共查询到20条相似文献,搜索用时 78 毫秒
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为调控儿茶素氧化条件,以表没食子酸儿茶素没食子酸酯(EGCG)为代表,考察温度、反应体系pH、EGCG初始质量浓度、氧化剂与EGCG质量比对氧化反应速率的影响。对EGCG氧化产物进行了HPLC-MS分析,结果表明,EGCG体外氧化符合二级动力学反应特征。随温度的升高,EGCG反应速率加快,在0、25、40℃时的反应速率常数k分别为0.145 9、0.260 9、0.359 1 m in-1;EGCG反应速率在pH≥7.0时,随pH增高而加快,pH=7.0、8.0、9.0时的反应速率常数k分别为0.389 1、0.568 9、0.797 0 m in-1;EGCG初始质量浓度≥1.00 mg/mL时,反应速率随其增大而加快,ρ(EGCG)为1.00、2.00、3.00 mg/mL时的反应速率常数k分别为0.253 1、0.304 6、0.351 1 m in-1;随氧化剂所占质量比的增大,EGCG反应速率加快,m(氧化剂)∶m(EGCG)为1∶1、1.5∶1、2∶1时的反应速率常数k分别为0.145 9、0.229 9、0.480 7 m in-1。在40℃、pH=9.0、m(氧化剂)∶m(EGCG)=2∶1条件下氧化EGCG,氧化体系中w(EGCG)=14.05%。氧化产物的HPLC-MS分析结果表明,EGCG氧化产物Ⅰm/Z:911,产物Ⅱm/Z:929,产物Ⅲm/Z:911。产物Ⅰ、产物Ⅲ为EGCG脱氢二聚体;产物Ⅱ为EGCG邻醌二聚体。 相似文献
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高纯度表没食子儿茶素没食子酸酯(EGCG)的分离与制备 总被引:11,自引:0,他引:11
绿茶的乙醇浸提液经过浓缩、脱色和萃取,得到茶多酚粗品。用葡聚糖凝胶LH-20层析柱和制备型HPLC分离提纯儿茶素组分EGCG,结构鉴定结果证明所获得的EGCG其纯品达到色谱纯级。 相似文献
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利用寡聚环糊精配基键合介质分离表没食子儿茶素没食子酸酯的新方法 总被引:1,自引:1,他引:0
研究了利用寡聚环糊精配基键合的高效凝胶介质分离纯化茶多酚中的表没食子儿茶素没食子酸酯的新方法。考察了不同种类的流动相对分离效果的影响。最终确定采用水/乙醇/乙腈为57/30/13(体积比)进行等梯度洗脱,一次色谱分离的收率和纯度分别为73%、98%,介质经过0.5mol/L的NaOH-水-30%乙酸简单再生后即可重复利用。 相似文献
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《中国生物制品学杂志》2014,(6)
目的探讨酯化型表没食子儿茶素没食子酸酯(epigallocatechin gallate,EGCG)对人乳腺癌细胞株MCF-7(Myc依赖性)和MDA-MB-231(Myc非依赖性)凋亡的影响。方法采用脂肪酶催化法对EGCG进行酯化修饰,2次硅胶柱层析纯化后,通过高效液相色谱-质谱(HPLC-MS)进行鉴定,并分析纯化的酯化型EGCG的稳定性。流式细胞术检测纯化的酯化型EGCG对MCF-7和MDA-MB-231细胞凋亡的影响。结果经酶法修饰并纯化后获得了EGCG单棕榈酸酯(EGCG-C16),HPLC中不同保留时间的酯化产物的相对分子质量一致,均为696;EGCG在普通培养基里产生的H2O2量远高于其在酸性培养基里及EGCG-C16在普通培养基里产生的H2O2量(P0.000 1),表明EGCG-C16的稳定性较EGCG好;EGCG-C16对MCF-7细胞具有明确的促进凋亡效应,而对MDA-MB-231细胞则无此效应。结论酯化型EGCG对Myc依赖性乳腺癌细胞具有特异性的促进凋亡效应,为进一步深入研究EGCG的抗肿瘤效应奠定了基础。 相似文献
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没食子单宁是一种天然的没食子酰酯,由没食子酰基与糖(或多元醇、酚)以酯键结合,主要存在于中国五倍子、土耳其倍子、漆叶、南美塔拉等自然界植物体内。五倍子单宁的化学结构是1个β-D-葡萄糖核上结合5~12个没食子酰基;土耳其倍子单宁分子中的葡萄糖的6个碳原子上,有1个羟基未被酯化;漆叶单宁具有与五倍子单宁基本相同的化学结构,每个分子含8~9个没食子酰基;塔拉单宁是没食子酰基与D-奎尼酸酯化而产生。 相似文献
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Elena Ferrari Saverio Bettuzzi Valeria Naponelli 《International journal of molecular sciences》2022,23(11)
Autophagy is an evolutionarily conserved process for the degradation of redundant or damaged cellular material by means of a lysosome-dependent mechanism, contributing to cell homeostasis and survival. Autophagy plays a multifaceted and context-dependent role in cancer initiation, maintenance, and progression; it has a tumor suppressive role in the absence of disease and is upregulated in cancer cells to meet their elevated metabolic demands. Autophagy represents a promising but challenging target in cancer treatment. Green tea is a widely used beverage with healthy effects on several diseases, including cancer. The bioactive compounds of green tea are mainly catechins, and epigallocatechin-gallate (EGCG) is the most abundant and biologically active among them. In this review, evidence of autophagy modulation and anti-cancer effects induced by EGCG treatment in experimental cancer models is presented. Reviewed articles reveal that EGCG promotes cytotoxic autophagy often through the inactivation of PI3K/Akt/mTOR pathway, resulting in apoptosis induction. EGCG pro-oxidant activity has been postulated to be responsible for its anti-cancer effects. In combination therapy with a chemotherapy drug, EGCG inhibits cell growth and the drug-induced pro-survival autophagy. The selected studies rightly claim EGCG as a valuable agent in cancer chemoprevention. 相似文献
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Yingjie Luo Yiwei Zhang Cimin Tao Hongfei Ni Xuesong Liu Yong Chen Yongjiang Wu Hang Song Tengfei Xu 《International journal of molecular sciences》2022,23(20)
Imidazolium-based ionic liquids are wildly used in natural product adsorption and purification. In this work, one typical polymeric ionic liquid (PIL) was synthesized by using L-proline as the anion, which exhibited excellent adsorption capacity toward tea polyphenol epigallocatechin gallate (EGCG). The adsorption conditions were optimized with the response surface method (RSM). Under the optimum conditions, the adsorption capacity of the PIL for EGCG can reach as high as 552 mg/g. Dynamics and isothermal research shows that the adsorption process of EGCG by the PIL particularly meets the quasi-second-order kinetic equation and monolayer adsorption mechanism. According to thermodynamic parameter analysis, the adsorption process is endothermic and spontaneous. The results of theoretical calculation by molecular docking also demonstrated the interaction mechanisms between EGCG and the ionic liquid. Considering the wide application of imidazolium-based ionic liquids in component adsorption and purification, the present study can not only be extended to other similar experimental mechanism validation, but also be representative for guiding the synthesis of PIL and optimization of adsorption conditions. 相似文献
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Ki Hyun Bae Fritz Lai Betul Oruc Motomi Osato Qingfeng Chen Motoichi Kurisawa 《International journal of molecular sciences》2023,24(1)
Chemoresistance is one of the major challenges for the treatment of acute myeloid leukemia. Epigallocatechin gallate (EGCG), a bioactive polyphenol from green tea, has attracted immense interest as a potential chemosensitizer, but its application is limited due to the need for effective formulations capable of co-delivering EGCG and anti-leukemic drugs. Herein, we describe the formation and characterization of a micellar nanocomplex self-assembled from EGCG and daunorubicin, an anthracycline drug for the first-line treatment of acute myeloid leukemia. This nanocomplex was highly stable at pH 7.4 but stimulated to release the incorporated daunorubicin at pH 5.5, mimicking an acidic endosomal environment. More importantly, the nanocomplex exhibited superior cytotoxic efficacy against multidrug-resistant human leukemia cells over free daunorubicin by achieving a strong synergism, as supported by median-effect plot analysis. The observed chemosensitizing effect was in association with enhanced nucleus accumulation of daunorubicin, elevation of intracellular reactive oxygen species and caspase-mediated apoptosis induction. Our study presents a promising strategy for circumventing chemoresistance for more effective leukemia therapy. 相似文献
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Andy C. Huang Ta-Chuan Yeh Nien-Chin Wu Chien-Yu Yeh Pei-Hua Lin Kuei-Ying Yeh 《International journal of molecular sciences》2022,23(17)
Sexual dysfunction is a common problem for men with diabetes. Epigallocatechin gallate (EGCG) is known to ameliorate erectile function in aging rats. However, there has not yet been a report to evaluate its effects on diabetic male rat sexual behavior in the literature. In this study, we investigated the effects of EGCG on male sexual behavior in diabetic rats. Diabetic rats were induced by a single intraperitoneal injection of 65 mg/kg of streptozotocin. After streptozotocin injection for one week, animals were then orally treated with 40 mg/kg of EGCG or vehicle. Copulatory behavior and fasting blood glucose levels were recorded before treatment, as well as 7 and 14 days after treatment. Serum LH, testosterone, and PDE5a levels were measured by EIA assay after the last behavioral test. Data showed that diabetic rats who had diminished sexual functions demonstrated significantly increased latencies in mount, intromission, and ejaculation, as well as significant decreases in frequencies of intromission and ejaculation, compared to non-diabetic controls, indicating sexual function recovery. Lower blood glucose levels were also found in diabetic rats after EGCG treatment. Additionally, the lower LH and higher PDE5a levels in diabetic rats than controls were also noted. The findings declared that EGCG had a protective effect on male sexual behavior in diabetic rats. 相似文献
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Laura Almeida-Toledano Vicente Andreu-Fernndez Rosa Aras-Lpez
scar García-Algar Leopoldo Martínez María Dolores Gmez-Roig 《International journal of molecular sciences》2021,22(2)
Fetal alcohol spectrum disorder is the main preventable cause of intellectual disability in the Western world. Although binge drinking is the most studied prenatal alcohol exposure pattern, other types of exposure, such as the Mediterranean, are common in specific geographic areas. In this study, we analyze the effects of prenatal alcohol exposure in binge and Mediterranean human drinking patterns on placenta and brain development in C57BL/6J mice. We also assess the impact of prenatal treatment with the epigallocatechin-3-gallate antioxidant in both groups. Study experimental groups for Mediterranean or binge patterns: (1) control; (2) ethanol; (3) ethanol + epigallocatechin-3-gallate. Brain and placental tissue were collected on gestational Day 19. The molecular pathways studied were fetal and placental growth, placental angiogenesis (VEGF-A, PLGF, VEGF-R), oxidative stress (Nrf2), and neurodevelopmental processes including maturation (NeuN, DCX), differentiation (GFAP) and neural plasticity (BDNF). Prenatal alcohol exposure resulted in fetal growth restriction and produced imbalances of placental angiogenic factors. Moreover, prenatal alcohol exposure increased oxidative stress and caused significant alterations in neuronal maturation and astrocyte differentiation. Epigallocatechin-3-gallate therapy ameliorated fetal growth restriction, attenuated alcohol-induced changes in placental angiogenic factors, and partially rescued neuronal nuclear antigen (NeuN), (doublecortin) DCX, and (glial fibrillary acidic protein) GFAP levels. Any alcohol consumption (Mediterranean or binge) during pregnancy may generate a fetal alcohol spectrum disorder phenotype and the consequences may be partially attenuated by a prenatal treatment with epigallocatechin-3-gallate. 相似文献
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用可再生资源微晶纤维素为原料,在催化剂的作用下,与含抗氧化基团的没食子酸作用,合成一种新型没食子酸酯。考察了对甲苯磺酸、十二烷基苯磺酸、磷钨酸三种催化剂对产物的影响,以酯化度为考察目标,对合成时间、温度、催化剂用量、没食子酸和微晶纤维素用量比等因素进行考察,确定最佳合成条件为:没食子酸和微晶纤维素的反应物配比(GA∶MCC)为4∶1时,以磷钨酸为催化剂,催化剂用量为相对于没食子酸质量的10%,在温度120℃下,反应10 h,没食子酸微晶纤维素酯的酯化度最高。通过红外检测,合成产物红外谱图中1680 cm-1处有酯中C=O伸缩振动吸收峰,证明没食子酸与微晶纤维素不是机械混合而是化学合成。 相似文献
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研究探讨二-(叔丁过氧化异丙基)苯(BIPB)规模化生产的氧化工艺条件。二-(叔丁过氧化异丙基)苯是一种性能优良的二烷基有机过氧化交联剂,具有高效率交联性能。通过优化二异丙苯氧化反应温度、空气流量、反应压力和反应深度等工艺参数,控制氧化反应速度,确立最佳反应条件为:反应温度85~105℃;压力控制范围0.20~0.35 MPa;反应时间20~24 h;氧化空气流量140 L/h。 相似文献
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In this review, we highlight the effects of epigallocatechin gallate (EGCG) against toxicities induced by heavy metals (HMs). This most active green tea polyphenol was demonstrated to reduce HM toxicity in such cells and tissues as testis, liver, kidney, and neural cells. Several protective mechanisms that seem to play a pivotal role in EGCG-induced effects, including reactive oxygen species scavenging, HM chelation, activation of nuclear factor erythroid 2-related factor 2 (Nrf2), anti-inflammatory effects, and protection of mitochondria, are described. However, some studies, especially in vitro experiments, reported potentiation of harmful HM actions in the presence of EGCG. The adverse impact of EGCG on HM toxicity may be explained by such events as autooxidation of EGCG, EGCG-mediated iron (Fe3+) reduction, depletion of intracellular glutathione (GSH) levels, and disruption of mitochondrial functions. Furthermore, challenges hampering the potential EGCG application related to its low bioavailability and proper dosing are also discussed. Overall, in this review, we point out insights into mechanisms that might account for both the beneficial and adverse effects of EGCG in HM poisoning, which may have a bearing on the design of new therapeutics for HM intoxication therapy. 相似文献