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

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 + Vc (aqueous solution), EGCG (glycerol solution) and EGCG + 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 + Vc (both 10 mg/kg), EGCG (10 mg/kg) + glycerol (60%), and EGCG (10 mg/kg) + Vc (10 mg/kg) + glycerol (60%) (n = 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 + Vc + 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 + Vc + 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 + Vc + 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 + Vc + 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.

Preparation and characterization of epigallocatechin gallate, ascorbic acid, gelatin, chitosan nanoparticles and their beneficial effect on wound healing of diabetic mice.

The wounds of diabetic patients are difficult to heal, which could lead to a limb amputation or even death. The experiment aims to develop a new type of nanoparticles that could accelerate wound healing. Epigallocatechin gallate, ascorbic acid, gelatin and chitosan nanoparticles (EV NPS) were prepared by ion cross-linking method, and their properties were studied. The optimal formula ratio of EV NPS is Vc:EGCG:Gel:CS = 0.2:3:1:1. Transmission electron microscope (TEM) images show that it is a roughly uniform spherical nanoparticle with a diameter of 200 nm. ICR mice were intraperitoneally injected with streptozocin (STZ) to establish diabetic mice. Full-thickness excisional wounds were established on the back of mice. The results showed that EV NPS can promote wound healing in diabetic mice, and the mechanism may be through increasing collagen accumulation, promoting angiogenesis and reducing the infiltration of inflammatory cells. EV NPS may have potential application values for wound healing in diabetic mice.