Assessing the disparity: comparative toxicity of Copper in zebrafish larvae exposes alarming consequences of permissible concentrations in Brazil.

Copper (Cu) is a naturally occurring metal with essential micronutrient properties. However, this metal might also pose increased adverse environmental and health risks due to industrial and agricultural activities. In Brazil, the maximum allowable concentration of Cu in drinking water is 2 mg/L. Despite this standard, the impact of such concentrations on aquatic organisms remains unexplored. This study aimed to evaluate the toxicity of CuSO4 using larval zebrafish at environmentally relevant concentrations. Zebrafish (Danio rerio) larvae at 72 hr post-fertilization (hpf) were exposed to nominal CuSO4 concentrations ranging from 0.16 to 48 mg/L to determine the median lethal concentration (LC50), established at 8.4 mg/L. Subsequently, non-lethal concentrations of 0.16, 0.32, or 1.6 mg/L were selected for assessing CuSO4 -induced toxicity. Morphological parameters, including body length, yolk sac area, and swim bladder area, were adversely affected by CuSO4 exposure, particularly at 1.6 mg/L (3.31 mm ±0.1, 0.192 mm2 ±0.01, and 0.01 mm2 ±0.05, respectively). In contrast, the control group exhibited values of 3.62 mm ±0.09, 0.136 mm2 ±0.013, and 0.3 mm2 ±0.06, respectively. Behavioral assays demonstrated impairments in escape response and swimming capacity, accompanied by increased levels of reactive oxygen species (ROS) and lipid peroxidation. In addition, decreased levels of non-protein thiols and reduced cellular viability were noted. Data demonstrated that exposure to CuSO4 at similar concentrations as those permitted in Brazil for Cu adversely altered morphological, biochemical, and behavioral endpoints in zebrafish larvae. This study suggests that the permissible Cu concentrations in Brazil need to be reevaluated, given the potential enhanced adverse health risks of exposure to environmental metal contamination.

Immobilization of Low-Cost Alternative Vegetable Peroxidase (Raphanus sativus L. peroxidase): Choice of Support/Technique and Characterization.

In the present work the radish (Raphanus sativus L.) was used as the low-cost alternative source of peroxidase. The enzyme was immobilized in different supports: coconut fiber (CF), calcium alginate microspheres (CAMs) and silica SBA-15/albumin hybrid (HB). Physical adsorption (PA) and covalent binding (CB) as immobilization techniques were evaluated. Immobilized biocatalysts (IBs) obtained were physicochemical and morphologically characterized by SEM, FTIR and TGA. Also, optimum pH/temperature and operational stability were determined. For all supports, the immobilization by covalent binding provided the higher immobilization efficiencies-immobilization yield (IY%) of 89.99 ± 0.38% and 77.74 ± 0.42% for HB and CF, respectively. For CAMs the activity recovery (AR) was of 11.83 ± 0.68%. All IBs showed optimum pH at 6.0. Regarding optimum temperature of the biocatalysts, HB-CB and CAM-CB maintained the original optimum temperature of the free enzyme (40 °C). HB-CB showed higher operational stability, maintaining around 65% of the initial activity after four consecutive cycles. SEM, FTIR and TGA results suggest the enzyme presence on the IBs. Radish peroxidase immobilized on HB support by covalent binding is promising in future biotechnological applications.

Developmental iron exposure induces locomotor alterations in Drosophila: Exploring potential association with oxidative stress.

Prenatal iron (Fe) exposure has been associated with learning and cognitive impairments, which may be linked to oxidative stress resulting from elevated Fe levels and harm to the vulnerable brain. Drosophila melanogaster has contributed to our understanding of molecular mechanisms involved in neurological conditions. This study aims to explore Fe toxicity during D. melanogaster development, assessing oxidative stress and investigating behaviors in flies that are related to neurological conditions in humans. To achieve this goal, flies were exposed to Fe during the developmental period, and biochemical and behavioral analyses were conducted. The results indicated that 20 mM Fe decreased fly hatching by 50 %. At 15 mM, Fe exposure increased lipid peroxidation, and GSH levels decreased starting from 5 mM of Fe. Superoxide Dismutase activity was enhanced at 15 mM, while Glutathione S-Transferase activity was inhibited from 5 mM. Although chronic Fe exposure did not alter acetylcholinesterase (AChE) activity, flies exhibited reduced locomotion, increased grooming, and antisocial behavior from 5 mM of Fe. This research highlights potential Fe toxicity risks during development and underscores the utility of D. melanogaster in unraveling neurological disorders, emphasizing its relevance for future research.

Increased Iron Levels and Oxidative Stress Mediate Age-Related Impairments in Male and Female Drosophila melanogaster.

Aging is characterized by a functional decline in the physiological functions and organic systems, causing frailty, illness, and death. Ferroptosis is an iron- (Fe-) dependent regulated cell death, which has been implicated in the pathogenesis of several disorders, such as cardiovascular and neurological diseases. The present study investigated behavioral and oxidative stress parameters over the aging of Drosophila melanogaster that, together with augmented Fe levels, indicate the occurrence of ferroptosis. Our work demonstrated that older flies (30-day-old) of both sexes presented impaired locomotion and balance when compared with younger flies (5-day-old). Older flies also produced higher reactive oxygen species (ROS) levels, decreased glutathione levels (GSH), and increased lipid peroxidation. In parallel, Fe levels were augmented in the fly's hemolymph. The GSH depletion with diethyl maleate potentiated the behavioral damage associated with age. Our data demonstrated biochemical effects that characterize the occurrence of ferroptosis over the age of D. melanogaster and reports the involvement of GSH in the age-associated damages, which could be in part attributed to the augmented levels of Fe.

Revealing Insights into Natural Products Against mcr-1-Producing Bacteria.

Bacterial resistance has become a major global concern, affecting about 500, 000 individuals in 22 countries. Thus, it is clear that Gram-negative bacteria have been receiving more attention in this scenario. These bacteria perform several resistance mechanisms, such as modifying lipid A from lipopolysaccharides as a product of the mcr-1 gene expression. This gene was initially identified in animals; however, it quickly spread to humans, spreading to 70 countries. Mcr-1 gene attributes resistance to polymyxin B and colistin, which are drugs established as the last alternative to combat Enterobacteriaceae bacteria. Notwithstanding the prevalence and lack of antibiotic therapies for such bacteria, this article aimed to compile information about natural compounds against the resistance attributed by this gene, including the activity of isolated colistin or its associations with other antibiotics. Among the studies that evaluated colistin's synergistic action with other compounds, azidothymidine and isoalantholactone stood out. On the other hand, the paenipeptin 1 analog showed satisfactory activities when associated with other antibiotics. Besides, it is worth mentioning that molecular docking results between ostole and eugenol toward phosphoethanolamine transferase MCR-1 revealed that these compounds could interact with critical amino acid residues for the catalytic action of this enzyme. Based on this, natural agents' role is evident against infections caused by mcr-1-positive bacteria, directly contributing to the development of new effective pharmacotherapies.

Caracterização química, atividade antimicrobiana e toxicidade dos óleos essenciais da Pimenta dioica L. (pimenta da Jamaica) e Citrus sinensis L. Osbeck (laranja doce) / Chemical characterization, antimicrobial activity, and toxicity of the essential oils of Pimenta dioica L. and Citrus sinensis L. Osbeck (laranja doce)

RESUMO Este estudo avaliou a toxicidade e a atividade antimicrobiana frente a Escherichia coli e Staphylococcus aureus dos óleos essenciais de Pimenta dioica Lindl. e Citrus sinensis L. Os óleos essenciais (OE) foram extraídos por hidrodestilação, com caracterização química através de cromatografía gasosa acoplada a espectrometria de massas (CG-EM). Os parâmetros físico-químicos foram determinados de acordo com a Farmacopeia Brasileira. O ensaio de toxicidade seguiu o bioensaio com Artemia salina Leach, os OE aprovados neste ensaio seguiram para avaliação das suas propriedades biológicas. A atividade antimicrobiana seguiu a metodologia descrita pelo Clinical and Laboratory Standards Institute utilizando o método de difusão de disco, diluição em caldo para concentração inibitória mínima (CIM) e posterior concentração bactericida mínima para avaliar a ação dos OE frente a Escherichia coli e Staphylococcus aureus. Ambos os OE apresentaram toxicidade baixa, e assim foram avaliados quanto as propriedades biológicas antimicrobianas. Ambos os OE apresentaram potenciais bactericidas frente aos microrganismos testados, exibindo resultados satisfatórios para a ação deles. Os resultados indicam que os OE avaliados são compostos por substâncias que propiciam e incentivam sua aplicação em virtude de seus potenciais para atividade biológicas moluscicida e antimicrobiana.

SUMMARY This study evaluated the toxicity and antimicrobial activity in the face of Escherichia coli and Staphylococcus aureus of essential oils of Pimenta dioica Lindl. and Citrus sinensis L. The essential oils (EO) were extracted by hydrodistillation, with chemical characterization by gas chromatography coupled and mass spectrometry (GC-MS). Physicochemical parameters were determined according to the Brazilian Pharmacopeia. The toxicity test followed the bioassay with Artemia salina Leach, the EO approved in this assay followed to evaluate its biological properties. The antimicrobial activity followed the methodology described by the Clinical and Laboratory Standards Institute using the disc diffusion method, broth dilution for minimum inhibitory concentration (MIC) and subsequent minimum bactericide concentration for to evaluate the action of EO against Escherichia coli and Staphylococcus aureus. Both OE showed low toxicity, and thus were evaluated for the biological antimicrobial properties. Both OE presented bactericidal potential against the microorganisms tested, showing satisfactory results for their action. The results indicate that the evaluated OE are composed of substances that provide and encourage their application due to their potentials for biological molluscicide and antimicrobial activity.