Study of antioxidant and mutagenic activity of different orange juices

Distribution, Antioxidant Capacity, Bioavailability and Biological Properties of Anthocyanin Pigments in Blood Oranges and Other Citrus Species

Anthocyanins are natural pigments that give a red, purple, and blue color to many plant, flower, fruit, and vegetable species. Their presence within the genus Citrus was first reported in 1916, and it is well-known that the red color of the flesh and rind of blood (red or pigmented) oranges (Citrus sinensis L. Osbeck) is due to the presence of anthocyanins. They are also present in the young shoots, flowers, and peel of lemon (Citrus limon (L.) Burm. f.), citron (Citrus medica L.), and other citrus species. Since then, the scientific community has expressed increasing interest in studying their profile and distribution, with many published studies focused on the quali-quantitative pattern in the different vegetative tissues belonging to the genus Citrus. Moreover, with the discovery of their relevant antioxidant activity, owing to their ability to capture free radicals, much research has been performed in the last two decades on their radical scavenging power, in vitro and in vivo biological properties, and anticarcinogenic capacity, also focusing attention on their bioavailability for humans. The present work is intended as a comprehensive review of the advances in scientific research on anthocyanin pigments naturally occurring within the genus Citrus, including their natural distribution, antioxidant capacity, bioavailability, and biological value and properties. The scientific evidence herein reported can be used to further increase the knowledge of this class of compounds and represents a valuable and comprehensive contribution to promoting anthocyanin-rich citrus fruit consumption as a healthy dietary habit.

Geniposidic Acid from Eucommia ulmoides Oliver Staminate Flower Tea Mitigates Cellular Oxidative Stress via Activating AKT/NRF2 Signaling

Eucommia ulmoides Oliver staminate flower (ESF) tea enjoys a good reputation in folk medicine and displays multiple bioactivities, such as antioxidant and antifatigue properties. However, the underlying biological mechanisms remain largely unknown. In this study, we aimed to investigate whether ESF tea can mitigate cellular oxidative stress. Crude ethyl alcohol extract and its three subfractions prepared by sequential extraction with chloroform, n-butyl alcohol and residual water were prepared from ESF tea. The results of antioxidant activity tests in vitro manifested n-butyl alcohol fraction (n-BUF) showed the strongest antioxidant capacity (DPPH: IC₅₀ = 24.45 ± 0.74 μg/mL, ABTS: IC₅₀ = 17.25 ± 0.04 μg/mL). Moreover, all subfractions of ESF tea, especially the n-BUF, exhibited an obvious capacity to scavenge the reactive oxygen species (ROS) and stimulate the NRF2 antioxidative response in human keratinocytes HaCaT treated by H₂O₂. Using ultra-high-performance liquid chromatography, we identified geniposidic acid (GPA) as the most abundant component in ESF tea extract. Furthermore, it was found that GPA relieved oxidative stress in H₂O₂-induced HaCaT cells by activating the Akt/Nrf2/OGG1 pathway. Our findings indicated that ESF tea may be a source of natural antioxidants to protect against skin cell oxidative damage and deserves further development and utilization.

The effect of ultra-high pretreatment on free, esterified and insoluble-bound phenolics from mango leaves and their antioxidant and cytoprotective activities

Ultra-high pressure (UHP) is a novel non-thermal pretreatment method in food processing for improving the extraction yield of polyphenols and functional properties. The present work investigated the phenolic profiles, antioxidant activities, and cytoprotective effects of the free, esterified, and insoluble-bound phenolic fractions from mango leaves before and after ultra-high pressure (UHP) treatment. UHPLC-Q-Orbitrap-MS/MS analysis resulted in the identification of 42 phenolic compounds in the different phenolic forms. UHP pretreatment could significantly influence the contents of total phenols, total flavonoids and individual compounds in the different phenolic fractions (p < 0.05). After UHP pretreatment, these phenolic fractions exhibited greater antioxidant activity, and inhibited reactive oxygen species production and cell apoptosis (p < 0.05). Meanwhile, IBP were the most potential antioxidative and cytoprotective ingredients. Therefore, UHP pretreated mango leaves with enhanced bioactivity could be used as biological agents in the health food industry to improve its application and economic values.

Ultrasound aided debittering of bitter variety of citrus fruit juice: Effect on chemical, volatile profile and antioxidative potential

In the present study, sonication assisted debittering of pomelo fruit juice was carried out and the effect of sonication along with resin/enzyme on the chemical, phytochemical and volatile composition of juice was also investigated. The optimum conditions for sonication coupled debittering using resin were 50 kHz, 2 min, and 45 ℃ while 50 kHz, 60 min, and 60 ℃ were obtained for enzyme hydrolysis. Sonication treatment not only reduced the debittering time but also enhanced the adsorption and hydrolysis of naringin by 17% and 20% in resin and enzyme respectively. In addition, enzymatic activity was also improved and weakened C-O bonds in naringin. At the same time, sonication significantly affected the bioactive compounds of juice, chemical composition, and volatile compounds of juice. Flavor compounds including octanal, linalool, citral, and ethyl butyrate were enhanced by sonication-assisted enzymatic treated juice.

Myrciaria dubia Juice (camu-camu) Exhibits Analgesic and Antiedematogenic Activities in Mice

The Myrciaria dubia (Myrtaceae) fruit is traditionally used to treat malnutrition due to its high levels of vitamin C and phenolic compounds. Because of its composition, this plant is very promising in the research of novel natural treatment for pain disorders. This study analyzed the phytochemical profile of M. dubia juice and assessed its antinociceptive and antiedematogenic potential. The phytochemical profile was determined through high-performance liquid chromatography (HPLC), the oral antinociceptive effect of M. dubia 50% juice (Md50) was evaluated by formalin, hot plate and Complete Freund's Adjuvant tests and the antiedematogenic activity by paw edema. HPLC revealed the presence of ascorbic acid, rutin, and ellagic acid as major compounds. Md50 showed an antinociceptive effect in the acute and chronic phases of the formalin test. In the hot plate test, Md50 also induced an antinociceptive effect of 0.5 up to 6 h, showing antinociceptive and antiedematogenic potential without changing the spontaneous locomotion of animals. All protocols were submitted and approved by the Ethics Committee for use of Animals of the Lutheran University of Brazil (protocol No. 2013-30P).

In vivo and in vitro safety evaluation of fermented Citrus sunki peel extract: acute and 90-day repeated oral toxicity studies with genotoxicity assessment

Background

Citrus sunki Hort. ex Tanaka peel has been traditionally used as an ingredient in folk medicine due to its therapeutic effects on promotion of splenic health and diuresis as well as relief of gastrointestinal symptoms. Although a growing interest in health-promoting natural products and the development of highly concentrated products have facilitated consumption of C. sunki peel, its safety assessment has not been explored, posing a potential health risk. In this study, we carried out a series of systemic and genetic toxicity tests on fermented C. sunki peel extract (FCPE) to provide the essential information required for safe use in human.

Methods

We conducted acute and 90-day repeated oral toxicity studies in Sprague-Dawley rats to evaluate systemic toxicity, and three genotoxicity assays to measure bacterial mutation reversion, cellular chromosome aberration and in vivo micronucleus formation.

Results

Single oral administration of FCPE did not cause any clinical signs and lethality in all animals, establishing LD50 to be over 2000 mg/kg BW. Repeated administration of up to 2000 mg/kg BW FCPE for 90 days revealed no test substance-related toxicity as demonstrated in analysis of body weight gain, food/water intake, blood, serum biochemistry, organ weight and histopathology, collectively determining that the no-observable-adverse-effect-level of FCPE is over 2000 mg/kg BW. In addition, we detected no mutagenicity and clastogenicity in FCPE at 5000 μg/plate for the in vitro assays and 2000 mg/kg BW for the in vivo micronucleus test.

Conclusion

FCPE did not cause systemic and genetic toxicity in our model systems at the tested dose levels. These results suggest a guideline for safe consumption of C. sunki peel in human.

Influences of chitosan coatings on functional compounds of sweet cherries

In this study, sweet cherries were coated with four chitosans (1%) [two of them produced from shrimp waste from Marmara Sea in Turkey (Chitosan-1, Chitosan-2) and two of them commercially produced (Commercial-1 and Commercial-2)] which have different deacetylation degree, and molecular weight (Chitosan-1, deacetylation degree: 78.20%, molecular weight: 182 kDa; Chitosan-2, deacetylation degree: 84.95%, molecular weight: 127 kDa; Commercial-1, deacetylation degree: 81.22%, molecular weight: 273 kDa; Commercial-2, deacetylation degree: 75.12%, molecular weight: 407 kDa) and stored at 4 °C for 25 days, and 20 °C for 15 days. Changes in the total phenolic content, antioxidant capacity, total anthocyanin content, ascorbic acid, total pectin content, firmness, and colour values were evaluated. The results revealed that Chitosan-1 had the highest firmness value; Chitosan-2 showed the highest total anthocyanin and total phenolic content and Commercial-1 exhibited the highest antioxidant capacity and ascorbic acid content at 4 °C. Furthermore, it was found that Chitosan-1 demonstrated the highest total phenolic content; Chitosan-2 displayed the highest total anthocyanin; Commercial-1 had the highest firmness value and C-2 exhibited the highest ascorbic acid content at 20 °C. In conclusion, each tested chitosan coatings have different effects on different quality attributes at different storage temperatures.

Antioxidant capacity in fruit of Citrus cultivars with marked differences in pulp coloration: Contribution of carotenoids and vitamin C

The purpose of this study was to evaluate the specific contribution of carotenoids and vitamin C to the lipophilic and hydrophilic antioxidant capacity, respectively, of the pulp of citrus fruits using the genetic diversity in pigmentation and in the carotenoid complement. To this end, six citrus varieties were selected: two mandarins, Clemenules (Citrus clementina) and Nadorcott (C. reticulata); two grapefruits (C. paradisi), Marsh and Star Ruby; and two sweet oranges (C. sinensis), Valencia late and Valencia Ruby. Total carotenoid content and composition in the pulp of fruits were very different, in relation to their color singularities. Valencia Ruby and Nadorcott had the highest carotenoid content, accumulating the former large amounts of linear carotenes (phytoene, phytofluene, and lycopene) and Nadorcott of β-cryptoxanthin. Orange fruits contained the highest amount of vitamin C while in Nadorcott mandarin it was substantially lower. Analysis of antioxidant capacity, evaluated by 2,2'-azino-di-(3-ethylbenzthiazoline sulfonate) (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assays, in the pulp of the different fruit varieties indicated a high and positive correlation between vitamin C content and hydrophilic antioxidant capacity. Nevertheless, a weak correlation was observed between carotenoids content and lipophilic antioxidant capacity in the pulp extracts assayed by ABTS. Overall, vitamin C in the pulp of citrus fruit had an important contribution to the hydrophilic antioxidant capacity, whereas that of carotenoids to lipophilic antioxidant capacity was very variable, being the highest that of Valencia Ruby orange, with large concentrations of lycopene and phytoene, followed by Nadorcott mandarin, with high β-cryptoxanthin content.

UHPLC-ESI-HRMS/MS analysis on phenolic compositions of different E Se tea extracts and their antioxidant and cytoprotective activities

E Se tea, prepared from the leaves of Malus toringoides (Rehd.) Hughes, is a traditional beverage, but there is little known about its chemical substances. This paper is aimed to investigate the chemical composition, antioxidant, and cytoprotective activities of the extract and fractions from E Se tea. Sixteen compounds were characterized by UHPLC-ESI-HRMS/MS. Phloridzin was the main compound, especially in ethyl acetate fraction (EAF). Moreover, EAF had the highest total phenolic and flavonoid contents with 197.54 ± 7.52 mg gallic acid equivalents/g extract and 85.94 ± 5.39 mg rutin equivalents/g extract, respectively, and exhibited the strongest antioxidant capacity (DPPH: IC₅₀ = 54.91 ± 3.38 μg/mL; ABTS: IC₅₀ = 98.08 ± 6.92 μg/mL). Different fractions of E Se tea, especially EAF, significantly inhibited intracellular ROS generation, reduced cell apoptosis, and decreased oxidative stress damage in H₂O₂-induced HepG-2 cells. Therefore, the obtained results highlight that E Se tea is a promising source for functional beverage or nutritional foods.

Influence of ultrasound and osmotic dehydration pretreatments on drying and quality properties of persimmon fruit

In this study, the effect of the ultrasound and osmotic dehydration pretreatments before the convective drying of the persimmon fruit was assessed via their drying behavior and quality properties. Ultrasound-assisted osmotic dehydration (30 °C, 45 °Brix) was performed at 35 kHz for 10, 20, and 30 min. Afterward, samples were placed first in 45 then in 70 °Brix sucrose solutions; the solutions were next shaken at 100 rpm. The control group without ultrasound treatment dehydrated osmotically. The samples were dried in a tray drier at a temperature of 60 °C and an air velocity of 1.5 m/s. Ultrasound-assisted osmotic drying treatments increased water loss and sugar gain; moreover, the osmotic dehydration time was shorter than in the untreated group. The ultrasound-assisted osmotic dehydration demonstrated a significantly decreased drying time, increased drying rates, and a 21% increase in effective water diffusivity by 30 min. The ultrasound pretreated osmotic dehydration prior to hot air-drying decreased the total required drying time. The ultrasound-assisted osmotic dehydration affected the rehydration rate and total phenolic content significantly and there was no significant difference between the color change (ΔE, ΔC, and Hue°) of the ultrasound treatment (30 min) group and the untreated group.

Nontargeted metabolomics approach to determine metabolites profile and antioxidant study of Tropical Almond (Terminalia catappa L.) fruit peels using GC-QTOF-MS and LC-QTOF-MS

The objective of the present study was to identify the metabolome pattern and study the biological efficacy of Almond (Terminalia catappa L.) peels. In the present study, metabolite profiling was carried out using GC-QTOF-MS and LC-QTOF-MS techniques, from the potent extract showed highest antioxidant efficacy. Antioxidant efficacy of the various extracts derived by six different extraction methods was assessed by different assays viz. 2,2-diphenyl-1-picrylhydrazyl, superoxide, 2,2'-Azino-bis-(3-ethyl)benzothiazoline)-6-sulfonic acid diammonium salt radical cation inhibition assays and ferric reducing antioxidant power. The methanolic maceration extract showed significant antioxidant activity in all assays and richest source of flavonoid content. The results showed that the extraction method significantly altered the antioxidant activity. The correlation between the antioxidant activities and total flavonoid content were ranging between 0.939 to 0.628. Methanolic maceration extraction method proved to be the best extraction method for the extraction of antioxidant. During the metabolite profiling employed by GC-QTOF-MS and LC-QTOF-MS and total 24 and 53 compounds belongs to different groups were detected and identified, will help to uncover the relation with potent antioxidant activity.

Response surface optimization of conditions for debittering of white mahlab (Prunus mahaleb L.) juice using polystyrene resins

In the current study, debittering of white mahlab (Prunus mahaleb L.) juice using polystyrene resins was investigated and optimized using the Box-Behnken response surface methodology. The effects of independent variables including resin type (cation exchange resin, anion exchange resin, and 50:50 cation/anion exchange resin), resin dosage (0.05, 0.075, and 0.1 g/mL) and agitation speed (50, 150, and 250 rpm) on total phenolic content, total flavonoid content, total anthocyanin content (TAC), antioxidant activity, and bitterness of white mahlab juice were studied. Effects of resin type and dosage were found to be significant (p < 0.05) for all responses. A dosage of 0.05 g/mL of the anion exchange resin and an agitation speed of 250 rpm were selected as the optimum conditions based on minimum bitterness (2.42) and maximum TAC (0.018 g/mol). We could conclude that the anionic resin can greatly reduce the intensity of bitterness and maintain the composition and characteristics of the P. mahaleb juice.

Thai generic-brand dry canine foods: mutagenicity and the effects of feeding in vivo and in vitro

Background

The commercial pet-food industry and the market value of the pet industry have increased. Most owners are concerned about their pets’ health, and prefer commercial pet foods as their regular diet. This study thus aimed to determine whether a selection of local generic-brand dry canine foods had any potential to promote chronic disease.

Methods

Five local, generic-brand, dry canine foods were studied for potential mutagenicity; the effects of long-term consumption were also observed in rats. All canine foods were extracted with distilled water and absolute ethanol. The Ames test was used to detect short-term genetic damage, using Salmonella typhimurium tester strains TA98 and TA100. Simultaneously, the long-term effects were studied in an animal model by observing rats fed with these canine foods, compared with normal rat food, for a period of 15 weeks.

Results

Using the water extracts, all dry canine foods studied showed considerable mutagenic effects on the tester strains. One brand affected both tester strains, whereas 3 showed positive to TA98, and one to TA100. With the absolute ethanol extract, three of the five brands had a considerable mutagenic effect on TA98, and another affected TA100. In the long-term test, all rats remained alive until the end of the experiment, exhibited no apparent signs of toxicity or serious illness, and maintained normal bodyweight and weight gain. Serum blood biochemistry and hematological parameters in canine food-fed rats showed some negative effects. Correspondingly, histopathological investigation of their liver and kidneys showed deterioration.

Conclusions

Mutagenic potential and the negative potential health impacts were observed in all local-brand dry canine foods tested.

Total Phenolic Content and Antioxidant Activity of Different Types of Chocolate, Milk, Semisweet, Dark, and Soy, in Cerebral Cortex, Hippocampus, and Cerebellum of Wistar Rats

Chocolate is a product consumed worldwide and it stands out for presenting an important amount of phenolic compounds. In this study, the total phenolic content and antioxidant activity in the cerebral cortex, hippocampus, and cerebellum of male Wistar rats when consuming different types of chocolate, including milk, semisweet, dark, and soy, was evaluated. The total polyphenols concentration and antioxidant activity in vitro by the method of DPPH radical-scavenging test were evaluated in chocolate samples. Lipid peroxidation (TBARS), protein oxidation (carbonyl), sulfhydryl groups, and activity of SOD enzyme in cerebral cortex, hippocampus, and cerebellum of rats treated or not with hydrogen peroxide and/or chocolate were also evaluated. The dark chocolate demonstrated higher phenolic content and antioxidant activity, followed by semisweet, soy, and milk chocolates. The addition of chocolate in the diet of the rats reduced lipid peroxidation and protein oxidation caused by hydrogen peroxide. In the sulfhydryl assay, we observed that the levels of nonenzymatic defenses only increased with the chocolate treatments The SOD enzyme activity was modulated in the tissues treated with the chocolates. We observed in the samples of chocolate a significant polyphenol content and an important antioxidant activity; however, additional studies with different chocolates and other tissues are necessary to further such findings.

Antioxidant activity of Citrus fruits

Citrus is well-known for its nutrition and health-promotion values. This reputation is derived from the studies on the biological functions of phytochemicals in Citrus fruits and their derived products in the past decades. In recent years, the antioxidant activity of Citrus fruits and their roles in the prevention and treatment of various human chronic and degenerative diseases have attracted more and more attention. Citrus fruits are suggested to be a good source of dietary antioxidants. To have a better understanding of the mechanism underlying the antioxidant activity of Citrus fruits, we reviewed a study on the antioxidant activity of the phytochemicals in Citrus fruits, introduced methods for antioxidant activity evaluation, discussed the factors which influence the antioxidant activity of Citrus fruits, and summarized the underlying mechanism of action. Some suggestions for future study were also presented.

Sugar levels in Charmat sparkling wines can affect the quality and resveratrol levels

Sparkling wines contain CO(2) obtained through a second fermentation by natural processes (Charmat method); they may be prepared with variable final sugar concentrations, resulting in physicochemical compositions and phenolic profiles different to those obtained with other natural methods. The purpose of this study was to verify the influence of sweetness on enological parameters, trans-resveratrol and trans-piceid levels, antioxidant capacity (power of scavenger the radical DPPH(•) (1,1-diphenyl-2-picrylhydrazyl) and mimetic enzymatic activities of superoxide dismutase (SOD-like) and catalase (CAT-like) assays, and β-glucosidase activities on Charmat sparkling wines. The interaction of polyphenol levels and sweetness was observed. Levels of trans-piceid and trans-resveratrol showed a decrease in function of glucose concentration up to 40 g/l. All samples showed antioxidant capacity and β-glucosidase activity was stable even in the presence of sugar. A positive correlation between SOD-like and DPPH(•) was observed. This work shows an approach able to clarify important aspects for the wine industry with regard to world-wide consumer demand for sweetened products.

Role of citrus juices and distinctive components in the modulation of degenerative processes: genotoxicity, antigenotoxicity, cytotoxicity, and longevity in Drosophila

It is well established that breakfast beverages contain high quantities of Citrus juices. The purpose of the present study was to assess the nutraceutical value of orange and lemon juices as well as two of their active compounds: hesperidin and limonene. Indicator assays were performed at three levels to evaluate different biological health promoter activities: (i) determination of the safety and DNA-damage protecting ability against free radicals by using the somatic mutation and recombination test (SMART) in Drosophila melanogaster, (ii) study of the modulating role for life span in Drosophila melanogaster, and (iii) measurement of the cytotoxic activity against the human tumor cell line HL60. The highest concentrations assayed for lemon juice and limonene (50% v/v and 0.73 mM, respectively) showed genotoxic activity as evidenced from SMART. Orange and lemon juices as well as hesperidin and limonene exhibit antigenotoxic activity against hydrogen peroxide used as an oxidative genotoxin. Life-span experiments revealed that the lower concentrations of orange juice, hesperidin, and limonene exerted a positive influence on the life span of Drosophila. Finally all substances showed cytotoxic activity, with hesperidin being least active. Taking into account the safety, antigenotoxicity, longevity, and cytotoxicity data obtained in the different assays, orange juice may be a candidate as a nutraceutical food as it (1) is not genotoxic, (2) is able to protect DNA against free radicals, and (3) inhibits growth of tumor cells.

In-vitro mutagenic potential and effect on permeability of co-administered drugs across Caco-2 cell monolayers of Rubus idaeus and its fortified fractions

This study investigated the mutagenic, anti-mutagenic and cytotoxic effects of acetone extract of raspberry, Rubus idaeus L. (v. Ottawa) Rosaceae, and the isolated and characterized ellagitannin and anthocyanin fractions thereof, suitable for food applications. The studied raspberry extract and fractions did not show any mutagenic effects determined in the miniaturized Ames test and were not cytotoxic to Caco-2 cells at the used concentrations. However, the anti-mutagenic properties were changed (i.e. decreased mutagenicity of 2-nitrofluorene in strain TA98, and slightly increased mutagenicity of 2-aminoanthracene in strain TA100) with metabolic activation. Further, their influence on the permeability of co-administered common drugs (ketoprofen, paracetamol, metoprolol and verapamil) across Caco-2 monolayers was evaluated. The apical-to-basolateral permeability of highly permeable verapamil was mostly affected (decreased) during co-administration of the raspberry extract or the ellagitannin fraction. Ketoprofen permeability was decreased by the ellagitannin fraction. Consumption of food rich in phytochemicals, as demonstrated here with chemically characterized raspberry extract and fractions, with well-absorbing drugs would seem to affect the permeability of some of these drugs depending on the components. Thus their effects on the absorption of drugs in-vivo cannot be excluded.

Influence of orange juice in the levels and in the genotoxicity of iron and copper

World consumption of natural juices is increasing as a consequence of the human search for a healthier life. The juice production industry, especially for orange juice, is expanding in several countries and particularly in Brazil. Despite scientific data reporting beneficial properties derived from juice consumption, some components of juices have been identified as mutagenic or carcinogenic. Carcinogenic or genotoxic effects may be mediated by the interaction of juice components with transition metals or by sub-products of juice auto-oxidation. In this study, the mutagenic potential of orange juice and two metallic agents used in dietary supplementation, FeSO(4) and CuSO(4), were investigated using the comet assay in mouse blood cells (in vivo). Both metal compounds were genotoxic for eukaryotic cells after 24h treatment at the doses used. Significant damage repair was observed after 48h of treatment with the same compounds. Orange juice had a modulating effect on the action of metallic sulfates. In the case of iron treatment, the presence of the orange juice had a preventive, but not restorative, effect. On the other hand, in the case of copper treatment, the effects were both preventive and restorative. PIXE (particle induced X-ray emission) analysis indicated a positive correlation between DNA damage and the hepatic levels of iron and a negative correlation between whole blood copper and DNA damage. A negative correlation between hepatic iron and whole blood copper content was also seen in the treatment with both ferrous and cupric sulfates.

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.

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.