Bioactivity-boosting strategy based on combination of anti-allergic O-methylated catechin with a Citrus flavanone, hesperetin

Many patients with allergies have anxiety about taking anti-allergic medicines due to their side effects and increased medical expenses. Thus, developing functional foods/agricultural products for allergy prevention is strongly desired. In this study, we revealed that a Citrus flavanone, hesperetin, amplified IgE/antigen-mediated degranulation-inhibitory potency of anti-allergic catechin, (-)-epigallocatechin-3-O-(3-O-methyl) gallate (EGCG3''Me), in the rat basophilic/mast cell line RBL-2H3. Hesperetin also significantly elevated the activation of acid sphingomyelinase (ASM), essential for eliciting anti-allergic effect of EGCG3''Me through the cell surficial protein, 67-kDa laminin receptor (67LR). Furthermore, oral administration of the highly absorbent hesperidin, α-glucosyl hesperidin, also enhanced the inhibitory potency of EGCG3''Me-rich 'Benifuuki' green tea (Camellia sinensis L.) on passive cutaneous anaphylaxis (PCA) reaction evoked by IgE/antigen in BALB/c mice. These observations indicate that hesperetin amplifies the ability of EGCG3''Me to inhibit the IgE/antigen-mediated degranulation through activating ASM signaling.

67-kDa Laminin Receptor-Mediated Cellular Sensing System of Green Tea Polyphenol EGCG and Functional Food Pairing

The body is equipped with a “food factor-sensing system” that senses food factors, such as polyphenols, sulfur-containing compounds, and vitamins, taken into the body, and plays an essential role in manifesting their physiological effects. For example, (–)-epigallocatechin-3-O-gallate (EGCG), the representative catechin in green tea (Camellia sinensi L.), exerts various effects, including anti-cancer, anti-inflammatory, and anti-allergic effects, when sensed by the cell surficial protein 67-kDa laminin receptor (67LR). Here, we focus on three representative effects of EGCG and provide their specific signaling mechanisms, the 67LR-mediated EGCG-sensing systems. Various components present in foods, such as eriodictyol, hesperetin, sulfide, vitamin A, and fatty acids, have been found to act on the food factor-sensing system and affect the functionality of other foods/food factors, such as green tea extract, EGCG, or its O-methylated derivative at different experimental levels, i.e., in vitro, animal models, and/or clinical trials. These phenomena are observed by increasing or decreasing the activity or expression of EGCG-sensing-related molecules. Such functional interaction between food factors is called “functional food pairing”. In this review, we introduce examples of functional food pairings using EGCG.

Redox and Other Biological Activities of Tea Catechins That May Affect Health: Mechanisms and Unresolved Issues

The beneficial health effects of green tea have been attributed to tea catechins. However, the molecular mechanisms of action, especially those in vivo, remain unclear. This article reviews the redox and other activities of tea catechins, using (-)-epigallocatechin-3-gallate (EGCG), as an example. EGCG is a well-known antioxidant. However, EGCG can be oxidized to generate reactive oxygen species and EGCG quinone. We propose that EGCG quinone can react with Keap-1 to activate Nrf2-regulated cytoprotective enzymes. Tissue levels of catechins are important for their biological activities; a section is devoted to reviewing the biological fates of tea catechins after ingestion. Possible EGCG oxidation in vivo and whether the oligomeric forms are biologically active in animals are discussed. We also review the effects of EGCG on the activities of enzymes, receptors, and other signaling molecules through binding and raise a question about whether the autoxidation of EGCG in vitro may lead to artifacts or misinterpretation in some studies. Finally, we discuss the challenges in the extrapolation of in vitro results to situations in vivo and the translation of laboratory studies to humans.

Eriodictyol-Amplified 67-kDa Laminin Receptor Signaling Potentiates the Antiallergic Effect of O-Methylated Catechin

(-)-Epigallocatechin-3-O-(3-O-methyl) gallate (1, EGCG3″Me), an antiallergic O-methylated catechin, is present in high quantities in the green tea cultivar "Benifuuki" (Camellia sinensis L.). Previous studies have shown that EGCG3″Me inhibited basophil degranulation mediated through the cell-surface 67-kDa laminin receptor (67LR), but the mechanisms are not fully elucidated. This study aimed to investigate the mechanisms underlying the inhibitory effect of EGCG3″Me on IgE/antigen (Ag)-mediated degranulation and the combined effect of EGCG3″Me with eriodictyol (2), a bioactive flavanone. EGCG3″Me inhibited β-hexosaminidase release from the rat basophilic/mast cell line RBL-2H3 stimulated by IgE/Ag and induced acid sphingomyelinase (ASM) activity. This induction was inhibited by anti-67LR antibody treatment. The ASM-specific inhibitor desipramine inhibited EGCG3″Me-induced suppression of degranulation. The soluble guanylate cyclase (sGC) inhibitor NS2028 weakened the potency of EGCG3″Me, and the sGC activator BAY41-2272 suppressed degranulation. The ability of EGCG3″Me to induce ASM activity and inhibit degranulation was amplified by eriodictyol. Furthermore, oral administration of the lemon-peel-derived eriodyctiol-7-O-glucoside (3) potentiated the suppressive effect of EGCG3″Me-rich "Benifuuki" green tea on the IgE/Ag-induced passive cutaneous anaphylaxis (PCA) reaction in BALB/c mice. These results suggest that EGCG3″Me inhibits IgE/Ag-mediated degranulation by inducing the 67LR/sGC/ASM signaling pathway, and eriodictyol amplifies this signaling.

An Inexpensive Paper-Based Photoluminescent Sensor for Gallate Derived Green Tea Polyphenols

This work describes a terbium luminescence-based protocol to selectively detect gallate-derived green tea polyphenols on a supramolecular gel immobilised paper platform for the first time. This user-friendly, inexpensive (€ 0.0015) approach requires very low sample volumes for the analysis. The developed strategy enables simultaneous detection of gallate polyphenols in multiple tea samples with the potential for practical applications.

Preparation of Strong Antioxidative, Therapeutic Nanoparticles Based on Amino Acid-Induced Ultrafast Assembly of Tea Polyphenols

Nanoformulations offer the opportunity to overcome the shortcomings of drug molecules, such as low solubility, side effects, insufficient stability, etc., but in most of the current nanomedicines, nanocarriers as excipients do not directly participate in the therapy procedure. Accordingly, it is promising to develop the nanotherapeutics composed entirely of pharmaceutically active molecules. Tea polyphenols, especially epigallocatechin gallate (EGCG), are a kind of natural antioxidants with various biological and health beneficial effects and are extensively investigated as nutrients and anticancer drugs. Here, the size-tunable and highly active polyphenol nanoparticles were conveniently synthesized in water and could be massively produced with a simple facility. Compared to the previous strategies, either molecular assembly via oxidative coupling or combination with other biomacromolecules, the present preparation was conducted by the amino acid-triggered Mannish condensation reactions, thus permitting the flexible molecular design of various polyphenol nanoparticles by selecting different amino acids. This straightforward and ultrafast method actually opens up a novel means to make use of naturally reproducible polyphenols. Moreover, inheriting the salient properties of EGCG, these nanoparticles show strong antioxidation capacity, 10-fold higher than the extensively investigated polydopamine nanoparticles, and they are biosafe but have therapeutic effects, according to the in vitro and in vivo assessments of anticancer activity, which is promising for various biomedical purposes.

Procyanidin C1 Inhibits Melanoma Cell Growth by Activating 67-kDa Laminin Receptor Signaling

SCOPE

Procyanidin C1 (PC1) is an epicatechin trimer found mainly in grapes that is reported to provide several health benefits. However, little is known about the molecular mechanisms underlying these benefits. The aim of this study is to demonstrate the molecular mechanisms by which PC1 operates.

METHODS AND RESULTS

A 67-kDa laminin receptor (67LR) is identified as a cell surface receptor of PC1, with a Kd value of 2.8 µm. PC1 induces an inhibitory effect on growth, accompanied by dephosphorylation of the C-kinase potentiated protein phosphatase-1 inhibitor protein of 17 kDa (CPI17) and myosin regulatory light chain (MRLC) proteins, followed by actin cytoskeleton remodeling in melanoma cells. These actions are mediated by protein kinase A (PKA) and protein phosphatase 2A (PP2A) activation once PC1 is bound to 67LR.

CONCLUSION

It is demonstrated that PC1 elicits melanoma cell growth inhibition by activating the 67LR/PKA/PP2A/CPI17/MRLC pathway.

Protective Effects of Epigallocatechin-3-Gallate from Green Tea in Various Kidney Diseases

Kidney diseases are common health problems worldwide. Various etiologies (e.g., diabetes, hypertension, drug-induced nephrotoxicity, infection, cancers) can affect renal function and ultimately lead to development of chronic kidney disease (CKD) and end-stage renal disease (ESRD). The global rise in number of CKD/ESRD patients during recent years has led to tremendous concern to look for effective strategies to prevent or slow progression of CKD and ESRD. Natural compounds derived from herbs or medicinal plants have gained wide attention for scientific scrutiny to achieve such goals. One of such natural compounds that has been extensively investigated is epigallocatechin-3-gallate (EGCG), a major polyphenol found in the tea plant (Camellia sinensis). A growing body of recent evidence has shown that EGCG may be a promising therapeutic or protective agent in various kidney diseases. This article thus highlights recent progress in medical research on beneficial effects of EGCG against a broad spectrum of kidney diseases, including acute kidney injury, cisplatin-induced nephrotoxicity, kidney stone disease, glomerulonephritis, lupus nephritis, renal cell carcinoma, diabetic nephropathy, CKD, and renal fibrosis. The renoprotective mechanisms are also detailed. Finally, future perspectives of medical research on EGCG and its potential use in clinical practice for treatment and prevention of kidney diseases are discussed.

"Cell-addictive" dual-target traceable nanodrug for Parkinson's disease treatment via flotillins pathway

α-synclein (αS) aggregation is a representative molecular feature of the pathogenesis of Parkinson's disease (PD). Epigallocatechin gallate (EGCG) can prevent αS aggregation in vitro. However, the in vivo effects of PD treatment are poor due to the obstacles of EGCG accumulation in dopaminergic neurons, such as the blood brain barrier and high binding affinities between EGCG and membrane proteins. Therefore, the key to PD treatment lies in visual examination of EGCG accumulation in dopaminergic neurons.

Methods: DSPE-PEG-B6, DSPE-PEG-MA, DSPE-PEG-phenylboronic acid, and superparamagnetic iron oxide nanocubes were self-assembled into tracing nanoparticles (NPs). EGCG was then conjugated on the surface of the NPs through the formation of boronate ester bonds to form a “cell-addictive” dual-target traceable nanodrug (B6ME-NPs). B6ME-NPs were then used for PD treatment via intravenous injection.

Results: After treatment with B6ME-NPs, the PD-like characteristics was alleviated significantly. First, the amount of EGCG accumulation in PD lesions was markedly enhanced and traced via magnetic resonance imaging. Further, αS aggregation was greatly inhibited. Finally, the dopaminergic neurons were considerably increased.

Conclusion: Due to their low price, simple preparation, safety, and excellent therapeutic effect on PD, B6ME-NPs are expected to have potential application in PD treatment.

Achievable Central Nervous System Concentrations of the Green Tea Catechin EGCG Induce Stress in Glioblastoma Cells in Vitro

The polyphenolic compounds present in green tea are preventative against cancer in several animal tumor models. However, direct cytotoxic effects on cancer cells have also been reported. In order to determine whether drinking of green tea has chemopreventive or cytotoxic effects on brain cancer cells, we investigated the effect of the major green tea polyphenol EGCG as a pure substance and as tea extract dietary supplement on primary human glioblastoma cell cultures at the CNS-achievable concentration of 100 nM reported in the literature. We compared this with the effect of the cytotoxic concentration of 500 μM determined to be specific for the investigated primary glioblastoma cultures. After treatment with 500 µM EGCG, strong induction of autophagy and apoptosis was observed. Under treatment with 100 nM EGCG, glioblastoma cells proliferated over the entire observation period of 6 days without any detectable signs of cell death. Only within the first 12 h of treatment was increased accumulation of autophagic vacuoles and increased reactive oxygen species production as a stress response demonstrated. Mild forms of stress, such as treatment with 100 nM EGCG, activate different endogenous repair mechanisms to protect cells. Our data imply that drinking of green tea may have chemopreventive effects, but no direct cytotoxic properties.

Coptisine Induces Apoptosis in Human Hepatoma Cells Through Activating 67-kDa Laminin Receptor/cGMP Signaling

Hepatocellular carcinoma (HCC) is the most common primary cancer of the liver. Hence, new anti-liver cancer treatment strategies need to be urgently developed. Coptisine is a natural alkaloid extracted from rhizoma coptidis which exhibits anticancer activity in various preclinical models, including liver cancer. However, the molecular mechanisms underlying the anti-liver cancer effects of coptisine remains unclear. We used flow cytometry to assess the binding of coptisine to 67LR expressed on the surface of SMMC7721, HepG2, LO2 and H9 cells. Then SMMC7721, HepG2 and BEL7402 cells, belonging to the HCC cell lines, were treated with coptisine. The cell viability was detected using a cell counting kit-8 assay. Apoptosis was evaluated using flow cytometry and transferase-mediated dUTP nick-end labeling (TUNEL) assay. Apoptotic-related proteins and tumor death receptor 67-kDa laminin receptor (67LR) were detected using Western blot analysis. The cyclic guanosine 3′,5′-monophosphate (cGMP) concentration was determined using enzyme-linked immunosorbent assay. sh67LR lentivirus, anti67LR antibody, and cGMP inhibitor NS2028 were used to determine how a 67LR/cGMP signaling pathway regulated coptisine-induced apoptosis. Tumor growth inhibited by coptisine was confirmed in a SMMC7721 cell xenograft mouse model. Coptisine selectively exhibited cell viability in human hepatoma cells but not in normal human hepatocyte cell line LO2 cells. Coptisine promoted SMMC7721 and HepG2 cell apoptosis by increasing 67LR activity. Both 67LR antibody and sh67LR treatment blocked coptisine-induced apoptosis and inhibition of cell viability. Coptisine upregulated the expression of cGMP. Moreover, cGMP inhibitor NS2028 significantly decreased coptisine-induced apoptosis and inhibition of cell viability. In vivo experiments confirmed that coptisine could significantly suppress the tumor growth and induce apoptosis in SMMC7721 xenografts through a 67LR/cGMP pathway. Coptisine-mediated 67LR activation may be a new therapeutic strategy for treating hepatic malignancy.

Size-controlled, colloidally stable and functional nanoparticles based on the molecular assembly of green tea polyphenols and keratins for cancer therapy

Molecular assembly of green tea polyphenols and keratins into size-controlled, colloidally stable and functional nanoparticles for enhanced cancer therapy was achieved.

Green Tea Catechins for Prostate Cancer Prevention: Present Achievements and Future Challenges

Green tea catechins (GTCs) are a family of chemically related compounds usually classified as antioxidant molecules. Epidemiological evidences, supported by interventional studies, highlighted a more than promising role for GTCs in human prostate cancer (PCa) chemoprevention. In the last decades, many efforts have been made to gain new insights into the mechanism of action of GTCs. Now it is clear that GTCs' anticancer action can no longer be simplistically limited to their direct antioxidant/pro-oxidant properties. Recent contributions to the advancement of knowledge in this field have shown that GTCs specifically interact with cellular targets, including cell surface receptors, lipid rafts, and endoplasmic reticulum, modulate gene expression through direct effect on transcription factors or indirect epigenetic mechanisms, and interfere with intracellular proteostasis at various levels. Many of the effects observed in vitro are dose and cell context dependent and take place at concentrations that cannot be achieved in vivo. Poor intestinal absorption together with an extensive systemic and enteric metabolism influence GTCs' bioavailability through still poorly understood mechanisms. Recent efforts to develop delivery systems that increase GTCs' overall bioavailability, by means of biopolymeric nanoparticles, represent the main way to translate preclinical results in a real clinical scenario for PCa chemoprevention.