State Key Laboratory of Tea Plant Biology and Utilization, Anhui Agricultural University, Hefei, China.
International Joint Laboratory on Tea Chemistry and Health Effects of Ministry of Education, Hefei, China.
Pharm Biol. 2021 Dec;59(1):157-166. doi: 10.1080/13880209.2021.1878235.
Epigallocatechin-3-gallate (EGCG) is unstable and easily oxidized, which limits its applications. Ascorbic acid (Vc) is a natural antioxidant.
The effects of EGCG combined with Vc and glycerol on stability and uric acid-lowering activity of EGCG were examined.
EGCG (aqueous solution), EGCG + Vc (aqueous solution), EGCG (glycerol solution) and EGCG + Vc (glycerol solution) were prepared and incubated under different conditions . 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%) ( = 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.
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).
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.
表没食子儿茶素没食子酸酯（EGCG）不稳定且容易氧化，这限制了它的应用。抗坏血酸（Vc）是一种天然抗氧化剂。
研究 EGCG 与 Vc 和甘油结合对 EGCG 稳定性和降尿酸活性的影响。
制备 EGCG（水溶液）、EGCG+Vc（水溶液）、EGCG（甘油溶液）和 EGCG+Vc（甘油溶液），并在不同条件下孵育。通过 HPLC 计算 EGCG 的回收率。昆明小鼠随机分为正常对照组、模型组、别嘌醇（5mg/kg）、EGCG（10mg/kg）、EGCG+Vc（均 10mg/kg）、EGCG（10mg/kg）+甘油（60%）和 EGCG（10mg/kg）+Vc（10mg/kg）+甘油（60%）（n=6）。别嘌醇腹腔注射小鼠，其余小鼠灌胃（2 次）。所有小鼠连续给药 7d，每天 1 次。
EGCG 组和 EGCG+Vc+甘油组在 80℃孵育 4h 时，EGCG 的回收率分别达到 32.34±1.86%和 98.90±0.64%。当 EGCG 与 Vc 和甘油孵育时，EGCG 的回收率分别达到 91.82±5.13%（在 pH8 下孵育 6h）和 88.85±2.63%（在模拟肠液中孵育 4h）。与模型组相比，EGCG+Vc+甘油组尿酸值降低了 43.49%，而 EGCG 组降低了 25.63%。EGCG+Vc+甘油组黄嘌呤氧化酶（XOD，31.41U/gprot）和腺苷脱氨酶（ADA，10.05U/mgprot）的活性以及葡萄糖转运蛋白 9（GLUT9，1.03）和尿酸转运蛋白 1（URAT1，0.44）的 mRNA 表达水平均显著低于 EGCG 组（38.12U/gprot、13.16U/mgprot、1.54 和 0.55）。EGCG+Vc+甘油组的三磷酸腺苷结合盒超家族 G 成员 2（ABCG2，1.39）和有机阴离子转运蛋白 1/2（OAT1/2，2.34、2.53）的 mRNA 表达水平均显著高于 EGCG 组（0.57、1.13 和 1.16）。
我们的研究结果表明，当 EGCG 与 Vc 和甘油联合使用时，可以有效提高其生物学活性，这可以推广到更广泛的药理学研究中。这为 EGCG 在食品和医药领域的开发和应用提供了新的思路。
