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

Abstract

Tea polysaccharides was one of the active ingredients of Qingzhuan dark tea, which had antioxidant, anti-tumor, and immuneenhancing 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.

Egg yolk peptide‐iron chelate: preparation, conformational structure, chelating mechanism and stability in vitro

“…The concentration of the non‐chelated Fe 2+ in the supernatant in Preparation of egg yolk peptides‐Fe (EYP‐Fe) complexes was measured according to Hou et al ., (2009). Briefly, two drops of phenanthroline were added to 4 mL supernatant and reacted for 10 min.…”

Analyzing and comparising capacity of glucose- and uric acid-lowering effects of yellow tea with different varieties and grades in zebrafish model

“…And the possible regulatory pathways of tea on glucolipid metabolism were as follows: inhibiting lipid absorption by forming complex with lipids and lipases (Xu et al, 2020), reducing glucose digestion and absorption by inhibiting amylase activity (Sun et al, 2017), inhibiting gluconeogenesis (Collins et al, 2007), enhancing glucose consumption and utilization (Lin & Lin, 2008) etc. Of course, researchers suggested that tea polyphenols (TPs) (Macena et al, 2022;Tan et al, 2022), caffeine (CAF), tea polysaccharide (Zhou et al, 2022a(Zhou et al, , 2023Kim et al, 2022), and other functional ingredients (Rubanka et al, 2020;Wang et al, 2023) contained in tea play a key role in lowering blood glucose levels. In addition, studies suggested that TPs (Zhou et al, 2022b), tea pigment (Liu et al, 2020) and other functional components contained in tea also play an important role in lowering uric acid levels.…”