Apigenin and naringenin suppress colon carcinogenesis through the aberrant crypt stage in azoxymethane-treated rats

Phenolic characterization and antimicrobial activity of folk medicinal plant extracts for their applications in olive production

Phytophthora spp is important in plant pathology due to the importance of the diseases it causes. In olive trees, severe damages are caused by the disease known as "dry branch" occasioned by Phytophthora nicotianae, P. citrophthora and P. palmivora. Much effort has been made to find efficient methods of control, with a low negative impact on environment. In this regard, treatment with plant extracts is a valid strategy. The aims of the present study are (i) to determine the polyphenol composition of extracts of Thymus vulgaris, Origanum vulgare, Matricaria recutita, and Larrea divaricata by CZE, (ii) correlate the analytical composition of these extracts with the inhibition on the mycelial growth, and (iii) determine the individual antimicrobial activity of the most active ingredients. A simple methodology was developed for the determination of catechin, naringenin, cinnamic acid, syringic acid, chlorogenic acid, apigenin, vanillic acid, luteolin, quercetin, and caffeic acid in plant extracts by CZE. The extraction of phenolic compounds in extract was performed by a miniaturized solid phase extraction using a home-made minicolumn packed with suitable filtering material (C18 , 50 mg). The optimized analyses conditions were: 30 mM boric acid buffer, pH 9.50; capillary, 57 cm full length, 50 cm effective length, 75 μm id, hydrodynamic injection 30 mbar, 2 s; 25 kV; 25°C, detection by UV absorbance at 290 nm. Sample results suggest that phenolic composition seems to have a great influence on inhibition of pathogens. The highest inhibitions of mycelial growth were observed for cinnamic acid and naringenin.

Naringenin attenuates CCl4 -induced hepatic inflammation by the activation of an Nrf2-mediated pathway in rats

The possible protective effects of naringenin, a naturally occurring citrus flavonone, on carbon tetrachloride (CCl4 )-induced liver injury in rats and the mechanism underlying its effects were investigated. Forty rats were divided into five groups. Rats in Groups I and II served as the normal and injured liver groups, respectively; Group III rats were treated with the standard drug silymarin as a positive control; and rats in Groups IV and V (naringenin-treated groups) were administrated 50 mg/kg, p.o., naringenin for 7 days. Liver samples were collected to evaluate mRNA and protein expression, histological changes and oxidative stress. Naringenin inhibited lipid peroxidation and reduced serum levels of hepatic enzymes induced by CCl4 . In addition, naringenin increased the liver content of reduced glutathione and the activity of anti-oxidant enzymes in rats treated with CCl4 . Naringenin attenuated liver inflammation by downregulating CCl4 -induced activation of tumour necrosis factor (TNF)-α, inducible nitric oxide synthase (iNOS) and cyclo-oxygenase (COX-2) at both the protein and mRNA levels. Naringenin treatment significantly increased NF-E2-related factor 2 (Nrf2) and heme oxygenase (HO-1) expression in injured livers. In rats treated with CCl4 alone, decreases were seen in nuclear Nrf2 expression and in the mRNA levels of its target genes (e.g. HO-1, NQO1 and glutathione S-transferase alpha 3 (GST-a3)). Together, the results suggest that naringenin can protect the liver against oxidative stress, presumably by activating the nuclear translocation of Nrf2 as well as attenuating the TNF-α pathway to elicit an anti-inflammatory response in liver tissue.

Chemopreventive and therapeutic potential of "naringenin," a flavanone present in citrus fruits

Cancer is one of the major causes of deaths in developed countries and is emerging as a major public health burden in developing countries too. Changes in cancer prevalence patterns have been noticed due to rapid urbanization and changing lifestyles. One of the major concerns is an influence of dietary habits on cancer rates. Approaches to prevent cancer are many and chemoprevention or dietary cancer prevention is one of them. Therefore, nutritional practices are looked at as effective types of dietary cancer prevention strategies. Attention has been given to identifying plant-derived dietary agents, which could be developed as a promising chemotherapeutic with minimal toxic side effects. Naringenin, a phytochemical mainly present in citrus fruits and tomatoes, is a frequent component of the human diet and has gained increasing interest because of its positive health effects not only in cancer prevention but also in noncancer diseases. In the last few years, significant progress has been made in studying the biological effects of naringenin at cellular and molecular levels. This review examines the cancer chemopreventive/therapeutic effects of naringenin in an organ-specific format, evaluating its limitations, and its considerable potential for development as a cancer chemopreventive/therapeutic agent.

A Review on Pharmacological and Analytical Aspects of Naringenin

Flavonoids are a widely distributed group of phytochemicals having benzo-pyrone nucleus, and more than 4,000 different flavonoids have been described and categorized into flavonols, flavones, flavanones, isoflavones, catechins and anthocyanidins. Flavonoids occurs naturally in fruits, vegetables, nuts, and beverages such as coffee, tea, and red wine, as well as in medical herbs. Flavonoids are responsible for the different colors of plant parts and are important constituents of the human diet. Flavanoids have different pharmacological activities, such as antioxidant, anti-allergic, antibacterial, anti-inflammatory, antimutagenic and anticancer activity. Naringenin belongs to the flavanones and is mainly found in fruits (grapefruit and oranges) and vegetables. Pharmacologically, it has anticancer, antimutagenic, anti-inflammatory, antioxidant, antiproliferative and antiatherogenic activities. Naringenin is used for the treatments of osteoporosis, cancer and cardiovascular diseases, and showed lipid-lowering and insulin-like properties. In the present review, detailed pharmacological and analytical aspects of naringenin have been presented, which revealed the impressive pharmacological profile and the possible usefulness in the treatment of different types of diseases in the future. The information provided in this communication will act as an important source for development of effective medicines for the treatment of various disorders.

The effect of citrus peel extracts on cytokines levels and T regulatory cells in acute liver injury

Background. T cell-mediated immune responses contribute to the hepatocellular injury during autoimmune hepatitis, viral infection, and hepatotoxins. Pharmacological compounds regulating immune responses are suitable candidates for prevention/treatment of this pathology. Therefore, the main aim of this study was to define the effects of antioxidant, anti-inflammatory mixture of citrus peel extract (CPE) on the immune-mediated liver injury. Methods. The influence of CPE on liver injury was determined by the activity of transaminases in plasma and the histological changes. Anti-inflammatory and antioxidant effects were studied by measuring frequency of T regulatory cells (Tregs), cytokines (TNF-α, IL-10, and IFN-γ), and nitric oxide levels. Results. The CPE application notably prevents development of liver injury through decreasing levels of both cytokines (TNF-alpha, INF) and regulatory T cells and increasing levels of IL-10. CPE injection also diminished the serum NO, which in turn resulted in evident reduction of the liver damage. Conclusion. Our findings represent the primary preclinical data indicating that the CPE in vivo could ameliorate Con A induced hepatitis. The low dose of CPE most likely can be used for the treatment of the T cell-mediated liver injury as in autoimmune hepatitis, alcoholic hepatitis, and chronic viral hepatitis.

Naringenin inhibits the growth of Dictyostelium and MDCK-derived cysts in a TRPP2 (polycystin-2)-dependent manner

BACKGROUND AND PURPOSE

Identifying and characterizing potential new therapeutic agents to target cell proliferation may provide improved treatments for neoplastic disorders such as cancer and polycystic diseases.

EXPERIMENTAL APPROACH

We used the simple, tractable biomedical model Dictyostelium to investigate the molecular mechanism of naringenin, a dietary flavonoid with antiproliferative and chemopreventive actions in vitro and in animal models of carcinogenesis. We then translated these results to a mammalian kidney model, Madin-Darby canine kidney (MDCK) tubule cells, grown in culture and as cysts in a collagen matrix.

KEY RESULTS

Naringenin inhibited Dictyostelium growth, but not development. Screening of a library of random gene knockout mutants identified a mutant lacking TRPP2 (polycystin-2) that was resistant to the effect of naringenin on growth and random cell movement. TRPP2 is a divalent transient receptor potential cation channel, where mutations in the protein give rise to type 2 autosomal dominant polycystic kidney disease (ADPKD). Naringenin inhibited MDCK cell growth and inhibited cyst growth. Knockdown of TRPP2 levels by siRNA in this model conferred partial resistance to naringenin such that cysts treated with 3 and 10 μM naringenin were larger following TRPP2 knockdown compared with controls. Naringenin did not affect chloride secretion.

CONCLUSIONS AND IMPLICATIONS

The action of naringenin on cell growth in the phylogenetically diverse systems of Dictyostelium and mammalian kidney cells, suggests a conserved effect mediated by TRPP2 (polycystin-2). Further studies will investigate naringenin as a potential new therapeutic agent in ADPKD.

Role of pomegranate and citrus fruit juices in colon cancer prevention

Colorectal cancer is the second leading cause of cancer-related deaths in the United States. Recent studies prove that though chemotherapeutic agents are being used for the treatment of colon cancer, they become non-effective when the cancer progresses to an invasive stage. Since consumption of certain dietary agents has been linked with various cancers, fruit juices have been investigated for their consistently protective effect against colon cancer. The unique biochemical composition of fruit juices is responsible for their anticancer properties. In this review, the chemo-preventive effect of fruit juices such as pomegranate and citrus juices against colon cancer are discussed. For this purpose, the bioavailability, in vitro and in vivo effects of these fruit juices on colorectal cancer are highlighted. Moreover, there is a scarcity of studies involving human trials to estimate the preventive nature of these juices against colon cancer. This review will support the need for more preclinical tests with these crude juices and their constituents in different colorectal cancer cell lines and also some epidemiological studies in order to have a better understanding and promote pomegranate and citrus juices as crusaders against colon cancer.

Anticancer mechanism of apigenin and the implications of GLUT-1 expression in head and neck cancers

Apigenin, a natural phytoestrogen flavonoid, has potential biological effects, including antioxidative, anti-inflammatory and anticancer activities. The mechanisms of anticancer activities of apigenin are unknown. Some studies have found that apigenin inhibits GLUT-1 mRNA and protein expression in cancer cells. Thus, we hypothesized that apigenin exerts similar effects on head and neck cancers through its inhibition of GLUT-1 expression. In this article, we review the anticancer mechanism of apigenin and the implications of GLUT-1 expression in head and neck cancers. In addition, we describe the current state of knowledge about the relationship between apigenin and GLUT-1 expression in head and neck cancers.

Antioxidant and hepatoprotective effects of naringenin and its β-cyclodextrin formulation in mice intoxicated with carbon tetrachloride: a comparative study

The present study evaluated the antioxidant and hepatoprotective effects of the flavonoid naringenin (NGN) and its β-cyclodextrin formulation at a dose of 50 mg/kg b.w. The assessment was done by the investigation of serum-enzymatic and liver antioxidant activity, histopathological and ultrastructural changes in male Swiss mice, which were subjected to acute experimental intoxication with CCl4. Formulated and free flavonoid were orally given to mice for 7 days and then were intraperitoneally injected with 1.0 mL/kg CCl4 on the 8th day. After 24 h of CCl4 administration, an increase in the levels of transaminases aspartate aminotransferase and alanine aminotransferase activities and malondialdehyde concentration occurred and a significant decrease in superoxide dismutase, catalase glutathione-peroxidase activities, and glutathione levels was detected as well. These were accompanied by extended centrilobular necrosis, steatosis, fibrosis, and an altered ultrastructure of hepatocytes. Pretreatment with formulated or free flavonoid retained the biochemical markers to control values. Histopathological and electron-microscopic examination confirmed the biochemical results. In conclusion, both NGN and NGN/β-cyclodextrin complex showed antioxidant and hepatoprotective effects against injuries induced by CCl4.

Integrated text mining and chemoinformatics analysis associates diet to health benefit at molecular level

Awareness that disease susceptibility is not only dependent on genetic make up, but can be affected by lifestyle decisions, has brought more attention to the role of diet. However, food is often treated as a black box, or the focus is limited to few, well-studied compounds, such as polyphenols, lipids and nutrients. In this work, we applied text mining and Naïve Bayes classification to assemble the knowledge space of food-phytochemical and food-disease associations, where we distinguish between disease prevention/amelioration and disease progression. We subsequently searched for frequently occurring phytochemical-disease pairs and we identified 20,654 phytochemicals from 16,102 plants associated to 1,592 human disease phenotypes. We selected colon cancer as a case study and analyzed our results in three directions; i) one stop legacy knowledge-shop for the effect of food on disease, ii) discovery of novel bioactive compounds with drug-like properties, and iii) discovery of novel health benefits from foods. This works represents a systematized approach to the association of food with health effect, and provides the phytochemical layer of information for nutritional systems biology research.

Until recently diet was considered a supplier of energy and building blocks for growth and development. However, current research in the field suggests that the complex mixture of natural compounds present in our food has a variety of biological activities and plays an important role for health maintenance and disease prevention. The mixture of bioactive components of our diet interacts with the human body through complex processes that modify network function and stability. In order to increase our limited understanding on how components of food affect human health, we borrow methods that are well established in medical and pharmacological research. By using text mining in PubMed abstracts we collected more than 20,000 diverse chemical structures present in our diet, while by applying chemoinformatics methods we could systematically explore their numerous targets. Integrating the above datasets with food-disease associations allowed us to use a statistical framework for identifying specific phytochemicals as perturbators of drug targets and disease related pathways.

Diet and supplements and their impact on colorectal cancer

BACKGROUND

Colorectal cancer is the third commonest cancer and the third leading cause of cancer death among men and women. It has been proposed that dietary factors are responsible for 70-90% of colorectal cancer and diet optimization may prevent most cases.

AIM

To evaluate the role of dietary components and supplements in colorectal cancer.

METHODS

Bibliographical searches were performed in Pubmed for the terms "diet and colorectal cancer", "diet and colon cancer", "diet and rectal cancer", "nutrition and colorectal cancer", "probiotics and colorectal cancer", "prebiotics and colorectal cancer", "alcohol and cancer" and "colorectal cancer epidemiology".

RESULTS

Consumption of processed or red meat, especially when cooked at high temperatures may be associated with increased risk of colorectal cancer. The evidence for dietary fibre is unclear but foods that contain high amounts of fibre are usually rich in polyphenols which have been shown to alter molecular processes that can encourage colorectal carcinogenesis. Meta-analyses provide evidence on the benefits of circulating, diet-derived and supplemented, vitamin D and Calcium. We also found that diets rich in Folate may prevent colorectal carcinoma. The evidence on dietary micronutrients such as Zinc and Selenium in association with colorectal cancer is not conclusive. It has been suggested that there may be a direct association between alcohol intake and colorectal cancer. In vitro and in vivo studies have highlighted a possible protective role of prebiotics and probiotics.

CONCLUSIONS

The lack of randomized trials and the presence of confounding factors including smoking, physical activity, obesity and diabetes may often yield inconclusive results. Carefully designed randomized trials are recommended.

Mediterranean diet and cancer: epidemiological evidence and mechanism of selected aspects

Background

Populations living in the area of the Mediterranean Sea suffered by decreased incidence of cancer compared with those living in the regions of northern Europe and US countries, attributed to healthier dietary habits. Nowadays, we are assisting to a moving away from the traditional Mediterranean dietary pattern, but whether this changing is influencing risk of cancers is still unclear. The aim of the study was to review recent evidence on potential relationship between the adherence to the Mediterranean diet and cancer.

Discussion

The most recent pooled analyses of epidemiological studies supported strongly the hypothesis that the Mediterranean diet may play a role in preventing several types of cancers, especially those of digestive tract, whereas contrasting results were reported for hormone-dependent cancers. Specific aspects of the Mediterranean diet such as high fruit and vegetables and low red processed meat intake may explain such protective effects. Moreover, evidence regarding olive oil and whole grains increase the beneficial effects of such dietary pattern against cancer.

Conclusions

Literature evidence actually demonstrates that the increased adherence to the Mediterranean dietary pattern is beneficial to health across populations and may translate a protective effect with certain cancers.

Gene expression analysis in cardiac tissues from infants identifies candidate agents for Tetralogy of Fallot

Tetralogy of Fallot (TOF) is the most common cyanotic heart defect and the most common cause of blue baby syndrome. Although great progress has been made, the molecular mechanisms of TOF are far from being fully understood, and treatment of this disease remains palliative. In this study, we downloaded gene expression data of TOF subjects with those of normally developing subjects from the Gene Expression Omnibus database and employed computational bioinformatics analyses to compare their gene expression patterns. Furthermore, small molecules that induce inverse gene changes to TOF were identified. A total of 2,274 genes involved in energy metabolism and protein binding were differentially expressed in TOF samples compared with samples from normal controls. Pathways associated with cellular oxygen tension were dysfunctional. In addition, we identified a group of small molecules that may be exploited as adjuvant drug to alleviate some symptoms for TOF patients. These drugs are clearly a direction that warrants additional consideration.

Pomegranate polyphenolics suppressed azoxymethane-induced colorectal aberrant crypt foci and inflammation: possible role of miR-126/VCAM-1 and miR-126/PI3K/AKT/mTOR

The antitumorigenic activities of polyphenols such as ellagitannins and anthocyanins in pomegranate (Punica granatum L.) have been previously studied where cytotoxic, anti-inflammatory and antioxidant effects were evident in various cancer models. The objective of this study was to investigate the role of miR-126/vascular cell adhesion molecule 1 (VCAM-1) and miR-126/phosphatidylinositol-3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) in pomegranate-mediated anti-inflammatory and anticarcinogenic effects in vivo and in vitro. Sprague-Dawley rats (n = 10 per group) received pomegranate juice (2504.74 mg gallic acid equivalents/l) or a polyphenol-free control beverage ad libitum for 10 weeks and were injected with azoxymethane (AOM) subcutaneously (15mg/kg) at weeks 2 and 3. Consumption of pomegranate juice suppressed the number of aberrant crypt foci (ACF) and dysplastic ACF by 29 and 53.5% (P = 0.05 and 0.04), respectively, and significantly lowered proliferation of mucosa cells. Pomegranate juice significantly downregulated proinflammatory enzymes nitric oxide synthase and cyclooxygenase-2 messenger RNA (mRNA) and protein expression. In addition, it suppressed nuclear factor-κB and VCAM-1 mRNA and protein expression in AOM-treated rats. Pomegranate also inhibited phosphorylation of PI3K/AKT and mTOR expression and increased the expression of miR-126. The specific target and functions of miR-126 were investigated in HT-29 colon cancer cell lines. In vitro, the involvement of miR-126 was confirmed using the antagomiR for miR-126, where pomegranate reversed the effects of the antagomiR on the expression of miR-126, VCAM-1 and PI3K p85β. In summary, therapeutic potentials of pomegranate in colon tumorigenesis were due in part to targeting miR-126-regulated pathways, which contributes in the underlying anti-inflammatory mechanisms.

Naringenin enhances intestinal barrier function through the expression and cytoskeletal association of tight junction proteins in Caco-2 cells

SCOPE

We have previously reported that naringenin promotes the tight junction (TJ) integrity in intestinal Caco-2 cells. This study investigated the naringenin-mediated effect in Caco-2 cells with a particular focus on the modulation of TJ structure and claudin-4 transcriptional regulation.

METHODS AND RESULTS

Naringenin (10~100 μM) dose-dependently enhanced TJ barrier integrity of Caco-2 cells, indicated by transepithelial electrical resistance and FITC-dextran flux. Immunoblot analysis showed that naringenin increased the cytoskeletal association of TJ proteins, zonula occludens-2, occludin, claudin-1, and claudin-4, simultaneously with increased occludin phosphorylation. The total expression of claudin-4 was also increased by naringenin. Quantitative RT-PCR and luciferase reporter assay revealed that naringenin transcriptionally increased the claudin-4 expression with activation of claudin-4 promoter. The mutation of the binding site of the transcriptional factor Sp1 in the claudin-4 promoter sequence and the pharmacological inhibition of Sp1 partially suppressed the naringenin-mediated activation of the claudin-4 promoter. Further, naringenin induced the heat shock protein 70 expression in the cells.

CONCLUSION

Naringenin enhances barrier integrity through the assembly and expression of TJ proteins in intestinal epithelial cells. Naringenin-mediated claudin-4 expression occurs, at least partially, through Sp1-dependent transcriptional regulation. The induction of heat shock protein 70 may be also involved in the increased claudin-4 expression.

Protective effects of naringenin on carbon tetrachloride-induced acute nephrotoxicity in mouse kidney

The ability of naringenin (NGN) to protect the kidney against CCl4-induced renal toxicity in male Swiss mice was investigated. The flavonoid was given orally to mice for 7days and then on the 8th day, these were intraperitoneally injected with 10mmol/kg CCl4. When the toxicant was administrated alone, an increase of malondialdehyde (MDA) concentration was observed and a significant decrease in superoxide dismutase (SOD), catalase (CAT) glutathione-peroxidase (GPx) specific activities as well as glutathione (GSH) levels was detected after 24h. These were accompanied by glomerular and tubular degenerations, vascular congestion, necrosis and fatty changes. Marked collagen deposition and strong TGF-β1 expression were observed mainly in the mesangial cells of the glomeruli and tubulointerstitial areas. Ultrastructural investigations showed proximal and distal tubular epithelial cells alterations including numerous lysosomes and dense granular bodies, altered mitochondria, appearance of "myeloid bodies" and basal enfolding dilatation. Pre-treatment with NGN resulted in the return of biochemical markers to control values. Histopathological and electron-microscopic examinations confirmed the biochemical results. In conclusion, NGN showed antioxidant and renal protective effects against injuries induced by CCl4.

Supplemental naringenin prevents intestinal barrier defects and inflammation in colitic mice

Intestinal barrier defects are involved in the pathogenesis of inflammatory bowel disease. The present study investigated the ameliorative effects of naringenin, a citrus polyphenol, on intestinal tight junction (TJ) barrier defects and inflammation in a murine model of colitis. In Expt. 1, using a 2 × 2 fractional design, the mice were administered water or 2% dextran sulfate sodium (DSS) in combination with feeding control or naringenin-containing diets for 9 d (severe disease stage). DSS administration caused severe colon damage and inflammation, as indicated by body weight loss, increased clinical sores, colon shortening, and gene expressions of inflammatory cytokines [interferon-γ, interleukin (IL)-6, macrophage inflammatory protein-2, and IL-17A). DSS administration also impaired TJ barrier integrity in the colon, as indicated by increased colon permeability and plasma LPS-binding protein levels, resulting from the impaired colonic expression of TJ proteins, occludin, junctional adhesion molecule-A, and claudin-3. Supplemental feeding with naringenin totally or partially attenuated these symptoms, suggesting that naringenin ameliorates the DSS-induced colitis at least partially through protection of the TJ barrier. In Expt. 2, analyses were performed at different disease stages (d 3, 6, and 9) to more widely examine the ameliorative role of naringenin on the initiation and development of colitis. DSS administration moderately induced colon shortening at d 3 and 6 and increased the disease activity index (DAI) and inflammatory cytokine (IL-6 and IL-17A) expression without any significant increases in colonic permeability. Feeding naringenin attenuated the increased DAI and colon shortening and tended to suppress the increased cytokine expression. These findings suggest that the presence of an additional mechanism underlying the naringenin-mediated, anticolitic effect along with barrier protection.

Red orange: experimental models and epidemiological evidence of its benefits on human health

In recent years, there has been increasing public interest in plant antioxidants, thanks to the potential anticarcinogenic and cardioprotective actions mediated by their biochemical properties. The red (or blood) orange (Citrus sinensis (L.) Osbeck) is a pigmented sweet orange variety typical of eastern Sicily (southern Italy), California, and Spain. In this paper, we discuss the main health-related properties of the red orange that include anticancer, anti-inflammatory, and cardiovascular protection activities. Moreover, the effects on health of its main constituents (namely, flavonoids, carotenoids, ascorbic acid, hydroxycinnamic acids, and anthocyanins) are described. The red orange juice demonstrates an important antioxidant activity by modulating many antioxidant enzyme systems that efficiently counteract the oxidative damage which may play an important role in the etiology of numerous diseases, such as atherosclerosis, diabetes, and cancer. The beneficial effects of this fruit may be mediated by the synergic effects of its compounds. Thus, the supply of natural antioxidant compounds through a balanced diet rich in red oranges might provide protection against oxidative damage under differing conditions and could be more effective than, the supplementation of an individual antioxidant.

Inhibitory effect of naringenin (citrus flavonone) on N-nitrosodiethylamine induced hepatocarcinogenesis in rats

We evaluated the effects of naringenin on N-nitrosodiethylamine (NDEA)-induced hepatocarcinogenesis in rats. Administration of NDEA induced hepatocellular carcinoma (HCC), as evidenced by changes in histopathological architecture, increased activity of cytochrome P450, decreased activity of glutathione S-transferase (GST) as well as decreased antioxidant status, enhanced lipid peroxidation and increased liver marker enzymes. Pre- and post-treatment with naringenin effectively suppressed NDEA-initiated hepatocarcinoma and the associated preneoplastic lesions by modulating xenobiotic-metabolizing enzymes (XMEs), alleviating lipid peroxidation (through both free radical scavenging and the enhanced antioxidant status), and decreased levels of liver marker enzymes. These results indicate that naringenin prevents lipid peroxidation and hepatic cell damage and also protects the antioxidant system in N-nitrosdithylamine-induced hepatocarcinogenesis.

The flavonoid chrysin attenuates colorectal pathological remodeling reducing the number and severity of pre-neoplastic lesions in rats exposed to the carcinogen 1,2-dimethylhydrazine

Phenolic compounds are naturally occurring, bioactive substances with marked antioxidant and anti-inflammatory potential. The flavonoid chrysin, found in high levels in honey bee propolis, inhibits the activity of enzymes involved in carcinogenesis. We have investigated the effect of chrysin on pre-neoplastic colorectal lesions (ACF, aberrant crypt foci) in a rat model of chemical carcinogenesis induced by 1,2-dimethylhydrazine (DMH). Female Wistar rats weighing 137.2 ± 24.3 g received weekly one subcutaneous injection of DMH (20 mg/kg) for 10 weeks. The animals were divided into five groups each with seven animals: Group 1, 0.9% saline; Group 2, DMH+0.9% saline; Group 3, DMH+chrysin (10 mg/kg); Group 4, DMH+chrysin (100 mg/kg); Group 5, DMH+chrysin (200 mg/kg). Groups 2 and 3 showed a significant increase in ACF number, nucleolus organizer regions per enterocyte nucleus and nitrite/nitrate serum levels compared with Group 1. Groups 4 and 5 presented a significant reduction in all these parameters compared with Group 2. The levels of antioxidant minerals (copper, magnesium, selenium, zinc) and the number of enteroendocrine and mucin-producing cells were significantly reduced in Groups 2 and 3 but were similar in Groups 4 and 5 compared with Group 1. Chrysin, at 100 mg/kg and 200 mg/kg, was effective in attenuating pathological colorectal remodeling, reducing the number of pre-neoplastic lesions in rats exposed to DMH. Some of these effects might be attributable to the recovery of antioxidant mineral levels, a reduction in systemic nitrosative stress and an inhibition of the cellular proliferation induced by this flavonoid.

Hesperidin alleviates oxidative stress and downregulates the expressions of proliferative and inflammatory markers in azoxymethane-induced experimental colon carcinogenesis in mice

OBJECTIVE

Colon cancer is a common malignant neoplasm causing huge morbidity and mortality worldwide. Current therapeutic interventions are unsatisfying, which necessitates novel chemopreventive strategies. The present study was intended to elucidate the chemopreventive efficacy of hesperidin against azoxymethane (AOM)-induced mouse colon carcinogenesis.

MATERIALS AND METHODS

Swiss albino mice were subjected to intraperitoneal injections of AOM once a week for 3 consecutive weeks. Hesperidin treatments were provided in the initiation or post-initiation phases. The number and multiplicity of aberrant crypt foci (ACF), tumor incidence and antioxidant status were determined. Histopathological analyses, proliferating cell nuclear antigen (PCNA) index and modulations in the expression of inflammatory markers such as nuclear factor kappa B (NF-κB), inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) were studied.

RESULTS

Hesperidin treatments significantly inhibited the number and multiplicities of AOM-induced ACF and tumor incidence. Hesperidin reduced oxidative stress parameters and enhanced antioxidant status. A marked decrease in the PCNA index was evident on hesperidin administration. Hesperidin treatments caused a prominent downregulation of NF-κB and its target molecules iNOS and COX-2, thereby combating inflammation.

CONCLUSION

This study proves the chemopreventive efficacy of hesperidin against the deleterious traits of colon carcinogenesis including accelerated proliferation, inflammation and persistent oxidative stress.

Plants vs. cancer: a review on natural phytochemicals in preventing and treating cancers and their druggability

Cancer remains to be one of the leading causes of death in the United States and around the world. The advent of modern drug-targeted therapies has undeniably improved cancer patients' cares. However, advanced metastasized cancer remains untreatable. Hence, continued searching for a safer and more effective chemoprevention and treatment is clearly needed for the improvement of the efficiency and to lower the treatment cost for cancer care. Cancer chemoprevention with natural phytochemical compounds is an emerging strategy to prevent, impede, delay, or cure cancer. This review summarizes the latest research in cancer chemoprevention and treatment using the bioactive components from natural plants. Relevant molecular mechanisms involved in the pharmacological effects of these phytochemicals are discussed. Pharmaceutical developmental challenges and opportunities in bringing the phytochemicals into the market are also explored. The authors wish to expand this research area not only for their scientific soundness, but also for their potential druggability.

Attenuation of NDEA-induced hepatocarcinogenesis by naringenin in rats

Chemoprevention is one of the most promising and realistic approaches in the prevention of cancer. Several bioactive compounds present in fruits and vegetables have revealed their cancer curative potential on hepatocellular carcinoma. Naringenin is one such naturally occurring flavonoid widely found in citrus fruits. In this study, we examined the molecular mechanisms by which naringenin inhibited NDEA-induced hepatocellular carcinoma in rats by analysing the expression patterns of proliferating cell nuclear antigen, Bcl-2, NF-κB, VEGF and MMP-2/9. Enhanced cell proliferation and apoptotic evasion in NDEA-induced hepatocarcinogenesis was associated with imbalance in pro-apoptotic and anti-apoptotic proteins together with upregulation of proliferating cell nuclear antigen (PCNA) and downregulation of caspase-3. Administration of pretreatment and posttreatment of naringenin decreased the expression of PCNA and Bcl-2 and increased the expression of Bax and caspase-3, indicating antiproliferative and apoptotic effects, respectively. Administration of NDEA increased the tumour expression of NF-κB, COX-2, VEGF, MMP-2 and MMP-9 that was correlated with more aggressive lesions and tumour growth. Downregulation of NF-κB, VEGF and MMPs by naringenin seen in the present study were correlated with the inhibition of liver tumour induced by NDEA. Our results suggest that naringenin could act as a legitimate agent by inhibiting cancer processes.

Synthetic flavanones augment the anticancer effect of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is considered as the most promising anticancer agent in the TNF superfamily because of its selective cytotoxicity against tumor cells versus normal primary cells. However, as more tumor cells are reported to be resistant to TRAIL-mediated death, it is important to develop new therapeutic strategies to overcome this resistance. Flavonoids have been shown to sensitize cancer cells to TRAIL-induced apoptosis. The aim of this study was to examine the cytotoxic and apoptotic activities of TRAIL on HeLa cancer cells in combination with two synthetic compounds: 6-hydroxyflavanone (6-HF) and its derivative 6-propionoxy-flavanone (6-PF) and to determine the mechanism by which the flavanones overcome the TRAIL-resistance. The cytotoxicity was measured by MTT and LDH assays. The apoptosis was detected by annexin V-FITC fluorescence staining in flow cytometry and microscopy. Death receptor (TRAIL-R1/DR4 and TRAIL-R2/DR5) expression were analysed using flow cytometry. Mitochondrial membrane potential was evaluated using DePsipher staining by fluorescence microscopy. The synthetic flavanones enhanced TRAIL-induced apoptosis in HeLa cells through increased expression of TRAIL-R2 death receptor and reduction of mitochondrial membrane potential. Our study indicates that the 6-HF and 6-PF augmented the anticancer effects of TRAIL and confirm a potential use of flavanones in TRAIL-based anticancer therapy and prevention.

The citrus flavanone naringenin suppresses CYP1B1 transactivation through antagonising xenobiotic-responsive element binding

Exposure to environmental toxicants or exogenous oestrogen increases the risk of cancer. Some toxicants such as polycyclic aromatic hydrocarbons (PAH) undergo biotransformation to become genotoxic agents. Cytochrome p450 (CYP) 1B1 is an enzyme catalysing this transformation. Consumption of fruit and vegetables is considered to be protective against carcinogenesis, and naringenin can be found abundantly in citrus fruits. In the present study, the effect of naringenin on the regulation of CYP1B1 was investigated in MCF-7 cells. Enzyme inhibition assays revealed that naringenin inhibited CYP1B1 at or above 5 μm but not CYP1A1 activity. Quantitative PCR analysis also demonstrated that 1 μm-naringenin reduced CYP1B1 mRNA expression induced by 7,12-dimethylbenz(α)anthracene (DMBA). Further study illustrated that the suppression was at the transcriptional level. Since previous studies have shown that oestrogen response element (ERE) and xenobiotic-responsive element (XRE) are functional binding sequences in the promoter region of CYP1B1, interference of DNA binding on these two elements was pursued. Employing reporter gene assays as well as the electromobility shift assay, we verified that naringenin counteracted DMBA-induced XRE binding at − 1675. These results supported the notion that fruit consumption could be a protective measure against PAH biotransformation.

The coumarin psoralidin enhances anticancer effect of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)

Coumarins are a very common type of secondary plant metabolites with a broad spectrum of biological activities. Psoralidin is a naturally occurring furanocoumarin isolated from Psoralea corylifolia possessing anticancer and chemopreventive properties. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) triggers apoptosis in cancer cells with no toxicity toward normal tissues. Endogenous TRAIL plays an important role in immune surveillance and defence against cancer cells. Coumarins can modulate TRAIL-mediated apoptosis in cancer cells. We examined the cytotoxic and apoptotic activities of psoralidin in combination with TRAIL on HeLa cancer cells. The cytotoxicity was measured by MTT and LDH assays. The apoptosis was detected using annexin V-FITC staining and mitochondrial membrane potential was evaluated using DePsipher staining by fluorescence microscopy. Death receptor (TRAIL-R1/DR4 and TRAIL-R2/DR5) expression was analyzed using flow cytometry. Psoralidin enhanced TRAIL-induced apoptosis in HeLa cells through increased expression of TRAIL-R2 death receptor and depolarization of mitochondrial membrane potential. Our study indicated that psoralidin augmented the anticancer effects of TRAIL and confirmed a potential use of coumarins in cancer chemoprevention.

Differential inhibition of human colon cancer cells by structurally similar flavonoids of citrus

A number of studies in the recent years have evaluated the anti-proliferative activity of flavonoids. Although certain studies investigated the structure-activity based on the phenotypic assays, no study has correlated the flavonoids structure with the ability to alter gene/protein expression. Present study was focused to understand the structure-function relationship of citrus flavonoids in terms of their ability to alter the gene expression in the colon adenocarcinoma cells. Eight structurally related flavonoids found in citrus were evaluated for their ability to inhibit colon cancer (SW480) cells, as well as change the expression of apoptosis related genes/proteins. Apigenin and quercetagetin demonstrated most significant inhibition of cell proliferation with 63.6% and 45.7% inhibition of cell growth at 200μM after 48h of incubation, respectively. The cell death was also confirmed by images of fluorescently tagged cells. Furthermore, up-regulation of Bax/Bcl2 protein ratio as well as activation of Caspase3 at 200μM at 48h confirmed the induction of apoptosis by apigenin and quercetagetin. In addition, results suggest that the change in Bax/Bcl2 ratio by apigenin and quercetagetin seems to be due to their ability to alter the expression of bax and bcl2 transcription. Results of the currents study suggest that among the citrus flavonoids, double bond between C2 and C3 and hydroxyl group at C3, C6 are highly decisive for the proliferation inhibition and apoptosis induction ability. Taken together, these results demonstrate that among the major flavonoids of citrus, apigenin and quercetagetin have potent anti-cancer activity through inducing apoptosis in SW480 human colon cancer cells.

Dietary folate protects against azoxymethane-induced aberrant crypt foci development and oxidative stress in rat colon

Azoxymethane (AOM) induces cancer and oxidative stress in rat colon. This study tested the hypothesis that dietary folate supplementation protects against AOM-induced oxidative stress and reduces aberrant crypt foci (ACF) development in rat colon. Fifty-four weanling male albino rats, with an average body weight of 50 ± 5 g, were randomly divided into three groups – A, B and C (18 rats per group) – and fed 2, 8 or 40 mg of folic acid per kg of supplemented diets, respectively, throughout the eight weeks' experimental period. The animals were supplied with diet and water ad libitum for four weeks and they reached an average body weight of 100 g. Thereafter each group was then further randomly subdivided into three subgroups (six rats per subgroup): control, vehicle and AOM-injected groups. The control group did not receive any treatment (neither AOM injection nor saline), the rats in the vehicle group were given 1 mL intraperitoneal injection of saline once a week for two weeks and the rats in the AOM-injected group were given two intraperitoneal injections of AOM dissolved in saline once a week for two weeks totaling 30 mg/kg body weight. After the last AOM injection, animals were continuously fed ad libitum their specified diet for two weeks of last AOM injection, all rats were sacrificed, and colon tissues were collected and used for ACF enumeration and measurements of glutathione (GSH) and total antioxidant capacity (TAC). The results revealed that AOM-injected rats showed lower levels of GSH and TAC as compared with control and vehicle groups. Folic acid-supplemented diets suppressed the AOM-induced ACF and GSH depletion in a dose-dependent manner and augmented the TAC. It was concluded that folic acid supplementation protects against the AOM-induced ACF formation by suppressing the AOM-induced GSH depletion in rat colon cells.

Molecular mechanisms for chemoprevention of colorectal cancer by natural dietary compounds

Colorectal cancer is one of the major causes of cancer-related mortality in both men and women worldwide. This review focuses on preventing the initiation and promotion of neoplastic growth in colorectal cancer, particularly with natural dietary compounds. Chemoprevention is defined as the use of natural dietary compounds and/or synthetic substances that can delay, prevent, or even reverse the development of adenomas, as well as the progression from adenoma to carcinoma. The molecular mechanisms of their chemopreventive action are associated with the modulation of signaling cascades, gene expressions involved in the regulation of cell proliferation, differentiation, and apoptosis and the suppression of chronic inflammation, metastasis, and angiogenesis. Here, we summarize the currently known targets and signaling pathways whereby natural dietary compounds interfere with the development of colorectal cancer, and thus providing evidence for these substances in colonic cancer chemopreventive action.