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Abstract: Seven flavonoid glycosides (1–7) and one theasaponin (8) were isolated from the defatted Camellia oleifera seeds using the isopropanol salting-out pretreatment (ISP) technique, followed by column chromatography. Among them, compounds 5, 7, and 8 are new compounds. The comparison of oxygen radical absorbance capacity (ORAC) of crude extracts extracted by the n-butanol partition (BP) with those extracted by the ISP showed that the latter method yields eight times greater scavenging capacities than that of the former approach. Besides, ISP exhibited almost twice the extraction efficiency than that of BP. ORAC and Trolox equivalent antioxidant capacity (TEAC) analysis revealed that the most potent antioxidants are compounds 1 and 2, which exhibited 1.78 and 1.41 times higher antioxidant activity than that of Trolox, respectively. These results indicated that the ISP approach improves the extraction efficiency in the isolation of potent antioxidants, making the defatted C. oleifera seeds valuable in the food additive industry. [Copyright &y& Elsevier]

Abstract: 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 1.06mg/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. [Copyright &y& Elsevier]

In this study, five flavonoid glycosides were extracted from defatted Camellia oleifera seeds by using a pressurized hot water extraction (PHWE) method. The independent experimental factors (temperature, time and pressure) influencing the PHWE efficiency of the flavonoid glycosides were optimized and quantified using an orthogonal array design and high-performance liquid chromatography – negative mode electron spray ionization/mass spectrometry (HPLC/(−)ESI–MS-MS), respectively. Based on the result of experimental design, the maximum extraction efficiency of flavonoid glycosides were obtained by selecting temperature at 140 °C, pressure at 600 psi, and time for 10 min. The recovery and overall yield of the flavonoid glycosides were greater than those in ultrasonic extraction (UE) (78.5% vs 68.4% and 18.8 mg/g vs 15.91 mg/g). In particularly, compounds 1 and 2, which are kaempferol derivatives, were higher 1.19–1.23 times than those of the compounds obtained through UE (6.63 mg/g vs 5.56 mg/g; 11.89 mg/g vs 9.66 mg/g, respectively). These two compounds have higher polarities and antioxidant capacities than the other three flavonoid glycosides. Thus, PHWE is an excellent alternative method for the extraction of flavonoid glycosides that are highly polar and potent antioxidants. [ABSTRACT FROM AUTHOR]