Studies on the Interaction between Catechin and Metal Ions

In conclusion, the UV-vis absorption spectra of the deaerated methanolic solution reacted with metal ions such as Cu2+, Zn2+, Co2+, and Fe3+ were changed as time passed after adding catechin followed by addition of catechin to methanol. This is strongly dependent not only on the presence of metal ion but on the storage time of the solution. The change has relevance to the oxidation of catechin. Oxidation of catechin is first initiated by the dissociation of -OH part of the catechol moiety in methanol and then the ionized anion forms are converted into their oxidized forms called quinones. The higher the standard reduction potential for metal-ion, the faster the oxidation occurs. The steady-state fluorescence emission spectra of catechin changed depending on the storage time of the solution. This finding indicates that oxidation of catechin is undergone by a sequence of multistep reactions in deaerated methanol solution