Effects of epigallocatechin-3-gallate combined with ascorbic acid and glycerol on the stability and uric acid-lowering activity of epigallocatechin-3-gallate

Abstract

Context: Epigallocatechin-3-gallate (EGCG) is unstable and easily oxidized, which limits its applications. Ascorbic acid (Vc) is a natural antioxidant. Objective: The effects of EGCG combined with Vc and glycerol on stability and uric acid-lowering activity of EGCG were examined. Materials and methods: EGCG (aqueous solution), EGCG þ Vc (aqueous solution), EGCG (glycerol solution) and EGCG þ Vc (glycerol solution) were prepared and incubated under different conditions in vitro. The recovery rate of EGCG was calculated by HPLC. Kunming mice were randomly divided into normal control group, model group, allopurinol (5 mg/kg), EGCG (10 mg/kg), EGCG þ Vc (both 10 mg/kg), EGCG (10 mg/kg) þ glycerol (60%), and EGCG (10 mg/kg) þ Vc (10 mg/kg) þ glycerol (60%) (n ¼ 6). Allopurinol was injected intraperitoneally to mice, others were administered intragastrically to (2 cases) mice. All mice were continuously administrated for 7 days, once a day. Results: EGCG recovery rates of EGCG group and EGCG þ Vc þ glycerol group respectively reached to 32.34 ± 1.86% and 98.90 ± 0.64% when they were incubated for 4 h at 80 C. EGCG recovery rates reached to 91.82 ± 5.13% (incubated for 6 h at pH 8) and 88.85 ± 2.63% (incubated for 4 h in simulated intestinal fluid) when EGCG incubated with Vc and glycerol. Compared with the model group, UA values of EGCG þ Vc þ glycerol group reduced by 43.49% while EGCG group reduced by 25.63%. The activities of xanthine oxidase (XOD, 31.41 U/gprot) and adenosine deaminase (ADA, 10.05 U/mgprot), and the mRNA expression levels of glucose transporter 9 (GLUT9, 1.03) and urate transporter 1 (URAT1, 0.44) in EGCG þ Vc þ glycerol group were notably lower than those of EGCG group (38.12 U/gprot, 13.16 U/ mgprot, 1.54, and 0.55). The mRNA expression levels of ATP-binding cassette superfamily G member 2 (ABCG2, 1.39) and organic anion transport 1/2 (OAT1/2, 2.34, 2.53) in EGCG þ Vc þ glycerol group were notably higher than those of EGCG group (0.57, 1.13, and 1.16). Discussion and conclusions: Our findings suggest that when EGCG used in combination with Vc and glycerol could effectively increase its biology activities and can be generalized to the broader pharmacological studies. This sheds light on the development and application of EGCG in the fields of food and medicine.

Integrated Metabolomic and Transcriptomic Analysis Reveals Differential Flavonoid Accumulation and Its Underlying Mechanism in Fruits of Distinct Canarium album Cultivars

“…Moreover, KEGG pathway enrichment analysis of DEGs identified between ‘Changying’ and ‘Huiyuan’ also revealed the significant enrichment of flavonoid biosynthesis pathway, confirming that the flavonoid accumulations in different C. album fruits varied considerably. Among the flavonoids, apigenin has been reported to have the ability to protect the liver and inhibit tumor cells [ 52 ], leucopelargonidin can alleviate diabetes [ 53 ], quercetin can resist oxidation and inflammation [ 54 ], (−)-epigallocatechin can reduce uric acid activity [ 55 ], aromadendrin can inhibit T cell activity [ 56 ], myricetin can resist oxidation and protect nerves and (2s)-liquiritigenin can inhibit tumors [ 57 , 58 ]. Since these active components were specifically enriched, they were inferred to be closely linked to the pharmacological properties of C. album fruits.…”

Development of Epigallocatechin and Ascorbic Acid Dual Delivery Transferosomes for Managing Alzheimer’s Disease: In Vitro and in Vivo Studies

“…13 AA, on the other hand, can enhance the clearance of beta-amyloid from the brain and increase the bioavailability of EGCG by stabilizing its molecular structure. 14 This could be a possible reason for the synergistic inhibition activity of EGCG-AA-TRANS.…”

“…13 AA, on the other hand, can enhance the clearance of beta-amyloid from the brain and increase the bioavailability of EGCG by stabilizing its molecular structure. 14 Nanomedicines have great potential as topical drug delivery carriers. Transferosomes, a unique type of vesicle, consist of concentric layers of phosphatidylcholine, cholesterol, and an edge activator with an aqueous or ethanolic core.…”

Mechanism of flavonoids inhibiting xanthine oxidase and alleviating hyperuricemia from structure–activity relationship and animal experiments: A review

“…Moreover, it significantly inhibited the activity of XO in the serum and liver and decreased the level of blood uric acid in hyperuricemic rats (Li et al., 2020). Vitamin C improved the bioavailability of EGCG, and the ability of EGCG to inhibit uric acid in hyperuricemic mice was increased from 25.63% to 43.29% due to the synergism of EGCG and vitamin C (Xie et al., 2021). Moreover, EGCG reduced the expression of cellular inflammatory factors, such as NF‐κB and monocyte chemotactic protein‐1, alleviated the dysfunction of human umbilical vein endothelial cells, and restored the activity of endothelial cells damaged by HUA (Xie et al., 2019).…”