Antiviral Effects of Green Tea EGCG and Its Potential Application against COVID-19

(–)-Epigallocatechin-3-O-gallate (EGCG), the most abundant component of catechins in tea (Camellia sinensis (L.) O. Kuntze), plays a role against viruses through inhibiting virus invasiveness, restraining gene expression and replication. In this paper, the antiviral effects of EGCG on various viruses, including DNA virus, RNA virus, coronavirus, enterovirus and arbovirus, were reviewed. Meanwhile, the antiviral effects of the EGCG epi-isomer counterpart (+)-gallocatechin-3-O-gallate (GCG) were also discussed.     

Characterization of the Trans-Epithelial Transport of Green Tea (C. sinensis) Catechin Extracts with In Vitro Inhibitory Effect against the SARS-CoV-2 Papain-like Protease Activity

This work describes an untargeted analytical approach for the screening, identification, and characterization of the trans-epithelial transport of green tea (Camellia sinensis) catechin extracts with in vitro inhibitory effect against the SARS-CoV-2 papain-like protease (PLpro) activity. After specific catechin extraction, a chromatographic separation obtained six fractions were carried out. The fractions were assessed in vitro against the PLpro target. Fraction 5 showed the highest inhibitory activity against the SARS-CoV-2 PLpro (IC₅₀ of 0.125 μg mL⁻¹). The untargeted characterization revealed that (−)-epicatechin-3-gallate (ECG) was the most abundant compound in the fraction and the primary molecule absorbed by differentiated Caco-2 cells. Results indicated that fraction 5 was approximately 10 times more active than ECG (IC₅₀ value equal to 11.62 ± 0.47 μg mL⁻¹) to inhibit the PLpro target. Overall, our findings highlight the synergistic effects of the various components of the crude extract compared to isolated ECG.     

茶叶及茶多酚中儿茶素的高效液相色谱分析方法研究

 筛选出HypersilBDSC18和ZorbaxSBC18两种适合同时分离茶叶和茶多酚中 7种儿茶素和咖啡因的反相柱。采用甲醇 水 醋酸 (或三氟醋酸 )作流动相 ,分别以等强度洗脱和梯度洗脱 (均在 30min内 )分离测定了我国 6种不同产地茶叶样品和 3种茶多酚样品中 7种儿茶素的含量。考察了 7种儿茶素和咖啡因的保留值与流动相组成及柱温的关系 ,优化了色谱条件及样品前处理方法。用电喷雾电离质谱 (ESI MS)定性确认没食子儿茶素没食子酸酯(GCG)和儿茶素没食子酸酯 (CG)两组分 ,并用高效液相色谱制备两对照品用于定量分析。     

高效液相色谱法测定红茶中的茶黄素

建立了一种用于分析红茶中茶黄素的高效液相色谱法。该方法采用反相C18柱;流动相A为2%醋酸,流动相B为乙腈-乙酸乙酯(体积比为21∶3),梯度洗脱,流速0.8 mL/min;紫外检测波长280 nm;柱温40 ℃;外标法定量。结果表明,所采用的标准曲线有良好的线性关系(r=0.9990~0.9992),加标回收率为96.88%~103.57%,方法的精密度良好(平均RSD<1.5%)。该方法简便、快速、准确,可用于实际样品的测定。     

Targeting 3CLpro and SARS-CoV-2 RdRp by Amphimedon sp. Metabolites: A Computational Study

Since December 2019, novel coronavirus disease 2019 (COVID-19) pandemic has caused tremendous economic loss and serious health problems worldwide. In this study, we investigated 14 natural compounds isolated from Amphimedon sp. via a molecular docking study, to examine their ability to act as anti-COVID-19 agents. Moreover, the pharmacokinetic properties of the most promising compounds were studied. The docking study showed that virtually screened compounds were effective against the new coronavirus via dual inhibition of SARS-CoV-2 RdRp and the 3CL main protease. In particular, nakinadine B (1), 20-hepacosenoic acid (11) and amphimedoside C (12) were the most promising compounds, as they demonstrated good interactions with the pockets of both enzymes. Based on the analysis of the molecular docking results, compounds 1 and 12 were selected for molecular dynamics simulation studies. Our results showed Amphimedon sp. to be a rich source for anti-COVID-19 metabolites.     

Effect of Water Hardness on Catechin and Caffeine Content in Green Tea Infusions

The health benefits of green tea are associated with its high catechin content. In scientific studies, green tea is often prepared with deionized water. However, casual consumers will simply use their local tap water, which differs in alkalinity and mineral content depending on the region. To assess the effect of water hardness on catechin and caffeine content, green tea infusions were prepared with synthetic freshwater in five different hardness levels, a sodium bicarbonate solution, a mineral salt solution, and deionized water. HPLC analysis was performed with a superficially porous pentafluorophenyl column. As water hardness increased, total catechin yield decreased. This was mostly due to the autoxidation of epigallocatechin (EGC) and epigallocatechin gallate (EGCG). Epicatechin (EC), epicatechin gallate (ECG), and caffeine showed greater chemical stability. Autoxidation was promoted by alkaline conditions and resulted in the browning of the green tea infusions. High levels of alkaline sodium bicarbonate found in hard water can render some tap waters unsuitable for green tea preparation.     

Identification of SARS-CoV-2 Receptor Binding Inhibitors by In Vitro Screening of Drug Libraries

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is responsible for the coronavirus disease 2019 (COVID-19) global pandemic. The first step of viral infection is cell attachment, which is mediated by the binding of the SARS-CoV-2 receptor binding domain (RBD), part of the virus spike protein, to human angiotensin-converting enzyme 2 (ACE2). Therefore, drug repurposing to discover RBD-ACE2 binding inhibitors may provide a rapid and safe approach for COVID-19 therapy. Here, we describe the development of an in vitro RBD-ACE2 binding assay and its application to identify inhibitors of the interaction of the SARS-CoV-2 RBD to ACE2 by the high-throughput screening of two compound libraries (LOPAC^®1280 and DiscoveryProbeTM). Three compounds, heparin sodium, aurintricarboxylic acid (ATA), and ellagic acid, were found to exert an effective binding inhibition, with IC50 values ranging from 0.6 to 5.5 µg/mL. A plaque reduction assay in Vero E6 cells infected with a SARS-CoV-2 surrogate virus confirmed the inhibition efficacy of heparin sodium and ATA. Molecular docking analysis located potential binding sites of these compounds in the RBD. In light of these findings, the screening system described herein can be applied to other drug libraries to discover potent SARS-CoV-2 inhibitors.     

Curcumin Inhibits In Vitro SARS-CoV-2 Infection In Vero E6 Cells through Multiple Antiviral Mechanisms

Due to the scarcity of therapeutic approaches for COVID-19, we investigated the antiviral and anti-inflammatory properties of curcumin against SARS-CoV-2 using in vitro models. The cytotoxicity of curcumin was evaluated using MTT assay in Vero E6 cells. The antiviral activity of this compound against SARS-CoV-2 was evaluated using four treatment strategies (i. pre–post infection treatment, ii. co-treatment, iii. pre-infection, and iv. post-infection). The D614G strain and Delta variant of SARS-CoV-2 were used, and the viral titer was quantified by plaque assay. The anti-inflammatory effect was evaluated in peripheral blood mononuclear cells (PBMCs) using qPCR and ELISA. By pre–post infection treatment, Curcumin (10 µg/mL) exhibited antiviral effect of 99% and 99.8% against DG614 strain and Delta variant, respectively. Curcumin also inhibited D614G strain by pre-infection and post-infection treatment. In addition, curcumin showed a virucidal effect against D614G strain and Delta variant. Finally, the pro-inflammatory cytokines (IL-1β, IL-6, and IL-8) released by PBMCs triggered by SARS-CoV-2 were decreased after treatment with curcumin. Our results suggest that curcumin affects the SARS-CoV-2 replicative cycle and exhibits virucidal effect with a variant/strain independent antiviral effect and immune-modulatory properties. This is the first study that showed a combined (antiviral/anti-inflammatory) effect of curcumin during SARS-CoV-2 infection. However, additional studies are required to define its use as a treatment for the COVID-19.     

等度反相高效液相色谱法测定茶多酚中的儿茶素和咖啡因

 介绍一种简便的等度反相高效液相色谱分析茶多酚中 5种儿茶素和咖啡因的快速方法。样品总的分析时间在 0 5h内。色谱柱为ResolveC18;流动相为水 体积分数为 85 %的磷酸水溶液 乙腈 N ,N 二甲基甲酰胺 (DMF)(体积比为 85 9∶1∶12 0∶2 0 ) ;柱温为 43℃ ;紫外检测波长为 2 80nm。研究了流动相中改良剂DMF与容量因子的关系。被测组分的含量与其峰面积有良好的线性关系 (r =0 .9992～ 0 .9999) ;加标回收率在 83.33%～ 10 4.42 %(RSD在 0 .74%～ 1.43% )。     

Electroanalytical Sensing of Green Tea Anticarcinogenic Catechin Compounds: Epigallocatechin Gallate and Epigallocatechin

A novel electroanalytical methodology for the sensing of anticarcinogenic catechin compounds epigallocatechin gallate (EGCG) and epigallocatechin (EGC) is presented. The protocol is based on the electrochemical oxidation of aminophenol in aqueous solutions, where the quinoneimine oxidation product chemically reacts with the EGCG or EGC compounds resulting in consumption of quinoneimine and consequently results in a reduction in the magnitude of the quinoneimine reduction wave, which is found to provide an analytical signal from which to indirectly detect EGCG and/or EGC.     

Green,Black and Rooibos Tea Inhibit Prostaglandin E2 Formation in Human Monocytes by Inhibiting Expression of Enzymes in the Prostaglandin E2 Pathway

The formation of prostaglandin E2 (PGE2) is associated with adverse inflammatory effects. However, long-term treatment with nonsteroidal anti-inflammatory drugs (NSAIDs) comes with risk of severe side effects. Therefore, alternative ways to inhibit PGE2 are warranted. We have investigated the effects of tea extracts and the polyphenols epigallocatechin gallate (EGCG) and quercetin on PGE2 formation, determined by immunoassay, and protein expression, determined by immunoblotting, of cytosolic phospholipase A2 (cPLA2), cyclooxygenase 2 (COX-2) and microsomal PGE synthase-1 (mPGES-1) in human monocytes. Green and black tea extracts, and with a lower potency, Rooibos tea extract, inhibited lipopolysaccharide (LPS) and calcium ionophore-induced PGE2 formation. In addition, all tea extracts inhibited the LPS-induced expression of mPGES-1, and the green and black tea extracts also inhibited, to a lesser extent, COX-2 expression. The tea extracts only marginally reduced cPLA2 expression and had no effect on COX-1 expression. EGCG, present in green and black tea, and quercetin, present in all three teas, also inhibited PGE2 formation and expression of mPGES-1, COX-2 and cPLA2. Cell-based and cell-free assays were also performed to evaluate direct effects on the enzymatic activity of COX and PGE synthases. Mainly, the cell-free assay demonstrated partial inhibition by the tea extracts and polyphenols. However, the inhibition required higher doses compared to the effects demonstrated on protein expression. In conclusion, green and black tea, and to a lesser extent Rooibos tea, are potent inhibitors of PGE2 formation in human monocytes, and mediate their effects by inhibiting the expression of the enzymes responsible for PGE2 formation, especially mPGES-1.     

Preparation of Catechin Nanoemulsion from Oolong Tea Leaf Waste and Its Inhibition of Prostate Cancer Cells DU-145 and Tumors in Mice

Anti-cancer activity of catechin nanoemulsions prepared from Oolong tea leaf waste was studied on prostate cancer cells DU-145 and DU-145-induced tumors in mice. Catechin nanoemulsions composed of lecithin, Tween-80 and water in an appropriate proportion was prepared with high stability, particle size of 11.3 nm, zeta potential of −67.2 mV and encapsulation efficiency of 83.4%. Catechin nanoemulsions were more effective than extracts in inhibiting DU-145 cell growth, with the IC₅₀ being 13.52 and 214.6 μg/mL, respectively, after 48 h incubation. Furthermore, both catechin nanoemulsions and extracts could raise caspase-8, caspase-9 and caspase-3 activities for DU-145 cell apoptosis, arresting the cell cycle at S and G2/M phases. Compared to control, catechin nanoemulsion at 20 μg/mL and paclitaxel at 10 μg/mL were the most effective in reducing tumor volume by 41.3% and 52.5% and tumor weight by 77.5% and 90.6% in mice, respectively, through a decrease in EGF and VEGF levels in serum.     

Profiling of In Vitro Bioaccessibility and Intestinal Uptake of Flavonoids after Consumption of Commonly Available Green Tea Types

The aim of this study was to profile the bioaccessibility and intestinal absorption of epicatechins and flavonols in different forms of green tea and its formulation: loose leaf tea, powdered tea, 35% catechins containing GTE, and GTE formulated with green tea-derived polysaccharide and flavonols (CATEPLUS™). The bioaccessibillity and intestinal absorption of epicatechins and flavonols was investigated by using an in vitro digestion model system with Caco-2 cells. The bioaccessibility of total epicatechins in loose leaf tea, powdered tea, GTE, and CATEPLUS™ was 1.27%, 2.30%, 22.05%, and 18.72%, respectively, showing that GTE and CATEPLUS™ had significantly higher bioaccessibility than powdered tea and loose leaf tea. None of the flavonols were detected in powdered tea and loose leaf tea, but the bioaccessibility of the total flavonols in GTE and CATEPLUS™ was 85.74% and 66.98%, respectively. The highest intestinal absorption of epicatechins was found in CATEPLUS™ (171.39 ± 5.39 ng/mg protein) followed by GTE (57.38 ± 9.31), powdered tea (3.60 ± 0.67), and loose leaf tea (2.94 ± 1.03). The results from the study suggest that formulating green tea extracts rich in catechins with second components obtained from green tea processing could enhance the bioavailability of epicatechins.     

Phytochemical Discrimination,Biological Activity and Molecular Docking of Water-Soluble Inhibitors from Saussurea costus Herb against Main Protease of SARS-CoV-2

Siddha medicine is one of the oldest medical systems in the world and is believed to have originated more than 10,000 years ago and is prevalent across ancient Tamil land. It is undeniable that inhibitor preferences rise with increasing solubility in water due to the considerations pertaining to the bioavailability and the ease of which unabsorbed residues can be disposed of. In this study, we showed the phytochemical discrimination of Saussurea costus extracted with water at room temperature as a green extraction procedure. A total of 48 compounds were identified using gas chromatography-mass spectrometry (GC-MS). The fatty acids had a high phytochemical abundance at 73.8%, followed by tannins at 8.2%, carbohydrates at 6.9%, terpenoids at 4.3%, carboxylic acids at 2.5%, hydrocarbons at 2.4%, phenolic compounds at 0.2%, and sterols at 1.5%. Of these compounds, 22 were docked on the active side and on the catalytic dyad of His41 and Cys145 of the main protease of SARS-CoV-2 (M^pro). Eight active inhibitors were carbohydrates, five were fatty acids, three were terpenoids, two were carboxylic acids, one was a tannin, one was a phenolic compound, and one was a sterol. The best inhibitors were 4,8,13-Cyclotetradecatriene-1,3-diol, 1,5,9-trimethyl-12-(1-methylethyl), Andrographolide, and delta.4-Androstene-3.beta.,17.beta.-diol, with a binding affinity that ranged from −6.1 kcal/mol to −6.5 kcal/mol. The inhibitory effect of Saussurea costus of SARS-CoV-2 entry into the cell was studied using a pseudovirus with Spike proteins from the D614G variant and the VOC variants Gamma and Delta. Based on the viral cycle of SARS-CoV-2, our results suggest that the Saussurea costus aqueous extract has no virucidal effect and inhibits the virus in the events after cell entry. Furthermore, the biological activity of the aqueous extract was investigated against HSV-1 virus and two bacterial strains, namely Staphylococcus aureus ATCC BAA 1026 and Escherichia coli ATCC 9637. According to this study, an enormous number of water-soluble inhibitors were identified from Saussurea costus against the M^pro, and this is unprecedented as far as we know.     

液相色谱-串联质谱法同时测定红茶和绿茶中7种硫代氨基甲酸酯类除草剂

建立了红茶和绿茶中7种硫代氨基甲酸酯类除草剂(禾草敌、克草敌、灭草敌、野麦畏、禾草丹、茵草敌和丁草敌)的高效液相色谱-串联质谱(LC-MS/MS)检测方法.样品制备后,取2.0 g样品,加6 mL水浸润1 h.然后加入2.5 g NaCl,并用20 mL乙腈分两次进行提取,提取液吹氮浓缩后过HLB柱,并用3 mL乙腈洗脱.洗脱液浓缩后用2.0 mL正己烷-丙酮(7∶ 3,V/V)溶解残渣,然后过Envi-Carb固相萃取柱,再用5 mL正己烷-丙酮洗脱,洗脱液浓缩后用乙腈-水(5∶ 5,V/V)定容.采用LC-MS/MS电喷雾电离,多反应监测模式对样品进行分析.以D_3-甲萘威为内标,测定7种硫代氨基甲酸酯除草剂的线性范围为0～200 μg/L,线性相关系数在0.9954～0.9988范围内,检出限在0.093～1.77 μg/L范围内.在添加浓度5～20 μg/kg范围内,7种硫代氨基甲酸酯除草剂的回收率均在77.3%～91.5%,相对标准偏差(RSD)小于15%.本方法被成功用于红茶和绿茶样品中硫代氨基甲酸酯除草剂的测定.     

Isolation and Purification of a Novel Long－chain Acyl Catechin from Lipophilic Tea Polyphenols

Llpophilic tea polyphenols (LTP) was prepared by esterification of green tea polyphenols (GTP) with hexadecanoyl chloride. A novel long-chaln acyl catechin was isolated and purified from LTP by high-speed countercurrent chromatography (HSCCC).Its molecular structure was elucidated as epigallocatechin-3-O-gallate-4‘-O-hexadecanate by elemental analysis, IR, MS and ^1H NMR spectra.     

In silico validation of anti-viral drugs obtained from marine sources as a potential target against SARS-CoV-2 Mpro

COVID-19 caused by Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) has threatened the whole world affecting almost 243 million people globally. Originating from China, it has now spread worldwide with USA and India being the two most affected countries which emphasizes the immense potential of the coronaviruses to cause severity in the human population. This study validates the efficacy of some marine antiviral agents to target the viral main protease (Mpro) of SARS-CoV-2 by in silico studies. A total of 14 marine-derived antiviral agents were screened from several databases including PubChem and DrugBank and docked against the crystallised 3D structure of SARS-CoV-2 Mpro. MD simulation of the top two ligands was carried out for 100 ns to validate the protein-ligand stability. Later, their physicochemical, pharmacokinetics, and drug-likeness properties were evaluated and toxicity prediction was performed using eMOLTOX webtool. We found that all the 14 compounds are acting as a good target for Mpro. Among them, avarol and AcDa-1 procured the best docking results with the estimated docking score of −8.05 and −7.74 ​kcal/mol respectively. MD simulation revealed good conformational stability. The docked conformation was visualised and subsequent ligand-amino acid interactions were analysed. Avarol revealed good pharmacokinetic properties with oral bioavailability. The overall finding suggested that these marine compounds may have the potential to be used for the treatment of COVID-19 to tackle this pandemic.     

糖基化在新型冠状病毒侵染中的机制及药物研发中的应用

冠状病毒(Coronavirus,CoV)是一类具有包膜的正股单链RNA病毒,可感染人类和多种动物.2019年末,一种新的β-冠状病毒SARS-CoV-2(Severe acute respiratory syndrome-coronavirus-2)开始在人际间传播,该病毒引发的疾病“COVID-19”(Corona...     

Physicochemical properties of SARS-CoV-2 for drug targeting,virus inactivation and attenuation,vaccine formulation and quality control

The material properties of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its proteins are discussed. We review the viral structure, size, rigidity, lipophilicity, isoelectric point, buoyant density and centrifugation conditions, stability against pH, temperature, UV light, gamma radiation, and susceptibility to various chemical agents including solvents and detergents. Possible inactivation, downstream, and formulation conditions are given including suitable buffers and some first ideas for quality-control methods. This information supports vaccine development and discussion with competent authorities during vaccine approval and is certainly related to drug-targeting strategies and hygienics. Several instructive tables are given, including the pI and grand average of hydropathicity (GRAVY) of SARS-CoV-1 and -2 proteins in comparison. SARS-CoV-1 and SARS-CoV-2 are similar in many regards, so information can often be derived. Both are unusually stable, but sensitive at their lipophilic membranes. However, since seemingly small differences can have strong effects, for example, on immunologically relevant epitope settings, unevaluated knowledge transfer from SARS-CoV-1 to SARS-CoV-2 cannot be advised. Published knowledge regarding downstream processes, formulations and quality assuring methods is, as yet, limited. However, standard approaches employed for other viruses and vaccines seem to be feasible including virus inactivation, centrifugation conditions, and the use of adjuvants.