Inhibition of clastogenicity of benzo[a]pyrene and of its trans-7,8-dihydrodiol in mice in vivo by fruits, vegetables, and flavonoids

Comprehensive evaluation of the flavonol anti-oxidants, alpha-glycosyl isoquercitrin and isoquercitrin, for genotoxic potential

Quercetin and its glycosides possess potential benefits to human health. Several flavonols are available to consumers as dietary supplements, promoted as anti-oxidants; however, incorporation of natural quercetin glycosides into food and beverage products has been limited by poor miscibility in water. Enzymatic conjugation of multiple glucose moieties to isoquercitrin to produce alpha-glycosyl isoquercitrin (AGIQ) enhances solubility and bioavailability. AGIQ is used in Japan as a food additive and has been granted generally recognized as safe (GRAS) status. However, although substantial genotoxicity data exist for quercetin, there is very little available data for AGIQ and isoquercitrin. To support expanded global marketing of food products containing AGIQ, comprehensive testing of genotoxic potential of AGIQ and isoquercitrin was conducted according to current regulatory test guidelines. Both chemicals tested positive in bacterial reverse mutation assays, and exposure to isoquercitrin resulted in chromosomal aberrations in CHO-WBL cells. All other in vitro mammalian micronucleus and chromosomal aberration assays, micronucleus and comet assays in male and female B6C3F1 mice and Sprague Dawley rats, and Muta™ Mouse mutation assays evaluating multiple potential target tissues, were negative for both chemicals. These results supplement existing toxicity data to further support the safe use of AGIQ in food and beverage products.

Antihyperlipidemic and Antioxidant Activities of Edible Tunisian Ficus carica L. Fruits in High Fat Diet-Induced Hyperlipidemic Rats

The phenolic constituents of the aqueous-ethanolic extract of Tunisian Ficus carica (F. carica) fruit (FE) and its antihyperlipidemic and antioxidant activities in high-fat diet-induced hyperlipidemic rats (HFD) were evaluated. The obtained results demonstrated that the FE improved the lipid profile by decreasing the total cholesterol, triglyceride, low-density lipoprotein cholesterol and increasing high-density lipoprotein cholesterol levels. It also reduced the content of thiobarbituric acid-reactive substances and increased the antioxidant enzymes in liver, heart and kidney in HFD-fed rats. These antihyperlipidemic effects and in vivo antioxidative effects correlated with the in vitro phenolic content scavenging ability. Thus, the major phenolic compounds were identified using reversed-phase ultra-high-performance liquid chromatography (RP-UHPLC) coupled with two detection systems: diode-array detection (DAD) and quadrupole time-of-flight (QTOF) mass spectrometry (MS). Therefore, in the negative ionization mode, 28 phenolic compounds, including hydroxybenzoic acids, hydroxycinnamic acids, flavanoids and hydroxycoumarins were characterized. Dihydroxybenzoic acid di-pentoside, the flavonol quercetin 3-O-rutinoside and the flavone assigned as apigenin 8-C-glucoside were the main representative compounds in 'Tounsi' fruits. This work was complemented by the detection of seven other phenolic compounds in the positive ionization mode, including anthocyanins and furanocoumarins. Overall, these results have shown that the FE has a significant hypocholesterolemic effect and antioxidant activity in HFD-fed rats. This beneficial effect may be partly due to these phenolic constituents, especially vitexin, dihydroxybenzoic acid di-pentoside as well as rutin.

Absence of Genotoxic and Mutagenic Effects of Zingiber zerumbet (L.) Smith (Zingiberaceae) Extract

The present study evaluated the potential genotoxicity of the ethanol extracts from the rhizome of Zingiber zerumbet (L.) Smith (EEZZR) using a standard battery of tests. Chemical analysis with liquid chromatography-tandem mass spectrometry revealed that EEZZR contained Zerumbone (200.3 ± 0.37 μg/g) and 6-gingerol (102.5 ± 0.28 μg/g). There were no increases in the number of revertant colonies with EEZZR at concentrations of 150–5000 μg per plate, regardless of the metabolic activation system (S-9 mix) used in the histidine-dependent auxotrophic mutants of Salmonella typhimurium (strains TA97, TA98, TA100, TA102, and TA1535) compared to the vehicle control. Furthermore, EEZZR at doses of 150–5000 μg mL⁻¹ did not increase the number of structural aberrations in Chinese hamster lung cells in the presence or absence of S-9 mix. An oral administration of EEZZR to ICR mice, with doses of up to 2000 mg/kg, caused no significant increases in the number of micronucleated polychromatic erythrocytes (MNPCEs) and mean ratio of polychromatic erythrocytes to total erythrocytes. Lastly, RZZEE did not increase the incidence of MNPCEs in bone marrow. Based on these findings, it may be concluded that the use of EEZZR in traditional medicine poses no risk of genotoxicity.

Investigation on the protective effects of cranberry against the DNA damage induced by benzo[a]pyrene

There are few reports that demonstrate the antigenotoxic potential of cranberries. Although the types of berry fruits consumed worldwide are many, this paper focuses on cranberries that are commonly consumed in Mexico (Vaccinium macrocarpon species). The purpose of the present study is to determine whether cranberry ethanolic extract (CEE) can prevent the DNA damage produced by benzo[a]pyrene (B[a]P) using an in vivo mouse peripheral blood micronucleus assay. The experimental groups were organized as follows: a negative control group (without treatment), a positive group treated with B[a]P (200 mg/kg), a group administered with 800 mg/kg of CEE, and three groups treated with B[a]P and CEE (200, 400, and 800 mg/kg) respectively. The CEE and benzo[a]pyrene were administered orally for a week, on a daily basis. During this period the body weight, the feed intake, and the determination of antigenotoxic potential were quantified. At the end of this period, we continued with the same determinations for one week more (recovery period) but anymore administration of the substances. The animals treated with B[a]P showed a weight increase after the first week of administration. The same phenomenon was observed in the lots combined with B[a]P and CEE (low and medium doses). The dose of 800 mg/kg of CEE showed similar values to the control group at the end of the treatment period. In the second part of the assay, when the substances were not administered, these experimental groups regained their normal weight. The dose of CEE (800 mg/kg) was not genotoxic nor cytotoxic. On the contrary, the B[a]P increases the frequency of micronucleated normochromatic erythrocytes (MNNE) and reduces the rate of polychromatic erythrocytes (PE) at the end of the treatment period. With respect to the combined lots, a significant decrease in the MN rate was observed from the sixth to the eighth day of treatment with the two high doses applied; the highest protection (60%) was obtained with 800 mg/kg of CEE. The same dose showed an anticytotoxic effect which corresponded to an improvement of 62.5% in relation to the animals administered with the B[a]P. In the second period, all groups reached values that have been seen in the control group animals. Our results suggest that the inhibition of clastogenicity of the cranberry ethanolic extract against B[a]P is related to the antioxidant capacity of the combination of phytochemicals present in its chemical composition.

Effects of organosulfurs, isothiocyanates and vitamin C towards hydrogen peroxide-induced oxidative DNA damage (strand breaks and oxidized purines/pyrimidines) in human hepatoma cells

The aim of this study was to evaluate the effects of organosulfurs, isothiocyanates and vitamin C towards hydrogen peroxide-induced DNA damage (DNA strand breaks and oxidized purines/pyrimidines) in human hepatoma cells (HepG2), using the Comet assay. Treatment with hydrogen peroxide (H(2)O(2)) increased the levels of DNA strand breaks and oxidized purine and pyrimidine bases, in a concentration and time dependent manner. Organosulfur compounds (OSCs) reduced DNA strand breaks induced by H(2)O(2). In addition, OSCs also decreased the levels of oxidized pyrimidines. However, none of the OSCs tested reduced the levels of oxidized purines. Isothiocyanates compounds (ITCs) and vitamin C showed protective effects towards H(2)O(2)-induced DNA strand breaks and oxidized purine and pyrimidine bases. The results indicate that removal of oxidized purine and pyrimidine bases by ITCs was more efficient than by OSCs and vitamin C. Our findings suggest that OSCs, ITCs and vitamin C could exert their protective effects towards H(2)O(2)-induced DNA strand breaks and oxidative DNA damage by the free radical-scavenging efficiency of these compounds.

Comparison of the effects of arsenic and cadmium on benzo(a)pyrene-induced micronuclei in mouse bone-marrow

This study was undertaken to investigate the genotoxic interactions between the common environmental pollutants: arsenic (As), cadmium (Cd) and benzo(a)pyrene (BaP), which are known to be human carcinogens. C57BL/6J/Han mice were pre-treated with 100mg cadmium chloride (Cd(2+))/L or 50mg sodium arsenite (As(3+))/L in drinking water for 7 days and then given a single dose of 200mg BaP/kg bw by intra-peritoneal injection. A third group of mice did not receive the pre-treatment and was given BaP alone. Mice were sacrificed before or at 12, 24, 48 or 72h after BaP administration. Chromosome damage in bone-marrow cells was assessed by use of the micronucleus test. The study revealed that BaP induced a statistically significant increase in micronucleus (MN) frequency at 48h after administration. In animals exposed to Cd in drinking water no enhancement of genotoxicity was observed compared with the control group that was given tap water only. In Cd/BaP co-exposed animals, the MN frequency at respective time points did not differ from that for the animals exposed solely to BaP. A statistically higher MN frequency was found in bone marrow of animals exposed to As compared with controls that received tap water (0.92+/-0.29% versus 0.38+/-0.13%, respectively). This effect was even more pronounced after combined exposure to As and BaP. In the co-exposed animals, significantly elevated levels of MN were detected in samples examined at 12, 24 and 48h after BaP administration, compared with animals receiving BaP alone (1.14+/-0.31%, 1.26+/-0.3% and 2.02+/-0.45% versus 0.44+/-0.13%, 0.44+/-0.11% and 1.04+/-0.44%, respectively). These findings imply strong interactions between As and BaP, but not between Cd and BaP, in inducing DNA damage in polychromatic erythrocytes in mouse bone-marrow.

A sub-acute study of metronidazole toxicity assessed in Egyptian Tilapia zillii

Metronidazole (MTZ), an antiparasitic and antibacterial compound, is one of the world's most widely used drugs. Despite being considered as a rodent mutagen and a carcinogen, it is still widely used in humans for the treatment of infections with anaerobic organisms. Therefore, the main objective of the current study was to evaluate the in vivo toxicity of MTZ using the micronucleus (MN) assay and random amplified polymorphism DNA (RAPD-PCR) analysis as well as histopathological examination in Tilapia zillii. Moreover, the protective effect of vitamin C (VitC) against toxicity of MTZ was investigated in the present study. Fish were treated with three doses of MTZ (5, 10 and 20 mg l(-1)) alone or in combination with VitC (200 mg kg(-1) food) at several time intervals (2 days, 7 days and 14 days). The results of the present study showed a significant effect of MTZ on micronucleus formation and changes in polymorphic band patterns as well as induction of different histopathological alterations in Tilapia zillii. The effects of the drug were reduced when fish were exposed to a combination of MTZ and VitC.

Influence of orange juice over the genotoxicity induced by alkylating agents: an in vivo analysis

There is considerable epidemiological evidence indicating an association between diets rich in fresh fruit and vegetables and a decreased incidence of cancers. Methyl methanesulfonate (MMS) and cyclophosphamide (CP) are alkylating agents that differ in their mode of action. MMS is a directly-acting, monofunctional agent, while CP is a bifunctional agent that requires metabolic activation to a reactive metabolite. To evaluate if orange juice could reduce DNA damage induced by these alkylating agents, mice were treated orally (by gavage) with MMS and CP, prior to and after treatment with orange juice. DNA damage was evaluated by the comet assay in peripheral white blood cells. Under these experimental conditions, orange juice reduced the extent of DNA damage caused by both mutagens. For MMS, the antigenotoxic effect of the orange juice was both protective (orange juice pre-treatment) and reparative (orange juice post-treatment); for CP, the effect was reparative only. The components of orange juice can have several biological effects, including acting as targets of toxicants and modulating metabolization/detoxification routes. Considering the different mechanisms of the action of the two drugs, different protective effects are suggested. These results demonstated the ability of the in vivo comet assay to detect in vivo modulation of MMS and CP mutagenicity by orange juice.

Comparative analysis of topoisomerase IB inhibition and DNA intercalation by flavonoids and similar compounds: structural determinates of activity

Flavonoids and other polyphenolic compounds have been shown to inhibit human topoisomerase IB (topo I) through both inhibition of relaxation activity and through stabilization of the cleavable complex (poisoning). Some flavonoids have also been shown to intercalate DNA, and an association of topoisomerase inhibition with intercalation has been noted. We surveyed 34 polyphenolic compounds, primarily flavonoid glycones and aglycones, for their ability to inhibit topo I and to intercalate DNA using an in vitro gel electrophoresis method. We show that the most potent topo I poisons are the flavones and flavonols, and that these generally, but not always, are found to be DNA intercalators. There was no clear correlation, however, of topo-I-poisoning activity with the degree of DNA unwinding. Surprisingly, both DNA intercalation and topo I poisoning were shown to occur with some flavone glycones, including the C-glycosylflavone orientin. Inhibition of relaxation activity by flavonoids was found to be difficult to quantify and was most likely to be due to non-specific inhibition through flavonoid aggregation. As part of a structure-activity analysis, we also investigated the acid-base chemistry of flavonoids and determined that many flavonoids show acid-base activity with a pK(a) in the physiological pH region. For this reason, subtle pH changes can have significant effects on solution activity of flavonoids and their concomitant biological activity. In addition, these effects may be complicated by pH-dependent aggregation and oxidative degradation. Finally, we develop a simple model for the intercalation of flavonoids into DNA and discuss possible consequences of intercalation and topoisomerase inhibition on a number of cellular processes.

Possible repair action of Vitamin C on DNA damage induced by methyl methanesulfonate, cyclophosphamide, FeSO4 and CuSO4 in mouse blood cells in vivo

Interaction between Vitamin C (VitC) and transition metals can induce the formation of reactive oxygen species (ROS). VitC may also act as an ROS scavenger and as a metal chelant. To examine these possibilities, we tested in vivo the effect of two doses of VitC (1 and 30 mg/kg of mouse body weight) on the genotoxicity of known mutagens and transition metals. We used the alkaline version of the comet assay to assess DNA damage in peripheral white blood cells of mice. Animals were orally given either water (control), cyclophosphamide (CP), methyl methanesulfonate (MMS), cupric sulfate or ferrous sulfate. A single treatment with each VitC dose was administered after treatment with the mutagens or the metal sulfates. Both doses of VitC enhanced DNA damage caused by the metal sulfates. DNA damage caused by MMS was significantly reduced by the lower dose, but not by the higher dose of VitC. For CP, neither post-treatment dose of VitC affected the DNA damage level. These results indicate a modulatory role of Vitamin C in the genotoxicity/repair effect of these compounds. Single treatment with either dose of VitC showed genotoxic effects after 24 h but not after 48 h, indicating repair. Double treatment with VitC (at 0 and 24 h) induced a cumulative genotoxic response at 48 h, more intense for the higher dose. The results suggest that VitC can be either genotoxic or a repair stimulant, since the alkaline version of the comet assay does not differentiate "effective" strand breaks from those generated as an intermediate step in excision repair (incomplete excision repair sites). Further data is needed to shed light upon the beneficial/noxious effects of VitC.