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茶叶功能成分有哪些健康作用 聚酯型儿茶素类 氧化多聚体

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Issuing time:2022-04-15 14:02

一、儿茶素衍生物的健康功能研究进展



相关研究主要聚焦在聚酯型儿茶素、儿茶素氧化多聚体(线粒体激活因子)、甲基化儿茶素、儿茶素与茶氨酸的缩合产物的健康作用等方面。


1


聚酯型儿茶素类



聚酯型儿茶素 (Theasinensins,TSs) 是茶叶鲜叶中的儿茶素类组分在发酵过程中氧化聚合生成的一类儿茶素二聚体,虽然 TSs 中儿茶素结构的聚合形式与茶黄素类(TFs)有所不同,但针对其健康功能方面的研究表明,TSs 在抗氧化、抗菌、抗病毒、抗癌、降脂减肥等方面均表现出与TFs相似的功能[36]。同时,有研究发现TSs对α-葡萄糖苷酶的活性有显著的抑制作用,表明 TSs 可能会在一定程度上影响机体的糖类代谢从而达到降低血糖的功效。



除了这些研究较多的功能之外,另有研究表明 TSs 可以通过抑制肝星状细胞的激活减少肝脏的纤维化,从而缓解四氯化碳诱导的小鼠肝损伤,起到保护肝脏的作用。另有研究表明,TSs可在减少细胞中黑色素生成的同时抑制色素沉淀,这类功能的发现使TSs与TFs一样可作为天然的添加剂用于开发新型护肤品。目前,新冠肺炎疫情备受关注,最新体外实验研究表明,TSs 对SARS-CoV-2 病毒有明显的抑制效果,因此,经常饮用含有 TSs 的发酵茶类可能对预防新冠肺炎有帮助。


2


儿茶素氧化多聚体 (线粒体激活因子)



2007年,Kikuchi等从发酵茶类 (红茶等) 中分离出了一类多酚物质,因其可以提高线粒体膜电位而将其命名为线粒体激活因子(Mitochondrial activation factors,MAFs)。后续研究表明,MAFs也是一类儿茶素氧化聚合产物,可能由茶黄素或聚酯型儿茶素进一步氧化聚合生成。MAFs是首个被报道的可以激活细胞线粒体呼吸的化合物,因此,其与能量代谢相关的功能备受研究人员关注。进一步的体内实验表明,MAFs可以根据参与运动的种类不同表达不同的功能,对小鼠骨骼肌能量代谢产生不同的影响。研究人员发现,MAFs的摄入与耐力训练相结合可以提高小鼠耐力训练的效果,增强小鼠骨骼肌的运动耐力。另一项研究表明,摄入富含MAFs的红茶提取物的小鼠在抗阻力训练中的训练效果也有所增加,相同的肌肉负荷下,MAFs可以促进小鼠肌肉组织的增大,达到更好的增肌效果。最近的一项相关研究发现,MAFs虽然无法防止废用(如长期卧床、失重等) 引起的肌肉萎缩,但可以辅助这类肌肉萎缩症状的恢复,在一定程度上增加肌肉质量,缓解肌肉萎缩。这些研究都表明,MAFs 的膳食干预有着辅助增加骨骼肌质量的功能,因此,这类物质或许可以通过开发新型功能产品来辅助提高运动效果或者缓解肌肉萎缩,但在此之前仍需要进一步的研究来阐明其作用的具体机制。


3


甲基化儿茶素类



甲基化儿茶素是一类儿茶素类化合物,主要有EGCG3"Me、EGCG"Me、ECG3"Me、ECG4"Me 等。前期的临床和细胞试验均表明,甲基化儿茶素可有效提高儿茶素的稳定性和生物利用率,具有比母本化合物更强的生物活性。



甲基化儿茶素生物活性主要包括抗过敏、抗氧化、抗炎、降脂减肥、降血压及预防心血管疾病等。根据体内外实验研究证明,甲基化儿茶素抗过敏效果显著,其作用机制主要包括 3 个方面:(1) 阻隔产生过敏反应的主要受体免疫球蛋白E (IgE);(2) 抑制IgE受体FcεRI的表达,从而抑制嗜碱细胞释放组织胺,与抗过敏药物药效相同,EGCG3"Me在各种儿茶素及衍生物中抗过敏作用最好;(3) 抑制多种肥大细胞蛋白激酶的活性。



此外,研究表明EGCG3"Me具有显著的调节代谢作用。一方面,通过增加有益微生物种群和影响氨基酸生物合成、双组分系统和ABC转运蛋白等代谢途径,对肠道微生态产生良好的影响,维护宿主健康的同时改善高脂饮食所致的肠道菌群失调;另一方面,EGCG3"Me对体外胰腺α淀粉酶活性、前脂肪细胞的增殖和分化具有抑制作用,可减少脂肪生成和脂质沉积。该研究还证明,EGCG3"Me 的抗肥胖活性优于 EGCG,显示出较低的细胞毒性。EGCG3"Me 对血管紧张素转换酶 (ACE) 活性有较强的抑制作用,且吸收率高,在血液中稳定性好,有助于预防高血压。EGCG3"Me 在老鼠肿瘤细胞中具有强抗氧化性和抗细胞毒素能力,且这种能力约为 EGCG 的1.5倍。赵新等的研究也证实,甲基化EGCG可能通过下调 Cyclin E、Bcl-2、Bcl-xL 的表达,使胃癌 SGC 7901 细胞的增殖和凋亡之间达到平衡,从而发挥抗肿瘤作用。


4


儿茶素与茶氨酸的缩合产物



茶叶中发现的N-乙基-2-吡咯烷酮取代的化合物成分是一类在儿茶素的C-8位或者C-6位进行N-乙基-2-吡咯烷酮取代的化合物,由茶叶中的儿茶素成分(EGCG、ECG、EGC、EC、C、GC等)与茶氨酸等游离氨基酸反应生成。



最早是在黑茶中发现了 8 种 EPSF 类化合物,其对过氧化氢诱导的人微血管内皮细胞损伤具有良好的保护作用,活性优于 EGCG 等儿茶素成分。之后在不同年份白茶中也发现了4 ~ 8种EPSF类成分。EPSF对乙酰胆碱酯酶和中性粒细胞明胶酶相关脂质运载蛋白有强抑制作用,可以改善阿尔茨海默症患者的胆碱功能,并缓解神经性紊乱症状,抑制细胞凋亡诱导血管生成。此外,在黄大茶中也发现了 11 种 EPSF 类的标志化合物,这些化合物在体外抑制α-葡萄糖苷酶和氧化损伤的形成。体内实验结构表明,EPSF对患有糖尿病的 ApoE(-/-)小鼠具有治疗作用,对早衰型SAMP8小鼠的神经退行性疾病具有显著抑制作用。在细胞实验中,EPSF通过抑制NF-кB信号通路活化发挥抗炎作用,对脂多糖诱导的RAW264.7巨噬细胞具有较强抗炎活性,活性优于EGCG和茶氨酸。

1. Research progress on the health function of catechin derivatives



Related research mainly focuses on the health effects of polyester catechins, catechin oxidized polymers (mitochondrial activators), methylated catechins, and condensation products of catechins and theanine.


1


Polyester catechins



Polyester catechins (Theasinensins, TSs) are a class of catechin dimers formed by oxidative polymerization of catechin components in fresh tea leaves during fermentation, although the aggregated form of catechin structure in TSs It is different from theaflavins (TFs), but studies on their health functions have shown that TSs have similar functions to TFs in terms of antioxidant, antibacterial, antiviral, anticancer, lipid-lowering and weight loss [36] ]. At the same time, some studies have found that TSs have a significant inhibitory effect on the activity of α-glucosidase, indicating that TSs may affect the body's carbohydrate metabolism to a certain extent to achieve the effect of lowering blood sugar.



In addition to these well-studied functions, other studies have shown that TSs can reduce liver fibrosis by inhibiting the activation of hepatic stellate cells, thereby alleviating carbon tetrachloride-induced liver injury in mice and protecting the liver. Another study has shown that TSs can inhibit pigmentation while reducing melanin production in cells. The discovery of such functions makes TSs, like TFs, as natural additives for the development of new skin care products. At present, the new coronary pneumonia epidemic has attracted much attention. The latest in vitro experimental studies have shown that TSs have a significant inhibitory effect on the SARS-CoV-2 virus. Therefore, regular consumption of fermented teas containing TSs may be helpful for the prevention of new coronary pneumonia.


2


Catechin oxidized polymer (mitochondrial activator)



In 2007, Kikuchi et al. isolated a class of polyphenols from fermented teas (black tea, etc.), and named them Mitochondrial activation factors (MAFs) because of their ability to increase mitochondrial membrane potential. Subsequent studies have shown that MAFs are also a class of catechin oxidative polymerization products, which may be further oxidatively polymerized by theaflavins or polyester catechins. MAFs are the first reported compounds that can activate mitochondrial respiration, so their functions related to energy metabolism have attracted much attention of researchers. Further in vivo experiments showed that MAFs can express different functions according to the type of exercise involved, and have different effects on the energy metabolism of mouse skeletal muscle. The researchers found that the intake of MAFs combined with endurance training can improve the effect of endurance training in mice and enhance the exercise endurance of skeletal muscles in mice. Another study showed that mice ingested black tea extract rich in MAFs also had an increased training effect during resistance training. Under the same muscle load, MAFs could promote the enlargement of muscle tissue in mice to achieve better muscle building effect. A recent related study found that although MAFs cannot prevent muscle atrophy caused by disuse (such as long-term bed rest, weightlessness, etc.), they can assist the recovery of such muscle atrophy symptoms, increase muscle mass to a certain extent, and relieve muscle atrophy. These studies have shown that dietary intervention of MAFs has the function of assisting in increasing skeletal muscle mass. Therefore, these substances may be able to help improve exercise performance or relieve muscle atrophy by developing new functional products, but further research is needed before this. Elucidation of the specific mechanism of its action.


3


methylated catechins



Methylated catechins are a class of catechin compounds, mainly including EGCG3"Me, EGCG"Me, ECG3"Me, ECG4"Me and so on. Preliminary clinical and cellular tests have shown that methylated catechins can effectively improve the stability and bioavailability of catechins, and have stronger biological activity than the parent compound.



The biological activities of methylated catechins mainly include anti-allergy, anti-oxidation, anti-inflammatory, lipid-lowering and weight-loss, lowering blood pressure and preventing cardiovascular diseases. According to experimental studies in vitro and in vivo, methylated catechins have significant anti-allergic effects, and their mechanism of action mainly includes three aspects: (1) Block immunoglobulin E (IgE), the main receptor for allergic reactions; (2) Inhibit The expression of IgE receptor FcεRI, thereby inhibiting the release of histamine from basophils, has the same efficacy as anti-allergic drugs, EGCG3"Me has the best anti-allergic effect among various catechins and derivatives; (3) Inhibits a variety of hypertrophy Activity of cellular protein kinases.



In addition, studies have shown that EGCG3"Me has a significant regulatory metabolic effect. On the one hand, it has a favorable impact on the gut microecology by increasing beneficial microbial populations and affecting metabolic pathways such as amino acid biosynthesis, two-component systems and ABC transporters, Maintain host health while improving gut dysbiosis induced by high-fat diet; on the other hand, EGCG3"Me has inhibitory effects on pancreatic α-amylase activity, proliferation and differentiation of preadipocytes in vitro, and reduces adipogenesis and lipogenesis. quality deposition. This study also demonstrated that EGCG3"Me has better anti-obesity activity than EGCG, showing lower cytotoxicity. EGCG3"Me has a strong inhibitory effect on angiotensin-converting enzyme (ACE) activity, and has a high absorption rate. Good stability in the blood helps prevent high blood pressure. EGCG3"Me has strong antioxidant and anti-cytotoxic ability in mouse tumor cells, and this ability is about 1.5 times that of EGCG. The study by Xin Zhao et al. also confirmed that methylated EGCG may reduce Cyclin E, Bcl- 2. The expression of Bcl-xL can balance the proliferation and apoptosis of gastric cancer SGC 7901 cells, thereby exerting anti-tumor effect.


4


Condensation product of catechin and theanine



The N-ethyl-2-pyrrolidone-substituted compounds found in tea are a class of compounds substituted with N-ethyl-2-pyrrolidone at the C-8 or C-6 positions of catechins. Catechin components (EGCG, ECG, EGC, EC, C, GC, etc.) react with free amino acids such as theanine.



Eight EPSF compounds were first discovered in black tea, which have a good protective effect on hydrogen peroxide-induced human microvascular endothelial cell damage, and their activity is better than EGCG and other catechins. Later, 4 to 8 EPSF components were also found in white tea of different years. EPSF has a strong inhibitory effect on acetylcholinesterase and neutrophil gelatinase-related lipocalin, which can improve choline function in patients with Alzheimer's disease, relieve symptoms of neurological disorders, and inhibit apoptosis-induced angiogenesis. In addition, 11 EPSF-class marker compounds were also found in Huang Da tea, which inhibited the formation of α-glucosidase and oxidative damage in vitro. The in vivo experimental structure shows that EPSF has a therapeutic effect on ApoE(-/-) mice with diabetes, and has a significant inhibitory effect on neurodegenerative diseases in progeria-type SAMP8 mice. In cell experiments, EPSF exerted an anti-inflammatory effect by inhibiting the activation of NF-κB signaling pathway, and had strong anti-inflammatory activity on LPS-induced RAW264.7 macrophages, and its activity was superior to that of EGCG and theanine.


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