title: Spectrophotometric and electrochemical determination of the formation constants of the complexes Curcumin-Fe(III)-water and Curcumin-Fe(II)-water.
abstract: The formation of complexes among the Curcumin, Fe(III) and Fe(II) was studied in aqueous media within the 5-11 pH range by means of UV-Vis spectrophotometry and cyclic voltammetry. When the reaction between the Curcumin and the ions present in basic media took place, the resulting spectra of the systems Curcumin-Fe(III) and Curcumin-Fe(II) presented a similar behaviour. The cyclic voltammograms in basic media indicated that a chemical reaction has taken place between the Curcumin and Fe(III) before that of the formation of complexes. Data processing with SQUAD permitted to calculate the formation constants of the complexes Curcumin-Fe(III), corresponding to the species FeCur (lob beta110 = 22.25 +/- 0.03) and FeCur(OH)- (log beta111 = 12.14 +/- 0.03), while for the complexes Curcumin-Fe(II) the corresponding formation constants of the species FeCur- (log beta110 = 9.20 +/- 0.04), FeHCur (log beta111 = 19.76 +/- 0.03), FeH2Cur+ (log beta112 = 28.11 +/- 0.02).
authors.affiliation: Departamento de Química, Area de Química, Analítica, Universidad Autónoma Metropolitana-Iztapalapa, San Rafel Altixco 186, Apdo Postal 55-534, C.P. 09340, México, D.F. México.
authors.forename: Marganta
authors.initials: M
authors.lastname: Bernabé-Pineda
authors.forename: Maria Teresa
authors.initials: MT
authors.lastname: Ramírez-Silva
authors.forename: Mario Alberto
authors.initials: MA
authors.lastname: Romero-Romo
authors.forename: Enrique
authors.initials: E
authors.lastname: González-Vergara
authors.forename: Alberto
authors.initials: A
authors.lastname: Rojas-Hernández
mesh_terms: D000465:Algorithms; D003474:Curcumin / Q000737:chemistry*; D004563:Electrochemistry / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D007477:Ions; D007501:Iron / Q000737:chemistry*; D008956:Models, Chemical; D012984:Software; D013053:Spectrophotometry / Q000379:methods*; D014466:Ultraviolet Rays; D014867:Water / Q000737:chemistry*
chemical_list: D007477:Ions; D014867:Water; D007501:Iron; D003474:Curcumin