Alleviation effects of epigallocatechin-3-gallate against acute kidney injury following severe burns.

BACKGROUND: Burn patients often face a high risk of acute kidney injury (AKI) after severe burn injuries, meanwhile epigallocatechin-3-gallate (EGCG) has been proven to be effective in alleviating organ injury. METHODS: This study used the classical burn model in rats. Thirty model rats were randomly divided into a Burn group, a Burn + placebo group, a Burn + EGCG (50 mg/kg) group, and ten non-model rats as Sham group. The urinary excretion of the rats was subsequently monitored for a period of 48 h. After 48 h of different treatments, rat serum and kidneys were taken for the further verification. The efficacy of EGCG was assessed in pathological sections, biochemical indexes, and at the molecular level. RESULTS: Pathological sections were compared between the Burn group and Burn + placebo group. The rats in the Burn + EGCG group had less kidney damage. Moreover, the EGCG group maintained significantly elevated urine volumes, biochemical indexes manifested that EGCG could reduce serum creatinine (Cr) and neutrophil gelatinase-associated lipocalin (NGAL) level and inhibit the oxidation-related enzyme malondialdehyde (MDA) level, meanwhile the superoxide dismutase (SOD) level was increased. The molecular level showed that EGCG significantly reduced the mRNA expression levels of the inflammation-related molecules interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α). CONCLUSION: The research indicated that EGCG had an alleviating effect on kidney injury in severely burned rats, and its alleviating effects were related to improving kidney functions, alleviating oxidative stress, and inhibiting the expression of inflammatory factors.

Beneficial Effects of Green Tea EGCG on Skin Wound Healing: A Comprehensive Review.

Epigallocatechin gallate (EGCG) is associated with various health benefits. In this review, we searched current work about the effects of EGCG and its wound dressings on skin for wound healing. Hydrogels, nanoparticles, micro/nanofiber networks and microneedles are the major types of EGCG-containing wound dressings. The beneficial effects of EGCG and its wound dressings at different stages of skin wound healing (hemostasis, inflammation, proliferation and tissue remodeling) were summarized based on the underlying mechanisms of antioxidant, anti-inflammatory, antimicrobial, angiogenesis and antifibrotic properties. This review expatiates on the rationale of using EGCG to promote skin wound healing and prevent scar formation, which provides a future clinical application direction of EGCG.

Pharmaceutical Topical Delivery of Poorly Soluble Polyphenols: Potential Role in Prevention and Treatment of Melanoma.

Melanoma is regarded as the fifth and sixth most common cancer in men and women, respectively, and it is estimated that one person dies from melanoma every hour in the USA. Unfortunately, the treatment of melanoma is difficult because of its aggressive metastasis and resistance to treatment. The treatment of melanoma continues to be a challenging issue due to the limitations of available treatments such as a low response rate, severe adverse reactions, and significant toxicity. Natural polyphenols have attracted considerable attention from the scientific community due to their chemopreventive and chemotherapeutic efficacy. It has been suggested that poorly soluble polyphenols such as curcumin, resveratrol, quercetin, coumarin, and epigallocatechin-3-gallate may have significant benefits in the treatment of melanoma due to their antioxidant, anti-inflammatory, antiproliferative, and chemoprotective efficacies. The major obstacles for the use of polyphenolic compounds are low stability and poor bioavailability. Numerous nanoformulations, including solid lipid nanoparticles, polymeric nanoparticles, micelles, and liposomes, have been formulated to enhance the bioavailability and stability, as well as the therapeutic efficacy of polyphenols. This review will provide an overview of poorly soluble polyphenols that have been reported to have antimetastatic efficacy in melanomas.

Prevention of Colorectal Cancer by Targeting Obesity-Related Disorders and Inflammation.

Colorectal cancer is a major healthcare concern worldwide. Many experimental and clinical studies have been conducted to date to discover agents that help in the prevention of this disease. Chronic inflammation in colonic mucosa and obesity, and its related metabolic abnormalities, are considered to increase the risk of colorectal cancer. Therefore, treatments targeting these factors might be a promising strategy to prevent the development of colorectal cancer. Among a number of functional foods, various phytochemicals, including tea catechins, which have anti-inflammatory and anti-obesity properties, and medicinal agents that ameliorate metabolic disorders, might also be beneficial in the prevention of colorectal cancer. In this review article, we summarize the strategies for preventing colorectal cancer by targeting obesity-related disorders and inflammation through nutraceutical and pharmaceutical approaches, and discuss the mechanisms of several phytochemicals and medicinal drugs used in basic and clinical research, especially focusing on the effects of green tea catechins.

Salivary hydrogen peroxide produced by holding or chewing green tea in the oral cavity.

Tea (Camellia sinensis) catechins have been studied for disease prevention. These compounds undergo oxidation and produce H(2)O(2). We have previously shown that holding tea solution or chewing tea leaves generates high salivary catechin levels. Herein, we examined the generation of H(2)O(2) in the oral cavity by green tea solution or leaves. Human volunteers holding green tea solution (0.1-0.6%) developed salivary H(2)O(2) with C(max) = 2.9-9.6 microM and AUC(0 --> infinity) = 8.5-285.3 microM min. Chewing 2 g green tea leaves produced higher levels of H(2)O(2) (C(max) = 31.2 microM, AUC(0 --> infinity) = 1290.9 microM min). Salivary H(2)O(2) correlated with catechin levels and with predicted levels of H(2)O(2) (C(max(expected)) = 36 microM vs C(max(determined)) = 31.2 microM). Salivary H(2)O(2) and catechin concentrations were similar to those that are biologically active in vitro. Catechin-generated H(2)O(2) may, therefore, have a role in disease prevention by green tea.

Deodorization of Garlic Breath by Foods, and the Role of Polyphenol Oxidase and Phenolic Compounds.

Garlic causes a strong garlic breath that may persist for almost a day. Therefore, it is important to study deodorization techniques for garlic breath. The volatiles responsible for garlic breath include diallyl disulfide, allyl mercaptan, allyl methyl disulfide, and allyl methyl sulfide. After eating garlic, water (control), raw, juiced or heated apple, raw or heated lettuce, raw or juiced mint leaves, or green tea were consumed immediately. The levels of the garlic volatiles on the breath were analyzed from 1 to 60 min by selected ion flow tube mass spectrometry (SIFT-MS). Garlic was also blended with water (control), polyphenol oxidase (PPO), rosemarinic acid, quercetin or catechin, and the volatiles in the headspace analyzed from 3 to 40 min by SIFT-MS. Raw apple, raw lettuce, and mint leaves significantly decreased all of the garlic breath volatiles in vivo. The proposed mechanism is enzymatic deodorization where volatiles react with phenolic compounds. Apple juice and mint juice also had a deodorizing effect on most of the garlic volatiles but were generally not as effective as the raw food, probably because the juice had enzymatic activity but the phenolic compounds had already polymerized. Both heated apple and heated lettuce produced a significant reduction of diallyl disulfide and allyl mercaptan. The presence of phenolic compounds that react with the volatile compounds even in the absence of enzymes is the most likely mechanism. Green tea had no deodorizing effect on the garlic volatile compounds. Rosmarinic acid, catechin, quercetin, and PPO significantly decreased all garlic breath volatiles in vitro. Rosmarinic acid was the most effective at deodorization.

Condensed catechins and their potential health-benefits.

Condensed catechins are commonly present in fermented tea, and are produced by the oxidation of monomeric catechins. Due to their auto-oxidation, catechins have diverse structural features, including different binding modes and degrees of polymerization. Because of their structural complexity, their physiological functions and possible health-benefits have not yet been fully investigated. This review focuses on the physiological potentials of dimeric and trimeric catechins in the intestine (regulation of absorption across the intestinal membrane), blood vessels (vasorelaxation in vessel regulation), and muscle organs (promotion of glucose uptake resulting in an anti-diabetic effect). Furthermore, the roles of non-absorbable theaflavins (dimeric catechins), absorbable theasinensins (dimeric catechins), and absorbable procyanidins (dimeric and trimeric catechins) on target organs are discussed.

Peroxidase-catalyzed generation of catechin oligomers that inhibit glucosyltransferase from Streptococcus sobrinus.

Oolong tea extract (OTE) and the purified polymeric polyphenols from OTE have been found to inhibit glucosyltransferase (GTase) of mutans streptococci. In view of the partial fermentation characteristic of oolong tea, we describe here an in vitro model reaction system to produce partially fermented products of D-(+)-catechin or green tea extract (GTE) using horseradish peroxidase. A dimeric catechin molecule was identified as dehydro-dicatechin A by instrumental analyses. The molecular size of some oligomeric catechins was estimated by the elution profile with HPLC. These catechin oligomers markedly inhibited GTase from Streptococcus sobrinus 6715. As the degree of polymerization of catechin or GTE increased, GTase was inhibited more effectively. These results suggest that polymeric polyphenols found in OTE are synthesized by partial fermentation due to oxidases/peroxidases present in tea leaves.

Effects of flavonoids on the susceptibility of low-density lipoprotein to oxidative modification.

Dietary flavonoid intake has been reported to be inversely associated with the incidence of coronary artery disease. To clarify the possible role of flavonoids in the prevention of atherosclerosis, we investigated the effects of some of these compounds on the susceptibility of low-density lipoprotein (LDL) to oxidative modification. In this study, six flavonoids, "apigenin, genistein, morin, naringin, pelargonidin and quercetin", were added to plasma and incubated for 3h at 37 degrees C. Then, the LDL fraction was separated by ultracentrifugation. The oxidizability of LDL was estimated by measuring conjugated diene (CD), lipid peroxides and thiobarbituric acid-reactive substances (TBARS) after cupric sulfate solution was added. We showed that among flavonoids used, quercetin and morin significantly (P<0.01 by ANOVA) and dose-dependently prolonged the lag time before initiation of oxidation reaction. Also, these two flavonoids suppressed the formation of lipid peroxides and TBARS more markedly than others. Their ability to prolong lag time and suppression of lipid peroxides and TBARS formation resulted to be in the following order: quercetin>morin>pelargonidin>genistein>naringin>apigenin. LDL exposed to flavonoids in vitro reduced oxidizability. These findings show that flavonoids may have a role in ameliorating atherosclerosis.