title: Binding of caffeine with caffeic acid and chlorogenic acid using fluorescence quenching, UV/vis and FTIR spectroscopic techniques.
abstract: The interactions of caffeine (CF) with chlorogenic acid (CGA) and caffeic acid (CFA) were investigated by fluorescence quenching, UV/vis and Fourier transform infrared (FTIR) spectroscopic techniques. The results of the study indicated that the fluorescence quenching between caffeine and hydroxycinnamic acids could be rationalized in terms of static quenching or the formation of non-fluorescent CF-CFA and CF-CGA complexes. From fluorescence quenching spectral analysis, the quenching constant (KSV), quenching rate constant (kq), number of binding sites (n), thermodynamic properties and conformational changes of the interaction were determined. The quenching constants (KSV) between CF and CGA, CFA are 1.84 × 10(4) and 1.04 × 10(4) L/mol at 298 K and their binding site n is ~ 1. Thermodynamic parameters determined using the Van't Hoff equation indicated that hydrogen bonds and van der Waal's forces have a major role in the reaction of caffeine with caffeic acid and chlorogenic acid. The 3D fluorescence, UV/vis and FTIR spectra also showed that the binding of CF with CFA and CGA induces conformational changes in CFA and CGA.
authors.affiliation: Department of Nanomaterial Engineering and Nanoconvergence Technology, Pusan National University, Miryang, 627-706, Korea.|Department of Physics, School of Natural Sciences, Adama Science and Technology University, P.O.Box 1888, Adama, Ethiopia.
authors.forename: Abebe
authors.initials: A
authors.lastname: Belay
authors.affiliation: Department of Nanomaterial Engineering and Nanoconvergence Technology, Pusan National University, Miryang, 627-706, Korea.
authors.forename: Hyung Kook
authors.initials: HK
authors.lastname: Kim
authors.affiliation: Department of Nanomaterial Engineering and Nanoconvergence Technology, Pusan National University, Miryang, 627-706, Korea.
authors.forename: Yoon-Hwae
authors.initials: YH
authors.lastname: Hwang
mesh_terms: D001665:Binding Sites; D002109:Caffeic Acids / Q000737:chemistry*; D002110:Caffeine / Q000737:chemistry*; D002726:Chlorogenic Acid / Q000737:chemistry*; D005453:Fluorescence; D013056:Spectrophotometry, Ultraviolet; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D002109:Caffeic Acids; D002726:Chlorogenic Acid; D002110:Caffeine; C040048:caffeic acid
keywords: FTIR; binding constant; caffeine; fluorescence quenching; hydroxycinnamic acids