title: Separation and identification of anthocyanin extracted from mulberry fruit and the pigment binding properties toward human serum albumin.
abstract: 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-(6″-O-α-rhamnopyranosyl-β-galactopyranoside) (also known as keracyanin) is the major component present in mulberry (41.3%). Other isolated pigments are cyanidin 3-O-(6″-O-α-rhamnopyranosyl-β-glucopyranoside) and petunidin 3-O-β-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 α-helical structure occur in the presence of keracyanin.
authors.affiliation: Institute of Agro-product Processing, Jiangsu Academy of Agricultural Sciences , Nanjing, P. R. China.
authors.forename: Feng
authors.initials: F
authors.lastname: Sheng
authors.forename: Yuning
authors.initials: Y
authors.lastname: Wang
authors.forename: Xingchen
authors.initials: X
authors.lastname: Zhao
authors.forename: Na
authors.initials: N
authors.lastname: Tian
authors.forename: Huali
authors.initials: H
authors.lastname: Hu
authors.forename: Pengxia
authors.initials: P
authors.lastname: Li
mesh_terms: D000872:Anthocyanins / Q000032:analysis* / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D055598:Chemical Phenomena; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D002942:Circular Dichroism; D003377:Countercurrent Distribution / Q000379:methods; D031541:Fluorescence Resonance Energy Transfer; D005638:Fruit / Q000737:chemistry*; D006801:Humans; D006860:Hydrogen Bonding; D031625:Morus / Q000737:chemistry*; D011485:Protein Binding; D017433:Protein Structure, Secondary; D012709:Serum Albumin / Q000737:chemistry / Q000378:metabolism*; D021241:Spectrometry, Mass, Electrospray Ionization; D053719:Tandem Mass Spectrometry
chemical_list: D000872:Anthocyanins; D012709:Serum Albumin; C020386:keracyanin