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- Title
Bioassay-guided isolation of antioxidants from Astragalus altaicus by combination of chromatographic techniques.
- Authors
Yang, Chunyan; Yang, Yi; Aisa, Haji Akber; Xin, Xuelei; Ma, Hairong; Yili, Abulimiti; Zhao, Yongxin
- Abstract
An efficient method for bioassay-guided preparative isolation of antioxidants from the n-butanol extract of Astragalus altaicus Bunge was ingeniously developed by combination of silica gel column chromatography and high-speed counter-current chromatography. Under the bioassay-guidance of antioxidant activities, the antioxidants were gradually separated from the crude sample of Astragalus altaicus Bunge by silica gel column chromatography and high-speed counter-current chromatography. Silica gel column chromatography separation was performed with chloroform, chloroform-methanol (100:1∼5:1, v/v) and chloroform-methanol-water (5:1:0.1∼2:1:0.1, v/v/v). High-speed counter-current chromatography separation was performed with a two-phase solvent system composed of ethyl acetate- n-butanol-water (2:1:6, v/v/v), which was successfully selected by thin layer chromatography analysis, at a flow rate of 1.5 mL/min. As a result, isorhamnetin-3-gentiobioside (20.8 mg), rutin (82.0 mg), and narcissin (12.8 mg) were obtained for the first time from 200 mg of the crude sample, ABS-5 of Astragalus altaicus Bunge. The purities were all at over 95% by high-performance liquid chromatography analysis, and their structures were unambiguously identified by mass spectroscopy, 1 H, and 13 C nuclear magnetic resonance spectroscopy. Antioxidant activities of the three compounds were also assayed by in vitro ABTS [2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid) diamonium salt] radical cation scavenging activity. Among them, rutin possessed the highest antioxidant capacity with SC50 value of 22.15 μg/m L.
- Publication
Journal of Separation Science, 2012, Vol 35, Issue 8, p977
- ISSN
1615-9306
- Publication type
Article
- DOI
10.1002/jssc.201101104