Elio A. Soria

Antioxidant activity of different extracts of Argentinian medicinal plants against arsenic-induced toxicity in renal cells.

Chronic toxicity of arsenic resulting from drinking water is a health problem encountered in humans, especially in South America and Asia, where a correlation between oxidative stress, tumor promotion, and arsenic exposure has been observed. Differential solvent extraction (petroleum ether (PE); dichloromethane (DCM); methanol (OL) and water (W)) was performed to compare the protective (antioxidant) activity of five Argentinian medicinal plants on arsenite-induced oxidative stress in Vero cells, assayed by hydroperoxide measurement. The results were analyzed using ANOVA followed by the LSD Fisher test. The data showed that arsenite was a pro-oxidant agent which acts in a time–dose-dependent manner. Extracts from Eupatorium buniifolium (PE), Lantana grisebachii (PE, W), Mandevilla pentlandiana (PE, W), and Sebastiania commersoniana (DCM, OL, W) prevented the formation of both aqueous and lipid hydroperoxides, but Heterothalamus alienus only impeded lipid ones. Therefore, antioxidant extracts are potentially beneficial and may have a protective activity against arsenite-induced renal injury. Among these, the aqueous extract of L. grisebachii may represent the most suitable preparation for humans since the traditional usage of this plant in popular medicine is through consumption of tea.

Immunotoxicological effects of arsenic bioaccumulation on spatial metallomics and cellular enzyme response in the spleen of male Wistar rats after oral intake

Arsenic (As) is a worldwide environmental contaminant, which compromises immunity and causes various associated disorders. To further investigate its immunotoxicity, male Wistar rats were exposed to 100ppm of sodium arsenite (inorganic AsIII) in drinking water for 2 months. Given that metals are significant immune regulators, their content and distribution were analysed in spleen tissues, to then evaluate subsequent changes of redox enzyme responses in spleen parenchyma cells (splenocytes). X-ray fluorescence spectrometry demonstrated As accumulation in both white and red pulps (p<0.005), and As-related pulp-dependent modifications of the content of Cu, Ca, Zn and Fe (p<0.01). Correlational path analysis revealed direct effects of As on their spatial distribution (Cu: -0.76, Ca: -0.61, Zn: 0.38; p<0.02). As-exposed splenocytes showed ɣ-glutamyltranspeptidase inhibition, peroxidase induction, and variable responses of nitric oxide synthase (p<0.05). Concanavalin A-treated splenocytes (T cell mitogen) were more susceptible in vitro to these As-related enzymatic changes than those treated with lipopolysaccharide (B cell mitogen) (p<0.05). The study thus established the impact of As bioaccumulation on metallic spatial homeostasis in the spleen, and then identified enzymatic dysfunctions in splenocytes. This suggested that arsenic disrupts biometal-dependent immune pathways and redox homeostasis, with mitogen exposure modifying the toxicological response.

Effects of oral phytoextract intake on phenolic concentration and redox homeostasis in murine encephalic regions.

Abstract Vegetable infusions (VI) are one of the main phenolic sources for humans. They may act as antioxidants in the central nervous system, but data about their effect are insufficient. The main objective of the study was to determinate the effects of oral VI of Argentinean plants on phenolic concentration and redox homeostasis in different murine encephalic regions. Redox changes (peroxides -HP-, anion superoxide -SO- and γ-glutamyltranspeptidase activity) and tissue phenolics were assessed in Balb/c mice of both sexes treated with the following VI extracts: Lantana grisebachii Seckt. var. grisebachii (Verbenaceae) (LG), Aspidosperma quebracho-blanco Schltdl. (Apocynaceae) (AQB), and Ilex paraguariensis A. St.-Hil. (Aquifoliaceae) (IP). Brain (telencephalon and diencephalon), midbrain, brainstem, and cerebellum were studied (analysis of variance, P < 0.05). A redox homeostasis depending on an appropriate phenolic balance was detected after marker analysis. Under situations without exogenous challenges, the excessive or deficient levels were deleterious on each region. This finding was confirmed independently of the utilized phytoextracts. LG and AQB caused such phenolic imbalance and triggered oxidative stress. IP group showed region-specific differential redox effects. Overall, the last extract exhibited the best redox profile when the complete encephalon was analyzed. Since this plant has sanitary impact due to its high human intake, new studies about it are warranted.

Modulation of Early Stress‐related Biomarkers in Cytoplasm by the Antioxidants Silymarin and Quercetin Using a Cellular Model of Acute Arsenic Poisoning

Several pathologies (e.g. cancer and diabetes) are increased in arsenic-exposed populations, with oxidative stress being a major toxicological mechanism. Since the flavonoids silymarin (S) and quercetin (Q) are antioxidants and may protect cells, it would be valuable to develop a model which allows assessing the potential of xenobiotic against arsenic cytotoxicity in an efficient and rapid way. Thus, the oxidant production [e.g. reactive oxygen species and reactive nitrogen species (RNS)], the molecular parameters of biological response [e.g. plasma membrane composition, actin microfilaments and activated diphosphorilated c-Jun N-terminal kinase (JNK)] and cellular viability were determined in CHO-K1 cells treated with arsenite (As), S and Q. Arsenic caused loss of the cellular viability in a time-dependent manner. This effect was accompanied by a lipid hydroperoxide (LHP) formation, with no RNS induction or ganglioside content changes being found. Both flavonoids counteracted oxidative damage. Despite all treatments had unspecific responses on nitrite cellular release along the time, there was no relation between them and the cellular viability. Arsenic induced cytoplasmic microfilament rearrangement (tight perinuclear distribution with projections, stress fibres and pseudopodia) which was reversed by S. Also, activated JNK showed a similar distribution to actin. Contrarily, Q caused a dysmorphic granular pattern, thus behaving as a toxic agent. Summing up, toxic levels of arsenic disturb the redox homeostasis with LHP induction and early triggering of stress responses in cytoskeleton and cell signalling. Using the proposed model, only S showed to protect cells from arsenical cytotoxicity without own toxic properties. Thus, S might be considered for modulation of the human arsenic susceptibility.

Effect of arsenite on nitrosative stress in human breast cancer cells and its modulation by flavonoids.

Arsenic (As) is used in the treatment of leukemia and breast cancer due to its oxidative cytotoxic action. However, it is also toxic to normal cells. One proposed anticancer mechanism induced by As might be nitrosative stress (NS). It is believed that antioxidant flavonoids in combination with As might reduce its toxic action on normal cells without interfering with its antitumor action. In the present study, we evaluated the antineoplastic potential of As on breast human cancer lines MCF-7 and ZR-75-1 treated with redox-modulating flavonoids, such as quercetin (Q) and silymarin (S). Even though both cell lines differed about their oxidative responsiveness, their viability was decreased by NS induction through γ-glutamyltranspeptidase inhibition. Arsenic triggered NS in both MCF-7 and ZR-75-1 cultures, with the formers more sensitive without recovering their pre-treatment capacity. ZR-75-1 cells maintained their antioxidant status, whereas MCF-7 ones treated with S, As, and As + Q did not. Silymarin did not interfere with the described As bioactivity. NS was an anticancer mechanism exerted by As depending on the redox cellular response that could be differentially modified by dietary antioxidants. Hence, it is worthwhile to consider the use of dietary antioxidants as adjuvant in cancer chemotherapy, especially when using As.

Development of an Antioxidant Phytoextract of Lantana grisebachii with Lymphoprotective Activity against In Vitro Arsenic Toxicity

Phytochemicals have been presumed to possess prophylactic and curative properties in several pathologies, such as arsenic- (As-) induced immunosuppression. Our aim was to discover a lymphoprotective extract from Lantana grisebachii Stuck. (Verbenaceae) (LG). We assessed its bioactivity and chemical composition using cell-based assays. Fractions produced from a hexane extract acutely induced nitrite formation in T-activated cell cultures (P < 0.0001). Water extraction released a fraction lacking nitrite inducing activity in both lymphocyte types. Aqueous LG was found to be safe in proliferated and proliferating cells. The infusion-derived extract presented better antioxidant capacity in proportion to phenolic amount in lymphocytes (infusive LG-1i at 100 μg/mL), which protected them against in vitro As-induced lymphotoxicity (P < 0.0001). This infusive LG phytoextract contained 10.23 ± 0.43 mg/g of phenolics, with 58.46% being flavonoids. Among the phenolics, the only predominant compound was 0.723 mg of chlorogenic acid per gram of dry plant, in addition to 10 unknown minor compounds. A fatty acid profile was assessed. It contained one-third of saturated fatty acids, one-third of ω9, followed by ω6 (~24%) and ω3 (~4%), and scarce ω7. Summing up, L. grisebachii was a source of bioactive and lymphoprotective compounds, which could counteract As-toxicity. This supports its phytomedical use and research in order to reduce As-related dysfunctions.

Interaction Between Retinoids and Eicosanoids: Their Relevance to Cancer Chemoprevention

Carcinogenesis involves a growing accumulation of genetic and epigenetic aberrations, leading to the deregulation of cellular homeostasis, followed by neoplastic progression. Although nutritional lipids play a critical role the specific transcriptional mechanisms involved in this process are not completely understood. In this review, we examine the biological effects of dietary essential fatty acids (n-3 and n-6 EFAs) and vitamin A, and the common pathways related to cancer chemoprevention. Eicosanoids (EFAs derivates) and retinoids (vitamin A derivates) are major mediators that act on their corresponding RXR-heterodimerized receptors (PPAR and RAR) and modify the carcinogenetic signalling pathways. Several effects of these mediators, mainly at DNA level, depend on specific molecular properties of the receptor isoforms and their differential affinities for their ligands, whose availability can be intentionally managed through diet. Nevertheless, the previous grade of differentiation in normal development or in cancer cells is an important modulatory factor of the cellular responses, especially when differentiating agents are evaluated. The potential of dietary EFAs and retinoids in chemoprevention and chemotherapy, through their actions on the cellular proliferation and differentiation processes, with particular reference to human breast cancer is discussed herein.

Modulation of Fatty Acids and Interleukin-6 in Glioma Cells by South American Tea Extracts and their Phenolic Compounds

ABSTRACT Dietary phenolic compounds are plant metabolites with beneficial effects on the central nervous system. Thus, our aim was to identify anti-inflammatory compounds from South American plants on glia, which regulates neuro-immune response. The compounds were extracted from Lantana grisebachii (LG), Aspidosperma quebracho-blanco (AQB), and Ilex paraguariensis (IP) teas and identified by HPLC-DAD-MS. Extracts (0–200 µg/ml) were tested on human T98-G and rat C6 glioma lines. Cellular viability (by the resazurin assay), fatty acid profile (by gas chromatography) and pro-inflammatory interleukin-6 release (IL-6 by ELISA) were determined. Data were analyzed by partial least-square regression to discriminate bioactive compounds. Twenty-one compounds were determined in LG, mainly iridoids, which were linked to ω-3 and ω-6 polyunsaturated fatty acids, but not to IL-6 release. Thirty-one compounds were found in AQB, mostly hydroxybenzoic derivatives, which were positively related to IL-6 release. Twenty-three compounds were identified in IP, including caffeoylquinic derivatives and mainly chlorogenic acid. They increased the ω-7 palmitoleic fatty acid, which was related to IL-6 decrease. These results enhances phytochemical knowledge of widely available plants, and suggest the lipid-related anti-inflammatory activity of IP phenolic compounds, which give nutritional relevance to the tea.

Delay of Lung Adenocarcinoma (LAC-1) Development in Mice by Dietary Oleic Acid

ABSTRACT Lung cancer is the leading cause of death by cancer, and is a major sanitary concern worldwide. Some nutrients, such as ω-9 fatty acids, have been proposed as anticancer agents. Thus, an olein-enriched diet was assayed in a murine model of lung adenocarcinoma (LAC-1) to evaluate neoplastic and paraneoplastic evolution in BALB/c mice. The organic assimilation of dietary fatty acids was confirmed in liver by gas chromatography. This experimental oleic acid-containing diet increased animal survival and tumour latency (analysed by the Kaplan-Meier method), improving neoplastic evolution and general status, with weak effects on the paraneoplastic syndrome (thymus atrophy, splenomegaly, splenocyte response to mitogen, blood anaemia, and leucocytosis). Tumour lipid oxidation was not involved. Thus, diet enrichment with olein, a natural source of the ω-9 oleic acid, significantly delayed progression of LAC-1 and increased tumour latency and mice survival. These results support its use in nutritional management of cancer, with further studies being encouraged.

Reduced food interaction and enhanced gastrointestinal tolerability of a new system based on risedronate complexed with Eudragit E100: Mechanistic approaches from in vitro and in vivo studies

Novel complexes consisting of Eudragit E100-risedronate are presented. The oral bioavailability of risedronate in rats was determined through its percentage excreted in urine after administration of complexed or free risedronate in fed and fasted conditions. The evaluation of the risedronate gastro-duodenal irritation potential was carried out by macroscopic and histological analyses in an experimental rat model. The degree of counterionic condensation between Eudragit E100 and risedronate was assessed by dialysis with, mechanistic information about the interaction with calcium and the release of risedronate from the complexes being obtained using physiological solution and simulated gastric fluid without pepsin. Non-significant differences were observed in the urinary excretion of risedronate when the complex or free risedronate was administered to fasted rats. However, the urinary excretion of risedronate in the complex group was 4-times higher than in the free risedronate group when animals were concomitantly administered with food. This behavior was related to the high degree of counterionic condensation in the complex (86.5%), which led to a reduction in the calcium induced rate and magnitude of risedronate precipitation and resulted in a decrease in the gastroduodenal damage from the complex, as evidenced by a lower frequency of gastric mucosae hemorrhage. A sustained release of risedronate from the complex was observed toward water, simulated gastric fluid or physiological solution, through an ionic-exchange mechanism. In conclusion, complexation with Eudragit E100 could be a useful strategy to overcome the unfavorable properties of risedronate.