Antimutagenic effect of plant flavonoids in the Salmonella assay system

In Vitro Modulation of Genotoxicity and Oxidative Stress by Polyphenol-Rich Fraction of Chinese Ladder Brake (Pteris vittata L.)

Pteris vittata L. is a terrestrial genus growing in moist, shady forests and on hillsides. The plant has considerable ethnomedicinal importance. Investigations have been carried out on chemical profiling and antioxidant compounds from some genera of pteridophytes but studies on the biological properties of P. vittata are lacking. Therefore, the present study investigates antioxidant, antigenotoxic, and antiproliferative potential of the aqueous fraction of P. vittata (PWE). A battery of assays were carried out to assess the antioxidant potential of the PWE. SOS chromotest and DNA nicking assay were used to evaluate the antigenotoxicity of the fraction. The cytotoxic effect of PWE was analyzed using MTT and Neutral Single Cell Gel Electrophoresis comet assay. EC50 of 90.188 µg/ml, 80.13 µg/ml, 142.836 µg/ml, and 12.274 µg/ml was obtained in DPPH, superoxide anion scavenging, reducing power and lipid peroxidation assays, respectively. PWE was potent in inhibiting Fenton's reagent-induced nicking of pBR322 plasmid. The fraction significantly inhibited hydrogen peroxide (H2O2) and 4-nitroquinoline-N-oxide (4NQO) induced mutagenicity and a reduction in induction factor was found with increased PWE concentration. GI50 of 147.16 µg/ml was obtained in MTT assay in human MCF-7 breast cancer cell line. PWE induced apoptosis as confirmed from confocal microscopy studies. The protective effects can be attributed to the presence of the phytochemicals in PWE. These results will be helpful in the development of functional food characteristics, as well as unravel the benefits of pteridophytes as promoters of health.

May phytophenolics alleviate aflatoxins-induced health challenges? A holistic insight on current landscape and future prospects

The future GCC-connected environmental risk factors expedited the progression of nCDs. Indeed, the emergence of AFs is becoming a global food security concern. AFs are lethal carcinogenic mycotoxins, causing damage to the liver, kidney, and gastrointestinal organs. Long-term exposure to AFs leads to liver cancer. Almost a variety of food commodities, crops, spices, herbaceous materials, nuts, and processed foods can be contaminated with AFs. In this regard, the primary sections of this review aim to cover influencing factors in the occurrence of AFs, the role of AFs in progression of nCDs, links between GCC/nCDs and exposure to AFs, frequency of AFs-based academic investigations, and world distribution of AFs. Next, the current trends in the application of PPs to alleviate AFs toxicity are discussed. Nearly, more than 20,000 published records indexed in scientific databases have been screened to find recent trends on AFs and application of PPs in AFs therapy. Accordingly, shifts in world climate, improper infrastructures for production/storage of food commodities, inconsistency of global polices on AFs permissible concentration in food/feed, and lack of the public awareness are accounting for a considerable proportion of AFs damages. AFs exhibited their toxic effects by triggering the progression of inflammation and oxidative/nitrosative stress, in turn, leading to the onset of nCDs. PPs could decrease AFs-associated oxidative stress, genotoxic, mutagenic, and carcinogenic effects by improving cellular antioxidant balance, regulation of signaling pathways, alleviating inflammatory responses, and modification of gene expression profile in a dose/time-reliant fashion. The administration of PPs alone displayed lower biological properties compared to co-treatment of these metabolites with AFs. This issue might highlight the therapeutic application of PPs than their preventative content. Flavonoids such as quercetin and oxidized tea phenolics, curcumin and resveratrol were the most studied anti-AFs PPs. Our literature review clearly disclosed that considering PPs in antioxidant therapies to alleviate complications of AFs requires improvement in their bioavailability, pharmacokinetics, tissue clearance, and off-target mode of action. Due to the emergencies in the elimination of AFs in food/feedstuffs, further large-scale clinical assessment of PPs to decrease the consequences of AFs is highly required.

Protective efficacy of naringenin against cadmium-induced redox imbalance in Labeo rohita: an integrated biomarker approach

The protective efficacy of dietary naringenin (NG) has been investigated against the toxicity caused by cadmium chloride (CdCl₂) using biomarkers of oxidative stress in the liver, gills and kidney of Labeo rohita. The fish were exposed to environmentally relevant concentrations of CdCl₂ (0.37 and 0.62 mg/L) and simultaneously orally administered with NG (50 mg/kg bw/day) for 60 days. Tissue (gills, liver and kidney) samples were collected on days 15, 30 and 60 of the experiment and analysed for endogenous antioxidants and oxidative stress biomarkers. CdCl₂ exposure for 15 and 30 days induced the development of adaptive mechanism as demonstrated by the enhanced activities of superoxide dismutase, catalase, glutathione peroxidase and glutathione-S-transferase in all three tissues. However, on the 60th day, CdCl₂-induced oxidative damage was stipulated by a decline in the enzyme activities and reduced glutathione (GSH) content significantly (p < 0.05) below control levels along with enhanced levels of lipid peroxidation. Oral administration of NG in toxicant exposed fish significantly restored the altered levels of antioxidants, oxidative enzymes and lipid peroxidation. Besides, integrated biomarker response (IBR) analysis was applied by combining all the biomarkers to indicate the overall stress response index. IBR analysis confirmed the altered levels of biomarkers, the oxidative stress induced by CdCl₂ exposure and the ameliorative potential of NG. The present study suggested that NG might have protective role against Cd-induced oxidative insult which might be ascribed to the ability of NG to chelate metals and scavenge free radicals.

The Gastroprotective Effect of Naringenin against Ethanol-Induced Gastric Ulcers in Mice through Inhibiting Oxidative and Inflammatory Responses

Naringenin is a major flavanone found in grapes, tangelos, blood oranges, lemons, pummelo, and tangerines. It is known to have anti-inflammatory, antioxidant, anticancer, antimutagenic, antifibrogenic, and antiatherogenic pharmacological properties. This study aims to investigate the anti-inflammatory effects of naringenin in ethanol-induced gastric damage in vivo and ethanol-stimulated KATO III cells in vitro. Our results showed that pretreatment with naringenin significantly protected mice from ethanol-induced hemorrhagic damage, epithelial cell loss, and edema with leucocytes. It reduced gastric ulcers (GU) by suppressing ethanol-induced nuclear factor-κB (NF-κB) activity and decreasing the levels of nitric oxide (NO), malondialdehyde (MDA), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-8 (IL-8), and myeloperoxidase (MPO). In addition, pretreatment with naringenin might inhibit the secretion of TNF-α, IL-6, and IL-8, as well as the proteins cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) via the suppression of NF-κB and mitogen-activated protein kinase (MAPK) signaling in ethanol-stimulated stomach epithelial KATO III cells. Together, the results of this study highlight the gastroprotective effect of naringenin in GU of mice by inhibiting gastric secretion and acidity, reducing inflammation and oxidative stress, suppressing NF-κB activity, and restoring the histological architecture. These findings suggested that naringenin has therapeutic potential in the alleviation of ethanol-induced GU.

The Antimutagenic and Antioxidant Activity of Fermented Milk Supplemented with Cudrania tricuspidata Powder

In this study, Cudrania tricuspidata (CT) containing abundant phytochemicals, such as xanthones and flavonoids, was evaluated as an additive to fortify the functionality and organoleptic quality of fermented milk. The physicochemical, functional, and sensory properties of fermented milk supplemented with different concentrations of CT powder were investigated. Increasing amounts of CT powder elevated the malic acid concentration, increasing the total acidity and decreasing the pH of fermented milk supplemented with CT powder. The viable cell count and free sugar contents of fermented milk indicated that supplementing with CT powder improved lactic acid fermentation slightly. The color of fermented milk supplemented with CT powder was darker, redder, yellower, and more pleasing than the control fermented milk. The total phenolic and flavonoid contents of fermented milk supplemented with CT powder rose as the concentration of supplemented CT powder increased, resulting in enhanced antioxidant and antimutagenic activities. The CT powder improved the functionality of the fermented milk; still, at 2% or more, it had some unfavorable sensory properties, such as sourness, taste, and texture, which reduced the overall consumer preference. Therefore, a CT powder concentration of 0.5% or 1% may be acceptable to consumers.

Antimutagenic components in Spatholobus suberectus Dunn against N-methyl-N-nitrosourea

BACKGROUND

An extract from Spatholobus suberectus (S. suberectus) Dunn has been reported to show potent antimutagenic effects against N-alkyl-N-nitrosoureas in umu screening. The aim of this study was to identify the antimutagenic components from extracts of S. suberectus against N-methyl-N-nitrosourea (MNU) in the Ames assay with Salmonella typhimurium strain TA1535 and to elucidate the antimutagenic mechanism of the flavonoids.

RESULTS

From the ethyl acetate fraction obtained from fractionation of the methanol extract of S. suberectus Dunn, medicarpin, formononetin and isoliquiritigenin were successfully isolated through a combination of normal- and reversed-phase chromatography. Genistein and naringenin, which were already reported to be contained in S. suberectus Dunn, were also tested for their antimutagenicity towards MNU, along with formononetin, isoliquiritigenin and medicarpin. Our results demonstrated that genistein, isoliquiritigenin, medicarpin and naringenin were antimutagenic against MNU without showing cytotoxicity. MNU is reported to cause not only DNA alkylation but also induce reactive oxygen species. The hydroxyl radical scavenging capacity of the flavonoids was correlated with the antimutagenic capacity, indicating that the hydroxyl radical scavenging activity was involved in their antimutagenicity towards MNU.

CONCLUSIONS

It is important to prevent DNA damage by N-nitrosamines for cancer chemoprevention. Genistein, isoliquiritigenin, medicarpin and naringenin were demonstrated to possess an antigenotoxic effects against carcinogenic MNU due to their radical scavenging activity.

LC-ESI-MS/MS Identification of Biologically Active Phenolic Compounds in Mistletoe Berry Extracts from Different Host Trees

A new, rapid, sensitive and selective liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) method was developed to determine the content of flavonoid aglycones and phenolic acids in mistletoe berries (Viscum album L.) harvested from six different Polish host trees. Additionally, the total phenolic content (TPC) and total flavonoid content (TFC) as well as an antioxidant and antiproliferative activity were evaluated for the first time. The plant material was selectively extracted using ultrasound assisted maceration with methanol/water (8:2) solution. The obtained TPC and TFC results varied from 7.146 to 9.345 mg GA g⁻¹ and from 1.888 to 2.888 mg Q g⁻¹ of dry extracts, respectively. The LC-ESI-MS/MS analysis demonstrated the highest content of phenolic acids in mistletoe berries from Populus nigra ‘Italica’ L. and flavonoid aglycones in mistletoe berries from Tilia cordata Mill. (354.45 µg and 5.955 µg per g dry extract, respectively). The moderate antioxidant activity of investigated extracts was obtained. The studies revealed that the examined extracts decreased the proliferation of human colon adenocarcinoma cells line LS180 in a dose-dependent manner without cytotoxicity in the human colon epithelial cell line CCD 841 CoTr. Moreover, the obtained results suggest considerable impact of polyphenols on the anticancer activity of these extracts.

The Citrus Flavanone Naringenin Protects Myocardial Cells against Age-Associated Damage

In recent years, the health-promoting effects of the citrus flavanone naringenin have been examined. The results have provided evidence for the modulation of some key mechanisms involved in cellular damage by this compound. In particular, naringenin has been revealed to have protective properties such as an antioxidant effect in cardiometabolic disorders. Very recently, beneficial effects of naringenin have been demonstrated in old rats. Because aging has been demonstrated to be directly related to the occurrence of cardiac disorders, in the present study, the ability of naringenin to prevent cardiac cell senescence was investigated. For this purpose, a cellular model of senescent myocardial cells was set up and evaluated using colorimetric, fluorimetric, and immunometric techniques. Relevant cellular senescence markers, such as X-gal staining, cell cycle regulator levels, and the percentage of cell cycle-arrested cells, were found to be reduced in the presence of naringenin. In addition, cardiac markers of aging-induced damage, including radical oxidative species levels, mitochondrial metabolic activity, mitochondrial calcium buffer capacity, and estrogenic signaling functions, were also modulated by the compound. These results suggested that naringenin has antiaging effects on myocardial cells.

Isolation and characterization of antimutagenic components of Glycyrrhiza aspera against N-methyl-N-nitrosourea

Background

A powdered ethanolic extract of Glycyrrhiza aspera root exhibits antimutagenic activity against N-methyl-N-nitrosourea (MNU) based on the Ames assay with Salmonella typhimurium TA1535. The aim of this study was to identify the antimutagenic components of the powdered ethanolic extract of G. aspera root.

Results

The powdered ethanolic extract of G. aspera root was sequentially suspended in n-hexane, carbon tetrachloride, dichloromethane, ethyl acetate, and ethanol, and each solvent soluble fraction and the residue were assayed for antimutagenic activity against MNU in S. typhimurium TA1535. The dichloromethane soluble fraction exhibited the highest antimutagenicity and was fractionated several times by silica gel chromatography. The fraction with the highest antimutagenic activity was further purified using HPLC, and the fractions were assayed for antimutagenicity against MNU in S. typhimurium TA1535. Finally, five components with antimutagenic activity against MNU were identified as glyurallin A, glyasperin B, licoricidin, 1-methoxyphaseollin, and licoisoflavone B.

Conclusions

The five components were demonstrated to possess an antigenotoxic effect against carcinogenic MNU for the first time. It is important to prevent DNA damage by N-nitrosamines for cancer chemoprevention.

Electronic supplementary material

The online version of this article (doi:10.1186/s41021-016-0068-2) contains supplementary material, which is available to authorized users.

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.

The Role of Natural Polyphenols in the Prevention and Treatment of Cervical Cancer-An Overview

Cervical cancer represents the second leading cause of death for women worldwide. The importance of the diet and its impact on specific types of neoplasia has been highlighted, focusing again interest in the analysis of dietary phytochemicals. Polyphenols have shown a wide range of cellular effects: they may prevent carcinogens from reaching the targeted sites, support detoxification of reactive molecules, improve the elimination of transformed cells, increase the immune surveillance and the most important factor is that they can influence tumor suppressors and inhibit cellular proliferation, interfering in this way with the steps of carcinogenesis. From the studies reviewed in this paper, it is clear that certain dietary polyphenols hold great potential in the prevention and therapy of cervical cancer, because they interfere in carcinogenesis (in the initiation, development and progression) by modulating the critical processes of cellular proliferation, differentiation, apoptosis, angiogenesis and metastasis. Specifically, polyphenols inhibit the proliferation of HPV cells, through induction of apoptosis, growth arrest, inhibition of DNA synthesis and modulation of signal transduction pathways. The effects of combinations of polyphenols with chemotherapy and radiotherapy used in the treatment of cervical cancer showed results in the resistance of cervical tumor cells to chemo- and radiotherapy, one of the main problems in the treatment of cervical neoplasia that can lead to failure of the treatment because of the decreased efficiency of the therapy.

Antigenotoxicity and antimutagenicity of ethanolic extracts of Brazilian green propolis and its main botanical source determined by the Allium cepa test system

Brazilian green propolis is a resinous substance prepared by bees from parts of the plant Baccharis dracunculifolia. As it possess several biological properties, this work assessed the cytotoxic/anticytotoxic, genotoxic/antigenotoxic and mutagenic/antimutagenic potential of ethanolic extracts of Brazilian green propolis (EEGP) and of B. dracunculifolia (EEBD), by means of the Allium cepa test system. The effects were evaluated by assessing the chromosomal aberrations (CA) and micronuclei (MN) frequencies on meristematic and F1 generation cells from onion roots. Chemical analyses performed with the extracts showed differences in flavonoid quality and quantity. No genotoxic or mutagenic potential was detected, and both extracts were capable of inhibiting cellular damage caused by methyl methanesulfonate (MMS) treatment, reducing the frequencies of CA and MN. By these data, we can infer that, independent of their flavonoid content, the extracts presented a protective effect in A. cepa cells against the clastogenicity of MMS.

Leaf extracts from Teucrium ramosissimum protect against DNA damage in human lymphoblast cell K562 and enhance antioxidant, antigenotoxic and antiproliferative activity

The in vitro antioxidant, antigenotoxic and antiproliferative activities of Teucrium ramosissimum extracts were investigated. The antioxidant activities of the tested extracts were evaluated through three chemical assays: The Cupric reducing antioxidant capacity, the reducing power and the ferric reducing antioxidant power. TR1 fraction from methanol extract showed the best antioxidant activity evaluated by the CUPRAC, RP and FRAP assays with TEAC values of 4.04, 1.77 and 1.48μM respectively compared to control. Yet, TR2 fraction exhibited the lowest antioxidant effect with a TEAC values of 1.97, 0.408 and 0.35μM respectively. All the tested extracts were also found to be effective in protecting plasmid DNA against the strand breakage induced by hydroxyl radicals. Furthermore, the effects of T. ramosissimum extracts on cell proliferation were also examined. The cytotoxic study revealed that methanol extract significantly inhibited the proliferation of K562 cells (IC50=150μg/mL). The antigenotoxic properties of these extracts were investigated by assessing the induction and inhibition of the genotoxicity induced by the direct-acting mutagen, hydrogen peroxide (H2O2), using an eukaryotic system; the "Comet assay." The results showed that all the extracts inhibited the genotoxicity induced by H2O2, and particularly TR2 fraction (96.99%) and methanol extract (96.64%). The present study has demonstrated that T. ramosissimum extract possess potent antioxidant, antiproliferative and antigenotoxic activities, which could be derived from compounds such as flavonoids and polyphenols.

Evaluation of the genotoxicity/mutagenicity and antigenotoxicity/antimutagenicity induced by propolis and Baccharis dracunculifolia, by in vitro study with HTC cells

The ethanolic extract of propolis, especially the Brazilian green type, is widely and mainly used for therapeutic purposes despite the lack of knowledge about its effects and its cellular mode of action. This type of propolis, derived from Baccharis dracunculifolia (alecrim-do-campo), has been extensively commercialized and the consumers use it to enhance health. This work aimed to assess the genotoxic/mutagenic and antigenotoxic/antimutagenic potentials of the ethanolic extracts of Brazilian green propolis and of B. dracunculifolia, on mammalian cells. It was not observed genotoxic and mutagenic effects by both extracts. After evaluate the exposure of the cells to each extract with a recognized mutagen, simultaneously, the results showed a significant reduction on DNA damage. The experiment carried out with a pre-incubation period was more effective than without incubation test, showing that the tested extracts were able to inactivate the mutagen before it could react with the DNA.

Anti-Proliferative Effect of Naringenin through p38-Dependent Downregulation of Cyclin D1 in Human Colorectal Cancer Cells

Naringenin (NAR) as one of the flavonoids observed in grapefruit has been reported to exhibit an anti-cancer activity. However, more detailed mechanism by which NAR exerts anti-cancer properties still remains unanswered. Thus, in this study, we have shown that NAR down-regulates the level of cyclin D1 in human colorectal cancer cell lines, HCT116 and SW480. NAR inhibited the cell proliferation in HCT116 and SW480 cells and decreased the level of cyclin D1 protein. Inhibition of proteasomal degradation by MG132 blocked NAR-mediated cyclin D1 downregulation and the half-life of cyclin D1 was decreased in the cells treated with NAR. In addition, NAR increased the phosphorylation of cyclin D1 at threonine-286 and a point mutation of threonine-286 to alanine blocked cyclin D1 downregulation by NAR. p38 inactivation attenuated cyclin D1 downregulation by NAR. From these results, we suggest that NAR-mediated cyclin D1 downregulation may result from proteasomal degradation through p38 activation. The current study provides new mechanistic link between NAR, cyclin D1 downregulation and cell growth in human colorectal cancer cells.

Forest biorefinery: Potential of poplar phytochemicals as value-added co-products

The global forestry industry after experiencing a market downturn during the past decade has now aimed its vision towards the integrated biorefinery. New business models and strategies are constantly being explored to re-invent the global wood and pulp/paper industry through sustainable resource exploitation. The goal is to produce diversified, innovative and revenue generating product lines using on-site bioresources (wood and tree residues). The most popular product lines are generally produced from wood fibers (biofuels, pulp/paper, biomaterials, and bio/chemicals). However, the bark and other tree residues like foliage that constitute forest wastes, still remain largely an underexploited resource from which extractives and phytochemicals can be harnessed as by-products (biopharmaceuticals, food additives and nutraceuticals, biopesticides, cosmetics). Commercially, Populus (poplar) tree species including hybrid varieties are cultivated as a fast growing bioenergy crop, but can also be utilized to produce bio-based chemicals. This review identifies and underlines the potential of natural products (phytochemicals) from Populus species that could lead to new business ventures in biorefineries and contribute to the bioeconomy. In brief, this review highlights the importance of by-products/co-products in forest industries, methods that can be employed to extract and purify poplar phytochemicals, the potential pharmaceutical and other uses of >160 phytochemicals identified from poplar species - their chemical structures, properties and bioactivities, the challenges and limitations of utilizing poplar phytochemicals, and potential commercial opportunities. Finally, the overall discussion and conclusion are made considering the recent biotechnological advances in phytochemical research to indicate the areas for future commercial applications from poplar tree species.

Iminoflavones combat 1,2-dimethyl hydrazine-induced aberrant crypt foci development in colon cancer

The aim of the present study was to evaluate the antitumor potential of iminoflavones in in vitro and in vivo anticancer models. Preliminary screening in various cancer cell lines revealed four potential iminoflavones out of which IMF-8 was taken based on its activity against colon cancer cells. This was further confirmed by observing the nuclear changes in the cells by AO/EB and Hoechst 33342 staining studies. In vivo activity was assessed by dimethyl hydrazine-(DMH-) induced colon cancer model in rats. Animals were administered DMH (20 mg/kg, b.w. for 10 weeks and 30 mg/kg b.w., i.p. for 10 weeks) and were supplemented with (IMF-8) iminoflavone-8 (200 mg/kg, p.o. for 14 days). Results showed that DMH induced 100% aberrant crypt foci (ACF) and polyps which were significantly reduced in the IMF-8 treated group. IMF-8 significantly increased the catalase and GSH levels whereas it reduced the TNF-α and IL-6 levels markedly which suggests the antioxidative and anti-inflammatory actions of flavonoids present in IMF-8. The histopathological images of the IMF-8 treated colon showed no signs of mucosal crypt abscess. These findings suggest that the semi-synthetic iminoflavones, IMF-8, effectively inhibit DMH-induced ACFs and colonic crypts by alleviating the oxidative stress and suppressing the inflammation.

Improved oxidation of naringenin to carthamidin and isocarthamidin by Rhodotorula marina

A novel single-step microbial transformation process for the efficient production of carthamidin and isocarthamidin from naringenin by yeast Rhodotorula marina in an aerated bioreactor was described. The biotransformation led to the total product concentration of 233 mg/l. The highest conversion efficiency observed for carthamidin was 0.31 mg/mg of naringenin and for isocarthamidin 0.47 mg/mg of naringenin.

Naringenin inhibits α-glucosidase activity: a promising strategy for the regulation of postprandial hyperglycemia in high fat diet fed streptozotocin induced diabetic rats

Obesity and the onset of diabetes are two closely linked medical complications prevalent globally. Postprandial hyperglycemia is one of the earliest abnormalities of glucose homeostasis associated with type 2 diabetes (T2D). Postprandial glucose levels can be regulated through α-glucosidase inhibition. The present study aims to demonstrate the potent inhibitory role of naringenin against α-glucosidase activity. The mode of inhibition of naringenin was examined by measuring enzyme activity in vitro with different concentrations of substrate using Lineweaver-Burk plot analysis. It shows competitive inhibition towards mammalian α-glucosidase thereby competing with α-limit dextrins and oligosaccharide residues for binding in the active site. Similar results have been obtained from the molecular docking analyses, where naringenin shows preferential binding for the active sites in each of the evaluated human intestinal α-glucosidase enzymes. Post-docking intramolecular hydrogen bonding analysis shows water molecule mediated hydrogen bonding for N-terminal maltase glucoamylase and N-terminal sucrase isomaltase. Naringenin's docked pose in the C-terminal maltase glucoamylase active site does not show any particular water mediated interaction similar to the co-crystallized acarbose. Further, our results suggest that naringenin (25 mg/kg) exerts significant inhibition of intestinal α-glucosidase activity in vivo thereby delaying the absorption of carbohydrates in T2D rats, thus resulting in significant lowering of postprandial blood glucose levels. Both in vitro and in vivo results were compared to the commercially available α-glucosidase inhibitor acarbose. Our findings clearly indicate that naringenin dampens postprandial glycemic response and offers a potential complementary approach in the management of T2D.

Anti-inflammatory role of naringenin in rats with ethanol induced liver injury

The aim of the study was to investigate the antiinflammatory effects of naringenin in rats induced liver damage by exposure to ethanol. Rats were divided into four groups, groups 1 and 2 received isocaloric glucose; groups 3 and 4 received 20% ethanol equivalent to 6 g/kg body weight everyday for the total experimental period of 60 days. In addition, groups 2 and 4 were supplemented with naringenin (50 mg/kg p.o.) everyday for the last 30 days of the experiment. The results showed significantly elevated levels/activities/expression of serum aspartate and alanine transaminases, iron, ferritin, transforming growth factor-alpha (TNF-α), interleukin-6 (IL-6), nuclear factor-kappa B (NF-κB), cyclooxygenase-2 (COX-2), macrophage inflammatory protein 2 (MIP-2) and CD14 in ethanol fed rats as compared to those of the control. Ethanol-fed rats exhibited increased staining for the presence of inducible nitric oxide (iNOS) protein adducts in the liver. Supplementation with naringenin for the last 30 days to ethanol-fed rats, significantly decreased the levels/activities/expression of serum aspartate and alanine transaminases, iron, ferritin, TNF-α, IL-6, NF-κB, COX-2, MIP-2, CD14 and iNOS protein adducts in the liver as compared to the untreated ethanol fed rats. The inhibition of TNF-α, IL-6, NF-κB, COX-2, MIP-2, iNOS and CD14 by naringenin may contribute to its antiinflammatory activity in ethanol fed rats.

Chemopreventive efficacy of naringenin-loaded nanoparticles in 7,12-dimethylbenz(a)anthracene induced experimental oral carcinogenesis

Nanochemoprevention has been introduced recently as a novel approach for improving phytochemicals bioavailability and anti-tumor effect. The present study is designed to evaluate the chemopreventive efficacy of prepared naringenin-loaded nanoparticles (NARNPs) relative to efficacy of free naringenin (NAR) against 7,12-dimethyl benz(a)anthracene (DMBA)-induced oral carcinogenesis by evaluating the status of lipid peroxidation, antioxidants and immunoexpression patterns of proliferating cell nuclear antigen (PCNA) and p53 proteins. Transmission electron microscope (TEM) and dynamic light scattering (DLS) investigations have confirmed a narrow size distribution of the prepared nanoparticles (40-90 nm) with ~88 % encapsulation efficiency. Oral squamous cell carcinoma (OSCC) was developed in the buccal pouch of golden Syrian hamsters by painting with 0.5 % DMBA in liquid paraffin three times a week for 14 weeks. DMBA painted animals revealed the morphological changes, hyperplasia, dysplasia and well-differentiated squamous cell carcinoma. Moreover, the status of lipid peroxidation, antioxidants and immunoexpression of PCNA and p53 were significantly altered during DMBA-induced oral carcinogenesis. Oral administration of NARNPs (50 mg NAR/kg body weight/day) to DMBA-treated animals completely prevented the tumor formation as compared to the free NAR and significantly reduced the degree of histological lesions, in addition to restoration of the status of biochemical and molecular markers during oral carcinogenesis. In addition, NARNPs have more potent anti-lipid peroxidative, antiproliferative effect and antioxidant potentials compared to free NAR in DMBA-induced oral carcinogenesis. In conclusion, the present study suggests that NARNPs could be a potentially useful drug carrier system for targeted delivery of naringenin for cancer chemoprevention.

Antioxidant, genotoxic and antigenotoxic activities of daphne gnidium leaf extracts

Background

Plants play a significant role in maintaining human health and improving the quality of human life. They serve humans well as valuable components of food, as well as in cosmetics, dyes, and medicines. In fact, many plant extracts prepared from plants have been shown to exert biological activity in vitro and in vivo. The present study explored antioxidant and antigenotoxic effects of Daphne gnidium leaf extracts.

Methods

The genotoxic potential of petroleum ether, chloroform, ethyl acetate, methanol and total oligomer flavonoid (TOF) enriched extracts from leaves of Daphne gnidium, was assessed using Escherichia coli PQ37. Likewise, the antigenotoxicity of the same extracts was tested using the “SOS chromotest test”. Antioxidant activities were studied using non enzymatic and enzymatic method: NBT/Riboflavine and xantine oxidase.

Results

None of the different extracts produced a genotoxic effect, except TOF extract at the lowest tested dose. Our results showed that D. gnidium leaf extracts possess an antigenotoxic effect against the nitrofurantoin a mutagen of reference. Ethyl acetate and TOF extracts were the most effective in inhibiting xanthine oxidase activity. While, methanol extract was the most potent superoxide scavenger when tested with the NBT/Riboflavine assay.

Conclusions

The present study has demonstrated that D. gnidium leaf extract possess antioxidant and antigenotoxic effects. These activities could be ascribed to compounds like polyphenols and flavonoid. Further studies are required to isolate the active molecules.

An in vitro study on the DNA damaging effects of phytochemicals partially isolated from an extract of Glinus lotoides

An extract of Glinus lotoides, a medicinal plant used in Africa and Asia for various therapeutic purposes, was recently shown to cause DNA damage in vitro. To further explore the potential genotoxicity of this plant, fractionation of the crude extract was performed using reverse phase solid-phase extraction and a stepwise gradient elution of methanol in water. Four fractions were collected and subsequently analysed for their DNA damaging effects in mouse lymphoma cells using an alkaline version of the comet assay. To identify potential genotoxic and non-genotoxic principles, each fraction was then subjected to liquid chromatography coupled to mass spectrometry, LC-MS/MS. 1D and 2D nuclear magnetic resonance analyses were used to confirm the identity of some saponins. Although fractions containing a mixture of flavonoids and oleanane-type saponins or oleanane-type saponins alone produced no DNA damage, those containing hopane-type saponins exhibited a pronounced DNA damaging effect without affecting the viability of the cells. To conclude, even if this study presents evidence that hopane-type of saponins are endowed with a DNA damaging ability, further studies are needed before individual saponins can be cited as a culprit for the previously reported genotoxicity of the crude extract of G. lotoides.

Effect of Naringenin on metabolic markers, lipid profile and expression of GFAP in C6 glioma cells implanted rat's brain

BACKGROUND

Naringenin, a flavanone, has been reported to exhibit a wide range of pharmacological properties including antitumor activity.

PURPOSE

We wanted to test the efficacy of Naringenin on C6 glioma cells-implanted into rats was investigated.

METHODS

Biochemical and immunohistochemical methods were used for analyzing various markers.

RESULTS

Injection of C6 glioma cells into rat brain resulted in increased metabolic markers {Lactatate Dehydrogenase (LDH), 5' Nucleotidase 5'ND), creatine kinase (CK), Hexokinase (HK) and Glucose 6-phosphate dehydrogenase (G6PD)} and lipid profile (triglycerides, free fatty acids, phos-pholipids, total cholesterol and free cholesterol). Oral administration of Naringenin (50 mg /kg of BW for 30 days) significantly altered this biochemical profile. Further, the immuno fluorescence expression of Glial fibrilary acidic protein (GFAP) was also studied.

CONCLUSION

In C6 glioma cells-implanted rats, increased expression of GFAP was noted on treatment with Naringenin. These observations suggest that Naringenin may participate by inhibiting glial cell tumorigenesis.

The effect of apigenin on cyclophosphamide and doxorubicin genotoxicity in vitro and in vivo

The aim of this study was to investigate the mutagenic and antigenotoxic effects of different doses of the flavonoid, apigenin, alone and in combination with the antitumor drugs, cyclophosphamide and doxorubicin, in vitro and in vivo. Using bacterial reverse mutation inhibition in vitro, with and without metabolic activation, the effect of apigenin (10-400 μg/plate) was studied on genotoxicity induced by cyclophosphamide (800 μg/plate) and by doxorubicin (0.2 μg/plate). Subsequent to a dose-finding study in vivo, CD1 mice were treated with either cyclophosphamide (40 mg/kg, i.p.) or doxorubicin (5 mg/kg, i.p.) with or without co-administration of apigenin (1-100 mg/kg, p.o.). Micronuclei were determined microscopically in blood smears and glutathione peroxidase (GPX), superoxide dismutase (SOD) and total antioxidative status (TAS) in whole blood, erythrocytes and plasma, respectively. Apigenin decreased doxorubicin-induced, but not cyclophosphamide-induced mutagenicity in vitro. In vivo, apigenin caused a statistically significant decrease in micronucleus frequency in response to cyclophosphamide, possibly due to active flavonoid metabolite formation or inhibition of cyclophosphamide metabolic activation. In animals treated with apigenin and doxorubicin, a significant decrease in micronucleus frequency was not observed, probably due to interindividual variability. No changes in GPX, SOD or TAS were observed in response to either cytotoxic agents or the flavonoid, possibly due to limited metabolic transformation of the drugs at the doses used. The results of the present study provide further evidence for the chemo-preventative properties of apigenin.

Antioxidant and antibacterial activity of extracts, fractions and isolated substances from the flowers of Acacia podalyriifolia A. Cunn. ex G. Don

The extracts and fractions from the flowers of A. podalyriifolia were analyzed previously for antibacterial activity using diffusion in disk, Antioxidant properties were evaluated by determining radical scavenging power (DPPH test) and total phenol content was measured (Folin method). The present study describes the in vitro antibacterial (determining minimum inhibitory concentration) and antioxidant activities (by thiobarbituric acid reactive species - TBARS method) for the ethanol extract, dichloromethane and ethyl acetate fractions and two flavanones (naringenin and 5-β-D-glycosyl-naringenin) isolated from the flowers of Acacia podalyriifolia A. Cunn. ex G. Don. The flavanones naringenin and 5-β-D-glycosyl-naringenin had not previously been obtained from this species. The most effective antibacterial activity was observed in the ethyl acetate fraction (MIC=0.25 mg mL-1 against Staphylococcus aureus ATCC 6538, MIC = 0.125 mg mL-1 against Staphylococcus epidermidis ATCC 12229, MIC=0.5 mg mL-1 against Streptococcus pyogenes ATCC 19615, Klebsiella pneumoniae ATCC 13883 and Proteus mirabilis ATCC 43071). The evaluated samples showed antioxidant activity on the TBARS test, especially for ethanol extract (1000 ppm), which was the most active (29.43% ± 0.65) followed by ethyl acetate fraction (1000 ppm, 24.84% ± 1,28), both demonstrating higher activity than that presented by ascorbic acid (1000 ppm, 21.73% ± 1.77), although lower than the BHT (1000 ppm 35.15% ± 3.42), both reference compounds. Naringenin and 5-β-D-glycosyl-naringenin demonstrated antioxidant action, but only naringenin inhibited the growth of gram-positive and gram-negative bacteria.

Naringenin modulates circulatory lipid peroxidation, anti-oxidant status and hepatic alcohol metabolizing enzymes in rats with ethanol induced liver injury

We have investigated the modulatory efficacy of naringenin on circulatory lipid peroxidation and anti-oxidant status, hepatic alcohol metabolizing enzymes in rats with ethanol induced hepatotoxicity. Rats were divided into four groups: groups 1 and 2 received isocaloric glucose and 0.5% carboxymethyl cellulose; groups 3 and 4 received 20% ethanol equivalent to 6 g/kg body weight everyday for the total experimental period of 60 days. In addition, groups 2 and 4 were given naringenin (50 mg/kg) everyday for the last 30 days of the experiment. The results showed significantly elevated levels/activities of bilirubin, alkaline phosphatase (ALP), lactate dehydrogenase (LDH), thiobarbituric acid reactive substances (TBARS), lipid hydroperoxides (LOOH), conjugated dienes (CD) and phase I enzymes, and significantly lowered the activities of alcohol dehydrogenase (ADH), aldehyde dehydrogenase (ALDH), superoxide dismutase (SOD), catalase (CAT) and phase II enzymes in ethanol-fed rats as compared to those of the control. Supplementation with naringenin for the last 30 days of the experiment to ethanol-fed rats, significantly decreased the levels/activities of bilirubin, ALP, LDH, TBARS, LOOH, CD and phase I enzymes, and significantly elevated the activities of ADH, ALDH, SOD, CAT and phase II enzymes as compared to control rats. These findings suggest that naringenin can effectively modulate the hepatic alcohol metabolizing enzymes in rats with ethanol induced liver injury.

Leaf and root extracts of Moricandia arvensis protect against DNA damage in human lymphoblast cell K562 and enhance antioxidant activity

Four extracts were prepared from the roots and leaves of Moricandia arvensis: root chloroform extract (ChlR), leaf chloroform extract (ChlL), root ethyl acetate extract (EAR) and leaf ethyl acetate extract (EAL). The genotoxic and antigenotoxic properties of these extracts were investigated by assessing the induction and inhibition of the genotoxicity induced by the direct-acting mutagen, hydrogen peroxide (H(2)O(2)), using the "Comet assay." It appears that none of the different extracts produces a genotoxic effect, except the highest tested concentrations of the leaf extracts which were capable to eliciting DNA damage. Human lymphoblast cells K562 were pretreated with different concentrations of each extracts and then treated by H(2)O(2), for the antigenotoxic study. The results showed that all extracts inhibited the genotoxicity induced by H(2)O(2) and particularly ChlR (42.5μg/ml) and ChlL (65μg/ml) extracts. In addition, antioxidant potential study of root and leaf extracts using different antioxidant tests indicated that root extracts possess a potent antioxidant activity through namely their capacity to transfer electrons.

Potential beneficial effect of naringenin on lipid peroxidation and antioxidant status in rats with ethanol-induced hepatotoxicity

Objectives

The aim was to study the effect of naringenin, a biologically active compound, on tissue antioxidant status and lipid peroxidation in ethanol-induced hepatotoxicity in rats.

Methods

Rats were divided into four groups: Groups 1 and 2 received isocaloric glucose and 0.5% carboxymethyl cellulose; groups 3 and 4 received 20% ethanol equivalent to 6 g/kg daily for 60 days. In addition, groups 2 and 4 were given naringenin (50 mg/kg) daily for the last 30 days of the experiment.

Key findings

The results showed significantly elevated levels of serum aspartate and alanine transaminases, γ-glutamyl transpeptidase, tissue thiobarbituric acid reactive substances, conjugated dienes, lipid hydroperoxides and protein carbonyl content, and significantly lowered activities/levels of antioxidants such as superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, glutathione-S-transferase, reduced glutathione and vitamins C and E in ethanol-treated rats compared with control rats. Administration of naringenin to rats with ethanol-induced liver injury significantly decreased the levels of serum aspartate and alanine transaminases, γ-glutamyl transpeptidase, tissue thiobarbituric acid reactive substances, conjugated dienes, lipid hydroperoxides and protein carbonyl content and significantly elevated the activities of superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase and glutathione-S-transferase, and the levels of reduced glutathione and vitamins C and E in the tissues compared with unsupplemented ethanol-treated rats. Histological changes observed in the liver correlated with the biochemical findings.

Conclusions

Taken together these findings suggest that naringenin has a therapeutic potential in the abatement of ethanol-induced hepatotoxicity.

Hesperidin gastroresistant microparticles by spray-drying: preparation, characterization, and dissolution profiles

Gastroresistant microparticles for oral administration of hesperidin (Hd) were produced by spray-drying using cellulose acetate phthalate (CAP) as enteric polymer in different polymer/Hd weight ratio (1:1, 3:1, and 5:1), and a series of enhancers of the dissolution rate, such as sodium carboxymethylcellulose crosslinked (CMC), sodium dodecylbenzene sulfonate (SDBS), or Tween85. The raw materials and the microparticles were investigated by differential-scanning calorimetry, X-ray diffraction, infrared spectroscopy and imaged using scanning electron and fluorescence microscopy. In vitro dissolution tests were conducted using a pH-change method to investigate the influence of formulative parameters on the dissolution/release properties of the drug. CAP/Hd microparticles showed a good gastro-resistance but incomplete drug dissolution in the simulated intestinal fluid (SIF). The presence of the enhancers in the formulation produced well-formed microparticles with different size and morphology, containing the drug well coated by the polymer. All the enhancers were able to increase the dissolution rate of Hd in the simulated intestinal environment without altering CAP ability to protect Hd in the acidic fluid. The spray-drying technique and process conditions selected were effective in microencapsulating and stabilizing the flavonoid giving satisfactory encapsulation efficiency, product yield, and microparticles morphology, and a complete drug release in the intestine.

Naringenin protects against cadmium-induced oxidative renal dysfunction in rats

Cadmium (Cd) is an environmental and industrial pollutant that affects various organs in human and experimental animals. Naringenin is a naturally occurring plant bioflavonoid found in citrus fruits, which has been reported to have a wide range of pharmacological properties. A body of evidence has accumulated implicating the free radical generation with subsequent oxidative stress in the biochemical and molecular mechanisms of cadmium toxicity. Since kidney is the critical target organ of chronic Cd toxicity, we carried out this study to investigate the effects of naringenin on Cd-induced toxicity in the kidney of rats. In experimental rats, oral administration of cadmium chloride (5mg/(kgday)) for 4 weeks significantly induced the renal damage which was evident from the increased levels of serum urea, uric acid, creatinine with a significant (p<0.05) decrease in creatinine clearance. Cadmium also significantly decreased the levels of urea, uric acid and creatinine in urine. A markedly increased levels of lipid peroxidation markers (thiobarbituric acid reactive substances and lipid hydroperoxides) and protein carbonyl contents with significant (p<0.05) decrease in non-enzymatic antioxidants (total sulfhydryl groups, reduced glutathione, vitamin C and vitamin E) and enzymatic antioxidants (superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione S-transferase (GST)) as well as glutathione metabolizing enzymes (glutathione reductase (GR) and glutathione-6-phosphate dehydrogenase (G6PD)) were also observed in cadmium-treated rats. Co-administration of naringenin (25 and 50mg/(kgday)) along with Cd resulted in a reversal of Cd-induced biochemical changes in kidney accompanied by a significant decrease in lipid peroxidation and an increase in the level of renal antioxidant defense system. The histopathological studies in the kidney of rats also showed that naringenin (50mg/(kgday)) markedly reduced the toxicity of Cd and preserved the normal histological architecture of the renal tissue. The present study suggest that the nephroprotective potential of naringenin in Cd toxicity might be due to its antioxidant and metal chelating properties, which could be useful for achieving optimum effects in Cd-induced renal damage.

Kaempferol, a mutagenic flavonol from Helichrysum simillimum

Helichrysum simillimum is native to South Africa. It is used for the treatment of coughs, colds, fever, infections, headache, and menstrual pain. Extracts of this species showed mutagenic effects in the Salmonella/microsome assay. The aim of this study was to isolate and determine the mutagenic constituents of H. simillimum. Bioassay-guided fractionation of 90% aqueous methanol extracts, using Salmonella typhimurium TA98, led to the isolation of the flavonol kaempferol.

Anti-carcinogenic effects of the flavonoid luteolin

Luteolin is a flavonoid which is part of our daily nutrition in relatively low amounts (less than 1 mg/day). Nevertheless, some epidemiological studies suggest an inverse correlation between luteolin intake and the risk of some cancer types. Luteolin displays specific anti-inflammatory and anti-carcinogenic effects, which can only partly be explained by its anti-oxidant and free radical scavenging capacities. Luteolin can delay or block the development of cancer cells in vitro and in vivo by protection from carcinogenic stimuli, by inhibition of tumor cell proliferation, by induction of cell cycle arrest and by induction of apoptosis via intrinsic and extrinsic signaling pathways. When compared to other flavonoids, luteolin was usually among the most effective ones, inhibiting tumor cell proliferation with IC(50) values between 3 and 50 microM in vitro and in vivo by 5 to 10 mg/kg i.p., intragastric application of 0.1-0.3 mg/kg/d, or as food additive in concentrations of 50 to 200 ppm. Luteolin has been shown to penetrate into human skin, making it also a candidate for the prevention and treatment of skin cancer.

The antimutagenic activity of the major flavonoids of rooibos (Aspalathus linearis): some dose-response effects on mutagen activation-flavonoid interactions

The antimutagenic properties of the most prevalent flavonoids in rooibos (Aspalathus linearis) were compared in the Salmonella typhimurium mutagenicity assay using tester strains TA98 and TA100 with, respectively, 2-acetamido-fluorene (2-AAF) and aflatoxin B(1) (AFB(1)) as mutagens in the presence of metabolic activation. The flavonoids included the dihydrochalcones aspalathin and nothofagin and their flavone analogues, orientin and isoorientin, and vitexin and isovitexin, respectively, as well as luteolin, chrysoeriol, (+)-catechin, quercetin, isoquercitrin, hyperoside and rutin. Flavonoid-mutagen interactions ranged from antimutagenic, comutagenic and promutagenic to mutagenic, while dose-response effects were mutagen-specific and ranged from typical to atypical including biphasic and threshold effects. Aspalathin and nothofagin and their structural flavonoid analogues displayed moderate antimutagenic properties while luteolin and to some extent, chrysoeriol, showed activities comparable to those of the green tea flavonoid (-) epigallocatechin gallate (EGCG). Apart from their mutagenic and promutagenic properties, quercetin and isoquercitrin exhibited concentration-dependent comutagenic and/or antimutagenic effects against 2-AAF- and AFB(1)-induced mutagenesis. Different structural parameters known to affect the antimutagenic properties of flavonoids include their hydrophilic or lipophilic nature due to the extent of hydroxylation and O-methylation, glycosylation on the A and B rings, the C4-keto group and the C2-C3 double bond. The C ring does not appear to be a prerequisite when comparing for the antimutagenic activity of the dihydrochalcones when compared of the dihydrochalcones with the structural flavone analogues.

Screening of antimutagenicity via antioxidant activity in different extracts from the leaves of Acacia salicina from the center of Tunisia

The effect of extracts obtained from Acacia salicina on genotoxicity and SOS response induced by Benzo(a)pyrene (B[a]P) as well as nifuroxazide was investigated in a bacterial assay system, i.e., the SOS chromotest with Escherichia coli PQ37. Preparations obtained from the leaves of A. salicina exhibited no genotoxicity either with or without the external S9 activation mixture. However, all extracts significantly decreased the genotoxicity induced by (B[a]P) and nifuroxazide. Ethyl acetate, methanol and TOF extracts exhibited the highest inhibition level of the SOS response induced by the direct mutagen nifuroxazide. Whereas, aqueous, ethyl acetate and methanol extracts displayed the greatest level of protection towards the indirect mutagen, (B[a]P), induced response. In addition to their antigenotoxic activity, TOF, aqueous, methanol and chloroform extracts showed an important free radical scavenging activity towards the 1,1-diphenyl 2-picrylhydrazyl (DPPH) free radical. These extracts showed IC(50) value of 36, 73, 65, and 87μg/ml respectively. Taken together, our finding showed that A. salicina exhibits significant antioxidant and antigenotoxic activities.

Influence of naringenin on oxytetracycline mediated oxidative damage in rat liver

Naringenin is a naturally occurring citrus flavanone, which has been reported to have a wide range of pharmacological properties. The present work was carried out to evaluate the effect of naringenin on antioxidant and lipid peroxidation status in liver of oxytetracycline-intoxicated rats. Intraperitonial administration of oxytetracycline 200 mg/kg for 15 days resulted a significant elevation in serum hepatospecific markers such as aspartate transaminase, alanine transaminase, alkaline phosphatase, lactate dehydrogenase, and bilirubin and the levels of lipid peroxidation markers (thiobarbituric acid reactive substances (TBARS) and lipid hydroperoxides) in liver. Oxytetracycline also caused a significant reduction in the activities of superoxide dismutase, catalase, glutathione peroxidase, reduced glutathione (GSH), vitamin C and vitamin E in liver. Oral administration of naringenin (50 mg/kg b.w.t.) with oxytetracycline significantly decreased the activities of serum aspartate transaminase, alanine transaminase, alkaline phosphatase, lactate dehydrogenase and the levels of bilirubin along with significant decrease in the levels of lipid peroxidation markers in the liver. In addition, naringenin significantly increased the activities of superoxide dismutase, catalase and GSH peroxidase as well as the level of GSH, vitamin C and vitamin E in liver of the oxytetracycline-treated rats. Our results demonstrate that naringenin exhibited antioxidant property and decrease the lipid peroxidation against oxytetracycline-induced oxidative stress in liver.

Evaluation of apigenin using in vitro cytochalasin blocked micronucleus assay

High doses of flavonoids are reported to be clastogenic in contrast to their potential to reduce oxidative DNA damage, retard growth of leukemia cells, obstruct cell signal transduction and induce cellular differentiation in cancers. In the present study, we evaluated apigenin, a plant-derived flavonoid in doses of 10, 33, and 100 microM per 5 ml culture using cytochalasin-B blocked micronucleus (CBMN) assay in peripheral human lymphocytes. Apigenin was found to induce micronuclei in a dose dependent manner indicating potential genotoxic hazard in humans. Hence, flavonoids may act as mutagen, pro-oxidant or as inhibitor of key enzymes to produce clastogenic effects depending upon the levels consumed as well as the physiological parameters.

Chromosomal malsegregation and micronucleus induction in vitro by the DNA topoisomerase II inhibitor fisetin

The plant flavonol fisetin is a common dietary component that has a variety of established biological effects, one of which is the inhibition of the enzyme DNA topoisomerase II (topo II). Compounds that inhibit topo II can exert genotoxic effects such as DNA double strand breaks, which can lead to the induction of kinetochore- or CREST-negative micronuclei. Despite reports that fisetin is an effective topoisomerase II inhibitor, its genotoxic effects have not yet been well characterized. Genotoxicity testing of fisetin was conducted in TK6 and HL60 cell lines and the cells were analyzed for malsegregating chromosomes as well as for the induction of micronuclei. Using the cytokinesis-blocked CREST micronucleus assay to discriminate between micronuclei formed from chromosomal breakage (CREST-negative) and chromosomal loss (CREST-positive), a statistically significant increase in CREST-positive micronuclei was seen for all doses tested in both cell lines. CREST-negative micronuclei, however, were significantly increased at the higher test concentrations in the TK6 cell line. These data indicate that at low concentrations fisetin is primarily exerting its genotoxic effects through chromosomal loss and that the induction of DNA breaks is a secondary effect occurring at higher doses. To confirm these results, the ability of fisetin to inhibit human topoisomerase II-alpha was verified in an isolated enzyme system as was its ability to interfere with chromosome segregation during the anaphase and telophase periods of the cell cycle. Fisetin was confirmed to be an effective topo II inhibitor. In addition, significant increases in the number of mis-segregating chromosomes were observed in fisetin-treated cells from both cell lines. We conclude that fisetin is an aneugen at low concentrations capable of interfering with proper chromosomal segregation and that it is also an effective topo II inhibitor, which exerts clastogenic effects at higher concentrations.

The flavonoid naringenin inhibits dimethylnitrosamine-induced liver damage in rats

Naringenin, a phytoalexin found in grapefruits and tomatoes, has been reported to exhibit a wide range of pharmacological properties. In this study, we investigated the protective effect of naringenin on hepatic injury induced by dimethylnitrosamine (DMN) in rats. Oral administration of naringenin (20 and 50 mg/kg daily for 4 weeks) remarkably prevented the DMN-induced loss in body and liver weights and inhibited the elevation of serum alanine transaminase, aspartate transaminase, alkaline phosphatase, and bilirubin levels. Naringenin also restored serum albumin and total protein levels, and reduced the hepatic level of malondialdehyde. Furthermore, DMN-induced collagen accumulation, as estimated by histological analysis of liver tissue stained with Sirius red, was reduced in the naringenin-treated rats. A reduction in hepatic stellate cell activation, as assessed by alpha-smooth muscle actin staining, was associated with naringenin treatment. In conclusion, these results demonstrate that naringenin exhibited in vivo hepatoprotective and anti-fibrogenic effects against DMN-induced liver injury. It suggests that naringenin may be useful in preventing the development of hepatic fibrosis.

Antimutagenic activity of flavonoids from the heartwood of Rhus verniciflua

Pretreatment of the methanolic extract of the heartwood of Rhus verniciflua (Anacardiaceae) to rats prevented the activation of hepatic microsomal cytochrome p(450) enzymes, inhibition of hepatic glutathione S-transferase by bromobenzene treatment, respectively, and therefore significantly decreased malondialdehyde content in the rat. The Ames test showed that the addition of 1.0 mg/plate of the methanolic extract or the EtOAc fraction of the Rhus verniciflua heartwood extract potentially inhibited the mutagenicity by aflatoxin B(1). Column chromatography of the EtOAc fraction yielded four flavonoids, garbanzol (1), sulfuretin (2), fisetin (3), fustin (4), mollisacasidin (5). When these components were subjected to the Ames test, it was found that sulfuretin might effectively prevent the metabolic activation or scavenge electrophilic intermediates capable of causing mutation. In contrast, fustin showed a dose-independent antimutagenic activity and it has mutagenic/antimutagenic activity. However, a mixture of sulfuretin and fustin (1:1) exhibited dose-dependent antimutagenicity indicating that sulfuretin inhibited the mutagenicity of fustin. These results suggest that the extract of Rhus verniciflua heartwood containing flavonoid complex could be a potent anticarcinogen.