Structural dynamics of DNA binding to tea catechins

Epigallocatechin Gallate Affects the Structure of Chromatosomes, Nucleosomes and Their Complexes with PARP1

The natural flavonoid epigallocatechin gallate has a wide range of biological activities, including being capable of binding to nucleic acids; however, the mechanisms of the interactions of epigallocatechin gallate with DNA organized in chromatin have not been systematically studied. In this work, the interactions of epigallocatechin gallate with chromatin in cells and with nucleosomes and chromatosomes in vitro were studied using fluorescent microscopy and single-particle Förster resonance energy transfer approaches, respectively. Epigallocatechin gallate effectively penetrates into the nuclei of living cells and binds to DNA there. The interaction of epigallocatechin gallate with nucleosomes in vitro induces a large-scale, reversible uncoiling of nucleosomal DNA that occurs without the dissociation of DNA or core histones at sub- and low-micromolar concentrations of epigallocatechin gallate. Epigallocatechin gallate does not reduce the catalytic activity of poly(ADP-ribose) polymerase 1, but causes the modulation of the structure of the enzyme-nucleosome complex. Epigallocatechin gallate significantly changes the structure of chromatosomes, but does not cause the dissociation of the linker histone. The reorganization of nucleosomes and chromatosomes through the use of epigallocatechin gallate could facilitate access to protein factors involved in DNA repair, replication and transcription to DNA and, thus, might contribute to the modulation of gene expression through the use of epigallocatechin gallate, which was reported earlier.

A General and Efficient Strategy for Gene Delivery Based on Tea Polyphenols Intercalation and Self-Polymerization

Gene therapy that employs therapeutic nucleic acids to modulate gene expression has shown great promise for diseases therapy, and its clinical application relies on the development of effective gene vector. Herein a novel gene delivery strategy by just using natural polyphenol (-)-epigallocatechin-3-O-gallate (EGCG) as raw material is reported. EGCG first intercalates into nucleic acids to yield a complex, which then oxidizes and self-polymerizes to form tea polyphenols nanoparticles (TPNs) for effective nucleic acids encapsulation. This is a general method to load any types of nucleic acids with single or double strands and short or long sequences. Such TPNs-based vector achieves comparable gene loading capacity to commonly used cationic materials, but showing lower cytotoxicity. TPNs can effectively penetrate inside cells, escape from endo/lysosomes, and release nucleic acids in response to intracellular glutathione to exert biological functions. To demonstrate the in vivo application, an anti-caspase-3 small interfering ribonucleic acid is loaded into TPNs to treat concanavalin A-induced acute hepatitis, and excellent therapeutic efficacy is obtained in combination with the intrinsic activities of TPNs vector. This work provides a simple, versatile, and cost-effective gene delivery strategy. Given the biocompatibility and intrinsic biofunctions, this TPNs-based gene vector holds great potential to treat various diseases.

Synergistic effects of L-theanine and epigallocatechin gallate in alleviating ovalbumin allergy by regulating intestinal immunity through inhibition of mast cell degranulation

Ovalbumin (OVA), a commonly consumed food protein, can cause severe allergies and intestinal immune disorders. L-Theanine (LTA) and epigallocatechin gallate (EGCG) regulate intestinal immunity. However, it is unclear whether an LTA and EGCG combined intervention can alleviate OVA allergy (OVA-A) by modulating intestinal-specific immunity, and it is unknown whether there is a synergistic effect between LTA and EGCG. Therefore, we treated BALB/c OVA-sensitized mice with LTA, EGCG, or a combination of both (LTA + EGCG) to investigate the effects of LTA and EGCG on intestinal-specific immunity regulation and underlying mechanisms. Female mice were intraperitoneally injected with OVA to establish OVA-sensitive mouse models. MLEO LTA + EGCG (20 mg kg^-1 d^-1 LTA + 80 mg kg^-1 d^-1 EGCG) and HLEO (30 mg kg^-1 d^-1 LTA + 120 mg kg^-1 d^-1 EGCG) exerted more beneficial effects on alleviating OVA-A (weight gain, allergy score, jejunum structure, mast cell [MC] degranulation, thymus and spleen indices) than LTA or EGCG alone (p < 0.01). Based on the alleviation of OVA-A by LTA + EGCG, we selected MLEO mice for 16S rDNA, flow cytometry, and western blot analyses. The 16S rDNA results showed that MLEO increased the abundance of Lactobacillaceae, Lachnospiraceae, and Ruminococcaceae, and decreased that of Helicobacteraceae (p < 0.01). The flow cytometry and western blotting results indicated that MLEO reduced the number of dendritic cells available to capture OVA, thereby lowering the Th2 immune response and decreasing the IL-4 and IL-13 levels. Meanwhile, the attenuation of the Th2 immune response inhibits the cross-linking of OVA and FcεRI, thus reducing MC degranulation and decreasing the serum HIS and mMCPT-1 levels through the FcεRI/Btk/PLCγ signaling pathway. LTA + EGCG also inhibits the Th2 immune response through the FcεRI/Lyn/Syk/PI3K/AKT signaling pathway and decreases the serum IL-4 and IL-13 levels. Notably, LTA + EGCG promotes the Treg and Th1 immune responses and inhibits the Th17 immune response, altering the levels of the corresponding cytokines. Therefore, LTA + EGCG can synergistically alleviate OVA-A by regulating intestinal immunity through MC degranulation inhibition.

Current Understanding of Modes of Action of Multicomponent Bioactive Phytochemicals: Potential for Nutraceuticals and Antimicrobials

Plants produce a diversity of plant secondary metabolites (PSMs), which function as defense chemicals against herbivores and microorganisms but also as signal compounds. An individual plant produces and accumulates mixtures of PSMs with different structural features using different biosynthetic pathways. Almost all PSMs exert one or several biological activities that can be useful for nutrition and health. This review discusses the modes of action of PSMs alone and in combinations. In a mixture, most individual PSMs can modulate different molecular targets; they are thus multitarget drugs. In an extract with many multitarget chemicals, additive and synergistic effects occur. Experiments with the model system Caenorhabditis elegans show that polyphenols and carotenoids can function as powerful antioxidative and longevity-promoting PSMs. PSMs of food plants and spices often exhibit antioxidant, anti-inflammatory, and antimicrobial properties, which can be beneficial for health and the prevention of diseases. Some extracts from food plants and spices with bioactive PSMs have potential for nutraceuticals and antimicrobials.

Metabolomics for a Millenniums-Old Crop: Tea Plant ( Camellia sinensis)

Tea cultivation and utilization dates back to antiquity. Today it is the most widely consumed beverage on earth due to its pleasant taste and several beneficial health properties attributed to specific metabolites. Metabolomics has a tremendous potential to correlate tea metabolites with taste and health properties in humans. Our review on the current application of metabolomics in the science of tea suggests that metabolomics is a promising frontier in the evaluation of tea quality, identification of functional genes responsible for key metabolites, investigation of their metabolic regulation, and pathway analysis in the tea plant. Furthermore, the challenges, possible solutions, and the prospects of metabolomics in tea science are reviewed.

Effect of tea catechins on tRNA structure and dynamics

AbbreviationsCcatechinECGepicatechin gallateEGCGEpigallocatechin gallateAAdenineCcytosineGGuanineUuracilFTIRFourier transform infraredCommunicated by Ramaswamy H. Sarma.