Structural characterization and antioxidant activities of 2 water-soluble polysaccharide fractions purified from tea (Camellia sinensis) flower

Abstract: The water‐soluble crude polysaccharide tea flower polysaccharide (TFP), obtained from tea (Camellia sinensis) flower by boiling‐water extraction and ethanol precipitation, was fractionated by Sephadex G‐100 column chromatography, giving 2 polysaccharide fractions termed TFP‐1 and TFP‐2. The structural features of TFP‐1 and TFP‐2 were investigated by high‐performance liquid chromatography (HPLC), gel‐permeation chromatography (GPC), rheometer, infrared (IR) spectra, nuclear magnetic resonance (NMR) spectroscopy, atomic force microscope (AFM), and scanning electron microscope (SEM). Results indicated that TFP‐1 was composed of glucose: xylose: rhamnose: galactose = 1.0:1.2:0.81:0.98 with a molecular weight of 167.5 KDa, while TFP‐2 comprised glucose: xylose: rhamnose: arabinose = 1.0:0.76:2.3:2.3 with a molecular weight of 10.1 KDa. The ¹H NMR revealed that TFP‐1 contained α‐L‐Rhap, α‐D‐Galp, α‐D‐GalpNAc, α‐D‐Xylp, α‐D‐Glcp, and β‐D‐Glcp residues, while TFP‐2 was illustrated to have α‐L‐Rhap, α‐L‐Arap, α‐D‐Xylp, α‐D‐Glcp, and α‐D‐GlcpNAc residues. Antioxidant activities of these fractions were investigated using various in vitro assay systems compared with ascorbic acid. In conclusion, TFP‐2 exhibited the higher antioxidant activities and could be explored as a novel potential antioxidant. Practical Application: At present, commonly low‐grade tea is preferred to extract the tea polysaccharide, to take full advantage of tea flower resource to extract polysaccharides can greatly reduce the cost of tea products. Thus, the search for plant‐derived biomaterials from this study could generate natural value‐added products from underutilized tea plant waste and used as a medicinal agent against chronic health problems, such as cancers, aging, and atherosclerosis caused by reactive free radicals that produced from oxidation.