounds. The extraction efficiencies of the four compounds were increased by 23.17%, 7.59%, 48.67% and 47.22% from those obtained with n-butanol partition extraction. This new extraction technique is simpler, faster and less expensive than the traditional extraction method. Accordingly, this salting-out method can potentially replace the existing one.