Aqueous and solid complexes of iron(III) with hyaluronic acid. Potentiometric titrations and infrared spectroscopy studies.
The coordination of iron(III) ion to hyaluronic acid (Hyal) in aqueous solutions and solid state was accomplished by potentiometric titrations and infrared spectroscopy. The potentiometric titration studies provided the binding constants for the complexes found in the systems and the speciation of these species according to the variation of pH values. The complexes found presented a complexing ability through both the chelating moieties of Hyal (via the N-glucosamine and D-glucoronic acid), showing no special preference for either one while in solid state, but when in aqueous solution the complexation via the N-glucosamine moiety was the preferred, forming two complexed species, ML and ML(2) (log K(ML)=8.2 and log K(ML2)=7.9). The presence of a mu-oxo complex via the D-glucoronic acid was also detected in both aqueous (log K=6.7) and solid states via the N-glucosamine and D-glucoronic acid simultaneously linked to two Hyal chains. A structure for this latter complex was suggested. The results indicated that these complexes could be used in eliminating the excess iron(III) in living organisms.
Mercê
Ana Lucia Ramalho
AL
Departamento de Química, Universidade Federal do Paraná, CP 19081, Centro Politécnico, Curitiba, 81531-990, Brazil. anamerce@quimica.ufpr.br
Marques Carrera
Luiz Carlos
LC
Santos Romanholi
Lilian Kelly
LK
Lobo Recio
María Angeles
MA
D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D006820:Hyaluronic Acid / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D058085:Iron Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D007700:Kinetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011199:Potentiometry / Q000379:methods*; D012996:Solutions / Q000737:chemistry; D013055:Spectrophotometry, Infrared / Q000379:methods*; D018502:Streptococcus equi
D058085:Iron Compounds; D012996:Solutions; D006820:Hyaluronic Acid