Açaí (Euterpe oleracea Mart.) green synthesis of silver nanoparticles: antimicrobial efficacy and ecotoxicological assessment.

The synthesis of silver nanoparticles (AgNPs) is usually based on expensive methods that use or generate chemicals that can negatively impact the environment. Our study presents a simple one-step synthesis process for obtaining AgNP using an aqueous extract of Amazonian fruit açai (Euterpe oleracea Mart.) as the reducing and stabilizing agents. The bio-synthesized AgNP (bio-AgNP) were comprehensively characterized by diverse techniques, and as a result, 20-nm spherical particles (transmission electron microscopy) were obtained. X-ray diffraction analysis (XRD) confirmed the presence of crystalline AgNP, and Fourier-transform infrared spectroscopy (FT-IR) suggested that polyphenolic compounds of açaí were present on the surface. The bio-AgNP showed antimicrobial activity against Staphylococcus aureus, Pseudomonas aeruginosa, and Acinetobacter baumannii. In Caenorhabditis elegans exposed to 10 µg/L bio-AgNP for 96 h, there were no significant effects on growth, reproduction, or reactive oxygen species (ROS) concentration; however, there was an increase in superoxide dismutase (SOD) and glutathione-S-transferase (GST) enzymatic activity. In contrast, when worms were exposed to chemically synthesized AgNP (PVP-AgNP), an increase in ROS, SOD, and GST activity and a reduction in oxidative stress resistance were observed. In conclusion, our study not only showcased the potential of açaí in the simple and rapid production of AgNP but also highlighted the broad-spectrum antimicrobial activity of the synthesized nanoparticles using our protocol. Moreover, our findings revealed that these AgNPs exhibited reduced toxicity to C. elegans at environmentally realistic concentrations compared with PVP-AgNP.

Effects of including of Japanese Pumpkin Seeds and Pomace in the Diets of Pacific White Shrimp (Penaeus vannamei).

A 60-day feeding trial was conducted to evaluate the effects of including pumpkin seeds and pomace in the diets of Pacific white shrimp Penaeus vannamei, and the effects of these supplements on growth performance, body composition, and total polyphenol, flavonoid and carotenoid contents, as well as on total antioxidant activity, and body color parameters. Five diets were evaluated: pumpkin seeds (PS) at 50 and 100 g·kg-1, pumpkin pomace (PP) at 50 and 100 g·kg-1, and a control treatment. Pacific white shrimp (P. vannamei) juveniles (0.60 ± 0.01 g) were stocked in 15 tanks (310 L), containing 30 shrimps per tank, and the treatments were randomly distributed in triplicate. At the end of the experiment, shrimps were euthanized, weighed, and dissected for further analyses. The inclusion of PS in the diets impaired growth performance, reduced the total flavonoid content and had a pro-oxidative effect on muscle. The inclusion of PP in the diets did not affect growth performance, improved the feed conversion ratio, increased the total flavonoid content in the diets and hepatopancreas, and improved the antioxidant activity of the feeds and shrimp muscle. The total carotenoid content of the feeds increased with the inclusion of PS or PP in the diets; however, the total carotenoid content of shrimp increased only in those fed PP diets. Shrimp fed with PS diets showed a yellowish color and higher saturation when fresh and a reddish color and yellow hue angle after cooking. Shrimp fed PP diets turned reddish and yellowish, both when fresh and after cooking. The inclusion of PS in P. vannamei diets is not recommended; however, PP can be included at 100 g·kg-1 without affecting the growth parameters. Further studies evaluating the inclusion of higher PP levels in shrimp diets are recommended.

The Effects of Lipoic Acid on Yolk Nutrient Utilization, Energy Metabolism, and Redox Balance over Time in Artemia sp.

Lipoic acid (LA) is a mitochondrial coenzyme that, depending on the concentration and exposure time, can behave as an antioxidant or pro-oxidant agent and has a proven ability to modulate metabolism by promoting lipid and glucose oxidation for energy production. To assess the effects of LA on energy metabolism and redox balance over time, Artemia sp. nauplii was used as an animal model. The administered concentrations of the antioxidant were 0.05, 0.1, 0.5, 1.0, 5.0, and 10.0 µM. Therefore, possible differences in protein, triglyceride, glucose, and lactate concentrations in the artemia samples and total ammoniacal nitrogen (TAN) in the culture water were evaluated. We also measured the effects of LA on in vivo activity of the electron transport system (ETS), antioxidant capacity, and production of reactive oxygen species (ROS) at 6, 12, 18, and 24 h post-hatching. There was a decrease in glucose concentration in the LA-treated animals, and a decrease in ammonia production was observed in the 0.5 µM LA treatment. ETS activity was positively regulated by the addition of LA, with the most significant effects at concentrations of 5.0 and 10.0 µM at 12 and 24 h. For ETS activity, treatments with LA presented the highest values at 24 h, a period when ROS production decreased significantly, for the treatment with 10.0 µM. LA showed positive regulation of energy metabolism together with a decrease in ROS and TAN excretion.

Interactive effects of freshwater acidification and selenium pollution on biochemical changes and neurotoxicity in Oreochromis mossambicus.

Effect of selenium and acidification in freshwater environment was assessed solitary but no reports are available on the impacts of both factors act together. In the present study, effects of combined simultaneous exposure to selenium (Se) and low pH were assessed in Mozambique tilapia, Oreochromis mossambicus. Responses were measured based on antioxidant defenses (enzymatic SOD, CAT, GPx and non-enzymatic GSH), biotransformation enzyme (GST), metallothionein levels (MT), oxidative damage (LPO, CP), Na+/K+-ATPase (NKA) activity in gills and liver tissues and neurotoxicity (acetylcholinesterase, AChE) response in brain tissue. Fish were exposed to combined treatment at different pH levels (7.5, control (optimum pH for tilapia growth); 5.5, low pH) and Se concentrations (0, 10, and 100 µg L-1). Toxicity levels of Se were not significantly different under control and low pH indicating that pH did not affect Se toxicity. Levels of GSH and MT were enhanced in Se-exposed fish at both pH. Combined effects of high Se concentration and low pH decreased SOD and CAT activities and increased those of GPx and GST. However, organisms were not able to prevent cellular damage (LPO and CP), indicating a condition of oxidative stress. Furthermore, inhibition of Na+/K+-ATPase activity was showed. Additionally, neurotoxicity effect was observed by inhibition of cholinesterase activity in organisms exposed to Se at both pH conditions. As a result, the combined stress of selenium and freshwater acidification has a slight impact on antioxidant defense mechanisms while significantly inhibiting cholinesterase and Na+/K + -ATPase activity in fish. The mechanisms of freshwater acidification mediating the toxic effects of trace non-metal element on freshwater fish need to investigate further.

Modulation of nodularin toxicity in shrimp Litopenaeus vannamei (BOONE, 1931) fed with dietary açai (Euterpe oleracea) inclusion.

This study evaluated the effect of dietary inclusion of lyophilized açaí Euterpe oleracea (LEO) on redox status of shrimp Litopenaeus vannamei (initial weight 1.5 ± 0.39 g) upon exposure to cyanotoxin nodularin (NOD) in bioflocs system. Three hundred juvenile shrimps were randomly divided into two groups and fed twice a day with two diets: one containing 0.00 (control diet) and the other 10.0% LEO (w/w) for 30-days. After the feeding period, both shrimp groups were submitted to three treatments (14 L; 7 shrimp/tank) with different concentrations of cyanotoxin NOD (0.00; 0.25; and 1.00 µg/L) dissolved in water with 96 h of exposure. Then, the shrimps were sampled (n = 15/treatment) for the determination of reduced glutathione (GSH), the activity of glutathione-S-transferase (GST), sulfhydryl groups associated to proteins (P-SH), and lipid peroxidation (TBARS) in the hepatopancreas, gills and muscle. The NOD accumulation was measured in the muscle. The results revealed that dietary LEO significantly increased GSH levels in the hepatopancreas and gills of the shrimps exposed to NOD. Toxin exposure did not modify GST activity in all organs. Muscle TBARS levels were lower in the shrimp fed with the LEO diet and exposed to NOD. The NOD toxin did not accumulate in the muscle but notably was detected in the control groups fed or not with dietary LEO. Açaí was able to induce the antioxidant system of L. vannamei, as well as lowered the oxidative damage in shrimps exposed to NOD, suggesting its use as a chemoprotectant against cyanotoxins.

Fish oil and meal replacement in mullet (Mugil liza) diet with Spirulina (Arthrospira platensis) and linseed oil.

This research evaluated the effect of the simultaneous substitution of fish meal and fish oil at 0, 30, 50, 70 and 100% (termed SS0, SS30, SS50, SS70 and SS100, respectively) with both Spirulina (Arthrospira platensis) and linseed oil. The effect on growth, colour, fatty acid (FA) profile, and liver and muscle antioxidant response in mullets (Mugil liza) were evaluated. A full substitution was not possible due to a final body weight reduction (p < 0.05). The colorimetric analyses showed an improvement in fillet colouration (p < 0.05). Also, we found a saturation of carotenoids in muscle at 30% substitution. The content of highly unsaturated fatty acids - HUFA (DHA, EPA and ARA) in muscle diminished as the substitution level increased and, at the same time, the level of these FAs in the diet diminished. We found interesting evidence of elongation from 18:3n-3 to 20:3n-3 when substitution with linseed oil levels was above 50% but no desaturation to 20:4 or 20:5n-3 was found, which could insinuate a certain n-3 HUFA requirement under the experimental conditions. Moreover, we noted an increase in the antioxidant capacity up to the treatment SS70; the SS100 treatment showed a diminution in the antioxidant capacity. It is concluded that a partial inclusion of Spirulina and linseed oil (50%) is possible, and that this replacement can increase antioxidant responses, improve its growth performance and can modulate the mullets fillet quality without affecting negatively fillet fatty acid content.

Biochemical responses over time in common carp Cyprinus carpio (Teleostei, Cyprinidae) during fed supplementation with α-lipoic acid.

The current study aimed to evaluate the influence of lipoic acid (LA) supplementation (439.84±6.71 mg LA/kg feed) on antioxidants responses throughout the time in intestine, liver and muscle of juvenile common carp Cyprinus carpio. Two experimental groups were fed during four weeks with a diet with or without LA. Glutathione-S-transferase (GST) activity, glutathione (GSH) content, antioxidant capacity against peroxyl radicals (ACAP) and lipid peroxidation (TBARS) were evaluated in these organs. Also, a technique to measure protein disulfide bonds and sulfhydryl groups was optimized for intestine samples. GST activity was significantly higher (p<0.05) in intestine after two weeks of supplementation. GSH content was also significantly higher (p<0.05) in intestine, liver and muscle of fish fed with LA after two and three weeks, respectively. Total capacity antioxidant against peroxyl radicals was significantly increased (p<0.05) in the muscle of animals fed with LA after the fourth week. Concentration of disulfide bonds was higher in the intestine of fish fed with LA but this group also showed higher concentration of sulfhydryl groups (p<0.05). It is concluded that supplementation with LA is a safe strategy to induce antioxidant responses and improves the antioxidant status in different organs of common carp. Two week of supplementation are required to induce antioxidant responses in intestine and liver and three week for muscle.

The role of lipoic acid in the protection against of metallic pollutant effects in the shrimp Litopenaeus vannamei (Crustacea, Decapoda).

The effects of cadmium (Cd) and arsenic (As), dosed alone or in combination have been poorly investigated in crustaceans. Besides, it is not known if dietary supplementation of exogenous antioxidants, like lipoic acid (LA), might prevent or even reverse toxic effects of Cd and As. The objective of the present study was to evaluate the role of lipoic acid in modulating biochemical responses after Cd and As exposures in Litopenaeus vannamei. Muscle from shrimp exposed to Cd alone or Cd+As showed a decrease in glutathione (GSH) levels, while the pre-treatment with LA reversed this situation. In this tissue, the pre-treatment with LA also induced an increase in glutathione-S-transferase (GST) activity in all groups. In hepatopancreas it was observed a marked accumulation of Cd and As, a decrease in the reactive oxygen species (ROS) concentration in response to Cd exposure alone (-LA); concomitant in the same group it was observed an increment of metallothionein-like content. As exposure induced an increase in GSH levels but LA reversed this increase. Also, LA showed to increase the GST activity in all groups treated. Besides, in this organ LA showed to augment total antioxidant competence. Obtained results indicate that LA can be used as a chemo-protectant against oxidative insults in shrimp.

The anesthetic efficacy of eugenol and the essential oils of Lippia alba and Aloysia triphylla in post-larvae and sub-adults of Litopenaeus vannamei (Crustacea, Penaeidae).

The aim of this study was to evaluate the anesthesia induction and recovery times of sub-adult and post-larvae white shrimp (Litopenaeus vannamei) that were treated with eugenol and the essential oils (EOs) from Lippia alba and Aloysia triphylla. Oxidative stress parameters in the hemolymph of this species were also analyzed. The concentrations of eugenol, A. triphylla EO and L. alba EO recommended for anesthesia were 200, 300 and 750 µL L(-1) for sub-adults and 175, 300 and 500 µL L(-1) for post-larvae, respectively. The concentrations studied during the transport of sub-adults were between 20 and 50 µL L(-1) eugenol, 20-30 µL L(-1)A. triphylla EO and 50 µL L(-1)L. alba EO. For post-larvae, the optimal concentrations for transport were 20 µL L(-1) eugenol and between 20 and 50 µL L(-1)A. triphylla EO. The white shrimp sub-adults that were exposed to A. triphylla EO (20 µL L(-1)) showed increases in their total antioxidant capacities (150%), catalase (70%) and glutathione-S-transferase (615%) activity after 6 h. L. alba EO (50 µL L(-1)) and eugenol (20 µL L(-1)) also increased GST activity (1292 and 1315%) after 6 h, and eugenol (20 µL L(-1)) decreased the total antioxidant capacity (100%). Moreover, concentrations above 30 µL L(-1) for the EOs of A. triphylla and L. alba and 20 µL L(-1) eugenol were effective at inducing anesthesia and improving the antioxidant system against reactive oxygen species (ROS) after 6 h.

Effect of melatonin in the antioxidant defense system in the locomotor muscles of the estuarine crab Neohelice granulata (Decapoda, Brachyura).

In vertebrates, many studies verified different effects of melatonin in the antioxidant defense system (ADS). In crustaceans, few studies have been conducted to verify this possibility. We verified the melatonin effects in the crab Neohelice granulata using low (0.002 and 0.02 pmol/crab) and high (2.0 and 20.0 pmol/crab) melatonin dosages in short-term (0.5h) and long-term (9.5h) experiments. We analyzed the antioxidant capacity against peroxyl radicals (ACAP), reactive oxygen species (ROS) concentration, levels of by products of lipid peroxidation (LPO), oxygen consumption (VO(2)), the activity of glutamate cysteine ligase (gamma-GCL) and catalase (CAT) and glutathione content (GSH). Finally, the effects of exogenous melatonin were verified in terms of melatonin and N(1)-acetyl-N(2)-formyl-5-methoxykynuramine (AFMK) content in the muscles of N. granulata. In short-term experiment and low dosages, melatonin increased the VO(2), gamma-GCL activity and GSH content (p<0.05) and decreased melatonin content (p<0.05) without effects in ROS, ACAP and LPO (p>0.05). Possibly, melatonin is acting in the ADS increasing its efficiency and/or acting in mitochondrial activity and/or through signaling muscles to increase its consumption. AFMK was only detected in the eyestalk and cerebroid ganglia. In high dosages melatonin effects decreased, possibly by the desensitization of their receptors. In long-term experiment, melatonin decreased ACAP (p<0.05), and CAT activity (p<0.05) in low dosages. In high dosages melatonin reduced VO(2) (p<0.05) and increased ACAP (p<0.05), possibly stimulating others components of the ADS. In conclusion, melatonin in the locomotor muscles of N. granulata affects the antioxidant/pro-oxidant balance in a time and dosage dependent manner.