Chemical composition and antimycobacterial, anti-Malassezia furfur and cytotoxic activities of essential oils from Callistemon viminalis (Sol. ex Gaertn.) G. Don leaves and flowers.

Callistemon viminalis has been widely known due to its therapeutic properties. Tuberculosis is a deadly infectious disease caused predominantly by Mycobacterium tuberculosis. Other respiratory diseases may also be caused by nontuberculous mycobacteria. Malassezia furfur causes dermal inflammation and tissue damage. This study aimed to evaluate in vitro inhibitory effects of essential oils (EOs) from C. viminalis leaves (EO-CL) and flowers (EO-CF) against M. tuberculosis, Mycobacterium kansasii, Mycobacterium avium and M. furfur strains. Their cytotoxic activity was evaluated by the brine shrimp assay. Resulting MIC values of all EOs under study were promising since they ranged from 50 to 100 µg/mL. Both EO-CL and EO-CF showed nontoxicity against Artemia salina by the brine shrimp assay (LC50 > 1000 µg/mL). GC-FID and GC-MS analyses showed that 1,8-cineole was the major component of both EOs. These results revealed the promising potential of EO-CL and EO-CF to develop new antibacterial and antifungal drugs.

New records on toxic cyanobacteria from Brazil: Exploring their occurrence and geography.

Cyanobacterial Harmful Algal Blooms (CyanoHABs) pose a significant threat to communities globally, impacting ecosystems and public health. This study provides an in-depth review of the current state of cyanotoxins and the distribution of CyanoHABs species in Brazil, while also detailing the methods used for their detection. Four hundred and twenty-one incidents were analyzed from 1993 to 2021, compiling cyanotoxin records and toxic CyanoHABs occurrences. The investigation begins with the first detection of microcystins in 1994 and highlights pivotal moments, like the 1996 "Caruaru Syndrome" outbreak. This event encouraged research and updated cyanotoxin-monitoring guidelines. The Brazilian drought period of 2015-2016 exacerbated cyanobacterial growth and saxitoxin levels, coinciding with Zika-related microcephaly. This study delves into methods used for cyanotoxin analysis, including ELISA, bioassays, HPLC, and LC-MS. Additionally, we investigated the toxicity of 37 cyanobacterial strains isolated from various Brazilian environments. Extracts were tested against Artemia salina and analyzed by LC-MS. Results revealed toxicity in extracts from 49 % of cyanobacterial strains. LC-MS results were analyzed using GNPS MS/MS molecular networking for comparing experimental spectra with those of cyanotoxin standards against in-house databases and the existing literature. Our research underscores the variability in cyanotoxin production among species and over time, extending beyond microcystins. LC-MS results, interpreted through the GNPS platform, revealed six cyanotoxin groups in Brazilian strains. Yet, compounds present in 75 % of the toxic extracts remained unidentified. Further research is crucial for fully comprehending the impact of potentially harmful organisms on water quality and public health management strategies. The study highlights the urgent need for continuously monitoring cyanobacteria and the cyanotoxin inclusion of management in public health policies.

Assessment of Anticancer Properties of Argemone mexicana L. and Berberine: A Comparative Study.

Argemone mexicana L. has been used in traditional Mexican medicine. Among its bioactive constituents, berberine (BER) has garnered attention for its cytotoxic properties against different tumor cell lines. This study investigates the in vitro toxicity against HEP-G2 (human hepatocellular carcinoma) and murine lymphoma (L5178Y-R) cells using the MTT assay of the methanol extract (AmexM), sub-partitions of A. mexicana, and BER. Selectivity indices (SIs) were determined by comparing their cytotoxic effects on VERO (monkey kidney epithelial) and PBMC (human peripheral blood mononuclear) non-tumoral cells. Additionally, the anti-hemolytic effect of these treatments was assessed using the AAPH method. The treatment with the most promising activity against tumor cells and anti-hemolytic efficacy underwent further evaluation for toxicity in Artemia salina and antioxidant activities using DPPH, ABTS, and FRAP assays. BER demonstrated an IC50 = 56.86 µg/mL in HEP-G2 cells and IC50 < 5.0 µg/mL in L5178Y-R cells, with SI values of 15.97 and >5.40 in VERO and PBMC cells, respectively. No significant hemolytic effects were observed, although AmexM and BER exhibited the highest anti-hemolytic activity. BER also demonstrated superior antioxidant efficacy, with lower toxicity in A. salina nauplii compared to the control. Additionally, BER significantly attenuated nitric oxide production. This study highlights the antiproliferative effects of A. mexicana, particularly BER, against HEP-G2 and L5178Y-R tumor cell lines, along with its selectivity towards normal cells. Furthermore, its anti-hemolytic and antioxidant potentials were demonstrated, suggesting that BER is a promising candidate for potent chemotherapeutic agents.

Application of ecotoxicological tools to evaluate the quality status of mangroves under restoration in the Yucatán Peninsula, Mexico.

Ecotoxicological tools, namely biomarkers and bioassays, may provide insights on the ecological quality status of mangroves under restoration. We investigated how 1) physicochemical parameters and water bioassays using Artemia franciscana; and 2) quantification of sublethal (osmoregulatory capacity, biochemical, and oxidative stress) and individual biomarkers (density, length-weight relationship [LWR], parasitic prevalence) in the sentinel fiddler crab Minuca rapax, can improve restoration indicators in mangroves from the Yucatán Peninsula, Southern Gulf of Mexico. We showed that water quality was improved with restoration, but still presented toxicity. Regarding sublethal biomarkers, M rapax from restored areas lower osmotic regulatory capacity, higher oxidative stress, and showed lipid peroxidation. As to the individual biomarkers, the density, LWR, and the prevalence of parasites in M. rapax was higher in restored areas. The use of bioassays/biomarkers were useful as early warning indicators to better assess the health of mangroves under restoration.

Assessment of the Artemia salina toxicity assay as a substitute of the mouse lethality assay in the determination of venom-induced toxicity and preclinical efficacy of antivenom.

Mice are routinely used in snake venom research but are costly and subject to pain and suffering. The crustacean Artemia salina could be an alternative to mice, but data to support its adoption in snake venom research is limited. The aim of the present study was to evaluate the suitability of A. salina as a surrogate of mice in assessing the toxicity of venoms and the preclinical efficacy of antivenoms. The toxicity of venoms from 22 snakes of medical importance in sub-Saharan Africa was evaluated in mice (intraperitoneally; i.p. and intravenously; i.v.) and in A. salina. Subsequently, the capacity of a commercial antivenom to neutralize the toxicity of these venoms in mice and A. salina was investigated. There was a positive correlation between the i.v. median lethal doses (LD50s) and the i.p. LD50s in mice (r = 0.804; p < 0.0001), a moderate correlation between the i.v. LD50s in mice and the median lethal concentrations (LC50s) in A. salina (r = 0.606; p = 0.003), and a moderate correlation between the i.p. LD50s in mice and the LC50s in A. salina (r = 0.426; p = 0.048). Moreover, there was a strong correlation between the i.p. median effective doses (ED50s) and the i.v. ED50s in mice (r = 0.941, p < 0.0001), between the i.p. ED50s in mice and the ED50s in A. salina (r = 0.818, p < 0.0001), and between the i.v. ED50s in mice and the ED50s in A. salina (r = 0.972, p < 0.0001). These findings present A. salina as a promising candidate for reducing reliance on mice in snake venom research. Future investigations should build upon these findings, addressing potential limitations and expanding the scope of A. salina in venom research and antivenom development.

Acute Toxicity Assays with the Artemia salina Model: Assessment of Variables.

The use of the brine shrimp Artemia salina (Leach) in acute toxicity assays has great potential due to its simplicity, low cost and reproducibility. In the current study, some of the variables that can influence the reliability of the assay in terms of test organism survival, were evaluated as part of its implementation in our laboratory. The quality and type of water used, the buffer components and other parameters (salinity, pH and dissolved oxygen level), were all evaluated for optimisation purposes. DMSO (dimethyl sulphoxide) was used as the test substance in the toxicity assay, to evaluate the concentration limits as a solvent in sample preparation. Regarding the buffer salinity, pH and dissolved oxygen level, we found that a 25% to 30% deviation from the standard values did not affect the survival of the nauplii (the first-instar larval stage) under assay conditions. In summary, we corroborate the potential use of this model for the prediction of the toxic potential of substances, to inform future testing strategies.

Chemical Composition of Piper nigrum L. Cultivar Guajarina Essential Oils and Their Biological Activity.

The essential oils and aroma derived from the leaves (L), stems (St), and spikes (s) of Piper nigrum L. cv. Guajarina were extracted; the essential oils were extracted using hydrodistillation (HD), and steam distillation (SD), and the aroma was obtained by simultaneous distillation and extraction (SDE). Chemical constituents were identified and quantified using GC/MS and GC-FID. Preliminary biological activity was assessed by determining the toxicity against Artemia salina Leach larvae, calculating mortality rates, and determining lethal concentration values (LC50). The predominant compounds in essential oil samples included α-pinene (0-5.6%), ß-pinene (0-22.7%), limonene (0-19.3%), 35 linalool (0-5.3%), δ-elemene (0-10.1%), ß-caryophyllene (0.5-21.9%), γ-elemene (7.5-33.9%), and curzerene (6.9-31.7%). Multivariate analysis, employing principal component analysis (PCA) and hierarchical cluster analysis (HCA), revealed three groups among the identified classes and two groups among individual compounds. The highest antioxidant activity was found for essential oils derived from the leaves (167.9 41 mg TE mL-1). Larvicidal potential against A. salina was observed in essential oils obtained from the leaves (LC50 6.40 µg mL-1) and spikes (LC50 6.44 µg mL-1). The in silico studies demonstrated that the main compounds can interact with acetylcholinesterase, thus showing the potential molecular interaction responsible for the toxicity of the essential oil in A. salina.

Efecto ecotóxico y preventivo del uso de aceites esenciales en la mastitis bovina / Ecotoxic and preventive effect of the use of essential oils in bovine mastitis

The essential oils of Lippia citriodora (Ort.) and Lippia origanoides (Kunth) have shown antimicrobial activity associated with mastitis. The objective of this study was to evaluate its ecotoxic effect with the Artemia salina bioassay and the prevention of mastitis through an in vivo test in cattle (n=20) with a product based on these oils using a conventional product as a control. Contact hypersensitivity, the effect on somatic cells, and residuality in mil k samples were evaluated. The results of the Artemia salina bioassay were 10.05 and 19.36 (µg/mL) respectively. No negative effects or contact hypersensitivity were observed, and no residual metabolites were found in post - test milk. The somatic cell count showed 75% effectiveness in the prevention of mastitis with essential oils compared to 62.5% with the conventional product. The evaluated formulation could be used in the prevention of bovine mastitis safely, further investigation is required.

Los aceites esenciales de Lippia citriodora (Ort.) y Lippia origanoides (Kunth), han mostrado acti vidad antimicrobiana asociada a la mastitis. El objetivo de este estudio fue evaluar su efecto ecotóxico con el bioensayo Artemia salina y la prevención de mastitis mediante un ensayo in vivo en bovinos (n=20) con un producto a base de estos aceites utiliz ando como control un producto convencional. Se evaluó la hipersensibilidad de contacto, efecto en células somáticas y residualidad en muestra de leche. Los resultados del bioensayo de Artemia salina fueron 10,05 y 19,36 (µg/mL) respectivamente. No se obser varon efectos negativos, ni hipersensibilidad de contacto, y no se encontraron metabolitos residuales en leche posterior al ensayo. El conteo de células somáticas mostró efectividad en la prevención de mastitis del 75% con aceites esenciales frente al 62.5 % del producto convencional. La formulación evaluada podría ser utilizada en la prevención de la mastitis bovina de forma segura, se requiere profundizar en la investigación.

Isolation of 4-nerolidylcatechol from leaves of Piper peltatum L., and evaluation of larvicidal activity in mosquito vectors, with emphasis on Aedes aegypti (Diptera: Culicidae)

ABSTRACT Synthetic chemical insecticides are widely used in population control of pests. Aedes aegypti is the primary vector of dengue, Zika, chikungunya and yellow fever to humans, and has proven resistance to chemical insecticides. As an alternative vector control method, the ethanolic extract of the leaves of Piper peltatum L. (Piperaceae) showed larvicidal activity against Ae. aegypti. Despite the wide medicinal use of this plant, the biological activity of its isolated constituents remains unexplored. In this sense, we isolated, identified and evaluated the larvicidal activity of 4-nerolidylcatechol (4-NC) from P. peltatum against Ae. aegypti, Culex quinquefasciatus and Anopheles darlingi, focusing on the larvicidal, adulticidal and genotoxic potential of 4-NC on Ae. aegypti. Larvae were captured in the city of Manaus, Amazonas state, Brazil. 4-NC was isolated from the extract of the leaves of P. peltatum via silica gel chromatography. This was identified using nuclear magnetic resonance spectroscopy and tested in Artemia franciscana (6.25, 12.5, 25, 50, 100 and 200 µg/mL). In the toxicity bioassay, Ae. aegypti larvae were exposed to 30, 50, 70, 90, and 110 µg/mL of 4-NC, while Cx. quinquefasciatus and An. darlingi were exposed to 6.25, 12.5, 25, 50 and 100 µg/mL. Ae. aegypti larvae were also subjected to 40 and 60 µg/mL of 4-NC (genotoxicity bioassay), and adult females to 62.5 to 1,000 µg/mL (adulticidal bioassay). The results of the 4-NC toxicity assays showed that there was 100% mortality in larvae of Ar. franciscana at the concentration of 200 µg/mL, with an LC50 of 8.0 μg/mL. In the larvae of Ae. aegypti, mortality was 100%, with an LC50 of 62 μg/mL. In larvae of Cx. quinquefasciatus, 97% mortality occurred, with an LC50 of 52.3 μg/mL, and in An. darlingi larvae there was an 83% mortality rate, with an LC50 of 55.8 μg/mL. In adults of Ae. aegypti, however, there was no adulticidal activity. In the larvae of Ae. aegypti, the genotoxic effect of 4-NC (40 and 60 µg/mL) showed significant frequency (p < 0.05) of cellular abnormalities (micronuclei, budding and nuclear bridges) of interphasic nuclei of neuroblasts and oocytes in relation to the negative control. This result may be associated with a decrease in oviposition of females, which was observed in two generations. We can confirm that 4-NC has larvicidal activity against Ae. aegypti, Cx. quinquefasciatus and An. darlingi. Although it does not present adulticidal activity in Ae. aegypti, it reduced the oviposition of females. Therefore, 4-NC seems to be a strong candidate for the development of an alternative method for the control of these mosquitoes in the immature phase.

Chemical Composition, Preliminary Toxicity, and Antioxidant Potential of Piper marginatum Sensu Lato Essential Oils and Molecular Modeling Study.

The essential oils (OEs) of the leaves, stems, and spikes of P. marginatum were obtained by hydrodistillation, steam distillation, and simultaneous extraction. The chemical constituents were identified and quantified by GC/MS and GC-FID. The preliminary biological activity was determined by assessing the toxicity of the samples to Artemia salina Leach larvae and calculating the mortality rate and lethal concentration (LC50). The antioxidant activity of the EOs was determined by the DPPH radical scavenging method. Molecular modeling was performed using molecular docking and molecular dynamics, with acetylcholinesterase being the molecular target. The OES yields ranged from 1.49% to 1.83%. The EOs and aromatic constituents of P. marginatum are characterized by the high contents of (E)-isoosmorhizole (19.4-32.9%), 2-methoxy-4,5-methylenedioxypropiophenone (9.0-19.9%), isoosmorhizole (1.6-24.5%), and 2-methoxy-4,5-methylenedioxypropiophenone isomer (1.6-14.3%). The antioxidant potential was significant in the OE of the leaves and stems of P. marginatum extracted by SD in November (84.9 ± 4.0 mg TE·mL-1) and the OEs of the leaves extracted by HD in March (126.8 ± 12.3 mg TE·mL-1). Regarding the preliminary toxicity, the OEs of Pm-SD-L-St-Nov and Pm-HD-L-St-Nov had mortality higher than 80% in concentrations of 25 µg·mL-1. This in silico study on essential oils elucidated the potential mechanism of interaction of the main compounds, which may serve as a basis for advances in this line of research.

Chitosan (CS)/Hydroxyapatite (HA)/Tricalcium Phosphate (ß-TCP)-Based Composites as a Potential Material for Pulp Tissue Regeneration.

This research focused on developing new materials for endodontic treatments to restore tissues affected by infectious or inflammatory processes. Three materials were studied, namely tricalcium phosphate ß-hydroxyapatite (ß-TCP), commercial and natural hydroxyapatite (HA), and chitosan (CS), in different proportions. The chemical characterization using infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analysis confirmed the composition of the composite. Scanning electron microscopy (SEM) demonstrated that the design and origin of the HA, whether natural or commercial, did not affect the morphology of the composites. In vitro studies using Artemia salina (A. salina) indicated that all three experimental materials were biocompatible after 24 h, with no significant differences in mortality rate observed among the groups. The subdermal implantation of the materials in block form exhibited biocompatibility and biodegradability after 30 and 60 days, with the larger particles undergoing fragmentation and connective tissue formation consisting of collagen type III fibers, blood vessels, and inflammatory cells. The implanted material continued to undergo resorption during this process. The results obtained in this research contribute to developing endodontic technologies for tissue recovery and regeneration.

Progress and promise of alternative animal and non-animal methods in biomedical research.

Cell culture and invertebrate animal models reflect a significant evolution in scientific research by providing reliable evidence on the physiopathology of diseases, screening for new drugs, and toxicological tests while reducing the need for mammals. In this review, we discuss the progress and promise of alternative animal and non-animal methods in biomedical research, with a special focus on drug toxicity.

Preliminary assessment of toxicity of aerosol samples from central-west Brazil using Artemia spp. bioassays.

The present study reports the development of a bioassay using Artemia spp. to analyse the preliminary ecotoxicity of atmospheric aerosols (PM), which can affect the environment and human health. Herein, PM samples were collected in the city of Goiânia (Brazil) in 2016, extracted with ultrapure water and subsequently filtered through membranes with different pore sizes (100, 0.8, and 0.22 µm), and the extracts employed in the bioassays. The mortality rates (endpoint analysed) declined to membranes with smaller pore sizes (15 ± 4%, 47 ± 10% and 43 ± 9% for pore sizes of 100 µm, 0.8 µm and 0.22 µm, respectively). In general, the toxicity of the extract depended on its concentration, except for the sample with a higher negative particle surface charge, which presents a lower affinity for the negatively charged surfaces of cellular membranes. Moreover, although the PM concentration was higher for the sample collected during the dry season (September), the mortality rate was not significantly different to that determined for a sample with similar physical and chemical characteristics collected in the rainy season (December). This result demonstrates the importance of monitoring PM toxicities and their chemical and physical characteristics, in addition to their concentrations. Therefore, the new protocol to provide a preliminary analysis of the toxicity of the extracts of aerosol emerges as a useful, accessible, and fast tool for monitoring possible environmental hazards, and can simplify fieldwork.

Chemical profile, antioxidant potential and toxicity of Smilax brasiliensis Sprengel (Smilacaceae) stems.

Smilax brasiliensis Sprengel is a monocotyledon of the Smilacaceae family, native to the Brazilian Cerrado, popularly known as "salsaparrilha" or "japecanga". In this study, the ethanol extract (EE) and the hexane (HEXF), dichloromethane (DCMF), ethyl acetate (ACF), and hydroethanol (HEF) fractions of the stems were obtained. The chemical composition was determined, the contents of phenolic compounds and flavonoids were quantified, and the antioxidant potential and the cytotoxic effect on Artemia salina were evaluated. Fatty acid esters, hydrocarbons, and phytosterols were identified in the HEXF analyzed by gas chromatography - mass spectrometry (GC-MS). The EE and DCMF, ACF, and HEF were analyzed by liquid chromatography coupled to a diode array detector and mass spectrometer (LC-DAD-MS), and the identified constituents included glycosylated (rutin, 3-O-ß-galactopyranosyl quercetin, 3-O-ß-glucopyranosyl quercetin, O-deoxyhexosyl-hexosyl quercetin, O-deoxyhexosyl-hexosyl kaempferol, O-deoxyhexosyl-hexosyl O-methyl quercetin, and others), and non-glycosylated (quercetin) flavonoids, phenylpropanoids (3-O-E-caffeoyl quinic acid, 5-O-E-caffeoyl quinic acid, O-caffeoyl shikimic acid, and others), neolignan, steroidal saponin (dioscin), and N-feruloyltyramine. The EE, DCMF, and ACF showed high total contents of phenolic compounds (112.99, 175.71, and 524.02 µg of GAE/mg, respectively), and in the ACF and DCMF a great content of flavonoids was also quantified (50.08 and 31.49 µg of QE/mg, respectively). The EE, DCMF, ACF, and HEF exhibited great antioxidant potential by DPPH (IC50 1.71 - 32.83 µg/mL) and FRAP (IC50 0.63 - 6,71 µg/mL) assays. A maximum cytotoxic activity on A. salina of 60% was observed for the DCMF (LC50 = 856.17 µg/mL). This study contributes to the phytochemical study of S. brasiliensis since these compounds were identified for the first time in the stems of this species. The S. brasiliensis stems demonstrated to be a rich source of polyphenols compounds and exhibited high antioxidant potential without toxicity. Thus, extract and fractions obtained from the S. brasiliensis stems can be used in food supplements or as natural antioxidants in the food industry.

Supervivencia, desarrollo y crecimiento de larvas de Penaeus vannamei alimentadas con dietas tradicionales y no-tradicionales

RESUMEN Objetivo. Evaluar el efecto de dietas tradicionales (Thalassiosira weissflogii y nauplios de Artemia) y otras dos alternativas (no tradicionales) a base de microalgas y rotíferos sobre la supervivencia, el desarrollo y crecimiento de larvas nauplio V (NV) hasta el día de cambio a postlarvas (PL1) de camarón Penaeus vannamei. Materiales y Métodos. Se realizaron dieciséis réplicas (unidades experimentales) para cada una de las tres dietas utilizadas. Las larvas se colocaron en contenedores de 12 L a 35 ups, 30°C y una densidad de 200 larvas/L. La supervivencia, etapa del desarrollo y el crecimiento se determinaron al inicio, cada 24 h y al final del experimento (PL1: día 8). A los datos obtenidos se les aplicó un ANAVA de una vía. Resultados. La dieta no tuvo influencia (p>0.05) sobre supervivencia y el peso. La supervivencia osciló entre 30.4% (dieta alternativa B) y 28.5% (dieta tradicional A). El desarrollo, longitud y peso más bajo a PL1 fue encontrado con la dieta tradicional (6.71; 3.53 mm; 58.37 μg/organismo) en comparación con las dietas alternativas suministradas B y C (6.86-6.76; 3.79-3.82 mm; 60.7-65.0 μg/organismo). Conclusiones. La alimentación más adecuada para la supervivencia, desarrollo y crecimiento larval se obtuvieron con las dietas alternativas no tradicionales (B y C) compuestas de rotíferos.

ABSTRACT Objetive. The effect of traditional diets (Thalassiosira weissflogii and Artemia nauplii) and two other alternatives (not traditional) based on microalgae with rotifers were evaluated on the survival, development and growth from nauplii V (NV) larvae until postlarvae (PL1) of Penaeus vannamei. Materials and methods. Sixteen replicates (experimental units) were applied for each of the three diets used. The larvae were placed in 12 L containers at 35 psu, 30°C and a density of 200larvae/L. At the beginning, every 24 h and the end of the experiment (PL1: day 8), samples of larvae were obtained to determine survival, development and growth (length and weight). A one-way ANOVA was applied to the data obtained. Results. Diet had no influence (p>0.05) on survival and weight. Survival ranged from 30.4% (alternative diet B) to 28.5% (traditional diet A). The lowest development, length and weight at PL1 was found with the traditional diet (6.71; 3.53 mm; 58.37 μg/organism) compared with the alternative diets supplied B and C (6.86-6.76; 3.79-3.82 mm; 60.7-65.0 μg/organism. Conclusions. Non-traditional alternative diet (B and C) composed of rotifers was the best diet for larval survival, development and growth.

Acute toxicity of titanium dioxide microparticles in Artemia sp. nauplii instar I and II.

In this study, the toxicity effects of titanium dioxide (MTiO2 ) microparticles on Artemia sp. nauplii instar I and II between 24 and 48 h was evaluated. The MTiO2 were characterized using different microscopy techniques. MTiO2 rutile was used in toxicity tests at concentration of 12.5, 25, 50, and 100 ppm. No toxicity was observed in Artemia sp. nauplii instar I at the time of 24 and 48 h. However, Artemia sp. nauplii instar II toxicity was observed within 48 h of exposure. MTiO2 at concentrations of 25, 50 and 100 ppm was lethal for Artemia sp. with a significant difference (p ≤ .05) in relation to the control artificial sea water with LC50 value at 50 ppm. Analysis of optical and scanning electron microscopy revealed tissue damage and morphological changes in Artemia sp. nauplii instar II. By using confocal laser scanning microscopy, cell damage was observed due to the toxicity of MTiO2 at a concentration of 20, 50, and 100 ppm. The high mortality rate is related to the filtration of MTiO2 by Artemia sp. nauplii instar II due to the complete development of the digestive tract.

Effects of live prey concentration, salinity, and weaning age on larviculture of Piaractus brachypomus reared in a recirculating aquaculture system.

This study evaluated the effects of live prey concentration (nauplii of Artemia sp.), water salinity, and weaning age on survival, growth, and stress resistance rate (Rs) of Piaractus brachypomus under larviculture in a recirculating aquaculture system (RAS). Larvae aged 6 days post-hatching (1.64 ± 0.11 mg) were distributed in 28-L tanks (five larvae L-1), in two RASs. The experiment was carried in a 2 × 2 × 2 factorial arrangement, as follows: two feeding strategies (sudden transition from live food to commercial food after 10 (FT10) and 20 (FT20) days of larviculture with Artemia); two daily initial prey concentrations (P350 = 350 and P700 = 700 nauplii larva-1, these being increased every 5 days); and two water salinities (S0 = fresh water and S2 = 2 g of salt L-1). Weight (W), total length (TL), and daily specific growth rate (SGR) were evaluated after 10, 20, 30, and 40 days of larviculture. After 40 days of larviculture, survival was evaluated and a test of air exposure was performed to determine stress resistance rate (Rs). Noteworthy results during this period are the lowest specific daily growth rate (SGR) after weaning for FT10 and the best growth results for S2 and P700. After 40 days, weight (W) and total length (TL) showed effects of P, FT, and S with higher values for P700, FT20, and S2 (P < 0.05). The interaction P × FT × S also had effects on survival and Rs at the end of the experiment, with higher survival and Rs for P700FT20S2 (P < 0.05). Larviculture of P. brachypomus in RAS, in association with the three managements-live prey concentration P700, salinity S2, and age at feed transition FT20-promotes maximization of survival, growth, and stress resistance rate of the animals. The larviculture of P. brachypomus in RAS must be carried out with an initial concentration of live prey of 700 nauplii larva-1, at a salinity of 2 g of salt L-1 and with the feeding transition starting in 20 days of larviculture, for maximization intensive larviculture of this species.

A Compact and Efficient Brine Shrimp Hatching Device.

BACKGROUND: Artemia is considered an indispensable live food for rearing many fish and crustacean larvae and can be used in toxicity tests as a safe, practical, and economical method. It is straightforward to create and manipulate; however, many cysts do not hatch as expected. METHODS: A new device was used to hatch Artemia salina. The device includes a tubularshaped reservoir, lid with a central hole, heater with a thermostat, air compressor, three porous stones, funnel-shaped bottom, light source, collection valve, switch, and electrical outlet, which permits better control of temperature and aeration in a single apparatus. Different patent devices were used for comparative analysis. RESULTS: Hatched eggs of Artemia showed that the device was 97% efficient; in comparison, commercial and other devices hatched approximately less than 80% of the cysts. Although Artemia is an easy-to-handle animal, the device described here facilitates changes in the growth parameters and produces more nauplii larvae. CONCLUSION: This paper presents a new device that is effective, compact, and successful for hatching brine shrimp cysts, thereby improving Artemia production.

Synthesis and evaluation of toxicity and antimicrobial activity of rifampicin associated with iron oxide nanoparticles

Rifampicin has broad-spectrum antimicrobial activity, but it can cause nephrotoxic and hepatotoxic damage because high doses are required. Nanosystems emerge as a perspective to improve the transport systems of this drug. In this work, iron oxide nanoparticles were synthesised, functionalized with lauric acid, and rifampicin was incorporated into the nanosystem. The samples were characterized by spectroscopic techniques: electronics in the visible ultraviolet region (UV-vis), vibrational absorption in the infrared region (IR), X-ray diffractometry (XRD), and dynamic light scattering (DSL). The toxicity of the nanocompounds and the antimicrobial activity against Staphylococcus aureus ATCC 25923 were studied by the Artemia salina lethality and disc diffusion techniques, respectively. As a result, IR analysis showed characteristic vibrations of laurate and rifampicin on the surface of the nanosystem. The presence of magnetic iron oxide was confirmed by XRD and the mean diameter of the crystallites was 8.37 nm. The hydrodynamic diameter of rifampicin associated with the nanosystem was 402 nm and that of the nanosystem without rifampicin was 57 nm. The compounds did not show toxicity to Artemia salina and the in vitro antimicrobial activity against Staphylococcus aureus was slightly decreased when rifampicin was associated with the nanosystem. In general terms, the results showed that iron oxide nanoparticles showed no toxicity and reduced the toxicity of rifampicin by 41.54% when carried compared to free rifampicin. Therefore, magnetic iron oxide nanoparticles may have the potential to act as a platform for associated drugs.

Chemical constituents and in vivo preliminary evaluation of the toxicological activity of Ouratea spectabilis (OCHNACEAE) and Clitoria guianensis (Fabaceae) leaves

Clitoria guianensis and Ouratea spectabilis, found in the Brazilian Cerrado, are used in folk medicine, despite the few chemical and biological studies reported in the literature. The present study aims to investigate the toxicity and effect of extracts from both species on the microcrustacean Artemia salina, and to determine the chemical composition of the hexane extract of O. spectabilis leaves and the EtOAc fraction of C. guianensis leaves. Kaempferitrin, a flavonoid isolated from of the EtOAc fraction of C. guianensis leaves, was identified by chemical analysis. Analysis of the hexane extract of O. spectabilis leaves using gas chromatography-mass spectrometry (GC-MS) suggested the presence of twenty-five known substances. The Hex, EtOAc, and EtOH crude extracts of C. guianensis leaves exhibited high and moderate toxicity against Artemia salina, with median lethal dose values (LD50) of 43.7, 25.4, and 233.4 mg.L−1, respectively. The acetone extract of O. spectabilis leaves showed moderate toxicity against Artemia salina with an LD50 value of 115.13 mg.L−1.