Antioxidant Activity and α-Glucosidase Inhibitory Activities of the Polycondensate of Catechin with Glyoxylic Acid

Abstract

In order to investigate polymeric flavonoids, the polycondensate of catechin with glyoxylic acid (PCG) was prepared and its chemically antioxidant, cellular antioxidant (CAA) and α-glucosidase inhibitory activities were evaluated. The DPPH and ABTS radical scavenging activities and antiproliferative effect of PCG were lower than those of catechin, while PCG had higher CAA activity than catechin. In addition, PCG had very high α-glucosidase inhibitory activities (IC50 value, 2.59 μg/mL) in comparison to catechin (IC50 value, 239.27 μg/mL). Inhibition kinetics suggested that both PCG and catechin demonstrated a mixture of noncompetitive and anticompetitive inhibition. The enhanced CAA and α-glucosidase inhibitor activities of PCG could be due to catechin polymerization enhancing the binding capacity to the cellular membrane and enzymes.

Antioxidant and α-amylase inhibitory activities of tannic acid

“…And in this protocol, the antioxidant activity of tannic acid (EC 50 , 13.19 ± 0.82 lg/mL; CAA, 101,734.35 ± 6099.02 lg/ mL) was higher than that of gallic aicd (EC 50 , 65.83 ± 4.32 lg/mL; CAA, 20,387.27 ± 1296.28 lg/ mL), which suggest that compared with gallic acid, tannic acid as the polymer of gallic aicd had the higher intracellular antioxidant activity. In our previous study, we also found the cellular antioxidant activity the polymer of catechin and glyoxylic acid in was higher than that of catechin in the ''PBS wash'' protocol (Geng et al 2016), which coincided with the result in this study. This phenomenon could be explained by the improvement of binding capacity of cell membrane, which was caused by the polymerization.…”

High‐theabrownins instant dark tea product by Aspergillus niger via submerged fermentation: α‐glucosidase and pancreatic lipase inhibition and antioxidant activity

“…The α ‐glucosidase inhibition assay was performed as described by Geng et al . An aliquot of the sample (0.3 mL at 0.1 mg mL −1 ) and 1 mL of 0.1 mol L −1 phopshate‐buffered saline (PBS) (pH 6.9) containing α ‐glucosidase solution (0.2 U mL −1 ) were mixed and pre‐heated at 37 °C for 10 min.…”

“…The -glucosidase inhibition assay was performed as described by Geng et al 20 An aliquot of the sample (0.3 mL at 0.1 mg mL −1 ) and 1 mL of 0.1 mol L −1 phopshate-buffered saline (PBS) (pH 6.9) containing -glucosidase solution (0.2 U mL −1 ) were mixed and pre-heated at 37 ∘ C for 10 min. Then, 1 mL of 1 mmol L −1 pNP-G in 0.1 mol L −1 PBS (pH 6.9) was added and incubated in a water bath for 20 min at 37 ∘ C. The reaction was terminated with 1 mL of anhydrous methanol.…”

A polyphenolic biomacromolecule prepared from a flavonoid: Catechin as degradable microparticles

“…Compounds naturally possessing antioxidant, 32 antiinflammatory, anticancer, 33 antimicrobial, and antifibrotic properties, such as, CAT, attract a great deal of interest for biomedical use. 7,34 To improve biocompatibility and bioactivity of CAT, 2 different natural polymers, such as, inulin, 16 dextran, 35 and hyaluronic acid 36 were widely investigated for grafting CAT or conjugation onto natural polymers or their derivatives.…”