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Separation and Identification of Anthocyanin Extracted from Mulberry Fruit and the Pigment Binding Properties toward Human Serum Albumin
- Sheng, Feng, Wang, Yuning, Zhao, Xingchen, Tian, Na, Hu, Huali, Li, Pengxia
- Journal of agricultural and food chemistry 2014 v.62 no.28 pp. 6813-6819
- acetonitrile, binding properties, circular dichroism spectroscopy, countercurrent chromatography, cyanidin, fluorescence, high performance liquid chromatography, human serum albumin, keracyanin, mulberries, petunidin, solvents, van der Waals forces
- Purple pigments were isolated from mulberry extracts using preparative high-speed countercurrent chromatography (HSCCC) and identified by ESI-MS/MS and high performance liquid chromatography (HPLC) techniques. The solvent system containing methyl tert-butyl ether, 1-butanol, acetonitrile, water, and trifluoroacetic acid (10:30:10:50:0.05; %, v/v) was developed in order to separate anthocyanins with different polarities. Cyanidin 3-O-(6â³-O-Î±-rhamnopyranosyl-Î²-galactopyranoside) (also known as keracyanin) is the major component present in mulberry (41.3%). Other isolated pigments are cyanidin 3-O-(6â³-O-Î±-rhamnopyranosyl-Î²-glucopyranoside) and petunidin 3-O-Î²-glucopyranoside. The binding characteristics of keracyanin with human serum albumin (HSA) were investigated by fluorescence and circular dichroism (CD) spectroscopy. Spectroscopic analysis reveals that HSA fluorescence quenched by keracyanin follows a static mode. Binding of keracyanin to HSA mainly depends on van der Waals force or H-bonds with average binding distance of 2.82 nm. The results from synchronous fluorescence, three-dimensional fluorescence, and CD spectra show that adaptive structure rearrangement and decrease of Î±-helical structure occur in the presence of keracyanin.