Investigation of alumina/(+)-catechin system properties. Part I: a study of the system by FTIR-UV–Vis spectroscopy

Abstract Catechin belongs to a group of flavonoids, which are present in many fruits and plants. Catechin is often employed in model investigations on antioxidant behavior of flavonoids. Recently also some anti-disease properties of flavonoids were reported. In this paper investigations were carried out on alumina/(+)-catechin solution system. FTIR spectra were taken for the catechin samples retaken from its aqueous solutions at pH 3, 5.5 (natural) and 10.5. In other series, the solutions were contacted with an alumina powder during 20 days. Also UV–Vis spectra were taken for similar solutions incubated for 1, 7, 20, 50 and 70 days with and without contact with alumina. It appeared that the alumina essentially accelerated the autooxidation processes occurring in the solutions. The results show that the processes have completed between day 20 and 50, because the UV–Vis spectra for day 50 and 70 overlapped. Moreover, it looks that this is a specific property of alumina, which behaves as a catalyst. Similar experiments with silica showed that during 50 days, this oxide affected the processes only slightly.