Apple peel polyphenols protect against gastrointestinal mucosa alterations induced by indomethacin in rats

The Behavior of Phenolic Compounds from Apples during Simulated Gastrointestinal Digestion with Focus on Chlorogenic Acid

The fate of phenolic compounds during digestion is important for their bioactive effects in the digestive tract. The aim was to study the various phenolic compounds occurring in the peel and flesh of apples in in vitro simulated gastrointestinal digestion, focusing on the behavior of chlorogenic acids. Additionally, the behavior of individual chlorogenic acids (chlorogenic, neochlorogenic, and cryptochlorogenic) was studied in models of simulated salivary, gastric, and intestinal fluid electrolyte solutions (SSF, SGF, SIF). At the end of the intestinal phase of the digestion of peel and flesh, the amount of recovered dihydrochalcones and flavonols increased or was similar to the amount in the gastric phase, which showed their stability. Anthocyanins and flavan-3-ols decreased, which suggests their biotransformation. Chlorogenic acid isomerized into neochlorogenic and cryptochlorogenic acid: chlorogenic acid from the peel into 22% and 41% of the isomers in the salivary and intestinal phases, respectively; chlorogenic acid from the flesh into 12% of the isomers in the intestinal phase. Similarly, chlorogenic acid isomerized in model solutions (20% and 26% of the isomers in SSF and SIF, respectively). Neochlorogenic and cryptochlorogenic acid isomerized in SSF and SIF into other two forms. They were all stable in SGF. For bioactive effects in the digestive tract, the biotransformation of chlorogenic acids should be considered.

Phenolic Compounds from Apples: From Natural Fruits to the Beneficial Effects in the Digestive System

Conditions in the gastrointestinal tract and microbial metabolism lead to biotransformation of parent, native phenolic compounds from apples into different chemical forms. The aim of this work was to review current knowledge about the forms of phenolic compounds from apples in the gastrointestinal tract and to connect it to their potential beneficial effects, including the mitigation of health problems of the digestive tract. Phenolic compounds from apples are found in the gastrointestinal tract in a variety of forms: native (flavan-3-ols, phenolic acids, flavonols, dihydrochalcones, and anthocyanins), degradation products, various metabolites, and catabolites. Native forms can show beneficial effects in the stomach and small intestine and during the beginning phase of digestion in the colon. Different products of degradation and phase II metabolites can be found in the small intestine and colon, while catabolites might be important for bioactivities in the colon. Most studies connect beneficial effects for different described health problems to the whole apple or to the amount of all phenolic compounds from apples. This expresses the influence of all native polyphenols from apples on beneficial effects. However, further studies of the peculiar compounds resulting from native phenols and their effects on the various parts of the digestive tract could provide a better understanding of the specific derivatives with bioactivity in humans.

Apple (Malus domestica Borkh) leaves attenuate indomethacin-induced gastric ulcer in rats

Malus domestica Borkh, the apple tree, exhibited numerous pharmacological properties including antioxidant, neuroprotective, anti-inflammatory, anticancer and antimicrobial activities. The present work aimed to annotate the secondary metabolites from a butanol fraction of apple leaves (BLE), evaluate the gastro-protective and healing effects of this fraction against indomethacin-induced gastric ulcers in rats and to identify its mechanism of action. BLE (100, and 200 mg/kg) was orally administered in rats as an acute treatment against indomethacin-induced gastric ulcer in comparison with famotidine as reference anti-ulcer drug. The stomachs of rats were collected to determine the ulcer index, the preventive ratio, measure the activity of glutathione peroxidase (GPx), and estimate the expression of cyclooxygenase-2 (COX-2), and heat shock protein 70 (HSP70). Furthermore, we evaluated both inflammatory and oxidative stress markers in the gastric tissues. We also performed histopathological study of gastric mucosa using H&E stain and periodic Schiff base stain to evaluate both gastric injury scores and gastric mucus content respectively. Pretreatment with BLE markedly lowered the severity of gastric injury induced by indomethacin, decreased oxidative stress, inflammatory cytokines, and COX-2 expression in the examined gastric tissues. The gastric healing effect of BLE was associated with increased mucoglycoproteins, and HSP70 expression. Additionally, gastric healing effect of high dose of BLE was superior to that of famotidine in decreasing gastric injury scores, COX-2, inflammatory cytokines, lipid peroxidation and in increasing gastric mucin content, HSP70, and reduced glutathione. These findings indicate that BLE is effective in accelerating ulcer healing by boosting HSP70 expression, and decreasing COX-2 expression, oxidative stress, and gastric inflammation which might be related to the presence of 21 phytoconstituents.

Wheat and Rice beyond Phenolic Acids: Genetics, Identification Database, Antioxidant Properties, and Potential Health Effects

Wheat and rice play a vital role in human nutrition and food security. A better understanding of the potential health benefits associated with consuming these cereals, combined with studies by plant scientists and food chemists to view the entire food value chain from the field, pre and post-harvest processing, and subsequent "fork" consumption, may provide the necessary tools to optimize wheat and rice production towards the goal of better human health improvement and food security, providing tools to better adapt to the challenges associated with climate change. Since the available literature usually focuses on only one food chain segment, this narrative review was designed to address the identities and concentration of phenolics of these cereal crops from a farm-to-fork perspective. Wheat and rice genetics, phenolic databases, antioxidant properties, and potential health effects are summarized. These cereals contain much more than phenolic acids, having significant concentrations of flavonoids (including anthocyanins) and proanthocyanidins in a cultivar-dependent manner. Their potential health benefits in vitro have been extensively studied. According to a number of in vivo studies, consumption of whole wheat, wheat bran, whole rice, and rice bran may be strategies to improve health. Likewise, anthocyanin-rich cultivars have shown to be very promising as functional foods.

Empire Apple (Malus domestica) Juice, Pomace, and Pulp Modulate Intestinal Functionality, Morphology, and Bacterial Populations In Vivo (Gallus gallus)

Approximately $20 billion of apple sales are generated annually in the United States. With an estimated 5 million tons produced yearly in the U.S. within the last decade, apple consumption is considered ubiquitous. Apples are comprised of bioactive constituents such as phytochemicals and prebiotics that may potentiate intestinal health and the gut microbiome. This study aimed to evaluate the effects of Empire apple juice, pomace, and pulp soluble extracts on intestinal functionality, morphology, and the microbiome in vivo (Gallus gallus). There were five treatment groups: non-injected (NI); 18 MΩ H2O (H2O); 6% apple juice (AJ); 6% apple pomace (APo); 6% apple pulp (APu). The eggs were treated by intra-amniotic administration of the samples on day 17 of incubation. After hatching, the blood, tissue, and cecum samples were collected for further analyses—including duodenal histomorphology, hepatic and duodenal mRNA expression, and cecal bacterial populations. Crypt depth was significantly (p < 0.5) shortest in AJ when compared to APo and APu. APo and APu soluble extracts significantly improved villi surface area compared to NI and H2O control groups. The highest count of Paneth cells per crypt was observed in APo as compared to all groups. In addition, the expression of brush border membrane micronutrient metabolism and functional proteins varied between treatments. Lastly, Lactobacillus cecal microbial populations increased significantly in the AJ group, while AJ, APu, and APu increased the abundance of Clostridium (p < 0.5). Ultimately, these results indicate the potential of Empire apple pomace to improve host intestinal health and the gut microbiome.

Emerging role of mitochondrial DAMPs, aberrant mitochondrial dynamics and anomalous mitophagy in gut mucosal pathogenesis

Gastroduodenal inflammation and ulcerative injuries are increasing due to expanding socio-economic stress, unhealthy food habits-lifestyle, smoking, alcoholism and usage of medicines like non-steroidal anti-inflammatory drugs. In fact, gastrointestinal (GI) complications, associated with the prevailing COVID-19 pandemic, further, poses a challenge to global healthcare towards safeguarding the GI tract. Emerging evidences have discretely identified mitochondrial dysfunctions as common etiological denominators in diseases. However, it is worth realizing that mitochondrial dysfunctions are not just consequences of diseases. Rather, damaged mitochondria severely aggravate the pathogenesis thereby qualifying as perpetrable factors worth of prophylactic and therapeutic targeting. Oxidative and nitrosative stress due to endogenous and exogenous stimuli triggers mitochondrial injury causing production of mitochondrial damage associated molecular patterns (mtDAMPs), which, in a feed-forward loop, inflicts inflammatory tissue damage. Mitochondrial structural dynamics and mitophagy are crucial quality control parameters determining the extent of mitopathology and disease outcomes. Interestingly, apart from endogenous factors, mitochondria also crosstalk and in turn get detrimentally affected by gut pathobionts colonized during luminal dysbiosis. Although mitopathology is documented in various pre-clinical/clinical studies, a comprehensive account appreciating the mitochondrial basis of GI mucosal pathologies is largely lacking. Here we critically discuss the molecular events impinging on mitochondria along with the interplay of mitochondria-derived factors in fueling mucosal pathogenesis. We specifically emphasize on the potential role of aberrant mitochondrial dynamics, anomalous mitophagy, mitochondrial lipoxidation and ferroptosis as emerging regulators of GI mucosal pathogenesis. We finally discuss about the prospect of mitochondrial targeting for next-generation drug discovery against GI disorders.

Revisiting the Oxidation of Flavonoids: Loss, Conservation or Enhancement of Their Antioxidant Properties

Flavonoids display a broad range of health-promoting bioactivities. Among these, their capacity to act as antioxidants has remained most prominent. The canonical reactive oxygen species (ROS)-scavenging mode of the antioxidant action of flavonoids relies on the high susceptibility of their phenolic moieties to undergo oxidation. As a consequence, upon reaction with ROS, the antioxidant capacity of flavonoids is severely compromised. Other phenol-compromising reactions, such as those involved in the biotransformation of flavonoids, can also markedly affect their antioxidant properties. In recent years, however, increasing evidence has indicated that, at least for some flavonoids, the oxidation of such residues can in fact markedly enhance their original antioxidant properties. In such apparent paradoxical cases, the antioxidant activity arises from the pro-oxidant and/or electrophilic character of some of their oxidation-derived metabolites and is exerted by activating the Nrf2–Keap1 pathway, which upregulates the cell’s endogenous antioxidant capacity, and/or, by preventing the activation of the pro-oxidant and pro-inflammatory NF-κB pathway. This review focuses on the effects that the oxidative and/or non-oxidative modification of the phenolic groups of flavonoids may have on the ability of the resulting metabolites to promote direct and/or indirect antioxidant actions. Considering the case of a metabolite resulting from the oxidation of quercetin, we offer a comprehensive description of the evidence that increasingly supports the concept that, in the case of certain flavonoids, the oxidation of phenolics emerges as a mechanism that markedly amplifies their original antioxidant properties. An overlooked topic of great phytomedicine potential is thus unraveled.

Protection against indomethacin-induced loss of intestinal epithelial barrier function by a quercetin oxidation metabolite present in onion peel: In vitro and in vivo studies

Oxidative stress is directly implicated in the loss of intestinal epithelial barrier function (IEBF) induced by non-steroidal anti-inflammatory drugs (NSAIDs). Previous studies by our research team demonstrated that 2-(3,4-dihydroxybenzoyl)-2,4,6-trihydroxy-3(2H)-benzofuranone (BZF), a quercetin oxidation metabolite that naturally occurs in onion peels, exhibits an antioxidant potency notably higher than quercetin. Thus, we assessed the potential of BZF and a BZF-rich onion peel aqueous extract (OAE) to protect against the loss of IEBF in Caco-2 cell monolayers and in rats exposed to indomethacin. In vitro, pure BZF and OAE standardized in BZF (100 nM), protected against the drop in transepithelial electrical resistance by 70 - 73%. Likewise, it prevented the increase in fluorescein-isothiocyanate labelled dextran (FITC-dextran) paracellular transport by 74% and oxidative stress by 84 - 86%. In vivo, BZF, given orally at a dose 80 µg/Kg bw as OAE, totally abolished a 30-fold increase in FITC-dextran serum concentration induced by indomethacin. This effect was dose-dependent and largely conserved (85%) when OAE was given 180-min prior to indomethacin. The IEBF-protective effect of OAE was accompanied by a full prevention of the NF-ĸB activation, and the increases in interleukine-8 secretion and myeloperoxidase activity induced by indomethacin. The protection was also associated with a 21-fold increase in Nrf2, and a 7-fold and 9-fold increase in heme oxygenase-1 and NAD(P)H-quinone oxidoreductase 1, respectively. The IEBF-protecting effect of OAE involves, most likely, its dual capacity to activate Nrf2 while inhibiting NF-ĸB activation. The extremely low doses of BZF needed to promote such actions warrants extending its IEBF-protective effects to other NSAIDs.

Azoxymethane-Induced Colorectal Cancer Mice Treated with a Polyphenol-Rich Apple Extract Show Less Neoplastic Lesions and Signs of Cachexia

Obesity is considered a risk factor for the development of colorectal cancer. In rodents, high-fat (HF) diets are able to increase the formation of azoxymethane (AOM)-induced polyps. Polyphenol-rich apple extracts have antioxidant and anti-inflammatory activities and may induce an amelioration of the manifestations of colorectal cancer. Twenty-seven male Crl:CD-1 mice received AOM during four weeks and were subsequently divided into three groups fed a HF diet (n = 9 each group): a non-supplemented group, a second group supplemented with apple extract at 1%, and a third group supplemented with the same apple extract at 1.5%. Energy metabolism and the respiratory quotient were not affected by the supplementation with the apple extract. Although body weight was not affected by the treatment, the mice supplemented with the apple extract showed less signs of cachexia than the non-treated mice. In the intestine, the mice supplemented with the apple extract showed lower sucrase, dipeptidyl-peptidase IV, and aminopeptidase N activities, and less intestinal lesions (aberrant crypt foci and polyps). Administration of a polyphenol-rich apple extract reduces the number of neoplastic lesions in mice with AOM-induced colorectal cancer and contributes to preserve adipose tissue mass.

Quercetin Oxidation Metabolite Present in Onion Peel Protects Caco-2 Cells against the Oxidative Stress, NF-kB Activation, and Loss of Epithelial Barrier Function Induced by NSAIDs

The potential of 2-(3,4-dihydroxybenzoyl)-2,4,6-trihydroxy-3(2H)-benzofuranone (BZF), a quercetin oxidation metabolite, and that of a BZF-rich onion peel aqueous extract (OAE) to protect Caco-2 monolayers against the oxidative stress (OS) and an increased permeability (IP) induced by five nonsteroidal anti-inflammatory drugs (NSAIDs) (indomethacin, diclofenac, piroxicam, ibuprofen, and metamizole) were investigated. Under identical OS conditions, the NSAIDs substantially differed in their ability to induce an IP and/or NF-kB activation. The OAE (100 nM BZF) protected in identical magnitude (84-86%) against OS but in a highly dissimilar manner against the IP (18-73%). While all NSAIDs activated NF-kB, the OAE prevented only that induced by indomethacin. Results reveal that the IP has no direct relationship with the OS and that with the exception of indomethacin, the prevention of NSAIDs-induced OS and/or NF-kB activation plays no fundamental role in the IP-protecting effect of OAE. These results warrant the in vivo evaluation of OAE against indomethacin-induced loss of intestinal barrier function.

The Role of Fruit by-Products as Bioactive Compounds for Intestinal Health

The fruit processing industry generates large amounts of wastes (pomace, seeds, peels) that causes negative environmental impact with considerable treatment expenses. Nevertheless, various studies demonstrated that these by-products are still rich in bioactive compounds, especially dietary fibres and phenolic compounds, thus leading to significant chemical, physical and biological properties. These characteristics make fruits by-products a good source for new supplements in food products having important effect on intestinal function. Thus, the aim of this review is to evaluate the different bioactive compounds isolated from fruit by-products and to analyse their application in various formulations for the food and nutraceutical industries. In consideration of the biological properties of these compounds, their role in the functioning and action on intestine and gut flora was discussed.

Granny Smith apple procyanidin extract upregulates tight junction protein expression and modulates oxidative stress and inflammation in lipopolysaccharide-induced Caco-2 cells

Granny Smith apple procyanidin extracts upregulate tight junction protein expression, probably acting via the modulation of oxidative stress and inflammation in lipopolysaccharide-induced Caco-2 cells.

Effects of flavonoids on intestinal inflammation, barrier integrity and changes in gut microbiota during diet-induced obesity

Diet-induced obesity is associated with low-grade inflammation, which, in most cases, leads to the development of metabolic disorders, primarily insulin resistance and type 2 diabetes. Although prior studies have implicated the adipose tissue as being primarily responsible for obesity-associated inflammation, the latest discoveries have correlated impairments in intestinal immune homeostasis and the mucosal barrier with increased activation of the inflammatory pathways and the development of insulin resistance. Therefore, it is essential to define the mechanisms underlying the obesity-associated gut alterations to develop therapies to prevent and treat obesity and its associated diseases. Flavonoids appear to be promising candidates among the natural preventive treatments that have been identified to date. They have been shown to protect against several diseases, including CVD and various cancers. Furthermore, they have clear anti-inflammatory properties, which have primarily been evaluated in non-intestinal models. At present, a growing body of evidence suggests that flavonoids could exert a protective role against obesity-associated pathologies by modulating inflammatory-related cellular events in the intestine and/or the composition of the microbiota populations. The present paper will review the literature to date that has described the protective effects of flavonoids on intestinal inflammation, barrier integrity and gut microbiota in studies conducted using in vivo and in vitro models.

Anti-ulcer mechanisms of polyphenols extract of Euphorbia umbellata (Pax) Bruyns (Euphorbiaceae)

ETHNOPHARMACOLOGICAL RELEVANCE

Euphorbia umbellata (leitosinha) is used in southern Brazilian folk medicine to treat gastric problems, as well as for its analgesic and anti-inflammatory properties.

AIM OF STUDY

To evaluate the anti-ulcer effects of methanolic bark fraction (MF) against in vivo and in vitro assays, as well as an antioxidant, antibacterial and chromatographic study of this fraction.

MATERIALS AND METHODS

In vivo anti-ulcer activity was performed using ethanol and indomethacin models with different MF concentrations (50, 100 or 200mg/Kg). The stomachs of the animals were applied to histological evaluation, and the serum to evaluate the ABTS(•+) radical capture. The 200mg/Kg dose was used to analyze the mechanisms involved in antiulcerogenic properties of methanolic fraction. The in vitro activity was performed using several different antioxidant assays, in addition to anti-Helicobacter pylori and anti-urease experiments. The chromatographic study was carried out by LC-MS analysis.

RESULTS

Pharmacological investigation of the MF showed an anti-ulcer potential in ethanol and indomethacin in vivo assays. The material presented a high antioxidant activity for several oxidant in vitro systems (DPPH(•), ABTS(•+), O2(•-), HOCl, TauCl and HRP), as well as an ABTS(•+) capture increasing (7.5%) by the treated animals serum (when compared to the negative control). Prostaglandins, nitric oxide/ cyclic guanosine monophosphate pathway and involvement of the protein components of the glutathione complex are some of the mechanisms related with this potential anti-ulcer action. The histological examination of the stomachs of the animals showed that the MF also prevents local action of offensive agents. Chemical analysis using LC-QTOF-MS revealed the presence of ellagic and gallic acid derivatives and flavonols.

CONCLUSION

The findings provide scientific basis to the ethnopharmacological purpose of the studied plant and the biological activities of MF of E. umbellata stem bark may be due to the presence of phenolic compounds.

Deleterious Effect of p-Cresol on Human Colonic Epithelial Cells Prevented by Proanthocyanidin-Containing Polyphenol Extracts from Fruits and Proanthocyanidin Bacterial Metabolites

The protective effect of proanthocyanidin-containing polyphenol extracts from apples, avocados, cranberries, grapes, or proanthocyanidin microbial metabolites was evaluated in colonic epithelial cells exposed to p-cresol, a deleterious compound produced by the colonic microbiota from l-tyrosine. In HT29 Glc(-/+) cells, p-cresol significantly increased LDH leakage and decreased ATP contents, whereas in Caco-2 cell monolayers, it significantly decreased the transepithelial electrical resistance and increased the paracellular transport of FITC-dextran. The alterations induced by p-cresol in HT29 Glc(-/+) cells were prevented by the extracts from cranberries and avocados, whereas they became worse by extracts from apples and grapes. The proanthocyanidin bacterial metabolites decreased LDH leakage, ameliorating cell viability without improving intracellular ATP. All of the polyphenol extracts and proanthocyanidin bacterial metabolites prevented the p-cresol-induced alterations of barrier function. These results suggest that proanthocyanidin-containing polyphenol extracts and proanthocyanidin metabolites likely contribute to the protection of the colonic mucosa against the deleterious effects of p-cresol.

Polyunsaturated fatty acid induces cardioprotection against ischemia-reperfusion through the inhibition of NF-kappaB and induction of Nrf2

The mechanistic evidence to support the cardioprotective effects of polyunsaturated fatty acids (PUFA) are controversial. The aim was to test cardioprotective mechanisms induced by PUFA supplementation against cardiac ischemia-reperfusion (IR) injury. Ten-week-old male Wistar rats (225 ± 14 g, n = 14) were divided in two groups: rats without supplementation ( n = 7) and a PUFA group, supplemented by PUFA (0.6 g/kg/day; DHA:EPA = 3:1) for eight weeks ( n = 7). Hearts were perfused with Krebs-Henseleit buffer for 20 min (control conditions); others were subjected to control conditions, 30 min of global ischemia and 120 min of reperfusion (IR group). Infarct size (IS) and left ventricular developed pressure (LVDP) were measured at 120 min of reperfusion. Oxidative stress biomarkers (TBARS, total carbonyls), antioxidant status (CAT, catalase; SOD, superoxide dismutase; GSH-Px, glutathione peroxidase activity and GSH/GSSG ratio), myeloperoxidase activity, ATP levels and nuclear transcription factor erythroid 2-related factor 2 (Nrf2) and nuclear factor kappaB (NF-κB) were determined in both experimental conditions. At the end of reperfusion, hearts supplemented with PUFA showed lower IS and a higher LVDP compared with the nonsupplemented rats. Hearts in the group supplemented with PUFA showed lower levels of oxidative stress markers and higher antioxidant activity, decreased MPO activity and NF-κB and Nrf2 activation compared with the nonsupplemented group. Cardioprotective effects of PUFA are exerted through induction of anti-inflammatory and antioxidant mechanism at tissue level.

Potential Prophylactic Properties of Apple and Characterization of Potent Bioactive from cv. "Granny Smith" Displaying Strong Antimutagenicity in Models Including Human Lymphoblast TK6(+/-) Cell Line

Potential prophylactic attributes in terms of antimutagenicity, antioxidant, and radioprotective properties were evaluated for 8 common apple cultivars namely "Fuji," "Golden Delicious," "Granny Smith," "Ambri Kashmiri," "Kinnaur," "Red Delicious," "Royal Gala," and "Shimla," where cultivar based significant variation was observed. Cv. "Granny Smith" displayed significantly higher and broad spectrum antimutagenicity in Escherichia coli rpoB based rifampicin resistance (Rif(R) ) assay, whereas, "Ambri Kashmiri," "Royal Gala," and "Shimla" showed lower antimutagenicity. Cultivars "Ambri Kashmiri," "Kinnaur," and "Red Delicious" exhibited strong antioxidant activity than cv. "Granny Smith" as assayed by radical scavenging, reducing potential and radioprotective property assays. The antioxidant and radioprotective properties were found to be better correlated than antimutagenicity. Suppression of error-prone DNA repair pathway (such as E. coli SOS response) was found to be one of the possible mechanisms contributing to its antimutagenicity. Phenolic extract of "Granny Smithˮ showing higher antimutagenicity was HPLC purified and the bioactive fraction (tR 35.4 min) contributing maximally (∼80%) to the observed antimutagenicity was identified as procyanidin dimer (PD) by ESI-MS/MS. The above observed antimutagenicity in bacterial assay system was well reproduced in Thymidine Kinase Mutation (TKM) assay performed using human lymphoblast cell line (TK6(+/-) ) cell line making the findings more prophylactically relevant.

Ω3 Supplementation and intermittent hypobaric hypoxia induce cardioprotection enhancing antioxidant mechanisms in adult rats

Intermittent hypobaric hypoxia (IH) is linked with oxidative stress, impairing cardiac function. However, early IH also activate cardio-protective mechanisms. Omega 3 fatty acids (Ω3) induce cardioprotection by reducing infarct size and reinforcing antioxidant defenses. The aim of this work was to determine the combined effects of IH and Ω3 on cardiac function; oxidative balance and inflammatory state. Twenty-eight rats were randomly divided into four groups: normobaric normoxia (N); N + Ω3 (0.3 g·kg⁻¹·day⁻¹); IH; and IH + Ω3. IH was induced by 4 intercalate periods of hypoxia (4 days)—normoxia (4 days) in a hypobaric chamber during 32 days. At the end of the exposure, hearts were mounted in a Langendorff system and subjected to 30 min of ischemia followed by 120 min of reperfusion. In addition, we determined HIF-1α and ATP levels, as well as oxidative stress by malondialdehyde and nitrotyrosine quantification. Further, the expression of the antioxidant enzymes superoxide dismutase, catalase, and glutathione peroxidase was determined. NF-kappaB and myeloperoxidase levels were assessed in the hearts. Relative to N hearts, IH improved left ventricular function (Left ventricular developed pressure: N; 21.8 ± 3.4 vs. IH; 42.8 ± 7.1 mmHg; p < 0.05); reduced oxidative stress (Malondialdehyde: N; 14.4 ± 1.8 vs. IH; 7.3 ± 2.1 μmol/mg prot.; p < 0.05); and increased antioxidant enzymes expression. Supplementation with Ω3 induces similar responses as IH group. Our findings suggest that both, IH and Ω3 in an independent manner, induce functional improvement by antioxidant and anti-inflammatory mechanisms, establishing cardio-protection.

A novel triterpenoid isolated from apple functions as an anti-mammary tumor agent via a mitochondrial and caspase-independent apoptosis pathway

A novel triterpenoid, named 3β-trans-cinnamoyloxy-2α-hydroxy-urs-12-en-28-oic acid (CHUA), was one of the main components of apple peels and showed potent in vitro antitumor activity against human tumor cells. In vivo antitumor experiments showed that CHUA could significantly inhibit the growth of mammary tumor in a nude mouse xenograft model at a dose of 50 mg/kg/day without body weight loss and mortality. In vitro, CHUA could induce apoptosis in MDA-MB-231 cells through the detection of DNA fragments and LDH activity. Simultaneously, mitochondrial transmembrane potential was markedly reduced and the release of cytochrome c was increased after CHUA treatment. It also up-regulated the expression ratio of mitochondrial Bax/Bcl-2 regulated by SIRT1 and p53. Interestingly, z-VAD-fmk and z-DEVD-fmk augmented cell death after CHUA treatment. Other protease(s) different from caspase-3 might be responsible for the degradation of PARP. These results suggested that the pro-apoptotic activity of CHUA may be adjusted by mitochondrial and caspase-independent pathways.

Protective effects of (1-(4-hydroxy-phenyl)-3-m-tolyl-propenone chalcone in indomethacin-induced gastric erosive damage in rats

Background

Non-steroidal anti-inflammatory drugs (NSAIDs) can result in peptic ulcer disease (PUD) which is a common condition worldwide. The aim of this study was to evaluate the antiulcer properties of (1-(4-hydroxy-phenyl)-3-m-tolyl-propenone) (HPTP) chalcone in rats using indomethacin as ulcerogenic agent.

Results

None of the rats showed symptoms of kidney and liver toxicity during the term of the study. Administration of HPTP had decreased the acidity, increased gastric wall mucus and flattening of gastric mucosa and reducing erosive gastric damage area. HPTP also showed dose dependent increase in SOD, GPx activity and PGE₂ level and decrease MDA. H & E stain showed decreased infiltration of leucocytes with edema of submucosal layer. PAS staining showed intense uptake of magenta color of gastric wall mucus in rats fed with HPTP, and immunohistochemical staining of gastric mucosa revealed over-expression of HSP70 protein, down-expression of Bax protein and over expression of TGF-β in rats administered with HPTP.

Conclusion

This study has revealed that chalcone1-(4-hydroxy-phenyl)-3-m-tolyl-propenone can serve as a safe and effective antiulcer agent as it has been proved to increase pH and gastric wall mucus, increase GPx, SOD, PGE₂, and decrease MDA level, ultimately, it has also contributes towards the over-expression of HSP protein andTGF-β, and down-expression of Bax protein.

Electronic supplementary material

The online version of this article (doi:10.1186/s12917-014-0303-7) contains supplementary material, which is available to authorized users.

Polyphenols and mitochondria: an update on their increasingly emerging ROS-scavenging independent actions

Polyphenols, ubiquitously present in fruits and vegetables, have been traditionally viewed as antioxidant molecules. Such contention emerged, mainly from their well established in vitro ability to scavenge free radicals and other reactive oxygen species (ROS). During the last decade, however, increasing evidence has emerged supporting the ability of certain polyphenols to also exert numerous ROS-scavenging independent actions. Although the latter can comprise the whole cell, particular attention has been placed on the ability of polyphenols to act, whether favorably or not, on a myriad of mitochondrial processes. Thus, some particular polyphenols are now recognized as molecules capable of modulating pathways that define mitochondrial biogenesis (i.e., inducing sirtuins), mitochondrial membrane potential (i.e., mitochondrial permeability transition pore opening and uncoupling effects), mitochondrial electron transport chain and ATP synthesis (i.e., modulating complexes I to V activity), intra-mitochondrial oxidative status (i.e., inhibiting/inducing ROS formation/removal enzymes), and ultimately mitochondrially-triggered cell death (i.e., modulating intrinsic-apoptosis). The present review describes recent evidence on the ability of some polyphenols to modulate each of the formerly mentioned pathways, and discusses on how, by acting on such mitochondrial processes, polyphenols may afford protection against those mitochondrial damaging events that appear to be key in the cellular toxicity induced by various xenobiotics as well as that seen during the development of several ROS-related diseases.

Application of an Optimized HPLC Method for the Detection of Various Phenolic Compounds in Apples from Lithuanian Cultivars

A specific analytical procedure including sample preparation and HPLC analysis was developed and validated for the detection of phenolic compounds in the samples of different apples from popular Lithuanian cultivars “Aldas,” “Auksis,” “Ligol,” and “Šampion.” The conditions for phenol extraction were optimized: the solvent of the extraction was 70% (v/v) ethanol, and the extraction was performed in an ultrasound bath for 20 min at the temperature of 40°C. The HPLC mobile phase consisted of 2% (v/v) acetic acid in water and 100% (v/v) acetonitrile. Using the HPLC technique, 11 analytes were identified, and their specificity was confirmed: procyanidin B1, (+)-catechin, chlorogenic acid, procyanidin B2, (−)-epicatechin, rutin, hyperoside, isoquercitrin, avicularin, quercitrin, and phloridzin. Chlorogenic acid was the major component in “Aldas,” “Auksis,” and “Ligol” and procyanidin B2 in “Šampion.” Hyperoside and avicularin were the dominant compounds of all the identified quercetin derivatives in “Aldas” and “Auksis;” hyperoside in “Šampion;” and quercitrin in “Ligol.” The total content of phenolic compounds varied from 1641.0 ± 47.9 μg/g (cv. “Ligol”) to 4291.3 ± 154.2 μg/g (cv. “Aldas”).

Polyphenols protect the epithelial barrier function of Caco-2 cells exposed to indomethacin through the modulation of occludin and zonula occludens-1 expression

The aim of this study was to determine the protective effect of quercetin, epigallocatechingallate, resveratrol, and rutin against the disruption of epithelial integrity induced by indomethacin in Caco-2 cell monolayers. Indomethacin decreased the transepithelial electrical resistance and increased the permeability of the monolayers to fluorescein-dextran. These alterations were abolished by all the tested polyphenols but rutin, with quercetin being the most efficient. The protective effect of quercetin was associated with its capacity to inhibit the redistribution of ZO-1 protein induced in the tight junction by indomethacin or rotenone, a mitochondrial complex-I inhibitor, and to prevent the decrease of ZO-1 and occludin expression induced by indomethacin. The fact that the antioxidant polyphenols assayed in this study differ in their protective capacity against the epithelial damage induced by indomethacin suggests that this damage is due to the ability of this agent to induce not only oxidative stress but also mitochondrial dysfunction.

Apple peel polyphenols and their beneficial actions on oxidative stress and inflammation

Since gastrointestinal mucosa is constantly exposed to reactive oxygen species from various sources, the presence of antioxidants may contribute to the body’s natural defenses against inflammatory diseases.

Validation of a surgical technique for rat intestinal irradiation: potential side effects prevention by dietary grape phenolics

AIMS

This study evaluates and defines the histological and biochemical consequences of irradiation on the Hauer-Jensen intestinal model and investigates the potential effects of dietary polyphenols.

MAIN METHODS

Sprague-Dawley rats were orchiectomized, and an ileal loop was transposed to the left part of the scrotum, then irradiated 2 weeks after surgery with a single dose of 21 Gy (4.49 Gy/min). Four groups of rats received either phenolic extracts from grape seeds (EGS) and from red wine (ACYS, EGT), or pure quercetin 3-O-β-glucoside (Q3G), for 5 days before the irradiation and were sacrificed 2 weeks after. Antioxidant enzyme activities, i.e. superoxide dismutase (SOD) and glutathione peroxidase activity (GSHPx), and oxidative markers such as myeloperoxidase activity (MPO) and thiobarbituric acid reactive substances (MDA) were measured as well as cytokine-induced neutrophil chemoattractant level (CINC-1), a chemokine involved in inflammation.

KEY FINDINGS

Irradiated rats exhibited a high radiation injury score (RIS) with a thickened serosa, mucosal loss and ulceration, and epithelial atypicality. Intestinal MPO activity and CINC-1 concentration were significantly increased in irradiated animals (60 and 66 %, respectively). Higher plasma MDA levels (58 %) and SOD activity (32 %) were accompanied by a reduced GSHPx activity (79 %). However, feeding phenolic extracts remarkably reduced levels of blood SOD activity (34 % on average), intestinal CINC-1 (25-75 % range) and MPO activity (36-84 %). Except for Q3G, phenolics preserved the intestinal structure.

SIGNIFICANCE

These findings show that irradiation triggers an inflammation, and an oxidative stress by disturbing the pro-oxidant/antioxidant balance and indicate that phenolics supply exerts preventive effects against radio-induced intestinal impairment.

Inhibition of mitochondrial complex I by various non-steroidal anti-inflammatory drugs and its protection by quercetin via a coenzyme Q-like action

Mitochondrial dysfunction plays a major role in the development of oxidative stress and cytotoxicity induced by non-steroidal anti-inflammatory drugs (NSAIDs). A major objective of the present study was to investigate whether in vitro the NSAIDs, aspirin, indomethacin, diclofenac, piroxicam and ibuprofen, which feature different chemical structures, are able to inhibit mitochondrial complex I. All NSAIDs were effective inhibitors when added both, directly to mitochondria isolated from rat duodenum epithelium (50 μM) or to Caco-2 cells (250 μM). In the former system, complex I inhibition was concentration-dependent and susceptible to competition and reversion by the addition of coenzyme Q (32.5-520 μM). Based on reports suggesting a potential gastro-protective activity of quercetin, the ability of this flavonoid to protect isolated mitochondria against NSAIDs-induced complex I inhibition was evaluated. Low micromolar concentrations of quercetin (1-20 μM) protected against such inhibition, in a concentration dependent manner. In the case of aspirin, quercetin (5 μM) increased the IC50 by 10-fold. In addition, the present study shows that quercetin (5-10 μM) can behave as a "coenzyme Q-mimetic" molecule, allowing a normal electron flow along the whole electron transporting chain (complexes I, II, III and IV). The exposed findings reveal that complex I inhibition is a common deleterious effect of NSAIDs at the mitochondrial level, and that such effect is, for all tested agents, susceptible to be prevented by quercetin. Data provided here supports the contention that the protective action of quercetin resides on its, here for first time-shown, ability to behave as a coenzyme Q-like molecule.

Differential protective effects of quercetin, resveratrol, rutin and epigallocatechin gallate against mitochondrial dysfunction induced by indomethacin in Caco-2 cells

The beneficial effects of dietary polyphenols on health are due not only to their antioxidant properties but also to their antibacterial, anti-inflammatory and/or anti-tumoral activities. It has recently been proposed that protection of mitochondrial function (which is altered in several diseases such as Alzheimer, Parkinson, obesity and diabetes) by these compounds, may be important in explaining the beneficial effects of polyphenols on health. The aim of this study was to evaluate the protective effects of dietary polyphenols quercetin, rutin, resveratrol and epigallocatechin gallate against the alterations of mitochondrial function induced by indomethacin (INDO) in intestinal epithelial Caco-2 cells, and to address the mechanism involved in such damaging effect by INDO, which generates oxidative stress. INDO concentration dependently decreases cellular ATP levels and mitochondrial membrane potential in Caco-2 cells after 20min of incubation. INDO also inhibits the activity of mitochondrial complex I and causes accumulation of NADH; leading to overproduction of mitochondrial O(2)()(-), since it is prevented by pyruvate. Quercetin (0.01mg/ml), resveratrol (0.1mg/ml) and rutin (1mg/ml) protected Caco-2 cells against INDO-induced mitochondrial dysfunction, while no protection was observed with epigallocatechin gallate. Quercetin was the most efficient in protecting against mitochondrial dysfunction; this could be due to its ability to enter cells and accumulate in mitochondria. Additionally its structural similarity with rotenone could favor its binding to the ubiquinone site of complex I, protecting it from inhibitors such as INDO or rotenone. These findings suggest a possible new protective role for dietary polyphenols for mitochondria, complementary of their antioxidant property. This new role might expand the preventive and/or therapeutic use of PPs in conditions involving mitochondrial dysfunction and associated with increased oxidative stress at the cellular or tissue levels.

Apple peel polyphenol extract protects against indomethacin-induced damage in Caco-2 cells by preventing mitochondrial complex I inhibition

The aim of this work was to investigate the role of mitochondrial dysfunction in the development of oxidative stress and cytotoxicity induced by indomethacin and to evaluate the potential of an apple peel polyphenol extract (APPE) in protecting against these events. Indomethacin induced, time-dependently, mitochondrial and oxidative perturbations which led to cell losses. An inhibition of complex I activity, shown for first time here, which resulted in a concomitant drop in cellular ATP and an increment in mitochondrial superoxide production, was observed after 10 min of exposure. These early cytotoxicity-triggering events were followed by an increase in the intracellular production of superoxide (20 min), an elevation in the activity of xanthine oxidase which led to an increased lipid peroxidation (30 min), and a decline in cell viability which manifested after 40 min. These events were selectively prevented using allopurinol, tempol and APPE (a standardized apple peel polyphenol extract). While the oxidative and cell lytic effects of indomethacin were equally prevented by the three agents, only APPE protected against complex I inhibition and its downstream oxidative consequences. Since tempol (a SOD mimetic) prevented the elevation in xanthine oxidase activity, and allopurinol (a xanthine oxidase inhibitor) totally abolished the increment in lipid peroxidation and loss of cell viability, it appears that a superoxide-dependent increase in xanthine oxidase activity is critical to trigger cytotoxicity. Thus, preventing the early increment in superoxide formation that, as a result of inhibiting complex I, takes place within mitochondria would be key toward protecting the cells against the oxidative and cytolytic effects of indomethacin. The ability of APPE in preventing the inhibition of complex I and the subsequent superoxide-dependent increase in XO activity warrants further studies to evaluate the mechanism involves in the protecting effect of APPE against the indomethacin-associated adverse effects in vivo.