Pu-erh black tea extract supplementation attenuates the oxidative DNA damage and oxidative stress in Sprague–Dawley rats with renal dysfunction induced by subchronic 3-methyl-2-quinoxalin benzenevinylketo-1,4-dioxide exposure

Quercetin Attenuates Quinocetone-Induced Cell Apoptosis In Vitro by Activating the P38/Nrf2/HO-1 Pathway and Inhibiting the ROS/Mitochondrial Apoptotic Pathway

Quinocetone (QCT), a member of the quinoxaline 1,4-di-N-oxides (QdNOs) family, can cause genotoxicity and hepatotoxicity, however, the precise molecular mechanisms of QCT are unclear. This present study investigated the protective effect of quercetin on QCT-induced cytotoxicity and the underlying molecular mechanisms in human L02 and HepG2 cells. The results showed that quercetin treatment (at 7.5–30 μM) significantly improved QCT-induced cytotoxicity and oxidative damage in human L02 and HepG2 cells. Meanwhile, quercetin treatment at 30 μM significantly inhibited QCT-induced loss of mitochondrial membrane potential, an increase in the expression of the CytC protein and the Bax/Bcl-2 ratio, and an increase in caspases-9 and -3 activity, and finally improved cell apoptosis. Quercetin pretreatment promoted the expression of the phosphorylation of p38, Nrf2, and HO-1 proteins. Pharmacological inhibition of p38 significantly inhibited quercetin-mediated activation of the Nrf2/HO-1 pathway. Consistently, pharmacological inhibitions of the Nrf2 or p38 pathways both promoted QCT-induced cytotoxicity and partly abolished the protective effects of quercetin. In conclusion, for the first time, our results reveal that quercetin could improve QCT-induced cytotoxicity and apoptosis by activating the p38/Nrf2/HO-1 pathway and inhibiting the ROS/mitochondrial apoptotic pathway. Our study highlights that quercetin may be a promising candidate for preventing QdNOs-induced cytotoxicity in humans or animals.

Combination of Oxytetracycline and Quinocetone Synergistically Induces Hepatotoxicity via Generation of Reactive Oxygen Species and Activation of Mitochondrial Pathway

Oxytetracycline (OTC) and Quinocetone (QCT) are antimicrobials, whose residues have been found in food and environment. These two are sometimes used simultaneously in livestock and aquaculture, potentially resulting in the simultaneous consumption of multi-antimicrobials by consumers. However, the combined toxic effects of this phenomenon have yet to be addressed. Since the liver is a major target of both OTC and QCT, we tested their hepatotoxic effect using both cell cultures and animal models. Results showed that the QCT (5-25 μM) or OTC (20-100 μM) treatments alone caused dose-dependent reductions in cell numbers, while their combination strongly further enhanced inhibitory effects. Mechanistically, the combination enhanced the generation of reactive oxygen species (ROS) and activated mitochondrial cell death pathways. It also showed that the combination of OTC (800 mg/kg, i.g., 5d) and QCT (5000 mg/kg, i.g., 5d) resulted in significantly enhanced liver toxicity in C57BL/6N mice, the serum alanine transaminase (ALT) and aspartate transaminase (AST) were significantly increased by the OTC/QCT. These findings indicate the necessity of considering the combined toxicity of these two antimicrobials in safety assessments.

Aqueous raw and ripe Pu-erh tea extracts alleviate obesity and alter cecal microbiota composition and function in diet-induced obese rats

Pu-erh tea is attracting increased attention worldwide because of its unique flavor and health effects, but its impact on the composition and function of the gut microbiota remains unclear. The aim of this study was to investigate the effects of aqueous extracts of fermented (ripe) and non-fermented (raw) Pu-erh teas on the composition and function of the intestinal microbiota of rats with diet-induced obesity. We conducted a comparative metagenomic and meta-proteomic investigation of the microbial communities in cecal samples taken from obese rats treated with or without extracts of raw or ripe Pu-erh teas. By analyzing the composition and diversity of 16S rRNA amplicons and expression profiles of 814 distinct proteins, we found that despite differences in the chemical compositions of raw and ripe Pu-erh teas, administration of either tea at two doses (0.15- and 0.40-g/kg body weight) significantly (P < 0.05) increased microbial diversity and changed the composition of cecal microbiota by increasing the relative abundances of Firmicutes and decreasing those of Bacteroidetes. Community metabolic processes, including sucrose metabolism, glycolysis, and syntheses of proteins, rRNAs, and antibiotics were significantly (P < 0.05) promoted or had a tendency (0.10 < P < 0.05) to be promoted due to the enrichment of relevant enzymes. Furthermore, evidence at population, molecular, and metabolic levels indicated that polyphenols of raw Pu-erh tea and their metabolites potentially promote Akkermansia muciniphila growth by stimulating a type II and III secretion system protein, the elongation factor Tu, and a glyceraldehyde-3-phosphate dehydrogenase. This study provides new evidence for the prebiotic effects of Pu-erh tea.

Aplysin Protects Against Alcohol-Induced Liver Injury Via Alleviating Oxidative Damage and Modulating Endogenous Apoptosis-Related Genes Expression in Rats

We investigated the protective effects and possible mechanisms of Aplysin against alcohol-induced liver injury. Rats were given daily either alcohol only (alcohol model group; 8 to 12 mL/kg body weight), one of three doses of Aplysin (50, 100, or 150 mg/kg Aplysin) plus alcohol, or volume-matched saline. After 6 weeks, the effects of Aplysin were assessed in terms of changes in histology, biochemical indices, and DNA oxidative damage. Potential mechanisms were analyzed through measurements of lipid peroxidation, antioxidant defense systems, expression of cytochrome P450 2E1, and expression of apoptosis-related genes. We found that Aplysin significantly protected the liver against alcohol-induced oxidative injury, evidenced by improved hepatic histological structure, inhibited alcohol-induced elevation of serum biochemical indices, attenuated extents of hepatocellular DNA damage. At a mechanistic level, Aplysin alleviated alcohol-induced oxidative stress as illustrated by the revivification of erythrocyte membrane fluidity, the attenuation of glutathione depletion, the restoration of antioxidase activities, and reduced malondialdehyde overproduction. Furthermore, the mRNA levels of Bax, cytochrome c, and cytochrome P450 2E1 were significantly down-regulated, whereas those of Bcl-2 and caspase-9 and caspase-3 were markedly up-regulated. These findings suggest that Aplysin provides significant protection against alcohol-induced liver injury, possibly through alleviating oxidative damage and modulating endogenous apoptosis-related genes expression.

PRACTICAL APPLICATION

Many natural components derived from alga have been used in the food, cosmetics, and biomedicine industries. Aplysin, a marine bromosesquiterpene, was extracted from the red alga Laurencia tristicha, which could effectively protect against alcohol-induced liver injury, might be a potential natural sources for preventing alcoholic liver damage.

Flavanols from the Camellia sinensis var. assamica and their hypoglycemic and hypolipidemic activities

α-Glucosidase and lipase inhibitors play important roles in the treatment of hyperglycaemia and dyslipidemia. To identify novel naturally occurring inhibitors, a bioactivity-guided phytochemical research was performed on the pu-erh tea. One new flavanol, named (–)-epicatechin-3-O-(Z)-coumarate (1), and 16 known analogs (2—17) were isolated from the aqueous extract of the pu-erh tea. Their structures were determined by spectroscopic and chemical methods. Furthermore, the water extract of pu-erh tea and its fractions exhibited inhibitory activities against α-glucosidases and lipases in vitro; compound 15 showed moderate inhibitory effect against sucrase with an IC₅₀ value of 32.5 μmol/L and significant inhibitory effect against maltase with an IC₅₀ value of 1.3 μmol/L. Compounds 8, 10, 11 and 15 displayed moderate activity against a lipase with IC₅₀ values of 16.0, 13.6, 19.8, and 13.3 μmol/L, respectively.

Natural Phenol Polymers: Recent Advances in Food and Health Applications

Natural phenol polymers are widely represented in nature and include a variety of classes including tannins and lignins as the most prominent. Largely consumed foods are rich sources of phenol polymers, notably black foods traditionally used in East Asia, but other non-edible, easily accessible sources, e.g., seaweeds and wood, have been considered with increasing interest together with waste materials from agro-based industries, primarily grape pomace and other byproducts of fruit and coffee processing. Not in all cases were the main structural components of these materials identified because of their highly heterogeneous nature. The great beneficial effects of natural phenol-based polymers on human health and their potential in improving the quality of food were largely explored, and this review critically addresses the most interesting and innovative reports in the field of nutrition and biomedicine that have appeared in the last five years. Several in vivo human and animal trials supported the proposed use of these materials as food supplements and for amelioration of the health and production of livestock. Biocompatible and stable functional polymers prepared by peroxidase-catalyzed polymerization of natural phenols, as well as natural phenol polymers were exploited as conventional and green plastic additives in smart packaging and food-spoilage prevention applications. The potential of natural phenol polymers in regenerative biomedicine as additives of biomaterials to promote growth and differentiation of osteoblasts is also discussed.

Safety evaluation and antihyperlipidemia effect of aqueous extracts from fermented puerh tea

Fermented puerh tea, having undergone a long period of secondary oxidization and fermentation, has become more and more popular in recent years. In the present paper, a safety evaluation of aqueous extracts from fermented puerh tea (EFPT) was performed, including an oral acute toxicity study in rats and mice, mutation tests, a mouse micronucleus test, mouse sperm abnormality test and a 30 day feeding study in rats. Meanwhile, the antihyperlipidemia effect of EFPT was investigated as well. It was found that the oral maximum tolerated dose of EFPT was more than 10.0 g per kg body weight both in rats and mice. And it had no mutagenicity as judged by negative experimental results of the mutation test. No abnormal symptoms, clinical signs or deaths have been found in rats in each group throughout the experiments. In addition, EFPT in this study showed certain effects on hyperlipidemia.

Pu-erh tea powder preventive effects on cisplatin-induced liver oxidative damage in Wistar rats

BACKGROUND

Chemotherapy is one of the major means for control of malignancies, with cisplatin (CDDP) as one of the main agents, widely used for the treatment of various malignant solid tumors. However, prevention of hepatotoxicity from cisplatin is one of the urgent issues in cancer chemotherapy. In this study, we aimed to investigate the effects of pu-erh tea on hepatotoxicity through body weight and tissue antioxidant parameters like, liver coefficient, serum alanine aminotransferase (ALT), serum aspartate aminotransferase (AST), superoxide dismutase (SOD), glutathione peroxidase (GSH-PX), malondialdehyde(MDA) and glutathione (GSH) levels, and light microscopic evaluation by histological findings.

MATERIALS AND METHODS

The rats were randomly divided into five groups: Control (n=10), cisplatin (3 mg/kg p.i., n=10), cisplatin+pu-erh (0.32 g/kg/day i.g., n=10), cisplatin+pu-erh (0.8 g/kg/day i.g., n=10) and cisplatin+pu-erh (1.6 g/kg/day i.g., n=10). Pu-erh tea powder was administrated for 31 consecutive days. The rats were sacrificed at the end on the second day after a single dose of cisplatin treatment for measuring indices.

RESULTS

Pu-erh tea powder exhibited a protective effect by decreasing MDA and GSH and increasing the SOD and GSH-PX levels and GSH-PX/MDA ratio in comparison with the control group. Besides, pu-erh tea was also able to alleviate the pathological damage to some extent.

CONCLUSION

Pu-erh tea powder is protective against cisplatin-induced liver oxidative damages, especially at the medium dosage (0.8 g/kg/d).

Investigation of quinocetone-induced mitochondrial damage and apoptosis in HepG2 cells and compared with its metabolites

Quinocetone (QCT) has been widely used as an animal growth promoter in China. However, amounts of available data indicated that QCT probably had potential toxicity. The present study was aimed to investigate the genotoxicity, mitochondrial damage and apoptosis in HepG2 cells for QCT and its metabolites, DQCT and MQCA. QCT has seriously cytotoxic to HepG2 cells. The cell viability test and cytokinesis-block micronucleus test showed that the micronucleus frequency of cells treated with QCT has increased significantly, compared with DQCT and MQCA. With increasing of QCT concentrations, the genomic template stability and mitochondrial damage of HepG2 cells were aggravated. QCT-induced apoptosis in HepG2 cells were also observed. Data of caspase activities in measurement and real-time RT-PCR possibly suggested both of the mitochondria-dependent and mitochondria-independent pathways participated in the HepG2 cells apoptosis. However, all the results suggested that DQCT and MQCA showed only a little cytotoxic to HepG2 cells. In a word, QCT had toxic effects on HepG2 cells and resulted in the mitochondria-dependent and mitochondria-independent pathways of apoptosis, but the intermediate metabolites of QCT (DQCT and MQCA) were not.

Tissue depletion of quinocetone and its five major metabolites in pigs, broilers, and carp fed quinocetone premix

A residue depletion study was performed to investigate the tissue kinetics of quinocetone (1) and its major metabolites. Quinocetone and its major metabolites were simultaneously quantitated with a high-performance liquid chromatography-ultraviolet (HPLC-UV) method. A total of 25 pigs, 30 broilers, and 50 carp were fed 100 mg/kg quinocetone for 90, 42, and 60 days, respectively. Liver, kidney, muscle, and fat (skin) tissues were collected at five different withdrawal times for analysis. Results revealed that quinocetone, 1-desoxyquinocetone (2), carbonyl-reduced 4-desoxyquinocetone (4), 3-methylquinoxaline-2-carboxylic acid (5), and carbonyl-reduced dideoxyquinocetone (6) could be depleted quickly in tissues; by contrast, dideoxyquinocetone, 3, persisted for a long time in the liver. Therefore, the liver is possibly the target tissue of quinocetone, and 3 is the residual marker; the recommended withdrawal times (WDTs) are 0 days in pigs and carp and 3 days in broilers. These results provided clear monitoring tools and technical standards to evaluate the food safety of quinocetone.

Polyphenol-rich foods exhibit DNA antioxidative properties and protect the glutathione system in healthy subjects

SCOPE

Polyphenols (ingested via food items) can decrease DNA, and oxidative damage of proteins and lipids. However, polyphenol effects in healthy populations have not been well defined. The aim of this study was to assess the relationship between urinary total polyphenol excretion (TPE), a biomarker of total polyphenol intake (TPI), polyphenol-rich foods, and oxidative stress biomarkers in healthy adults of different ages participating in the cross-sectional PAScual MEDicina study.

METHODS AND RESULTS

Urinary TPE was determined by Folin-Ciocalteau method in spot urine samples of 81 participants (46 women), classified into three age groups: 18 to 39, 40 to 54, and 55 to 72 years of age. TPI was quantified from 3-day dietary records using the Phenol-Explorer database. Urinary TPE increased with age (p < 0.001). Urinary TPE was inversely associated with urinary 8-hydroxydeoxyguanosine (8-OHdG; p<0.001) and erythrocyte-oxidized glutathione concentrations (p < 0.05). A negative association between urinary 8-OHdG and daily intake of polyphenols from vegetables and fermented beverages such as red wine was observed.

CONCLUSION

Urinary TPE increased with age and may reflect attenuation of oxidative damage. These results could explain the beneficial effects in healthy individuals of a diet rich in vegetables and moderate red wine; food items typical of the Mediterranean diet.

Hypoglycemic effect of the water extract of Pu-erh tea

The water extraction and composition of pu-erh tea, as well as the hypoglycemic effect of the water extract of pu-erh tea (WEPT) in vivo and in vitro, are reported to investigate its hypoglycemic effect on diabetes. High-performance liquid chromatography and colorimetric methods are used to analyze the tea catechins, caffeine, polyphenols, amino acids, and polysaccharides of the WEPT. The effect of the WEPT on glucose uptake by cultured HepG2 cells and the inhibition effect of rat intestinal sucrase, maltase, and porcine pancreatic amylase are determined in vitro. Then, the blood glucose and insulin levels of intragastrically administered WEPT on fasting and oral glucose tolerance test (OGTT) using type 2 diabetic db/db (BKS.Cg-m +/+ Lepr(db)/J) mice are determined in vivo. The results showed that the WEPT dose-dependently and significantly increased glucose uptake by HepG2 cells and inhibited rat intestinal sucrase, maltase, and porcine pancreatic amylase activity. The WEPT intragastrically given for 4 weeks suppressed the increase in blood insulin and glucose levels of db/db mice fasted overnight. In OGTT, the WEPT improved impaired glucose tolerance and ameliorated retarded insulin response at 60 and 120 min in db/db mice. These results suggest that the WEPT has beneficial effects on glucose homeostasis in type 2 diabetes and in amendment of insulin resistance.