Preparation, characterization and antioxidant activity of polysaccharides copper from Qingzhuan dark tea

Tea polysaccharides was one of the active ingredients of Qingzhuan dark tea, which had antioxidant, anti-tumor, and immune-enhancing effects. The complexation of metal ions of tea polysaccharides was one of the current research hotspots. It can combine the advantages of tea polysaccharides and their complexed trace metal elements, and had great potential development. In this study, the trace element-copper required by the human body was used for complexation with Qingzhuan dark tea polysaccharides, and the structure was characterized by various chemical methods. The copper complexes of Qingzhuan dark tea polysaccharides were characterized by UV spectroscopy, FT-IR, thermogravimetric analysis, X-ray diffraction (XRD), SEM, AFM and X-ray photoelectron spectroscopy (XPS). The tests results show that it was successfully complexed with tea polysaccharides. Meanwhile, the Qingzhuan dark tea polysaccharides copper complex compound (termed TPS-Cu) showed higher scavenging activity of hydroxyl radical and ABTS free radical than the tea polysaccharides (termed TPS). Therefore, TPS-Cu can be used as a potentially effective and stable copper supplement and preventive agent.