Protective effects of melatonin-loaded lipid-core nanocapsules on paraquat-induced cytotoxicity and genotoxicity in a pulmonary cell line

Development and pharmacological evaluation of liposomes and nanocapsules containing paroxetine hydrochloride

Depression is one of the most common psychiatric disorders. Nanotechnology has emerged to optimize the pharmacological response. Therefore, the aim of this work was to develop and characterize liposomes and nanocapsules containing paroxetine hydrochloride and evaluate their antidepressant-like effect using the open field and tail suspension tests in mice. Liposomes and nanocapsules were prepared using the reverse-phase evaporation and nanoprecipitation methods, respectively. The particle size of the formulation ranged from 121.81 to 310.73 nm, the polydispersity index from 0.096 to 0.303, the zeta potential from -11.94 to -34.50 mV, the pH from 5.31 to 7.38, the drug content from 80.82 to 94.36 %, and the association efficiency was 98 %. Paroxetine hydrochloride showed slower release when associated with liposomes (43.82 %) compared to nanocapsules (95.59 %) after 10 h. In Vero cells, in vitro toxicity showed a concentration-dependent effect for paroxetine hydrochloride nanostructures. Both nanostructures decreased the immobility time in the TST at 2.5 mg/kg without affecting the number of crossings in the open field test, suggesting the antidepressant-like effect of paroxetine. In addition, the nanocapsules decreased the number of groomings, reinforcing the anxiolytic effect of this drug. These results suggest that the nanostructures were effective in preserving the antidepressant-like effect of paroxetine hydrochloride even at low doses.

Targeting Oxidative Stress as a Therapeutic Approach for Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic interstitial lung disease characterized by an abnormal reepithelialisation, an excessive tissue remodelling and a progressive fibrosis within the alveolar wall that are not due to infection or cancer. Oxidative stress has been proposed as a key molecular process in pulmonary fibrosis development and different components of the redox system are altered in the cellular actors participating in lung fibrosis. To this respect, several activators of the antioxidant machinery and inhibitors of the oxidant species and pathways have been assayed in preclinical in vitro and in vivo models and in different clinical trials. This review discusses the role of oxidative stress in the development and progression of IPF and its underlying mechanisms as well as the evidence of oxidative stress in human IPF. Finally, we analyze the mechanism of action, the efficacy and the current status of different drugs developed to inhibit the oxidative stress as anti-fibrotic therapy in IPF.

The STING-IRF3 pathway contributes to paraquat-induced acute lung injury

Immune and inflammatory responses play significant roles in paraquat (PQ)-induced acute lung injury (ALI), but the specific mechanisms remain unclear. Our study aimed to investigate the action of STING-IRF3 signaling on PQ-induced ALI in mice. Following PQ administration, samples were collected at 2, 12, 24, and 48 h for in vivo studies, and 24 h for in vitro studies. Following PQ administration (30 mg/kg, i.p.), injury to mouse lungs was evaluated by H&E staining and wet/dry ratios, and lung oxidative damage was evaluated by MDA and SOD assays. The mRNA levels of Sting, Irf3, and Ifnβ were detected by RT-PCR, the expression of STING and IRF3 were assessed by western blotting and IHC/IF, and the secretion of IFNβ was detected by ELISA. In vivo, PQ administration induced pathological changes and increased wet/dry ratios in lungs after 48 h. Sting, Irf3, and Ifnβ mRNA levels in lung tissues, STING and pIRF3 protein levels in lung tissues, and IFNβ secretion in serum, were upregulated by PQ in a time-dependent manner. PQ administration promoted IRF3 nuclear translocation in lung tissues after 48 h. The above changes were all attenuated by dexamethasone treatment (5 mg/kg, i.p., qd). In vitro, PQ induced STING and IRF3 translocation. Irf3 or Sting silencing decreased the mRNA levels and supernatant secretion of IFNβ in PQ-treated RAW264.7 mouse macrophages. Sting silencing also inhibited the protein and mRNA levels of IRF3 in vitro. Our study suggests that STING-IRF3 signaling contributes to PQ-induced ALI, providing new information for future treatment strategies.

Melatonin-Loaded Nanocarriers: New Horizons for Therapeutic Applications

The use of nanosized particles has emerged to facilitate selective applications in medicine. Drug-delivery systems represent novel opportunities to provide stricter, focused, and fine-tuned therapy, enhancing the therapeutic efficacy of chemical agents at the molecular level while reducing their toxic effects. Melatonin (N-acetyl-5-methoxytriptamine) is a small indoleamine secreted essentially by the pineal gland during darkness, but also produced by most cells in a non-circadian manner from which it is not released into the blood. Although the therapeutic promise of melatonin is indisputable, aspects regarding optimal dosage, biotransformation and metabolism, route and time of administration, and targeted therapy remain to be examined for proper treatment results. Recently, prolonged release of melatonin has shown greater efficacy and safety when combined with a nanostructured formulation. This review summarizes the role of melatonin incorporated into different nanocarriers (e.g., lipid-based vesicles, polymeric vesicles, non-ionic surfactant-based vesicles, charge carriers in graphene, electro spun nanofibers, silica-based carriers, metallic and non-metallic nanocomposites) as drug delivery system platforms or multilevel determinations in various in vivo and in vitro experimental conditions. Melatonin incorporated into nanosized materials exhibits superior effectiveness in multiple diseases and pathological processes than does free melatonin; thus, such information has functional significance for clinical intervention.

Melatonin attenuates branch chain fatty acid induced apoptosis mediated neurodegeneration

Valproic acid (VPA)-a short branched chain fatty acid (BCFA), is widely recognized as an anticonvulsant and a mood-stabilizing drug, but various adverse effects of VPA have also been investigated. However, the impact of BCFAs aggregation on brain cells, in the pathogenesis of neurodegeneration remains elusive. The objective of this study is to understand the cellular mechanisms underlying VPA-induced neuronal cell death mediated by oxidative stress, and the neuroprotective role of exogenous melatonin treatment on VPA-induced cell death. Neurotoxicity of VPA and protective role exerted by melatonin were assessed in vitro in SH-SY5Y cells and in vivo in the cerebral cortex and cerebellum regions of Wistar rat brain. The results show that melatonin pre-treatment protects the cells from VPA-induced toxicity by exerting an anti-apoptotic and anti-inflammatory effect by regulating apoptotic proteins and pro-inflammatory cytokines. The findings of the present study emphasize novel insights of melatonin as a supplement for the prevention and treatment of neuronal dysfunction induced by VPA.

The herbicide paraquat-induced molecular mechanisms in the development of acute lung injury and lung fibrosis

The herbicide paraquat (PQ; 1,1'-dimethyl-4,4'-bipyridylium dichloride) is a highly toxic organic heterocyclic herbicide that has been widely used in agricultural settings. Since its commercial introduction in the early 1960s, numerous cases of fatal PQ poisonings attributed to accidental and/or intentional ingestion of PQ concentrated formulations have been reported. The clinical manifestations of the respiratory system during the acute phase of PQ poisoning mainly include acute lung injury (ALI)/acute respiratory distress syndrome (ARDS), followed by pulmonary fibrosis in a later phase. The focus of this review is to summarize the most recent publications related to PQ-induced lung toxicity as well as the underlying molecular mechanisms for PQ-mediated pathologic processes. Growing sets of data from in vitro and in vivo models have demonstrated the involvement of the PQ in regulating lung oxidative stress, inflammatory response, epigenetics, apoptosis, autophagy, and the progression of lung fibrosis. The article also summarizes novel therapeutic avenues based on a literature review, which can be explored as potential means to combat PQ-induced lung toxicity. Finally, we also presented clinical studies on the association of PQ exposure with the incidence of lung injury and pulmonary fibrosis.

Melatonin supplementation over different time periods until ageing modulates genotoxic parameters in mice

The ageing process is a multifactorial phenomenon, associated with decreased physiological and cellular functions and an increased propensity for various degenerative diseases. Studies on melatonin (N-acetyl-5-methoxytryptamine), a potent antioxidant, are gaining attention since melatonin production declines with advancing age. Hence, the aim of this study was to evaluate the effects of chronic melatonin consumption on genotoxic and mutagenic parameters of old Swiss mice. Herein, 3-month-old Swiss albino male mice (n = 240) were divided into eight groups and subdivided into two experiments: first (three groups): natural ageing experiment; second (five groups): animals that started water or melatonin supplementation at different ages (3, 6, 12 and 18 months) until 21 months. After 21 months, the animals from the second experiment were euthanized to perform the comet assay, micronucleus test and western blot analysis. The results demonstrated that melatonin prolonged the life span of the animals. Relative to genomic instability, melatonin was effective in reducing DNA damage caused by ageing, presenting antigenotoxic and antimutagenic activities, independently of initiation age. The group receiving melatonin for 18 months had high levels of APE1 and OGG1 repair enzymes. Conclusively, melatonin presents an efficient antioxidant mechanism aiding modulating genetic and physiological alterations due to ageing.

Melatonin-loaded lipid-core nanocapsules protect against lipid peroxidation caused by paraquat through increased SOD expression in Caenorhabditis elegans

BACKGROUND

Melatonin has been described in the literature as a potent antioxidant. However, melatonin presents variable, low bioavailability and a short half-life. The use of polymeric nanoparticulated systems has been proposed for controlled release. Thus, the purpose of this study was to investigate the action of melatonin-loaded lipid-core nanocapsules (Mel-LNC) in the antioxidant system of Caenorhabditis elegans, and the possible protective effect of this formulation against lipid peroxidation caused by paraquat (PQ).

METHODS

The suspensions were prepared by interfacial deposition of the polymer and were physiochemically characterized. C. elegans N2 wild type and transgenic worm CF1553, muls84 [sod-3p::gfp; rol6(su1006)] were obtained from the Caenorhabditis Genetics Center (CGC). The worms were divided into 5 groups: Control, PQ 0.5 mM, PQ 0.5 mM + Mel-LNC 10 μg/mL, PQ + unloaded lipid-core nanocapsules (LNC), and PQ + free melatonin (Mel) 10 μg/mL. The lipid peroxidation was assessed through thiobarbituric acid (TBARS) levels and the fluorescence levels of the transgenic worms expressing GFP were measured.

RESULTS

The LNC and Mel-LNC presented a bluish-white liquid, with pH values of 5.56 and 5.69, respectively. The zeta potential was - 6.4 ± 0.6 and - 5.2 ± 0.2, respectively. The mean particle diameter was 205 ± 4 nm and 203 ± 3 nm, respectively. The total melatonin content was 0.967 mg/ml. The TBARS levels were significantly higher in the PQ group when compared to the control group (p < 0.001). Mel-LNC reduced TBARS levels to similar levels found in the control group. Moreover, only Mel-LNC significantly enhanced the SOD-3 expression (p < 0.05). Mel-LNC was capable of protecting C. elegans from lipid peroxidation caused by PQ and this was not observed when free melatonin was used. Moreover, Mel-LNC increased the fluorescence intensity of the transgenic strain that encodes the antioxidant enzyme SOD-3, demonstrating a possible mechanism of protection from PQ-induced damage.

CONCLUSION

These findings demonstrated that melatonin, when associated with nanocapsules, had improved antioxidant properties and the protective activity against PQ-induced lipid peroxidation could be associated with the activation of antioxidant enzymes by Mel-LNC in C. elegans.

Therapeutic potential of Origanum vulgare leaf hydroethanolic extract against renal oxidative stress and nephrotoxicity induced by paraquat in rats

Objective:

Paraquat is a herbicide with potent toxicity in humans and animals. This study aimed to evaluate the protective effects of Origanum vulgare (O. vulgare) leaf extract on the acute nephrotoxicity and renal oxidative stress caused by paraquat.

Materials and Methods:

We randomly assigned forty male rats into five groups (G1-G5). The G1 was used as control; G2 only received paraquat (25 mg/kg body weight (bw)/day, po); and G3, G4 and G5 received 25 mg/kg b.w/day oral doses of paraquat and O. vulgare hydroethanolic leaf extract (200, 400, 800 mg/kg bw/day, po, respectively). After 2 weeks, superoxide dismutase (SOD), renal catalase (CAT), vitamin C levels, histopathological changes, and tumor necrosis factor-α (TNF-α) gene expression as well as serum levels of urea, creatinine (Cr), and protein carbonyl (PC) were determined.

Results:

In G2, oral administration of paraquat significantly increased (p<0.05) serum Cr, urea, PC, and renal TNF-α gene expression relative to those of the control group. Renal catalase, superoxide dismutase, and vitamin C levels were decreased significantly (p<0.05) in G2 as compared to G1. Administration of O. vulgare leaf extract not only increased the renal vitamin C, CAT, and SOD but also decreased the renal TNF-α gene expression, malondialdehyde (MDA), serum urea and creatinine in paraquat-induced nephrotoxicity in rats.

Conclusion:

Our results show that O. vulgare leaf extract has protective effects against nephrotoxicity induced by paraquat in rats. It seems that the nephroprotective effects of O. vulgare extract may be related to its antioxidant and anti-inflammatory effects.

Protective and anti-inflammatory effects of hydroalcoholic leaf extract of Origanum vulgare on oxidative stress, TNF-α gene expression and liver histological changes in paraquat-induced hepatotoxicity in rats

CONTEXT

Toxicity with paraquat can lead to serious damages to the liver.

OBJECTIVE

The study investigates the protective effects of Origanum vulgare leaf extract against paraquat liver damage.

MATERIAL AND METHODS

Rats were divided into six groups. Group 1, the control group; group 2, rats that received paraquat only; group 3, rats that received paraquat plus silymarin; and groups 4, 5, and 6 were treated with paraquat and O. vulgare leaf extract. Then, the serum and tissue parameters of the oxidative stress were examined.

RESULTS

In group 2, paraquat caused a remarkable increase in the level of serum ALT, AST, ALP, lipid profiles, and liver TNF-α gene expression compared to group 1. The groups which received O. vulgare leaf extract exhibited significant ameliorations in abnormalities of paraquat-induced liver damage and serum biochemical parameters.

CONCLUSION

O. vulgare leaf extract has inhibitory effects on paraquat-induced liver damage due to its antioxidant properties.

Oxidative/nitrosative stress, autophagy and apoptosis as therapeutic targets of melatonin in idiopathic pulmonary fibrosis

INTRODUCTION

Idiopathic pulmonary fibrosis (IPF) is a fatal interstitial lung disease associated with disruption of alveolar epithelial cell layer and expansion of fibroblasts/myofibroblasts. Excessive levels of oxidative/nitrosative stress, induction of apoptosis, and insufficient autophagy may be involved in IPF pathogenesis; hence, the targeting of these pathways may ameliorate IPF. Areas covered: We describe the ameliorative effect of melatonin on IPF. We summarize the research on IPF pathogenesis with a focus on oxidative/nitrosative stress, autophagy and apoptosis pathways and discuss the potential effects of melatonin on these pathways. Expert opinion: Oxidative/nitrosative stress, apoptosis and autophagy could be interesting targets for therapeutic intervention in IPF. Melatonin, as a potent antioxidant, induces the expression of antioxidant enzymes, scavenges free radicals and modulates apoptosis and autophagy pathways. The effect of melatonin in the induction of autophagy could be an important mechanism against fibrotic process in IPF lungs. Further clinical studies are necessary to determine if melatonin could be a candidate for treating IPF.

The MTT-formazan assay: Complementary technical approaches and in vivo validation in Drosophila larvae

The MTT assay was the first widely accepted method to assess cytotoxicity and cell viability. However, there is controversy on whether this indicator is a useful tool. In this work we intend to expand the interpretability of the MTT study by its combination with widely used cellular biology techniques. We propose complementary approaches to the colorimetric assay, based on the use of measurements in three different settings: confocal microscopy, multi-well plate assay and flow cytometry. Using confocal microscopy, we confirmed that MTT uptake and reduction by cells is a time-dependent process, and that formazan accumulates in round-shaped organelles. Quantitative measurements with a multi-well fluorimeter combined with nuclear staining result in a useful method, yielding a ratio between formazan production and cell number that informs about the average cell metabolic state. We also found that flow cytometry is a suitable technique to measure MTT reduction in large cell populations. When assaying the effect of an oxidizing agent such as paraquat (PQ), this approach allows for the distinction of subpopulations of cells with different reducing power. Finally, we prove that it is feasible to monitor MTT reduction in an in vivo model, the Drosophila larvae, without affecting its survival rate. Formazan accumulates exclusively in the larval fat body, confirming its lipid solubility. The methods explored in this work expand the MTT potential as a useful tool to provide information of the physiological state of cells and organisms.

Sensitive detection of DNA oxidation damage induced by nanomaterials

From a toxicological point of view, nanomaterials are of interest; because - on account of their great surface area relative to mass - they tend to be more reactive than the bulk chemicals from which they are derived. They might in some cases have the potential to damage DNA directly, or could act via the induction of oxidative stress. The comet assay (single cell gel electrophoresis) is widely used to measure DNA strand breaks and also oxidised bases, by including in the procedure digestion with lesion-specific enzymes such as formamidopyrimidine DNA glycosylase (which converts oxidised purines to breaks) or endonuclease III (recognising oxidised pyrimidines). We summarise reports in which these enzymes have been used to study a variety of nanomaterials in diverse cell types. We also stress that it is important to carry out tests of cell viability alongside the genotoxicity assay, since cytotoxicity can lead to adventitious DNA damage. Different concentrations of nanomaterials should be investigated, concentrating on a non-cytotoxic range; and incubating for short and longer periods can give valuable information about the mode of damage induction. The use of lesion-specific enzymes can substantially enhance the sensitivity of the comet assay in detecting genotoxic effects.

Influence of exposure to pesticides on telomere length in tobacco farmers: A biology system approach

Various pesticides in the form of mixtures must be used to keep tobacco crops pest-free. Recent studies have shown a link between occupational exposure to pesticides in tobacco crops and increased damage to the DNA, mononuclei, nuclear buds and binucleated cells in buccal cells as well as micronuclei in lymphocytes. Furthermore, pesticides used specifically for tobacco crops shorten telomere length (TL) significantly. However, the molecular mechanism of pesticide action on telomere length is not fully understood. Our study evaluated the interaction between a complex mixture of chemical compounds (tobacco cultivation pesticides plus nicotine) and proteins associated with maintaining TL, as well as the biological processes involved in this exposure by System Biology tools to provide insight regarding the influence of pesticide exposure on TL maintenance in tobacco farmers. Our analysis showed that one cluster was associated with TL proteins that act in bioprocesses such as (i) telomere maintenance via telomere lengthening; (ii) senescence; (iii) age-dependent telomere shortening; (iv) DNA repair (v) cellular response to stress and (vi) regulation of proteasome ubiquitin-dependent protein catabolic process. We also describe how pesticides and nicotine regulate telomere length. In addition, pesticides inhibit the ubiquitin proteasome system (UPS) and consequently increase proteins of the shelterin complex, avoiding the access of telomerase in telomere and, nicotine activates UPS mechanisms and promotes the degradation of human telomerase reverse transcriptase (hTERT), decreasing telomerase activity.

Novel therapeutic mechanisms determine the effectiveness of lipid-core nanocapsules on melanoma models

Melanoma is a severe metastatic skin cancer with poor prognosis and no effective treatment. Therefore, novel therapeutic approaches using nanotechnology have been proposed to improve therapeutic effectiveness. Lipid-core nanocapsules (LNCs), prepared with poly(ε-caprolactone), capric/caprylic triglyceride, and sorbitan monostearate and stabilized by polysorbate 80, are efficient as drug delivery systems. Here, we investigated the effects of acetyleugenol-loaded LNC (AcE-LNC) on human SK-Mel-28 melanoma cells and its therapeutic efficacies on melanoma induced by B16F10 in C57B6 mice. LNC and AcE-LNC had z-average diameters and zeta potential close to 210 nm and -10.0 mV, respectively. CytoViva(®) microscopy images showed that LNC and AcE-LNC penetrated into SK-Mel-28 cells, and remained in the cytoplasm. AcE-LNC in vitro treatment (18-90×10(9) particles/mL; 1 hour) induced late apoptosis and necrosis; LNC and AcE-LNC (3-18×10(9) particles/mL; 48 hours) treatments reduced cell proliferation and delayed the cell cycle. Elevated levels of nitric oxide were found in supernatant of LNC and AcE-LNC, which were not dependent on nitric oxide synthase expressions. Daily intraperitoneal or oral treatment (days 3-10 after tumor injection) with LNC or AcE-LNC (1×10(12) particles/day), but not with AcE (50 mg/kg/day, same dose as AcE-LNC), reduced the volume of the tumor; nevertheless, intraperitoneal treatment caused toxicity. Oral LNC treatment was more efficient than AcE-LNC treatment. Moreover, oral treatment with nonencapsulated capric/caprylic triglyceride did not inhibit tumor development, implying that nanocapsule supramolecular structure is important to the therapeutic effects. Together, data herein presented highlight the relevance of the supramolecular structure of LNCs to toxicity on SK-Mel-28 cells and to the therapeutic efficacy on melanoma development in mice, conferring novel therapeutic mechanisms to LNC further than a drug delivery system.

Caenorhabditis elegans as an alternative in vivo model to determine oral uptake, nanotoxicity, and efficacy of melatonin-loaded lipid-core nanocapsules on paraquat damage

Caenorhabditis elegans is an alternative in vivo model that is being successfully used to assess the pharmacological and toxic effects of drugs. The exponential growth of nanotechnology requires the use of alternative in vivo models to assess the toxic effects of theses nanomaterials. The use of polymeric nanocapsules has shown promising results for drug delivery. Moreover, these formulations have not been used in cases of intoxication, such as in treatment of paraquat (PQ) poisoning. Thus, the use of drugs with properties improved by nanotechnology is a promising approach to overcome the toxic effects of PQ. This research aimed to evaluate the absorption of rhodamine B-labeled melatonin (Mel)-loaded lipid-core nanocapsules (LNC) by C. elegans, the application of this model in nanotoxicology, and the protection of Mel-LNC against PQ damage. The formulations were prepared by self-assembly and characterized by particle sizing, zeta potential, drug content, and encapsulation efficiency. The results demonstrated that the formulations had narrow size distributions. Rhodamine B-labeled Mel-LNC were orally absorbed and distributed in the worms. The toxicity assessment of LNC showed a lethal dose 50% near the highest dose tested, indicating low toxicity of the nanocapsules. Moreover, pretreatment with Mel-LNC significantly increased the survival rate, reduced the reactive oxygen species, and maintained the development in C. elegans exposed to PQ compared to those worms that were either untreated or pretreated with free Mel. These results demonstrated for the first time the uptake and distribution of Mel-LNC by a nematode, and indicate that while LNC is not toxic, Mel-LNC prevents the effects of PQ poisoning. Thus, C. elegans may be an interesting alternative model to test the nanocapsules toxicity and efficacy.