Valorization of Polysaccharides Obtained from Dark Tea: Preparation, Physicochemical, Antioxidant, and Hypoglycemic Properties

Abstract

The structure and hypoglycemic activity of tea polysaccharides has been extensively studied, while there are few reports on the characterization and hypoglycemic activity of dark tea polysaccharides. The crude dark tea polysaccharide (CDTPS) was optimally extracted from Fuzhuan dark tea. Six polysaccharide fractions (namely DTPS-1, DTPS-2, DTPS-3, DTPS-4, DTPS-5, and DTPS-6) were isolated from CDTPS, and their physicochemical, structural, and biological properties were compared and analyzed. The results revealed that the compositions, structural characteristics, and biological properties of the six DTPSs were different. Therein, DTPS-4 and DTPS-6 had looser morphology, faster solubility, and a more stable structure. Additionally, DTPS-4 had the optimum in vitro antioxidant capabilities, and DTPS-6 had the strongest in vitro hypoglycemic capabilities. In addition, a correlation analysis revealed that the molecular weight and uronic acid content were significantly related to their antioxidant and hypoglycemic activities. Our results indicated that DTPS-4 and DTPS-6 could be further developed into functional foods or additives, respectively.

Valorization of Polysaccharides From Benincasa hispida: Physicochemical, Moisturizing, and Antioxidant Skincare Properties

“…The chemical composition of the obtained fraction was analyzed (Table 1). Our results show that the prepared BPS (the BPS mentioned below is a purified sample) contained 94.41% total sugar and 3.66% water-soluble protein, indicating that some binding proteins in BPS may still exist even after the separation and removal of impurities (Zhu et al, 2021b). In addition, 23.42% uronic acid was found in BPS but no polyphenol was detected, which indicates that BPS may be an acidic polysaccharide.…”

“…Further monosaccharide composition analysis (Figure 1B) reveals that BPS was composed of four monosaccharides, including arabinose, galactose, glucose, and GalA, with a molar ratio of 9.19:12.11:10.46:10.19. A series of characteristic absorption peaks (3425.95, 2938.04, 1735.63, 1632.46, 1428.04, and 1086.74 cm −1 ) in the FT-IR analysis (Figure 1C) confirm that BPS was an acidic polysaccharide with a small amount of bound protein (Zhu et al, 2019;Zhu et al, 2020a;Zhu et al, 2021b). In addition, SEM analysis reveals that BPS showed a fragmented and loose morphology presented by yellow arrow (Figure 1D).…”

“…The in vitro antioxidant assays, including DPPH, ABTS, hydroxyl radical (OH), superoxide anion (SOA) radical scavenging assays, were conducted based on the procedure reported by Zhu et al (Zhu, et al, 2021b), and vitamin C (Vc) was applied for the positive control.…”

“…Natural plant polysaccharides are considered superior functional ingredients and exhibit a variety of excellent bioactivities (Chen et al, 2018;Zhu et al, 2021b), and skincare is one of them. For example, Marva nut polysaccharide has superior moisturizing performance, and the developed skin moisturizing gel containing Marva nut polysaccharide shows improved performance over benchmark tamarind and algae polysaccharide gels (Kanlayavattanakul et al, 2017).…”

“…For example, Marva nut polysaccharide has superior moisturizing performance, and the developed skin moisturizing gel containing Marva nut polysaccharide shows improved performance over benchmark tamarind and algae polysaccharide gels (Kanlayavattanakul et al, 2017). Likewise, another study indicated that tea polysaccharides could effectively scavenge various free radicals (Zhu et al, 2021b). Additionally, polysaccharides from Laminaria japonica exhibit excellent anti-melanogenesis capability (Chen et al, 2019).…”