title: Physicochemical properties and biological activities of DEAE-derivatized Sphingomonas gellan.
abstract: Physicochemical characteristics and biological activities of Sphingomonas gellan (S-gellan) were investigated. The S-gellan weight fractions of Glc and GlcUA were 0.45 and 0.25, respectively, and the molar ratio of Glc:Rha:GlcUA was approximately 4:2:3. The S-gellan was chemically derivatized with diethylaminoethyl chloride-HCl (DEAE-HCl), and the resulting modified S-gellan contained both positive and negative charges. The elemental and IR analyses were conducted to confirm the successful incorporation of DEAE groups into S-gellan. A large increase in nitrogen fraction was observed from the derivatized S-gellan by elemental analysis. The IR absorption bands induced by C-H, C-N, and C-O-C stretching were noticeable at 2950, 1310-1380, and 1000-1150 cm(-1), respectively, resulting from the DEAE substitution. The characteristic CH3 and CH2 peaks originated from the DEAE group were detected in the 1H NMR spectrum of the derivatized S-gellan as well. The solubility of native S-gellan was improved almost twice from 40% to 75% after DEAE derivatization, while water holding capacity (WHC) drastically decreased from 10026% to 245%. Oil binding capacity (OBC) of S-gellan also significantly dropped from 1528% to 331% after the derivatization. The bile acid binding capacity of S-gellan was indirectly determined by measuring the holding capability of cholic acid inside the dialysis membrane (MWCO 12,000-14,000 Da). Once S-gellan was DEAE derivatized, there was substantial increase in the cholic acid retardation index (CRI). Up to 9 h of dialysis, the derivatized S-gellan released 29.3% less of cholic acid compared to the control group that did not contain S-gellan. From these results of the improved water solubility and stronger bile acid binding capacity, it would be suggested that the DEAE-derivatized S-gellan has more advantages than gellan itself for functional food applications.
authors.affiliation: Department of Food Science and Technology, Sejong University, 98 Gunja-Dong, Gwangjin-Gu, Seoul 143-747, Korea.
authors.forename: Sang-Ho
authors.initials: SH
authors.lastname: Yoo
authors.forename: Kyung Hee
authors.initials: KH
authors.lastname: Lee
authors.forename: Ji-Soo
authors.initials: JS
authors.lastname: Lee
authors.forename: Jaeho
authors.initials: J
authors.lastname: Cha
authors.forename: Cheon Seok
authors.initials: CS
authors.lastname: Park
authors.forename: Hyeon Gyu
authors.initials: HG
authors.lastname: Lee
mesh_terms: D001647:Bile Acids and Salts / Q000378:metabolism; D002241:Carbohydrates / Q000032:analysis; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D004983:Ethanolamines / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D011135:Polysaccharides, Bacterial / Q000737:chemistry* / Q000378:metabolism; D012995:Solubility; D013055:Spectrophotometry, Infrared; D020578:Sphingomonas / Q000737:chemistry*
chemical_list: D001647:Bile Acids and Salts; D002241:Carbohydrates; D004983:Ethanolamines; D011135:Polysaccharides, Bacterial; C048288:gellan gum; C007369:2-diethylaminoethanol