Modulatory effect of naringenin on N-methyl-N'-nitro-N-nitrosoguanidine- and saturated sodium chloride-induced gastric carcinogenesis in male Wistar rats

Network pharmacology- and molecular docking-based exploration of the molecular mechanism underlying Jianpi Yiwei Recipe treatment of gastric cancer

BACKGROUND

Traditional Chinese medicine (TCM) is widely used as an important complementary and alternative healthcare system for cancer treatment in Asian countries. Network pharmacology, which utilizes various database platforms and computer software to study the interactions between complex drug components in vivo, is particularly useful for studying the pharmacodynamic mechanisms of multi-pathway and multi-target Chinese medicines.

AIM

To explore the potential targets and function of Jianpi Yiwei Recipe treatment of gastric cancer (GC) through network pharmacology and molecular docking.

METHODS

Data on the components of Jianpi Yiwei Recipe (Radix Astragali, Radix Codonopsis, Agrimonia eupatoria, Atractylodes macrocephala Koidz., Poria cocos, stir-baked rhizoma dioscoreae, Amomum villosum Lour., fried Fructus Aurantii, pericarpium citri reticulatae, Rhizoma Pinelliae Preparata, and Radix Glycyrrhizae Preparata) were collected and screened by using the TCM systems pharmacology database and analysis platform (TCMSP). Then the targets of these compounds were predicted. GC-related targets were screened using the GeneCards database. Venn diagram was used to identify common targets. An active ingredient-core target interaction network and a protein-protein interaction (PPI) network were built. Moreover, we performed gene ontology (GO) functional annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses on the core targets and validated them by molecular docking.

RESULTS

TCMSP screening revealed 11 active components and 184 targets, whereas GeneCards found 10118 disease-related targets, with 180 shared targets between them. Topology analysis of the PPI network identified 38 targets, including ATK1, TP53, and tumor necrosis factor, as key targets for the treatment of GC by Jianpi Yiwei Recipe. Quercetin, naringenin, luteolin, etc., may be the main active components of Jianpi Yiwei Recipe. GO enrichment analysis identified 2809, 1218, and 553 functions related to biological process, molecular function, and cellular component, respectively. KEGG pathway enrichment analysis revealed 167 related pathways, mainly involved in cancer, endocrine resistance, and AGE-RAGE signaling in diabetic complication. Validation with molecular docking analysis showed docking of key active components with core targets.

CONCLUSION

Jianpi Yiwei Recipe plays a therapeutic role in GC through multiple components, targets, and pathways. These findings form a basis for follow-up exploration of Jianpi Yiwei Recipe in the treatment of GC.

Flavouring Group Evaluation 413 (FGE.413): Naringenin

The EFSA Panel on Food Additives and Flavourings (FAF) was requested to evaluate the safety of naringenin [FL-no: 16.132] as a new flavouring substance, in accordance with Regulation (EC) No 1331/2008. No other substances with sufficient structural similarity have been identified in existing FGEs that could be used to support a read-across approach. The information provided on the manufacturing process, the composition and the stability of [FL-no: 16.132] was considered sufficient. From studies carried out with naringenin, the Panel concluded that there is no concern with respect to genotoxicity. The use of naringenin as a flavouring substance at added portions exposure technique (APET) exposure levels is unlikely to pose a risk for drug interaction. For the toxicological evaluation of naringenin, the Panel requested an extended one-generation toxicity study on naringenin, in line with the requirements of the Procedure and to investigate the consequence of a possible endocrine-disrupting activity. The Panel considered that changes in thymus weight, litter size, post-implantation loss and a consistent reduced pup weight in the high-dose F2 generation could not be dismissed and selected therefore, the mid-dose of 1320 mg/kg body weight (bw) per day for the parental males as the no observed adverse effect level (NOAEL) of the study. The exposure estimates for [FL-no: 16.132] (31,500 and 50,000 μg/person per day for children and adults, respectively) were above the threshold of toxicological of concern (TTC) for its structural class (III). Using the NOAEL of 1320 mg/kg bw per day at step A4 of the procedure, margins of exposure (MoE) of 1590 and 630 could be calculated for adults and children, respectively. Based on the calculated MoEs, the Panel concluded that the use of naringenin as a flavouring substance does not raise a safety concern.

The Role of Propolis as a Natural Product with Potential Gastric Cancer Treatment Properties: A Systematic Review

Gastric cancer is one of the most common, aggressive, and invasive types of malignant neoplasia. It ranks fifth for incidence and fourth for prevalence worldwide. Products of natural origin, such as propolis, have been assessed for use as new complementary therapies to combat cancer. Propolis is a bee product with antiproliferative and anticancer properties. The concentrations and types of secondary metabolites contained in propolis mainly vary according to the geographical region, the season of the year, and the species of bees that make it. The present study is a systematic review of the main articles related to the effects of propolis against gastric cancer published between 2011 and 2021 in the PubMed and Science Direct databases. Of 1305 articles published, only eight studies were selected; among their principal characteristics was the use of in vitro analysis with cell lines from gastric adenocarcinoma and in vivo murine models of the application of propolis treatments. These studies suggest that propolis arrests the cell cycle and inhibits proliferation, prevents the release of oxidizing agents, and promotes apoptosis. In vivo assays showed that propolis decreased the number of tumors by regulating the cell cycle and the expression of proteins related to apoptosis.

Anti-Inflammatory and Antioxidant Effects of Carvacrol on N-Methyl-N′-Nitro-N-Nitrosoguanidine (MNNG) Induced Gastric Carcinogenesis in Wistar Rats

Carvacrol is a dietary polyphenol from Lamiaceae plants that has been shown to possess a wide range of biological activities including antioxidant and antitumor effects. This study aimed to investigate its anti-inflammatory and antioxidant effects on N-methyl-N′-nitro-N-nitrosoguanidine (MNNG) induced gastric carcinogenesis in Wistar rats. Forty-nine rats were randomly assigned to four treatment and three control groups. Over 60 days, MNNG (200 mg/kg BW) was orally applied to animals of groups 1–5 while the rats in groups 2–5 also received different doses of carvacrol (10, 25, 50, and 100 mg/kg BW, respectively) until the end of the experiment. Group 6 rats were treated with 100 mg/kg BW carvacrol and no MNNG whereas group 7 was the control group without any treatment. After the euthanasia of all rats, the inflammatory cytokines and oxidative stress parameters were assessed in the blood and tissues. The expression of caspase 9, Bax, and Bcl-2 proteins in the stomach tissues were investigated through histopathological examinations. Statistically significant differences were observed in the body weight, oxidative stress, and inflammation parameters of groups 1 to 6 compared to group 7 (p ≤ 0.001). Animals in MNNG groups 2 and 3 treated with the low dose carvacrol (10 and 25 mg/kg BW) showed significantly reduced oxidative stress, inflammation, and apoptotic effect compared to animals of the MNNG groups receiving increased doses of carvacrol (50 and 100 mg/kg BW) or no carvacrol. Rats exposed to MNNG exhibited gastric cancer cells in several areas. In the MNNG group receiving 100 mg/kg BW carvacrol, the inflammatory cell infiltration was observed in gastric mucosal and submucosal areas whereas MNNG rats supplemented with 10 and 25 mg/kg BW carvacrol showed no pathological alterations of the gastric cells. The results of this study indicate that significant antioxidant and anti-inflammatory effects induced by carvacrol at doses of 10 and 25 mg/kg BW interfered with gastric carcinogenesis induced by MNNG in Wistar rats as well as provide hepatoprotection. However, high doses of carvacrol (50 and 100 mg/kg BW) increased oxidative stress, inflammation, and apoptosis.

Naringenin: A potential flavonoid phytochemical for cancer therapy

Naringenin is an important phytochemical which belongs to the flavanone group of polyphenols, and is found mainly in citrus fruits like grapefruits and others such as tomatoes and cherries plus medicinal plants derived food. Available evidence demonstrates that naringenin, as herbal medicine, has important pharmacological properties, including anti-inflammatory, antioxidant, neuroprotective, hepatoprotective, and anti-cancer activities. Collected data from in vitro and in vivo studies show the inactivation of carcinogens after treatment with pure naringenin, naringenin-loaded nanoparticles, and also naringenin in combination with anti-cancer agents in various malignancies, such as colon cancer, lung neoplasms, breast cancer, leukemia and lymphoma, pancreatic cancer, prostate tumors, oral squamous cell carcinoma, liver cancer, brain tumors, skin cancer, cervical and ovarian cancer, bladder neoplasms, gastric cancer, and osteosarcoma. Naringenin inhibits cancer progression through multiple mechanisms, like apoptosis induction, cell cycle arrest, angiogenesis hindrance, and modification of various signaling pathways including Wnt/β-catenin, PI3K/Akt, NF-ĸB, and TGF-β pathways. In this review, we demonstrate that naringenin is a natural product with potential for the treatment of different types of cancer, whether it is used alone, in combination with other agents, or in the form of the naringenin-loaded nanocarrier, after proper technological encapsulation.

Systemic Analysis of the Anticancer Effects of Sijunzi Decoction on Gastric Cancer Based on Network Pharmacology

Objective:

Sijunzi decoction (SJZD) has been used for alleviating peptic ulcer or gastric discomfort, and treating spleen disorders since the Song Dynasty, but its pharmacological effect on human gastric cancer (GC) is still unclear. In this research, a network pharmacology-based strategy was applied to explore active ingredients, potential targets, and molecular mechanisms of SJZD against GC.

Methods:

The active compounds and potential targets of SJZD, as well as GC-associated gene targets, were retrieved from publicly available databases. Bioinformatics approaches were used to assess the network interaction, functional regulation, and signaling pathways between SJZD ingredients and GC targets. The anticancer effects of SJZD against GC were verified in vivo by a mouse subcutaneous model.

Results:

The results of network analysis showed that quercetin was the most active ingredient in SJZD. Several prominent target genes of SJZD were identified, such as AKT1 and STAT3. Gene ontology analysis revealed that the core anti-GC targets of SJZD included transcription factor activity and kinase activity. Pathway enrichment analysis indicated that GC patients could be benefited from SJZD treatment via modulation of signaling pathways related to endocrine system, cancer, and infectious disease. Furthermore, in vivo experiments showed that high-dose SJZD could inhibit GC xenograft tumor growth, reduce GC cell proliferation, induce GC cell apoptosis, and decrease the expression of p-AKT1 and p-STAT3.

Conclusions:

Taken together, our results suggest that SJZD can serve as an effective adjuvant therapeutic agent for GC patients.

Comprehensive review on naringenin and naringin polyphenols as a potent anticancer agent

Though the incidence of several cancers in Western societies is regulated wisely, some cancers such as breast, lung, and colorectal cancer are currently rising in many low- and middle-income countries due to increased risk factors triggered by societal and development problems. Surgery, chemotherapy, hormone, radiation, and targeted therapies are examples of traditional cancer treatment approaches. However, multiple short- and long-term adverse effects may also significantly affect patient prognosis depending on treatment-associated clinical factors. More and more research has been carried out to find new therapeutic agents in natural products, among which the bioactive compounds derived from plants have been increasingly studied. Naringin and naringenin are abundantly found in citrus fruits, such as oranges and grapefruits. A variety of cell signaling pathways mediates their anti-carcinogenic properties. Naringin and naringenin were also documented to overcome multidrug resistance, one of the major challenges to clinical practice due to multiple defense mechanisms in cancer. The effective parameters underlying the anticancer effects of naringenin and naringin include GSK3β inactivation, suppression of the gene and protein activation of NF-kB and COX-2, JAK2/STAT3 downregulation, downregulation of intracellular adhesion molecules-1, upregulation of Notch1 and tyrocite-specific genes, and activation of p38/MAPK and caspase-3. Thus, this review outlines the potential of naringin and naringenin in managing different types of cancers.

Therapeutic potential of flavonoids in cancer: ROS-mediated mechanisms

Cancer is a leading cause of morbidity and mortality around the globe. Reactive oxygen species (ROS) play contradicting roles in cancer incidence and progression. Antioxidants have attracted attention as emerging therapeutic agents. Among these are flavonoids, which are natural polyphenols with established anticancer and antioxidant capacities. Increasing evidence shows that flavonoids can inhibit carcinogenesis via suppressing ROS levels. Surprisingly, flavonoids can also trigger excessive oxidative stress, but this can also induce death of malignant cells. In this review, we explore the inherent characteristics that contribute to the antioxidant capacity of flavonoids, and we dissect the scenarios in which they play the contrasting role as pro-oxidants. Furthermore, we elaborate on the pathways that link flavonoid-mediated modulation of ROS to the prevention and treatment of cancer. Special attention is given to the ROS-mediated anticancer functions that (-)-epigallocatechin gallate (EGCG), hesperetin, naringenin, quercetin, luteolin, and apigenin evoke in various cancers. We also delve into the structure-function relations that make flavonoids potent antioxidants. This review provides a detailed perspective that can be utilized in future experiments or trials that aim at utilizing flavonoids or verifying their efficacy for developing new pharmacologic agents. We support the argument that flavonoids are attractive candidates for cancer therapy.

Dietary Salt Intake and Gastric Cancer Risk: A Systematic Review and Meta-Analysis

The results of prospective cohort studies regarding the role of salt intake and subsequent gastric cancer risk are inconsistent. Thus, we performed a systematic review and meta-analysis to summarize the strength of the association of salt intake with gastric cancer morbidity and mortality. PubMed, EmBase, and Cochrane Library were systematically searched to identify eligible studies published throughout September 2021. The effect estimates with 95% confidence intervals (CIs) for gastric cancer morbidity or mortality in each study were applied to calculate the pooled results; these analyses were performed using the random-effects model. Twenty-six prospective cohort studies involving 4,956,350 individuals were selected; these studies reported 19,301 cases of gastric cancer and 2,871 cases of gastric cancer-associated mortality. High (RR: 1.25; 95%CI: 1.10–1.41; P = 0.001) or moderate (RR: 1.20; 95%CI: 1.04–1.38; P = 0.012) salt intake was associated with a greater risk of gastric cancer. High pickled food intake was associated with an increased gastric cancer risk (RR: 1.28; 95%CI: 1.05–1.57; P = 0.017), while moderate pickled foods intake had no significant effect on gastric cancer risk (RR: 1.10; 95%CI: 0.88–1.37; P = 0.390). Neither high (RR: 1.14; 95%CI: 0.95–1.36; P = 0.161) nor moderate (RR: 1.10; 95%CI: 0.87–1.40; P = 0.436) salted fish intake were associated with gastric cancer risk. A high intake of processed meat was significantly associated with a higher risk of gastric cancer (RR: 1.24; 95%CI: 1.03–1.49; P = 0.023), while moderate processed meat intake had no significant effect on the gastric cancer risk (RR: 1.01; 95%CI: 0.92–1.11; P = 0.844). High (RR: 1.04; 95%CI: 0.90–1.19; P = 0.626) and moderate (RR: 1.02; 95%CI: 0.94–1.11; P = 0.594) miso-soup intake had no effects on the gastric cancer risk. High intakes of salt, pickled food, and processed meat are associated with significantly increased risks of gastric cancer; these increased risks are also seen when participants consumed moderate amounts of salt.

Naringenin as a potential immunomodulator in therapeutics

Naringenin, a citrus flavonoid that possesses various biological activities, has emerged as a potential therapeutic agent for the management of a variety of diseases. Studies using cell culture system have shown that naringenin can inhibit inflammatory response in diverse cell types. Moreover, research using various animal models has further demonstrated therapeutic potentials of naringenin in the treatment of several inflammation-related disorders, such as sepsis, fulminant hepatitis, fibrosis and cancer. The mechanism of action of naringenin is not completely understood but recent mechanistic studies revealed that naringenin suppresses inflammatory cytokine production through both transcriptional and post-transcriptional mechanisms. Surprisingly, naringenin not only inhibits cytokine mRNA expression but also promotes lysosome-dependent cytokine protein degradation. This unique property of naringenin stands in sharp contrast with some widely-studied natural products such as apigenin and curcumin, which regulate cytokine production essentially at the transcriptional level. Therefore, naringenin may provide modality for the development of novel anti-inflammatory agent. This review article summarizes our recent studies in understanding how naringenin acts in cells and animal models. Particularly, we will discuss the anti-inflammatory activities of naringenin in various disease context and its potential use, as an immunomodulator, in the treatment of inflammatory related disease.

Biochemical studies evaluating the chemopreventive potential of brucine in chemically induced mammary carcinogenesis of rats

The present study was aimed to investigate the dose dependent chemopreventive activity of brucine against 7, 12-dimethylbenz (a) anthracene induced mammary gland tumorigenesis in rats. The mammary tumor was induced by a single dose of DMBA (25 mg/rat) injected subcutaneously near the mammary gland. We observed reduced body weight and increase in tumor incidence, the total number of tumors, and tumor volume in DMBA alone injected rats and also observed decreased antioxidant status (SOD, CAT, GPX, and GSH) and increased lipid peroxidation (TBARS and LOOH) in plasma and mammary tissues. Increased levels of CYP450, Cyt-b5 and decreased levels of phase II (GST and GR) biotransformation enzymes were noticed in the liver and mammary tissues. Further, increased levels of lipid profile (TC, TG, PL, and FFA) and lipoprotein (LDL and VLDL) were noticed. Whereas, decrease in the levels of HDL in plasma and decreased levels of PL and FFA in mammary tissues were observed. Oral administration of brucine in different doses (2, 4 and 8 mg/kg bw) inhibited the tumor incidence and restored the levels of biochemical markers near to normal in dose responsive manner. Biochemical findings are supported by histopathological studies. The results suggest that brucine at a dose of 8 mg/kg bw shows more significant chemopreventive activity in DMBA-induced mammary carcinogenesis.

Naringenin protects keratinocytes from oxidative stress injury via inhibition of the NOD2-mediated NF-κB pathway in pemphigus vulgaris

Naringenin is known to have anti-oxidative activity; however, the effect of naringenin on the progression of pemphigus vulgaris (PV) still remains unclear. This study aims to analyze the effect of naringenin on HaCaT cell apoptosis and oxidative damage under the treatment of PV serum. The results showed that PV serum significantly induced cell apoptosis compared with the control group; whereas, comparing with PV group, naringenin inhibited cell apoptosis. Moreover, PV serum increased the expression of bax and caspase-3, and decreased the expression of bcl-2; but naringenin significantly suppressed the expression of bax and caspase-3, induced the expression of bcl-2. Naringenin inhibited PV serum-induced disruption of cell-cell contacts. Naringenin also down-regulated the expression of Dsg1, Dsg3 and E-cadherin compared with the PV group. Additionally, naringenin noticeably decreased the PV serum-induced ROS production and alleviated PV serum induced the drop of mitochondrial membrane potential. Furthermore, naringenin increased the activity of SOD, GSH-Px and TAC under the treatment of PV serum. Naringenin also decreased the expression of NOD2, RIPK2 and NF-κB p-p65, but this effect could be reversed by muramyl dipeptide (MDP). In conclusion, these results suggested that naringenin protected keratinocytes from apoptosis and oxidative stress injury through inhibition of the NOD2-mediated NF-κB pathway.

Preventive effect of Actinidia valvata Dunn extract on N-methyl-N'-nitro-N-nitrosoguanidine-induced gastrointestinal cancer in rats

PURPOSE

This study was conducted to assess the preventive effect of Actinidia valvata Dunn (AVD) extract on an animal model of gastrointestinal carcinogenesis on the basis of changes in tumor incidence, cell proliferation, and apoptosis.

MATERIALS AND METHODS

Seventy-five male Wistar rats were divided into five different treatment groups with 15 rats in each group. Group I was given normal feed, whereas Groups II to IV were treated with 10% sodium chloride in the first six weeks and 100 ug/mL of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) in drinking water for 24 weeks. Group II was then given normal feed, whereas Group III was given AVD extract (0.24 g/kg/day) for 12 weeks. Group IV was given AVD extract from the first week to the 36th week, whereas Group V was treated with AVD extract alone for 36 weeks. All rats were sacrificed at the end of the 36-week experiment and assessed for the presence of gastrointestinal tumors. The occurrence of cancer was evaluated by histology. Bax, Bcl-2, Caspase-3, and cyclinD1 were determined by immunohistochemical staining and Western blotting.

RESULTS

The incidences of gastric cancer were 0% in Group I, 73.3% in Group II, 33.3% in Group III, 26.7% in Group IV, and 0% in Group V. Bcl-2 and cyclinD1 expression was decreased in AVD extract treated groups, whereas Bax and Caspase-3 expression was increased. Comparison with group II revealed significant differences (p<0.01).

CONCLUSIONS

AVD extract exhibits an obvious preventive effect on gastrointestinal carcinogenesis induced by MNNG in rats through the regulation of cell proliferation and apoptosis.

Chemopreventive Agents and Inhibitors of Cancer Hallmarks: May Citrus Offer New Perspectives?

Fruits and vegetables have long been recognized as potentially important in the prevention of cancer risk. Thus, scientific interest in nutrition and cancer has grown over time, as shown by increasing number of experimental studies about the relationship between diet and cancer development. This review attempts to provide an insight into the anti-cancer effects of Citrus fruits, with a focus on their bioactive compounds, elucidating the main cellular and molecular mechanisms through which they may protect against cancer. Scientific literature was selected for this review with the aim of collecting the relevant experimental evidence for the anti-cancer effects of Citrus fruits and their flavonoids. The findings discussed in this review strongly support their potential as anti-cancer agents, and may represent a scientific basis to develop nutraceuticals, food supplements, or complementary and alternative drugs in a context of a multi-target pharmacological strategy in the oncology.

Naringenin-Mediated ATF3 Expression Contributes to Apoptosis in Human Colon Cancer

Naringenin (NAR) as one of the flavonoidsobserved in grapefruit has been reported to exhibit an anti-cancer activity. Activating transcription factor 3 (ATF3) is associated with apoptosis in human colon cancer cells. This study was performed to investigate the molecular mechanism by which NAR stimulates ATF3 expression and apoptosis in human colon cancer cells. NAR reduced the cell viability and induced an apoptosis in human colon cancer cells. ATF3 overexpression increased NAR-mediated cleaved PARP, while ATF3 knockdown attenuated the cleavage of PARP by NAR. NAR increased ATF3 expression in both protein and mRNA level, and increased the luciferase activity of ATF3 promoter in a dose-dependent manner. The responsible region for ATF3 transcriptional activation by NAR is located between -317 and -148 of ATF3 promoter. p38 inhibition blocked NAR-mediated ATF3 expression, its promoter activation and apoptosis. The results suggest that NAR induces apoptosis through p38-dependent ATF3 activation in human colon cancer cells.

Naringenin suppresses TPA-induced tumor invasion by suppressing multiple signal transduction pathways in human hepatocellular carcinoma cells

Naringenin, a common dietary flavonoid abundantly present in fruits and vegetables, is believed to possess strong anti-proliferative properties and the ability to induce apoptosis in hepatoma cell lines. However, there are no reports describing its effects on the invasion and metastasis of hepatoma cell lines, and the detailed molecular mechanisms of its effects are still unclear. In this study, we investigated the mechanisms underlying naringenin-mediated inhibition of 12-O-Tetradecanoylphorbol-13-acetate (TPA)-induced cell invasion and inhibition of secreted and cytosolic MMP-9 production in human hepatoma cells (HepG2, Huh-7, and HA22T) and murine embryonic liver cells (BNL CL2). Naringenin suppressed MMP-9 transcription by inhibiting activator protein (AP)-1 and nuclear factor-κB (NF-κB) activity. It suppressed TPA-induced AP-1 activity through inhibiting the phosphorylation of the extracellular signal-related kinase (ERK) and c-Jun N-terminal kinase (JNK) signaling pathways, and it suppressed TPA-induced inhibition of NF-κB nuclear translocation through IκB. Additionally, it suppressed TPA-induced activation of ERK/phosphatidylinositol 3-kinase/Akt upstream of NF-κB and AP-1. These data suggest that naringenin suppresses the invasiveness and metastatic potential of hepatocellular carcinoma (HCC) by inhibiting multiple signal transduction pathways.

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.

Antioxidants and human diseases

Oxidative stress plays a pivotal role in the development of human diseases. Reactive oxygen species (ROS) that includes hydrogen peroxide, hyphochlorus acid, superoxide anion, singlet oxygen, lipid peroxides, hypochlorite and hydroxyl radical are involved in growth, differentiation, progression and death of the cell. They can react with membrane lipids, nucleic acids, proteins, enzymes and other small molecules. Low concentrations of ROS has an indispensable role in intracellular signalling and defence against pathogens, while, higher amounts of ROS play a role in number of human diseases, including arthritis, cancer, diabetes, atherosclerosis, ischemia, failures in immunity and endocrine functions. Antioxidants presumably act as safeguard against the accumulation of ROS and their elimination from the system. The aim of this review is to highlight advances in understanding of the ROS and also to summarize the detailed impact and involvement of antioxidants in selected human diseases.

Anticarcinogenic effect of brucine in diethylnitrosamine initiated and phenobarbital-promoted hepatocarcinogenesis in rats

We evaluated the effects of brucine on N-nitrosodiethylamine (DENA)-induced hepatocarcinogenesis in rats. Initiation of hepatocarcinogenesis was done by intraperitoneal injection of diethylnitrosamine (DENA) followed by promotion with phenobarbital. The rats were exposed to dietary brucine for 4 weeks prior to initiation, and the treatment was continued for 22 consecutive weeks. Brucine decreased the incidence, total number, multiplicity, size and volume of preneoplastic hepatic nodules in a dose-dependent manner. Administration of DENA induced hepatocellular carcinoma (HCC), as evidenced by changes in histopathological architecture, increased activity of cytochrome P450, decreased activity of glutathione Stransferase (GST) as well as decreased antioxidant status, enhanced lipid peroxidation, increased liver marker enzymes. Western blot analysis showed decreased expression of cyclin D1 and Bcl-2 with activation of caspase-3 and increased expression of Bax. Immunohistochemical demonstrated the decreased expression of the PCNA and VEGF. These results indicate that brucine prevents lipid peroxidation and hepatic cell damage and also protects the antioxidant system in DENA-induced hepatocarcinogenesis.

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.

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.

Carcinoma of the stomach: A review of epidemiology, pathogenesis, molecular genetics and chemoprevention

Carcinoma of the stomach is still the second most common cause of cancer death worldwide, although the incidence and mortality have fallen dramatically over the last 50 years in many regions. The incidence of gastric cancer varies in different parts of the world and among various ethnic groups. Despite advances in diagnosis and treatment, the 5-year survival rate of stomach cancer is only 20 per cent. Stomach cancer can be classified into intestinal and diffuse types based on epidemiological and clinicopathological features. The etiology of gastric cancer is multifactorial and includes both dietary and nondietary factors. The major diet-related risk factors implicated in stomach cancer development include high content of nitrates and high salt intake. Accumulating evidence has implicated the role of Helicobacter pylori (H. pylori) infection in the pathogenesis of gastric cancer. The development of gastric cancer is a complex, multistep process involving multiple genetic and epigenetic alterations of oncogenes, tumor suppressor genes, DNA repair genes, cell cycle regulators, and signaling molecules. A plausible program for gastric cancer prevention involves intake of a balanced diet containing fruits and vegetables, improved sanitation and hygiene, screening and treatment of H. pylori infection, and follow-up of precancerous lesions. The fact that diet plays an important role in the etiology of gastric cancer offers scope for nutritional chemoprevention. Animal models have been extensively used to analyze the stepwise evolution of gastric carcinogenesis and to test dietary chemopreventive agents. Development of multitargeted preventive and therapeutic strategies for gastric cancer is a major challenge for the future.