Echinodorus macrophyllus: Acute toxicological evaluation of hydroxycinnamoyl derivatives from SF1 subfractions

ETHNOPHARMACOLOGICAL RELEVANCE

Echinodorus macrophyllus (Kunth.) Micheli (Alismataceae), known as chapéu-de-couro in Brazil, is popularly used to treat inflammatory diseases. We have previously demonstrated a significant reduction in the acute inflammation for the aqueous extract of E. macrophyllus (AEEm) and its ethanolic fraction (Fr20) and described that hydroxycinnamoyl derivatives present in SF1 (Fr20 subfraction) showed higher anti-inflammatory properties by mechanisms that include a reduction of TNF-α, IL-1β, CKCL1/KC, LTB4, and PGE2 levels in exudate.

AIM OF THE STUDY

This work describes the acute toxicological effect of SF1 subfraction on SW mice treated orally for five days in the air pouch model by evaluating the hematological and biochemical determinations on the blood samples; the relative organ weight and its histopathological analysis; the liver genotoxicity assessment and the activity of liver enzymes from xenobiotic metabolism.

MATERIALS AND METHODS

Fr20 was earlier fractionated on the Sephadex LH-20 column, yielding mainly four subfractions, including SF1. The SF1 toxicity was evaluated in mice challenged with carrageenan on the air pouch inflammation model and orally treated for five days. The body weight was monitored daily, and the organs were weighed after the euthanasia. Hematological and biochemical determinations were carried out using specific commercial kits and following the protocols provided by the manufacturers. The organs were fixed, sectioned, processed for hematoxylin and eosin staining, and analyzed by light microscopy. Genotoxicity assessment was performed by the alkaline single-cell gel electrophoresis. Livers were processed for ethoxyresorufin-O-deethylase (EROD) and Glutathione S-transferase (GST) assays.

RESULTS

SF1 exhibited low toxicity, as no significant discrepancy was observed in the relative weight of the body organs of mice. Moreover, the daily treatment with SF1 did not alter the number and percentage of red blood cells or hemoglobin concentration in the blood. The treatment with SF1 did not affect the creatinine concentration, but the 25 mg/kg dose reduced the plasma urea level and uric acid, suggesting its use in treating acute renal failure. The parameters analyzed did not present biochemical alterations indicative of liver disease. Regarding serum triglyceride and cholesterol levels, a significant decrease was detected in both parameters in mice treated with SF1. In addition, the histopathological analysis showed that inflammatory focus in the livers seemed more relevant in the control groups than in those treated. There were no significant changes in the renal or splenic tissues of animals treated with SF1. Treatment with SF1 also does not have a genotoxic effect on liver cells.

CONCLUSION

Treatment with SF1 showed no toxicity in mice at doses equivalent to those recommended for humans, which provides evidence of the safety of the therapeutic use of this subfraction.

Chimarrão consumption and prognostic factors in breast cancer: Correlation with antioxidants and blood caffeine levels

Breast cancer is the second most common malignancy among women. Ilex paraguariensis A. St. Hil, known as yerba mate, is widely consumed in southern Brazil as a hot infusion drink known as chimarrão. This herb has a complex chemical composition and is rich in antioxidants, which may interfere in the course of chronic inflammatory diseases as breast cancer. This study investigated the impact of chimarrão consumption on the clinicopathological profile of women with breast cancer attended at Francisco Beltrão Cancer Hospital, Paraná, Brazil. Blood antioxidants and caffeine profiles were assessed. Decreases in reduced glutathione and metallothionein levels, and increase in catalase activity were observed among breast cancer patients that were chimarrão consumers. The levels of circulating caffeine in breast cancer patients with luminal A tumors were higher than those in patients with luminal B and HER-2 subtypes. Furthermore, overweight patients presented higher caffeine levels than the eutrophic ones. It was found positive associations between chimarrão intake and high body mass index, and chimarrão intake and menopause at diagnosis. Altogether, these findings suggest that chimarrão consumption affects the blood antioxidants of breast cancer patients, and that the caffeine present in this mixture may favor the development of tumor of good prognosis. HIGHLIGHTS: Chimarrão consumption may affect the course of chronic inflammatory diseases, as breast cancer. Chimarrão intake changed blood antioxidants in breast cancer patients who were current consumers when compared to the non-consumers ones. High levels of caffeine were detected in patients bearing luminal A tumors, suggesting a protective role.

Glutathione peroxidase and glutathione S-transferase in blood and liver from a hypoxia-tolerant fish under oxygen deprivation

Liver enzyme activities can be employed as biomarkers, but liver can only be obtained with death of the specimen. On the other hand, blood withdrawal is a non-lethal procedure. Accordingly, the hypothesis of this study is to verify if glutathione peroxidase (GPX) and glutathione S-transferase (GST) activities in blood parallel those in the liver of the hypoxia-tolerant fish, Piaractus mesopotamicus (pacu), submitted to hypoxia conditions. GPX was assayed with H₂O₂ in cytosols from both liver and erythrocytes and exhibited no significant variation, either in erythrocytes or in liver, when comparing pacus under normoxia with those under hypoxia (42 h). GST activity with chloro-dinitrobenzene (CDNB), an artificial substrate suitable for almost all GST isoenzymes, was compared to activity with 4-hydroxy-nonenal (4-HNE), a physiological endogenous substrate. GST activity with CDNB did not change in liver or in erythrocyte cytosols in pacus under hypoxia compared to those under normoxia. On the other hand, a significant decrease in erythrocyte activity with 4-HNE was observed after 42 h of hypoxia in both erythrocytes and liver, which may be a response to increased lipid oxidation in erythrocytes. Erythrocyte GST activity was 3-fold higher with 4-HNE than with CDNB, indicating that 4-HNE is a more appropriate substrate to determine GST activity in pacu erythrocytes.

Behaviour of the oxidant scavenger metallothionein in hypoxia-induced neotropical fish

The pacu (Piaractus mesopotamicus) is a hypoxia-tolerant neotropical fish species. There is little or no information in this species regarding biochemical adaptations to waters with different oxygen concentrations, such as the production of reactive oxygen species and antioxidant scavengers, which might be of interest in the study of antioxidant defense mechanisms. Metallothioneins (MT) have been widely applied as biomarkers for metal exposure in fish liver, and, recently, in bile. These metalloproteins, however, have also been reported as free radical scavengers, although studies in this regard are scarce in fish. In this context, normoxic and hypoxic controlled experiments were conducted with pacu specimens and MT levels were quantified in both liver and bile. Reduced glutathione (GSH) indicative of oxidative stress, and thiobarbituric acid reactive substances (TBARS), indicative of lipid peroxidation, were also determined in liver. The results demonstrate that hypoxic fish present significantly lower metallothionein levels in liver and bile and lower reduced glutathione levels in liver, whereas lipid peroxidation was not significantly different between hypoxic and normoxic fish. The results of the present study seem to suggest that metallothioneins may actively participate in redox regulation in hypoxic fish in both bile and liver. MT levels in these organs may be temporarily suppressed, supporting the notion that down-regulation of oxidant scavengers during the oxidative burst is important in defense signaling in these adapted organisms.

Melatonin affects conjugation of 4-hydroxynonenal with glutathione in liver of pacu, a hypoxia-tolerant fish

In cytosol from liver of pacu, Piaractus mesopotamicus, a hypoxia-tolerant fish that dwells in Pantanal, we found an enzyme activity capable of modulating the alkenal 4-hydroxy-2-nonenal (HNE) by conjugating it with glutathione (GST-HNE activity). HNE is a downstream metabolite from the oxidation of polyunsaturated fatty acids by reactive oxygen species arisen from mitochondria of animal cells. HNE production may increase more intensively under oxidative stress. Harmful effects to cell survival may occur when HNE increases over 10(-4) M. Pacus submitted to hypoxia in July (cold season in Pantanal) showed 40% less of this GST-HNE conjugating activity in their liver cytosol. Injecting pacus subjected to hypoxia during the cold season with a summer physiological dose of melatonin caused their liver cytosolic GST-HNE activity to increase up to the levels found in the warm season. From October to March (warm season in Pantanal), pacus are prone to oxidative stress particularly during potamodromous active oxygen-demanding swimming, when they migrate up rivers to spawn. Thus, our findings point out that the higher levels of melatonin in circulation during the summer are important to avoid the increase of 4-HNE inside liver cells of this fish species.

Enzymatic GST levels and overall health of mullets from contaminated Brazilian Lagoons

Glutathione S-transferase (GST) assays in non-mammalian organisms are usually conducted inappropriately, since no previous standardization of the optimal concentrations of proteins and substrates and adequate pH is conducted. Standardization is a key task to adjust enzyme assays at their kinetically correct maximal initial velocities, if one wants these velocities to indicate the amount of enzyme in a sample. In this paper GST assays were standardized in liver cytosol to compare seasonal GST levels in liver of mullet from two contaminated lagoons in the Rio de Janeiro to those from a reference bay. GST potential as a biomarker of sublethal intoxication in this species was also evaluated. Mullet liver GST levels assayed with substrates that corresponded to three different GST isoenzymes varied throughout the year. The differences indicated that mullets are suffering from sublethal intoxication from contaminants in these lagoons. Seasonal variations of activity were relevant, since these could indicate differences in xenobiotic input into the areas. An analysis of overall mullet health condition using a morphological index (the Fulton Condition Factor) and macroscopic abnormalities corroborated the differences in GST levels, with fish from one of the sites in worse overall health condition showing lower and significantly different FCF when compared to the reference site. Therefore, GST standardized activity levels are useful biomarkers of environmental contamination for mullet.

Alterations in morphometric and organosomatic indices and histopathological analyses indicative of environmental contamination in Mullet, Mugil liza, from Southeastern Brazil

Mullet (Mugil liza) were sampled in five different areas along the Guanabara Bay, southeastern Brazil, classified as non-contaminated, moderately contaminated and contaminated. Morphometric (Fulton condition factor, relative condition factor and weight to length scaling coefficient) and organosomatic (hepatosomatic index) indices of environmental stress were analysed. Fish from the differentially contaminated areas show statistically different Fulton and relative condition factors and hepatosomatic indices, but not the weight to length scaling coefficient. The Kn and the FCF followed the same trend, with fish from São Gonçalo (1.07 ± 0.04 and 0.89 ± 0.03), Itaipu (0.84 ± 0.01 and 0.86 ± 0.01) and the Rodrigo de Freitas Lagoon (1.03 ± 0.01 and 0.87 ± 0.20) showing higher FCFs than fish from Magé (0.96 ± 0.01 and 0.81 ± 0.01). Fish from Itaipu showed significantly higher HSI values than the other sampling sites (1.68 ± 0.07), with fish from Olaria and Ipiranga showing the lowest (1.56 ± 0.12 and 1.60 ± 0.07, respectively).

Fish bile as a biomarker for metal exposure

Fish accumulate several trace elements in muscle, gills and liver, however studies also indicate that metals can be excreted through bile. Since metal contamination leads to modifications in bile composition, biliary excretion offers an alternative way to evaluate the presence of trace-elements. Bile is easier to obtain than other organs and presents a simpler matrix, making it easier for chemical pre-treatment. To verify if bile can be useful as a biomonitoring tool for metal contamination, liver and bile trace element concentrations were determined and correlated. The Artificial Neural Networks statistical technique was used to verify if liver trace-element quantification could be substituted by bile analysis. Results show that significant correlations were obtained between trace elements in bile and liver and the ANN validated the hypothesis that certain trace-elements in bile could be utilized instead of liver trace-elements. Further studies in this field are of interest to further validate this biomarker.

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.

Cytosolic glutathione peroxidase from liver of pacu (Piaractus mesopotamicus), a hypoxia-tolerant fish of the Pantanal

Pacu (Piaractus mesopotamicus Holmberg, 1887, Characiformes) dwells in waters of Pantanal, in which it has adapted for alternate concentrations of dissolved oxygen. Intracellular antioxidant protection should be vital for such an adaptation. Accordingly, we found that cytosol from liver of pacu has the highest antioxidant glutathione peroxidase activity so far reported for fish and murine species. To clarify whether this activity was due to a selenium independent glutathione S-transferase or to a glutathione peroxidase, we purified it and studied its kinetics. The substrates cumene hydroperoxide and hydrogen peroxide were promptly reduced by the enzyme, but peroxidized phosphatidylcholine had to undergo previous fatty acid removal with phospholipase A(2). Augmenting concentrations (from 2 to 6 mM) of reduced glutathione activated the pure enzyme. Curves of velocity versus different micromolar concentrations of hydrogen peroxide in the presence of 2, 4 or 8 mM reduced glutathione indicated that at least 2.5 mM reduced glutathione should be available in vivo for an efficient continuous destruction of micromolar concentrations of hydrogen peroxide by this peroxidase. Molecular exclusion HPLC and SDS-polyacrylamide gel electrophoresis indicated that the purified peroxidase is a homotetramer. Data from internal sequences showed selenocysteine in its primary structure and that the enzyme was a homologue of the type-1 glutathione peroxidase found in rat, bull, trout, flounder and zebra fish. Altogether, our data establish that in liver cells of pacu, a hypoxia-tolerant fish from South America, there are high levels of a cytosolic GPX-1 capable of quenching hydrogen peroxide and fatty acid peroxides, providing an effective antioxidant action.