Repurposing Strategy of Atorvastatin against Trypanosoma cruzi: In Vitro Monotherapy and Combined Therapy with Benznidazole Exhibit Synergistic Trypanocidal Activity.

Statins are inhibitors of cholesterol synthesis, but other biological properties, such as antimicrobial effects, have also been assigned to them, leading to their designation as pleiotropic agents. Our goal was to investigate the activity and selectivity of atorvastatin (AVA) against Trypanosoma cruzi by using in vitro models, aiming for more effective and safer therapeutic options through drug repurposing proposals for monotherapy and therapy in combination with benznidazole (BZ). Phenotypic screening was performed with different strains (Tulahuen [discrete typing unit {DTU} VI] and Y [DTU II]) and forms (intracellular forms, bloodstream trypomastigotes, and tissue-derived trypomastigotes) of the parasite. On assay of the Tulahuen strain, AVA was more active against intracellular amastigotes (selectivity index [SI] = 3). Also, against a parasite of another DTU (Y strain), this statin was more active (2.1-fold) and selective (2.4-fold) against bloodstream trypomastigotes (SI = 51) than against the intracellular forms (SI = 20). A cytomorphological approach using phalloidin-rhodamine permitted us to verify that AVA did not induced cell density reduction and that cardiac cells (CC) maintained their typical cytoarchitecture. Combinatory approaches using fixed-ratio methods showed that AVA and BZ gave synergistic interactions against both trypomastigotes and intracellular forms (mean sums of fractional inhibitory concentration indexes [∑FICIs] of 0.46 ± 0.12 and 0.48 ± 0.03, respectively). Thus, the repurposing strategy for AVA, especially in combination with BZ, which leads to a synergistic effect, is encouraging for future studies to identify novel therapeutic protocols for Chagas disease treatment.

Protection against UV-induced oxidative stress and DNA damage by Amazon moss extracts.

Amazon mosses, such as Holomitriopsis laevifolia and Leucobryum sp. are naturally exposed to high levels of solar ultraviolet (UV) radiation. Theoretically, under environmental stress conditions these mosses have developed protective chemical and metabolic strategies against UV damage, by way of biosynthesis of secondary metabolites, such as flavonoids. The present paper aimed to evaluate the free-radical scavenging activity, and the photoprotective, mutagenic and photomutagenic potencies of the methanolic (ME), aqueous (AE), hydroalcoholic (HE), ethanolic (EE) extracts of H. laevifolia and Leucobryum sp. The phenolic contents were evaluated by spectrophotometry and by High-Performance Liquid Chromatography (HPLC). The present findings showed that the AE and HE of H. laevifolia and the AE of Leucobryum sp. presented the highest phenolic contents. The HPLC analysis indicated the presence mainly of phenolic and cinnamic acids, flavonols, flavones and flavanones. The AE and EE of H. laevifolia and the AE and HE of Leucobryum sp. efficiently scavenged the 2,2'-diphenyl-1-picrylhydrazyl (DPPH) radical. All extracts showed significant values of in vitro Sun Protection Factor alone, and HE of Leucobryum sp. showed a synergistic effect in association with benzophenone-3. None of the extracts induced mutagenicity in the auxotrophic strains for histidine of Salmonella typhimurium, and photomutagenicity of the TA102 and TA104 strains was not detected after exposure to UV-A radiation. Besides, all extracts showed photoprotective activity against UV-A radiation for the TA104 strain, including synergistic protection in association with BP-3. Thus, the constituents in H. Laevifolia and Leucobryum sp. could be good candidates for cosmetic and dermatological applications, particularly in association with synthetic UV filters, since the concentration of the filters in the final product could be reduced.

Impacts of discarded coffee waste on human and environmental health.

Coffee is one of the most widely consumed beverages throughout the world. So far, many studies have shown the properties of coffee beverages, but little is known about its impacts on human and environmental health from its discard in the environment. So, the present work aims to investigate the mutagenic, genotoxic, cytotoxic and ecotoxic effects of leached (LE) and solubilized (SE) extracts from coffee waste, simulating the disposal of this residue in landfills and via sewage systems, respectively. Chemical analyses were also carried out. LE and SE induced mutagenicity in the TA98 Salmonella strain with and without exogenous metabolization (S9). In the TA100 only SE induced mutagenicity, what was observed without S9. An increase in the frequency of micronuclei was observed in HepG2 cell line after 3 and 24h of exposure to both extracts. No cytotoxic effects were observed in HepG2 cells by WST-1 assay. The EC50 values for the LE and SE were 1.5% and 11.26% for Daphnia similis, 0.12% and 1.39% for Ceriodaphnia dubia and 6.0% and 5.5% for Vibrio fischeri, respectively. Caffeine and several transition metals were found in both extracts. Coffee waste discarded in the environment may pose a risk to human and environmental health, since this compound can cause DNA damage and present toxicity to aquatic organisms.

Investigation of the mutagenic and genotoxic activities of LLL-3, a STAT3 inhibitor.

LLL-3, an anthracene derived compound, has been shown to be a promising therapeutic agent for the treatment of some kinds of cancer such as chronic myeloid leukemia and glioblastoma. However, no data regarding the toxic properties of this compound have yet been described in the literature. The present work aimed to investigate the mutagenic and genotoxic activities of LLL-3 using the TA97, TA98, TA100, TA102 and TA104 Salmonella/microsome strains for the Ames test and the micronucleus assay with the mouse macrophage cell line RAW 264.7. The findings showed that LLL-3, at doses of 0.001, 0.01, 0.1, 1.0 and 10.0 µg/plate, did not induce mutagenic activity in the Salmonella strains used under the conditions tested, and nor did it present genotoxicity in RAW 264.7 cells, at 10.0, 100.0 and 1000.0 µg/mL doses. Moreover, it is important to point out that the mitotic index of the cells decreased after exposure to LLL-3 under the same conditions tested, which may suggest some cytostatic effect, since this compound acts by inhibiting STAT3. Since most drugs used in the treatment of cancer present mutagenic activity as an adverse effect, these results suggest that LLL-3 is a promising drug for cancer therapy.

Effects of Ilex paraguariensis (yerba mate) on the hypothalamic signalling of insulin and leptin and liver dysfunction in adult rats overfed during lactation.

Ilex paraguariensis (yerba mate) has a beneficial effect in the management of obesity. Here, we studied the effects of yerba mate on hypothalamic changes in leptin and insulin signalling, oxidative stress and liver morphology and metabolism in postnatal early overfeeding (EO) Wistar rats. To induce EO, the litter size was reduced to three pups per dam, and litters with 10 pups per dam were used as a control (10 litters each). On postnatal day (PN) 150, EO offspring were subdivided into EO and EO+mate groups (10 animals each), which were treated with water or mate tea [1 g/kg body weight (BW)/day, by gavage], respectively, for 30 days. The C offspring received water. On PN180, yerba mate treatment prevented BW gain and reduced total body fat, visceral fat and food intake in comparison with the EO group. Leptin and insulin signalling in the hypothalamus measured by Western blotting was reduced only in the EO group. Yerba mate treatment had a greater impact on insulin signalling normalization. In the liver, yerba mate treatment normalized antioxidant enzyme activities and, consequently, decreased lipid peroxidation, determined by malondialdehyde content. In addition, the steatosis level and the liver triglyceride content were also restored. Thus, for the first time, yerba mate was demonstrated to increase antioxidant defences and improve liver metabolism in adult rats that were overfed during lactation, possibly through improvements in the hypothalamic action of insulin. These findings may be important for the treatment of obesity-related disorders.

Protection against UV-induced toxicity and lack of mutagenicity of Antarctic Sanionia uncinata.

Antarctica moss Sanionia uncinata (Hedw.) Loeske is exposed in situ to damaging levels of ultraviolet (UV) radiation. This moss has the ability to respond to UV radiation exposure producing secondary metabolites such as flavonoids, and has been recommended as a potential source of photoprotective compounds and antioxidants. The aim of the present paper was to investigate the free-radical scavenging activity and mutagenic and photomutagenic properties of methanolic (ME), hydroethanolic (HE) and ethanolic (EE) extracts of S. uncinata. The phenolic contents were evaluated by high-performance liquid chromatography (HPLC) and spectrophotometry. The findings showed that ME and EE presented the highest phenolic contents and inhibited free radical-scavenging activity against 2,2'-diphenyl-1 picrylhydrazyl (DPPH) and the HPLC analysis indicated several classes of phenolic acids and flavonoids. The sun protection factors (SPF) were determined by an in vitro method and the results showed significant values. The SPF values of BZ-3 at 50µg/mL increased significantly in association with ME, HE and EE. The extracts did not induce mutagenicity in auxotrophic Salmonella typhimurium histidine and photomutagenicity was not detected in the TA102 and TA104 strains after exposure to UV-A at doses of up to 6.5J/cm2 for the TA102 strain and up to 0.24J/cm2 for the TA104 strain. In addition, with the exception of ME, all the extracts induced photoprotective effects in the presence of the TA104 strain at 0.04J/cm2. The present results suggest that S. uncinata extracts did not induce photomutation and showed promise for photoprotection against the photobiological and ROS-inducing effects of the UV-A radiation.

Comparison of the sensitivity of strains of Salmonella enterica serovar Typhimurium in the detection of mutagenicity induced by nitroarenes.

The use of strains of Salmonella enterica serovar Typhimurium with different metabolic capacities can indicate the class or classes of compounds present in an environmental sample and enable the diagnosis of the mutagenic activity of these pollutants adsorbed on particulate matter (PM) in the air. In the present study, the sensitivity of Salmonella strains TA98NR, TA98/1,8-DNP6, YG1021, and YG1024 to detect nitro compounds adsorbed on samples of PM 2.5 was compared from three sites in Rio de Janeiro city. Samples were collected using a high-volume sampler at three sites: one with light traffic and two with heavy traffic. The assays were performed in the presence of 10-50 µg/ plate organic extracts with and without exogenous metabolization. The YG1021 and YG1024 strains showed the highest rev/m(3) values, confirming their enhanced sensitivity. As YG1024 also demonstrated sensitivity to nitro and amino compounds, we suggest its use in research into environmental contamination.

Mutagenicity, genotoxicity, and scavenging activities of extracts from the soft coral Chromonephthea braziliensis: a possibility of new bioactive compounds.

Coral reefs are diverse ecosystems that have a high density of biodiversity leading to intense competition among species. These species may produce unknown substances, many with pharmacological value. Chromonephthea braziliensis is an invasive soft coral from the Indo-Pacific Ocean that is possibly transported by oil platforms and whose presence can be a threat to a region's biodiversity. This species produces secondary metabolites that are responsible for inducing damage to the local ecosystem. In the present study, extracts were prepared from dried colonies of C. braziliensis (solvents: hexane, dichloromethane, ethyl acetate, and methanol). We evaluated their mutagenicity using the Salmonella reverse mutation assay (TA97, TA98, TA100, and TA102 strains), their genotoxicity using the DNA breakage analysis and micronucleus assay, and scavenging activity using the 1,1-diphenyl-2-picrylhydrazyl-free radical assay. Cytotoxicity and mutagenicity were not observed for any of the extracts. Genotoxicity was observed for the dichloromethane, ethyl acetate, and methanol extracts at high concentrations, but no DNA damage was observed in the micronucleus assay. Scavenging activity was not detected.

Prediction of health risk due to polycyclic aromatic hydrocarbons present in urban air in Rio de Janeiro, Brazil.

Risk assessment can provide a comprehensive estimate of potential effects of contaminants under specific, well-defined, and well-described circumstances, providing quantitative relationships between exposure and effects to identify and to define areas of concern. We investigated the mutagenic activity of particulate matter in air samples collected from three sites in Rio de Janeiro city. Samples were collected using a high-volume sampler at Avenida Brasil, at Campus of Universidade do Estado do Rio de Janeiro, and at Rebouças Tunnel. Six polycyclic aromatic hydrocarbons were quantified by gas chromatography/mass spectrometry. Salmonella typhimurium TA98 and the derivative strains TA98/1.8-DNP(6), YG1021, and YG1024, commonly used in mutagenicity assays, were treated (10-50 µg/plate), with and without exogenous metabolization. The highest values for the polycyclic aromatic hydrocarbons were detected at Rebouças Tunnel. For chrysene, as an example, the concentration was nearly 200 times higher than that established by the US Environmental Protection Agency. Frequent traffic jams can place bus drivers who go through the Rebouças Tunnel at risk of exposure to up to 0.69 ng/m(3) benzo(a) pyrene. Independent of exogenous metabolization, mutagenicity was detected in strains YG1021 and YG1024 at all the sites, suggesting nitro and amino derivatives of polycyclic aromatic hydrocarbons. Rebouças Tunnel air samples gave the highest values for rev/µg and rev/m(3). This could be due to the fact that the long, enclosed passageway through a mountain restricts ventilation. The cancer risk estimate in this study was 10(-3) for the benzo(a)pyrene, at the two sites, indicating a high risk.

The role of Fpg protein in UVC-induced DNA lesions.

We previously demonstrated that reactive oxygen species (ROS) could be involved in ultraviolet-C (UVC)-induced DNA damage in Escherichia coli cells. In the present study, we evaluated the involvement of the GO system proteins in the repair of the 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxoG, GO) lesion, which is ROS-induced oxidative damage. We first found that the mutant strain Δfur, which produces an accumulation of iron, and the cells treated with 2,2'-dipyridyl, a iron chelator, were both as resistant to UVC-induced lethality as the wild strain. The 8-oxoG could be mediated by singlet oxygen ((1)O(2)). The Fpg protein repaired this lesion when it was linked to C (cytosine), whereas the MutY protein repaired 8-oxoG when it was linked to A (adenine). The survival assay showed that the Fpg protein, but not the MutY protein, was important to UVC-induced lethality and interacted with the UvrA protein, a nucleotide excision repair (NER) protein involved in UVC repair. The GC-TA reversion assay in the mutant strains from the '8-oxoG-repair' GO system showed that UVC-induced mutagenesis in the fpg mutants, but not in the MutY strain. The transformation assay demonstrated that the Fpg protein is important in UVC repair. These results suggest that UVC could also cause indirect ROS-mediated DNA damage and the Fpg protein plays a predominant role in repairing this indirect damage.

Mutagenicity induced by UVC in Escherichia coli cells: reactive oxygen species involvement.

We previously demonstrated that reactive oxygen species (ROS) could be involved in the DNA damage induced by ultraviolet-C (UVC). In this study, we evaluated singlet oxygen ((1)O(2)) involvement in UVC-induced mutagenesis in Escherichia coli cells. First, we found that treatment with sodium azide, an (1)O(2) chelator, protected cells against UVC-induced lethality. The survival assay showed that the fpg mutant was more resistant to UVC lethality than the wild-type strain. The rifampicin mutagenesis assay showed that UVC mutagenesis was inhibited five times more in cells treated with sodium azide, and stimulated 20% more fpg mutant. These results suggest that (1)O(2) plays a predominant role in UVC-induced mutagenesis. (1)O(2) generates a specific mutagenic lesion, 8-oxoG, which is repaired by Fpg protein. This lesion was measured by GC-TA reversion in the CC104 strain, its fpg mutant (BH540), and both CC104 and BH540 transformed with the plasmid pFPG (overexpression of Fpg protein). This assay showed that mutagenesis was induced 2.5-fold in the GC-TA strain and 7-fold in the fpg mutant, while the fpg mutant transformed with pFPG was similar to GC-TA strain. This suggests that UVC can also cause ROS-mediated mutagenesis and that the Fpg protein may be involved in this repair.

N-nitrosodiethylamine genotoxicity evaluation: a cytochrome P450 induction study in rat hepatocytes.

In rats, N-nitrosodiethylamine (NDEA) induces tumors mainly in the liver. This could be because various enzymes are responsible for the metabolic activation of NDEA, besides the hepatic NDEA metabolizing enzyme, CYP2E1. We examined NDEA genotoxicity and cytotoxicity in primary cultures of female rat hepatocytes; we also looked at how it affected CYP mRNA expression. Single incubation with 0.9% NaCl resulted in a mean of 0.2% apoptotic cells, which doubled with 105 µg NDEA/mL. The frequency of necrosis with NDEA treatment was also doubled. Besides the cytotoxic effects, there was also a 4-fold decrease in mitotic index and a 3-fold decrease in the percentage of cells with micronuclei. A significant increase in micronucleus cells when hepatocytes were incubated with 2.1 µg NDEA/mL suggests that DNA repair was inactive. The chromosomal aberration evaluation revealed a discrete dose-response curve. Treatment with NDEA induced increases in CYP mRNA: CYP2B2 (1.8 times) and CYP2E1 (1.6 times) with non-cytotoxic NDEA concentrations (0.21-21 µg/mL). CYP2B1 mRNA levels decreased at 0.21 µg NDEA/mL (2.5-fold), while CYP4A3 mRNA decreased 1.3-fold. NDEA treatment at 2.1 µg/ mL induced a 1.9-fold increase in CYP3A1 mRNA. Understanding the cumulative effects in target cells during precarcinogenesis is crucial to understanding the mode of action of potential carcinogens and in order to develop comprehensive chemical toxicity profiles.

In vitro and in vivo toxicological evaluation of extract and fractions from Baccharis trimera with anti-inflammatory activity.

ETHNOPHARMACOLOGICAL RELEVANCE: Baccharis trimera (Less) DC. (Asteraceae), popularly known in Brazil as "carqueja", have been used in folk medicine to treat gastrointestinal, hepatic and renal diseases, and inflammatory processes as rheumatism. AIM OF THE STUDY: To evaluate the in vitro and in vivo toxicological effects of anti-inflammatory Baccharis trimera aqueous extract and fractions. MATERIALS AND METHODS: Aqueous extract of Baccharis trimera (AEBt) was produced by infusion in boiling water. After lyophylization AEBt was extracted with 80% ethanol, originating the ethanolic supernatant fraction (EFBt) and the aqueous sediment fraction (AFBt). Anti-inflammatory properties of AEBt, EFBt or AFBt (3, 30 or 300 µg/kg b.w.) were evaluated by the carrageenan-induced mouse paw edema using indomethacin (10mg/kg) as positive control. The growth of rat hepatoma cells (HTC) and human embryo kidney epithelial cells (HEK) was determined by protein staining assay. Cytotoxicity was assayed by the tetrazolium salt (MTT) reduction. Cyclosporin was used as reference cytotoxic drug for spleen cells and doxorubicin for HTC and HEK cells. For in vivo toxicological evaluation SW male mice were daily and oral (gavage) treated with extract/fractions at 4.2mg/kg or 42 mg/kg during 15 days. After treatment liver or kidney cells were submitted to comet assay to determine the DNA damage index, and the glutathione S-transferase activity was assayed towards ETHA (class Pi) and CDNB (several classes). Mutagenicity was evaluated by the Ames test using Salmonella typhimurium strains TA97, TA98, TA100, and TA102. RESULTS: The anti-inflammatory effects of EFBt were higher than those of AEBt or AFBt. Mice treatment (3-300 µg/kg) with AFBt reduced the paw edema (3h) at lower levels (29.2-37.3%; P<0.01), than those observed for AEBt (44.7-54.2%; P<0.001), EFBt (49.3-58.2%; P<0.001) or indomethacin (64.6%, P<0.001, 10mg/kg). The growth of kidney cells (HEK) was inhibited by AEBt (IC(50) 182.6 µg/ml), EFBt (IC(50) 78.1 µg/ml) and AFBt (IC(50) 86.2 µg/ml), with lower effects on HTC hepatic cell (IC(50) 308.8 µg/ml, 396.5 µg/ml and 167.9 µg/ml, respectively). As evaluated by MTT test, AFBt exhibited cytotoxicity for HEK cells (IC(50) 372.5 µg/ml), but none for HTC ones; by the way, AFBt stimulated spleen cells (EC(50) 2.2 µg/ml) while cyclosporine, a cytotoxic reference drug inhibited them with IC(50) of 0.42 µg/ml; the IC(50) for doxorubicin for HEK and HTC cells was 0.28 µg/ml and 14.4 µg/ml, respectively, at 96h. No mutagenic potential was observed. Mice treatment with AEBt or AFBt at 42 mg/kg for 15 days altered the kidney relative weight, but not at 4.2mg/kg. Baccharis trimera did not change liver, spleen or popliteal lymph node relative weight. DNA damage index of kidney cells was observed on mice treated with AEBt/AFBt, but not on animals treated with EFBt, while DNA lesions were detected on liver cells only after AFBt treatment. The general activities of hepatic GST and Pi GST were reduced by EFBt and AFBt treatment, respectively. CONCLUSIONS: Baccharis trimera did not show mutagenicity, inhibited the GST activity, a hepatic detoxification enzyme, and induced in vivo (genotoxicity) and in vitro toxicological effects to kidney cells.

Genotoxic and antigenotoxic evaluation of extracts from Arenosclera brasiliensis, a Brazilian marine sponge.

The marine environment is a rich source of biological active compounds and the sponges can be considered the most productive one. This diversity gives rise to unique chemical compounds with potential pharmacological properties. Our study is focused on the genotoxic and antigenotoxic evaluation of two crude extracts obtained from the Brazilian endemic marine sponge Arenosclera brasiliensis. Salmonella typhimurium reverse mutation test with TA97, TA98, TA100 and TA102 strains were performed. For antimutagenic analysis, a pre-, co-, and post-treatment to evaluate, respectively, intracellular and extracellular reactions and possible modulation on DNA repair. Additionally, in order to verify the influence of the crude extracts on DNA damage induction, a plasmid-DNA treatment was assayed. No mutagenicity was observed in Salmonella reverse mutation test, neither DNA strand induced damage. Antimutagenic activity was observed in pre-, co-, and post-treatment. A significant antigenotoxic effect was observed in the crude extract, which suggests that A. brasiliensis extract has the potential to protect DNA from the action of 4NQO, 2-aminofluorene, sodium azide and mitomycin C.

Cytotoxic, mutagenic and antimutagenic screening of Arenosclera brasiliensis acetone and ethanol extracts.

The marine environment is a rich source of biologically active compounds with pharmacological properties. Marine organisms often produce secondary metabolites with structural features different from those produced by terrestrial ones, and the Phylum Porifera seems to be one of the most productive in this sense. This study was undertaken to provide data on mutagenic and antimutagenic activities from an acetone (Areac) and an ethanol (Areet) extract obtained from Arenosclera brasiliensis, an endemic Brazilian sponge. A qualitative Salmonella reverse mutation test was performed with the TA97, TA98, TA100, and TA102 strains by incubating cells with Areac and Areet in the presence and absence of a known mutagen. A cytotoxic evaluation of the extracts was also performed. A. brasiliensis did not display any mutagenic activity, but Areac showed significant toxicity against test strains. In the antimutagenic assay, a reduction in the number of his+ revertants was observed for the TA97, TA100 and TA102 strains treated with Areac when compared to the positive controls. Areet treatment showed protective activity against DNA lesions only for the TA100. These results are in agreement with those obtained previously with other A. brasiliensis extracts, suggesting an antimutagenic activity.

Cytotoxic, mutagenic and antimutagenic screening of Arenosclera brasiliensis acetone and ethanol extracts

The marine environment is a rich source of biologically active compounds with pharmacological properties. Marine organisms often produce secondary metabolites with structural features different from those produced by terrestrial ones, and the Phylum Porifera seems to be one of the most productive in this sense. This study was undertaken to provide data on mutagenic and antimutagenic activities from an acetone (Areac) and an ethanol (Areet) extract obtained from Arenosclera brasiliensis, an endemic Brazilian sponge. A qualitative Salmonella reverse mutation test was performed with the TA97, TA98, TA100, and TA102 strains by incubating cells with Areac and Areet in the presence and absence of a known mutagen. A cytotoxic evaluation of the extracts was also performed. A. brasiliensis did not display any mutagenic activity, but Areac showed significant toxicity against test strains. In the antimutagenic assay, a reduction in the number of his+ revertants was observed for the TA97, TA100 and TA102 strains treated with Areac when compared to the positive controls. Areet treatment showed protective activity against DNA lesions only for the TA100. These results are in agreement with those obtained previously with other A. brasiliensis extracts, suggesting an antimutagenic activity.

Absence of mutagenicity of acid pyrogallol-containing hair gels.

In the present work, three commercial acid (pH 3.5-4) pyrogallol-containing hair gels, SunSet Alizador Negro (two formulations) and Embelleze Henê Gel, were tested for mutagenicity using two well-established assays. In the Salmonella mutagenicity assay using 648-5000 microg/plate of cosmetic samples, none of the samples reached a 2-fold increase in revertants relative to the controls. Both in the absence and in the presence of S9, the dose-response relation in strains TA98, TA100, TA102, TA1535, and TA1537 was not significant (p>0.01). In the mouse bone marrow micronucleus assay, 10 Swiss male mice were orally administered 2000 mg/kg of sample per body weight/day. The ratio between polychromatic and normochromatic erythrocytes as well as the presence of micronuclei in bone marrow cells were determined. Equal numbers of micronucleated polychromatic erythrocytes were detected between the cells of each treated group and the negative control, using ANOVA and chi-square analyses. Thus, none of the products induced mutagenesis in either assay. Previous studies have shown pyrogallol is mutagenic in various test systems, including Salmonella. However studies have also shown that acidic conditions may repress the reactive-oxygen species (ROS) produced by pyrogallol, and ROS is considered the primary mechanism for the mutagenicity of pyrogallol. Consistent with this are our results, which show that acidic, commercially available pyrogallol-containing hair gels are neither mutagenic in Salmonella nor induce micronuclei in mouse bone marrow in vivo.

Reactive oxygen species mediate lethality induced by far-UV in Escherichia coli cells.

The involvement of reactive oxygen species (ROS) in the induction of DNA damage to Escherichia coli cells caused by UVC (254 nm) irradiation was studied. We verified the expression of the soxS gene induced by UVC (254 nm) and its inhibition by sodium azide, a singlet oxygen (1O2) scavenger. Additional results showed that a water-soluble carotenoid (norbixin) protects against the lethal effects of UVC. These results suggest that UVC radiation can also cause ROS-mediated lethality.

Antigenotoxic and antimutagenic potential of an annatto pigment (norbixin) against oxidative stress

Carotenoids are 40-carbon molecules with conjugated double bonds, making them particularly effective for quenching free radicals. They have always been believed to possess anticancer properties, which could be due to their antioxidant potential. Norbixin is an unusual dicarboxylic water-soluble carotenoid present as a component in the pericarp of the seeds of Bixa orellana L. (from the Bixaceae family), a tropical shrub commonly found in Brazil. The main carotenoids present in these seeds, bixin and norbixin, form a coloring material, known as annatto, which is mainly used in the food industry. As annatto is only used as a coloring material, most studies of annatto pigments have focused on the determination of annatto levels in food. However, little attention has been given to the biological properties of bixin and norbixin. We evaluated the effect of norbixin on the response of Escherichia coli cells to DNA damage induced by UV radiation, hydrogen peroxide (H2O2) and superoxide anions (O2*-)) and found that norbixin protects the cells against these agents. Norbixin enhanced survival at least 10 times. The SOS induction by UVC was inhibited 2.3 times more when cells were grown in the presence of norbixin. We also found that norbixin has antimutagenic properties, with a maximum inhibition of H2O2-induced mutagenic activity of 87%, based on the Salmonella mutagenicity test