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Naturally occurring oligostilbenes are receiving more attention because they exhibit several beneficial effects for health, including hepatoprotective, antitumor, anti-adipogenic, antioxidant, antiaging, anti-inflammatory, anti-microbial, antiviral, immunosuppressive and neuroprotective activities. Thus, they could be of some potentially therapeutic values for several diseases. In this study, we adopted the alkaline extraction-acid precipitation (AEAP) method for extraction of oligostilbenes from the seed kernel of Iris lactea Then, the high-speed counter-current chromatography (HSCCC) was used for preparative isolation and purification of oligostilbenes from the AEAP extracts. Finally, three oligostilbenes, namely vitisin D (73 mg), ampelopsin B (25 mg) and cis-vitisin A (16 mg), were successfully fractionated by HSCCC with a two-phase solvent system composed of n-hexane-ethyl acetate-methanol-water (2:5:3:6, v/v/v/v) from 300 mg of the AEAP extracts in ∼ 190 min. The purities of the three isolated oligostilbenes were all over 95.0% as analyzed by high performance liquid chromatography. They all were isolated from I. lacteal for the first time.The method of AEAP for the preparation of the oligostilbene-enriched crude sample was simple, and the HSCCC technique for the isolation and purification of oligostilbenes was efficient.
• HPLC-DAD-APCI/MS was set up for analysis of flavonoid aglycones in the RBP. • The method is capable of providing higher sensitivity and repeatability. • Four methods were applied and assessed for extraction of flavonoids from RBP. • The highest extraction efficiency of flavonoids from RBP was achieved by MAE. • MAE is of short extraction time, low solvent consumption and homogeneous conditions.<br>For identification and quantification of flavonoid aglycones in rape bee pollen (RBP) collected from the Qinghai-Tibetan Plateau, a high-performance liquid chromatography (HPLC) separation method with diode array detector (DAD) and atmospheric pressure chemical ionization/mass spectrometric (APCI/MS) detection and four extraction methods (i.e. microwave-assisted extraction, Soxhlet extraction, cold-soaked extraction, and heat reflux extraction) were developed in this study. The identification of flavonoid aglycones was based on retention time and mass spectra by comparison with standards. Results demonstrated that this method showed excellent reproducibility and correlation coefficient, and offered the detection limits of 0.77-15.50 pmol at signal-to-noise ratio of 3. Quercetin and kaempferol were presented in RBP, and microwave-assisted extraction (MAE) was superior to the other three methods in terms of efficiency, convenience and high content of quercetin (1.37 ± 0.059 mg/g) and kaempferol (23.44 ± 0.544 mg/g). Our work indicated that: 1) the proposed HPLC-DAD-APCI/MS was an accurate and precise analysis method to identify and quantify the flavonoid aglycones in RBP; and 2) MAE was efficient to extract flavonoids from RBP with short extraction time, low solvent consumption, and homogeneous extraction conditions.
A method of using high-speed counter-current chromatography (HSCCC) and semi-preparative reversed-phase liquid chromatography (semi-preparative RPLC) to preparatively separate flavone glucosides and lignan from the crude extracts of <i>Caragana korshinskii</i> has been established for the first time in this study. Five flavone glucosides, including 9 mg of kaempferol 3-O-{β-<i>d</i>-glucopyranosyl(1→2)-[α-<i>l</i>-rhamonopyranosyl(1 → 6)]-β-<i>d</i>-galactopyranoside}, 21 mg of kaempferol 3-O-α-<i>l</i>-rhamnopyranosyl(1→6)-β-<i>d</i>-galactopyranoside-7-O-α-<i>l</i>-rhamnopyranoside, 34 mg of kaempferol 3-O-β-<i>d</i>-galactopyranoside-7-O-α-<i>l</i>-rhamnopyranoside, 27 mg of kaempferol 3-O-β-<i>d</i>-glucopyranosyl-7-O-α-<i>l</i>-rhamnopyranoside, and 14 mg of calycosin 7-O-β-<i>d</i>-glucopyranoside, and one lignan, 16 mg of alangilignoside B, were successfully isolated from 1.8 g of the crude sample through the combination of HSCCC with a two-phase solvent system composed of ethyl acetate-<i>n</i>-butanol-0.5 % formic acid (4:1:5, <i>v/v/v</i>) and semi-preparative RPLC with a mobile phase of methanol-water (20:80, <i>v/v</i>). The purities of the six compounds are all over 95 % as determined by HPLC and the structures are confirmed by the analysis of UV, <sup>1</sup>H-NMR, and <sup>13</sup>C-NMR and compared with published data.
A method of using high-speed counter-current chromatography (HSCCC) for preparative isolation and purification of oligostilbenes from the ethanol extracts of seed kernel of Iris lactea Pall. var. chinensis (Fisch.) Koidz was established in this study. Four oligostilbenes were successfully separated and purified by HSCCC with two sets of two-phase solvent system, n-hexane-ethyl acetate-methanol-water (3:6:4.2:5.5, v/v/v/v) in the head-to-tail elution mode for the first separation to mainly isolate vitisin A (58 mg), ɛ-viniferin (76 mg) and peak II (43 mg) from 300 mg of the crude ethanol extracts, and then light petroleum-ethyl acetate-methanol-water (5:5:3:6, v/v/v/v) in the tail-to-head elution mode for the second separation to isolate vitisin B (52 mg) and vitisin C (11 mg) from 100mg of peak II. The purities of the isolated four oligostilbenes were all over 95.0% as determined by HPLC. Vitisin A, vitisin B and vitisin C, resveratrol tetramers, were isolated from Iris lactea for the first time. The preparation of crude sample was simple and the HSCCC method for the isolation and purification of four oligostilbenes was rapid, efficient and economical.