Oxidative responses in small juveniles of Colossoma macropomum anesthetized and sedated with Ocimum gratissimum L. essential oil.

This study evaluated the use of essential oil of Ocimum gratissimum (EOOG) for anesthesia and in transport of Colossoma macropomum. Experiment 1, Test 1, anesthesia induction and recovery times were determined using different EOOG concentrations (0, 20, 50, 100, 200, 300 mg L-1), with two size classes: Juveniles I (0.86 g) and Juveniles II (11.46 g) (independent tests in a completely randomized design). Based on the results of Test 1, in Test 2 Juveniles II were exposed to EOOG concentrations: 0, 20, 100 mg L-1. Tissue samples were collected immediately after induction and 1 h post-recovery, to assess oxidative status variables. Experiment 2, Juveniles I (0.91 g) and Juveniles II (14.76 g) were submitted to transport in water with different concentrations of EOOG (0, 5, 10 mg L-1) (independent tests in a completely randomized design). The effects on oxidative status variables were evaluated. Concentrations between 50 and 200 mg L-1 EOOG can be indicated for Juveniles I, while concentrations between 50 and 100 mg L-1 EOOG for Juveniles II. The concentration of 100 mg L-1 EOOG was able to prevent oxidative damage in the liver. In Experiment 2, the concentrations of 5 and 10 mg L-1 EOOG added to the transport water caused sedation for both studied size classes of juveniles and did not cause oscillations in water quality variables nor any mortality. The concentration of 10 mg L-1 EOOG improved the oxidative status. It can be concluded that EOOG can be used for anesthesia and transport of C. macropomum.

Redox profile of silver catfish challenged with Aeromonas hydrophila and treated with hexane extract of Hesperozygis ringens (Benth.) Epling through immersion bath.

The growing increase in the fish farming sector has favored the establishment of bacterial outbreaks caused by Aeromonas hydrophila in several species. The hexane extract of Hesperozygis ringens (HEHR) (Lamiaceae) leaves increased the survival rate of silver catfish (Rhamdia quelen) experimentally infected by A. hydrophila. However, it is noteworthy that no reports have been found on the possible mechanisms of action of this extract in infected fish. This study aimed to evaluate the effect of the HEHR, administered through single immersion bath, on lipid peroxidation and antioxidant defenses in muscle and liver tissue of silver catfish challenged with A. hydrophila. The results showed that the oxidative status of silver catfish was altered, although oxidative stress was not triggered during the experiment. HEHR at 30 mg/L (HEHR30) was not characterized as a pro-oxidant agent in the presence of infection, unlike florfenicol and HEHR at 15 mg/L treatments in some cases. In short, HEHR30 provided an important increase in hepatic catalase activity, characterizing one of the possible mechanisms involved in the greater survival of fish experimentally infected by A. hydrophila. Additionally, HEHR30 did not induce lipid peroxidation, nor reduced antioxidant defenses of silver catfish infected or not by A. hydrophila.

Impact of dietary supplementation with Cinnamomum cassia essential oil on silver catfish (Rhamdia quelen): Toxicological effects and muscle antioxidant and fatty acid profiles.

The aim of this study was to determine the biological effects of dietary supplementation with 0.05% and 0.1% cinnamon essential oil extracted from Cinnamomum cassia on silver catfish (Rhamdia quelen). The final body weight, weight gain, and specific growth rate were significantly higher in fish supplemented with 0.05% cinnamon essential oil than in the control(untreated) group. Muscle reactive oxygen species and lipid peroxidation levels were significantly lower in fish supplemented with 0.05% cinnamon essential oil but higher at the 0.1% concentration. Muscle antioxidant capacity against peroxyl radicals (ACAP) and superoxide dismutase activity were significantly higher in fish supplemented with 0.05% cinnamon essential oil, while ACAP levels were lower in fish supplemented with 0.1%. The total saturated fatty acid content was significantly higher in the muscle of supplemented fish than in controls, while the total monounsaturated fatty acid content was significantly higher only in fish fed 0.1% cinnamon essential oil. Finally, the total content of polyunsaturated fatty acids was significantly lower in fish fed 0.1% essential oil. Thus, data demonstrated that 0.05% C. cassia essential oil improves fish health by improving performance and muscle oxidant/antioxidant status. Higher doses of cinnamon essential oil produced oxidative stress in muscle, suggesting toxicity at the 0.1% level. Although this cinnamon essential oil diet exerted positive health effects, this diet impaired the muscle fatty acid profile, suggesting adverse impacts on human health.

Anesthetic and sedative efficacy of essential oil of Hesperozygis ringens and the physiological responses of Oreochromis niloticus after biometric handling and simulated transport.

This study aimed to evaluate different concentrations of the essential oil of Hesperozygis ringens (EOHR) and its effects on anesthesia and transport of Oreochromis niloticus. Experiment I evaluated the concentrations of 0, 150, 300, 450, and 600 µL L-1 EOHR for times of induction and recovery from anesthesia and ventilatory frequency (VF) of O. niloticus (26 g), with 10 repetitions each in a completely randomized design. Based on the results of Experiment I, Experiment II submitted fish (25 g) to three treatments-control (clean water), ethanol (5 mL ethyl alcohol), and 600 µL L-1 EOHR-and then handling for biometry. Blood was collected 1 and 24 h after exposure and handling to analyze hematological and biochemical parameters in a completely randomized design in a factorial arrangement (3 × 2). Experiment III submitted fish (35 g) to simulated transport (4.5 h) with 0, 10, or 20 µL L-1 EOHR and determined the effects on blood variables. Concentrations of 450 and 600 µL L-1 EOHR provoked deep anesthesia in juvenile O. niloticus and provided induction and recovery times within the limits considered ideal for fish. However, this essential oil was not able to attenuate the effects of stress caused by biometric handling. EOHR was able to attenuate the effects of stress from simulated transport, with 10 µL L-1 EOHR being responsible for causing a decrease in protein, triglycerides, and cholesterol values immediately after transport of O. niloticus.

Essential oil of Aloysia citriodora Paláu and citral: sedative and anesthetic efficacy and safety in Rhamdia quelen and Ctenopharyngodon idella.

OBJECTIVE: To verify the efficacy of citral in inducing sedation and anesthesia in silver catfish (Rhamdia quelen) and grass carp (Ctenopharyngodon idella) and to assess the safety of essential oil (EO) of Aloysia citriodora and citral in inducing and maintaining anesthesia in silver catfish. STUDY DESIGN: Clinical study, randomized, parallel, multi-arm with control group in target species. ANIMALS: A total of 96 juvenile and 72 adult silver catfish and 80 juvenile grass carp were used. METHODS: Silver catfish and grass carp were exposed to different concentrations of citral, 15-675 and 15-600 µL L-1, respectively, during the maximum period of 30 minutes to verify sedation and anesthesia induction and recovery times. In addition, for anesthetic induction, silver catfish were exposed to the EO of A. citriodora and citral at 225 µL L-1 for 3.5 minutes. Then, fish were transferred to an anesthesia maintenance solution at 50 µL L-1 for 10 minutes to assess hematologic and biochemical variables at 60 minutes, 2 and 6 days after treatment. RESULTS: Citral only induced sedation from 15, 25 and 40 µLL-1 in both species. Anesthesia without mortality was induced in silver catfish at 50-600 µL L-1 and grass carp at 75-450 µL L-1. At 675 and 600 µL L-1, mortality was recorded in silver catfish and grass carp, respectively. The EO of A. citriodora and citral were safe in inducing and maintaining anesthesia in silver catfish, with mean corpuscular hemoglobin concentration being the only variable that varied in relation to time and treatments. CONCLUSIONS AND CLINICAL RELEVANCE: Citral was effective in inducing sedation and anesthesia in both species. In addition, A. citriodora EO and citral were safe in inducing and maintaining anesthesia in silver catfish. Both agents are promising substances for the development of new drugs for fish.

Eugenol and Lippia alba essential oils as effective anesthetics for the Amazonian freshwater stingray Potamotrygon wallacei (Chondrichthyes, Potamotrygonidae).

This study assessed the potential of eugenol and the essential oil of Lippia alba (EOLA) in providing suitable anesthetic induction and recovery times, and their consequent effects on the blood and respiratory physiology, as well as the gill architecture of an Amazonian freshwater stingray, Potamotrygon wallacei, shortly after reaching the recovery and 48 h later. Juveniles of P. wallacei were exposed to increasing concentrations of eugenol (75, 100, 125, and 150 µL L-1) and EOLA (150, 175, 200, and 225 µL L-1) in an immersion bath. Anesthetic induction was found to be faster with the use of eugenol compared to EOLA. On the other hand, the stingrays anesthetized with eugenol displayed a longer recovery time than those exposed to EOLA. The highest concentrations of eugenol caused moderate to severe histological changes in the gills. No significant changes were found for hematocrit and plasma energy metabolites in the stingrays anesthetized with all concentrations of both eugenol and EOLA shortly after reaching the recovery from the ansthesia, when compared to those recovered after 48 h. Investigations regarding the potential use of these natural anesthetics are unprecedented for freshwater stingray species, and 200 µL L-1 EOLA is recommended as the most suitable anesthetic for use in juveniles of P. wallacei.

Linalool induces relaxation of the mantle of golden apple snail (Pomacea canaliculata).

The objective of this study was to evaluate the possible relaxing effect of essential oils (EOs) (Aloysia triphylla and Lippia alba) and phytochemicals (citral and linalool) in the gastropod Pomacea canaliculata. Animals were exposed to compounds at the concentrations range of 25-750 µL L-1. Magnesium chloride (MgCl2, 10-50 g L-1) and control group (ethanol 6.75 mL L-1, highest concentration used for treatment dilution) were also tested. The EOs, citral and MgCl2 had no relaxing effect at the concentrations range tested, and citral caused aversive behavior (closure of the operculum) from 90 µL L-1. Exposure to linalool at 25, 50, 100, 200 and 400 µL L-1 relaxed 28, 76, 88, 96 and 100% of the animals, respectively. The concentrations of 25, 50 and 400 µL L-1 differed statistically from each other, while 100 and 200 µL L-1 were equal to 50 and 400 µL L-1. All animals recovered up to 40 min, except at of 400 µL L-1. Linalool is effective for relaxing P. canaliculata and can be useful in management techniques that require relaxation. However, further studies are needed to certify whether linalool is appropriate for maintaining animal welfare in invasive procedures that require total insensitivity.

Comparing the efficacy of nutmeg essential oil and a chemical pesticide against Musca domestica and Chrysomya albiceps for selecting a new insecticide agent against synantropic vectors.

The insecticidal activity of Myristica fragrans (Houtt) essential seed oil, (Nutmeg) was evaluated against Musca domestica (Linnaeus) and Chrysomya albiceps (Wiedemann); both important infectious pathogenic disease vectors. The oil was extracted by distillation, and 21 components were identified during chemical analysis; principally ß-pinene (26%), α-pinene (10.5%), Sabinene (9.1%) and γ-terpinen (8.5%). Insecticidal properties were identified through larvicide and adulticide tests. Using the immersion method, the oil at 5% was found to be very effective (90 ± 1%) against M. domestica larvae. The results for adulticide activity varied by fly species, dosage, time, and method of exposure. Topical application (on the insect thorax) was more toxic to C. albiceps, where the lethal concentration at 50% (LC50) was 2.02 ± 0.56, and 8.57 ± 2.41 for the common flies. When the insects were exposed to oil impregnated paper, the results were similar for M. domestica and C. albiceps adults with respective LC50 values of 2.74 ± 0.24, and 3.65 ± 0.48. Thus, the results demonstrated that M. fragrans oil presents insecticidal activity and can be used for control of Musca domestica and Chrysomya albiceps.

The influence of dietary Motore™ supplement on antioxidant status to Aeromonas hydrophila infection in Rhamdia quelen.

This study points to evaluate the effects of pre-treatment with standardized dry extract of Curcuma longa (Motore™) added to the diet (0; 250; 500; and 750 mg/kg) on oxidative stress parameters, longevity, and therapeutic success in Rhamdia quelen experimentally infected with Aeromonas hydrophila (MF 372510). After treatment, the liver and kidney were collected to determine non-enzymatic oxidative parameters such as the formation of thiobarbituric acid reactive substances (TBARS), non-protein thiols (NPSH), and quantification of reactive oxygen species (ROS) levels. Also, two enzymatic antioxidant parameters were evaluated: superoxide dismutase (SOD) and catalase (CAT) activities. The results showed an increase of ROS and TBARS levels, a depletion in NPSH, and a decrease of SOD and CAT activities in infected fish compared to control. The highest Motore™ dose minimized the deleterious effect of A. hydrophila infection improving longevity, oxidative status, and survival rate. The addition of 750 mg Motore™/kg feed is recommended for silver catfish in fish farming. Serious economic losses in Rhamdia quelen culture caused by Aeromonas hydrophila infections can be prevented by the addition of Motore™ to the diet.

Essential oil of Ocimum gratissimum (Linnaeus, 1753): efficacy for anesthesia and transport of Oreochromis niloticus.

This study aimed to evaluate the essential oil of Ocimum gratissimum L. (EOOG) for anesthesia and in the transport of Oreochromis niloticus. Experiment I determined the time of anesthesia induction and recovery during anesthesia of O. niloticus exposed to different concentrations of EOOG (0, 30, 90, 150, and 300 mg L-1). Based on data from Experiment I, Experiment II evaluated the effect of 0, 30, and 90 mg L-1 EOOG on blood parameters and oxidative stress immediately after anesthesia induction and 1 h after recovery. Experiment III evaluated the effect of 0, 5, and 10 mg L-1 EOOG on blood variables immediately after 4.5 h of transport of juveniles. Concentrations between 90 and 150 mg L-1 EOOG were efficient for anesthesia and recovery. The use of 90 mg L-1 of EOOG prevented an increase in plasma glucose. Other changes in blood parameters and oxidative stress are discussed. The use of 10 mg L-1 EOOG in transport increased plasma glucose and decreased hematocrit values immediately after transport. It is concluded that the use of 90 and 150 mg L-1 EOOG causes anesthesia and recovery in O. niloticus within the time intervals considered ideal. The use of 90 mg L-1 EOOG favored stable plasma glucose soon after anesthesia induction and 1 h after recovery, but caused changes in the antioxidant defense system by increasing hepatic and kidney ROS. The transport of 12 g O. niloticus for 4.5 h can be performed with concentration of 5 mg L-1 of EOOG.

Anesthetic potential of different essential oils for two shrimp species, Farfantepenaeus paulensis and Litopenaeus vannamei (Decapoda, Crustacea) / Potencial anestésico de diferentes óleos essenciais para duas espécies de camarões, Farfantepenaeus paulensis e Litopenaeus vannamei (Decapoda, Crustacea)

ABSTRACT: The use of anesthetics in aquaculture ensures better animal welfare and survival during transport and the production cycle. The present study evaluated the anesthetic efficacy of essential oils (EOs) of Lippia alba (EOLA) and Ocimum gratissimum (EOOG) for pink shrimp Farfantepenaeus paulensis, and EOs of Origanum majorana (EOO) and Cymbopogon citratus (EOC) for white shrimp Litopenaeus vannamei. shrimp were exposed to (i) 500, 750 or 1000 µL L-1 of EOLA or (ii) 50, 100, 150 or 250 µL L-1 of EOOG, and L. vannamei were exposed to (iii) 150, 300 or 500 µL L-1 of EOC or (iv) 400 or 800 µL L-1 of EOO. The induction times were concentration dependent, with a decrease in induction time with the increase of the EOs concentration, but for EOLA, this pattern was observed only for anesthesia. Induction times for sedation and anesthesia were significantly shorter for shrimp exposed to EOC and EOO. The highest concentration of EOOG (250 µL L-1) resulted in 30% mortality. The recovery time was significantly longer for shrimp exposed to 800 µL L-1 of EOO compared to the other EOs. Overall, the action of EOs significantly differed between the two shrimp species. In conclusion, the tested EOs effectively anesthetized F. paulensis and L. vannamei.

RESUMO: O uso de anestésicos em procedimentos aquícolas pode garantir melhor bem-estar e sobrevivência dos animais durante o transporte e ciclo de produção. O presente estudo teve como objetivo avaliar a eficácia anestésica dos óleos essenciais (OEs) de Lippia alba (EOLA) e Ocimum gratissimum (EOOG) para o camarão rosa Farfantepenaeus paulensis, e Origanum majorana (EOO) e Cymbopogon citratus (EOC) para o camarão branco Litopenaeus vannamei. Os camarões foram expostos à: (i) 500, 750 ou 1000 µL L-1 EOLA e (ii) 50, 100, 150 ou 250 µL L-1 de EOOG para F. paulensis, e (iii) 150, 300 ou 500 µL L-1 EOC, e (iv) 400 ou 800 µL L-1 de EOO para L. vannamei. Os tempos de indução foram dependentes da concentração. Houve diminuição do tempo de indução, mas para EOLA esse padrão foi observado apenas na anestesia. Os tempos de indução para sedação e anestesia foram significativamente mais rápidos para os grupos EOC e EOO. A concentração de 250 µL L-1 de EOOG resultou em 30% de mortalidade. O tempo de recuperação foi significativamente maior a 800 µL L-1 de EOO em comparação aos outros OEs. No geral, a ação dos OEs foi significativamente diferente entre as duas espécies de camarões. Em conclusão, ambos os OEs anestesiaram efetivamente o F. paulensis e L. vannamei.

Adulticidal Activity of Melaleuca alternifolia (Myrtales: Myrtaceae) Essential Oil With High 1,8-Cineole Content Against Stable Flies (Diptera: Muscidae).

The stable fly, Stomoxys calcitrans (Linnaeus 1758), is a hematophagous fly responsible for causing loss of performance in horses, causing losses in cattle productivity, and impacting the animals' health through the spread of pathogenic microorganisms. The objective of this work was to investigate the insecticidal activity of essential oil obtained from Melaleuca alternifolia (Cheel), presenting high 1,8-cineole content, against S. calcitrans adults. Insecticidal activity was determined using surface application methods and exposure to oil impregnated paper. It was observed that treatments at 25 and 50 µg/cm2 (P < 0.05) present fumigant activity through exposure to the impregnated paper, and in the first 15 min of exposure, the mortality rates obtained for these treatments were, respectively (96.6 ± 3.3% and 100%), equivalent to the positive control. Using the superficial application method, the only treatment concentration presenting adulticidal action was 5% (w/v) (P < 0.05). Respective toxicities LC50 (%, w/v) and LC80 for the impregnated paper method were 1.06 ± 0.02 and 1.47 ± 0.17; for the superficial application method, they were 3.82 ± 0.65 and 5.53 ± 0.74. As demonstrated, M. alternifolia essential oil presents adulticidal potential against S. calcitrans.

Citral as food additive for common snook - zootechnical parameters and digestive enzymes / Citral como aditivo na ração para robalo flecha - parâmetros zootécnicos e enzimas digestivas

ABSTRACT: Essential oils of plants whose main compound is citral showed beneficial effects when added to fish feed. The objective of the present study was to evaluate the dietary effect of the addition of citral on zootechnical parameters and digestive enzyme activities of Centropomus undecimalis. Juveniles were fed for 45 days with diets containing different amounts of citral (0.0 - control, 0.5, 1.0, and 2.0 mL per kg of diet). The water quality parameters were kept stable during the experiment and no mortality was observed. At the end of the experimental period, the treatment 0.5 mL citral per kg of diet had the lowest weight gain and specific growth rate, and the highest feed conversion, while the same parameters did not differ between the other treatments. Pepsin activity was higher in the stomach of fish fed with 0.5 mL citral per kg of diet and amylase activity was higher in the intestine of fish fed with 0.5 and 2.0 mL citral per kg of diet compared to the control group. Intestinal lipase activity was higher in all groups that were fed with citral compared to the control group. Chymotrypsin and trypsin activities showed no difference between groups. Consequently, dietary addition of citral at any of the levels tested is not recommended for common snook.

RESUMO: Óleos essenciais de plantas, cujo composto majoritário é o citral, mostraram efeitos benéficos quando adicionados à ração para peixes. O objetivo do presente estudo foi avaliar o efeito da adição de citral sobre os parâmetros zootécnicos e atividades das enzimas digestivas de Centropomus undecimalis. Os juvenis foram alimentados por 45 dias com dietas contendo diferentes quantidades de citral (0,0 - controle, 0,5, 1,0 e 2,0 mL por kg de ração). Os parâmetros de qualidade da água foram mantidos estáveis ​​durante o experimento e nenhuma mortalidade foi observada. Ao final do período experimental, o tratamento 0,5 mL citral por kg de ração teve o menor ganho de peso e taxa de crescimento específico e a maior conversão alimentar, enquanto os mesmos parâmetros não diferiram entre os demais tratamentos. A atividade da pepsina foi maior no estômago de peixes alimentados com 0,5 mL de citral por kg de ração e a atividade de amilase foi maior no intestino de peixes alimentados com 0,5 e 2,0 mL citral por kg de ração comparado ao grupo controle. A atividade da lipase intestinal foi maior em todos os grupos que foram alimentados com citral, em comparação ao grupo controle. As atividades de quimotripsina e tripsina não mostraram diferença entre os grupos. Consequentemente, a adição de citral na ração em qualquer um dos níveis testados não é recomendada para robalo flecha.

GABAa receptor subunits expression in silver catfish (Rhamdia quelen) brain and its modulation by Nectandra grandiflora Nees essential oil and isolated compounds.

Studies using silver catfish (Rhamdia quelen) as experimental models are often applied to screen essential oils (EO) with GABAergic-mediated effects. However, the expression of GABAa receptors in the silver catfish brain remains unknown. Thus, we assessed whether silver catfish express GABAa receptor subunits associated with sedation/anesthetic process and/or neurological diseases. Additionally, we evaluated the brain expression of GABAa receptor subunits in fish sedated with Nectandra grandiflora EO and its isolated compounds, the fish anesthetic (+)-dehydrofukinone (DHF), and dehydrofukinone epoxide (DFX), eremophil-11-en-10-ol (ERM) and selin-11-en-4-α-ol (SEL), which have GABAa-mediated anxiolytic-like effects in mice. The expression of the subunits gabra1, gabra2, gabra3, gabrb1, gabrd and gabrg2 in the silver catfish brain were assessed after a 24h-sedation bath by real time PCR. Since qPCR data rarely describes mechanisms of action, which are usually found through interactions with receptors, we also performed an antagonist-driven experiment using flumazenil (FMZ). Real-time PCR detected the mRNA expression of all targeted genes in R. quelen brain. The expression of gabra1 was decreased in fish sedated with ERM; EO increased gabra2, gabra3, gabrb1 and gabrg2 expression; SEL increased gabrb1, gabrd and gabrg2 expression. EO and compounds DFX, SEL and ERM induced sustained sedation in fish and FMZ-bath prompted the recovery from ERM- and DFX-induced sedation. Our results suggest that the EO, SEL, ERM and DFX sedative effects involve interaction with the GABAergic system. Our findings support the use of the silver catfish as robust and reliable experimental model to evaluate the efficacy of drugs with putative GABAergic-mediated effects.

Nociceptive-like behavior and analgesia in silver catfish (Rhamdia quelen).

Fish are useful animal models in research and have been employed in developing new pharmacological approaches. This study aimed to establish the use of silver catfish (Rhamdia quelen) as an animal model to evaluate antinociceptive activity. Initially, different concentrations of acetic acid (2.5-20%), formalin 1% (1-10 µL), menthol 0.5% (1-10 µL) or vehicle were injected in the lips to establish which concentration of each sample promotes nociceptive-like behavior in various parameters. The effect of morphine (0.5-10 mg/kg) on locomotion parameters was also evaluated for antinociceptive concentration determination. Morphine was administered intramuscularly immediately prior to algogen administration. The inhibition was evaluated with the antagonist naloxone (5 mg/kg), which was administered in the same way. Recording time varied according to the algogen used in each test and locomotor activity was evaluated by ANY-maze® software. Acid acetic at 15%, 10 µL of 1% formalin, and 1 µL of 0.5% menthol were chosen since they promoted nociceptive-like behavior in several parameters. Morphine (5 mg/kg) reversed the algogen-induced nociceptive-like behavior and naloxone inhibited this effect. Therefore, the proposed experimental model demonstrated specificity for nociception, since the reversion of the nociceptive-like behavior for a compound with well-described analgesic activity was observed. This new pharmacological model contributes to evaluating compounds with analgesic potential and developing new analgesic drugs, in addition to being a promising alternative to use with rodents.

Essential Oils as Stress-Reducing Agents for Fish Aquaculture: A Review.

In fish, stressful events initiate a hormone cascade along the hypothalamus-pituitary-interrenal and hypothalamus-sympathetic-chromaffin (HSC) axis to evoke several physiological reactions in order to orchestrate and maintain homeostasis. Several biotic and abiotic factors, as well as aquaculture procedures (handling, transport, or stocking density), activated stress system inducing negative effects on different physiological processes in fish (growth, reproduction, and immunity). In order to reduce these consequences, the use of essential oils (EOs) derived from plants has been the focus of aquaculture studies due to their diverse properties (e.g., anesthetic, antioxidant, and antimicrobial), which have been shown to reduce biochemical and endocrine alterations and, consequently, to improve the welfare status. Recently, several studies have shown that biogenic compounds isolated from different EOs present excellent biological activities, as well as the nanoencapsulated form of these EOs may potentiate their effects. Overall, EOs presented less side effects than synthetic compounds, but their stress-reducing efficacy is related to their chemical composition, concentration or chemotype used. In addition, their species-specific actions must be clearly established since they can act as stressors by themselves if their concentrations and chemotypes used are not suitable. For this reason, it is necessary to assess the effect of these natural compound mixtures in different fish species, from marine to freshwater, in order to find the ideal concentration range and the way for their administration to obtain the desired biological activity, without any undesired side effects. In this review, the main findings regarding the use of different EOs as stress reducers will be presented to highlight the most important issues related to their use to improve fish welfare in aquaculture.

Nectandra grandiflora essential oil and its isolated sesquiterpenoids minimize anxiety-related behaviors in mice through GABAergic mechanisms.

Nectandra grandiflora Ness (Lauraceae) essential oil (EO) main constituent, the sesquiterpenoid (+)-dehydrofukinone (DHF), has sedative and anticonvulsant effects through GABAergic mechanisms. Other DHF-related sesquiterpenoids have been identified in the EO, such as, dehydrofukinone epoxide (DFX), eremophil-11-en-10-ol (ERM) and selin-11-en-4-α-ol (SEL). However, the neuronal effects of these compounds in mammals remain unknown. Therefore, the aim of this study was to evaluate the anxiolytic potential of the N. grandiflora EO and the isolated compounds in in mice. For this purpose, mice were administered orally with vehicle, 10, 30 or 100 mg/kg EO, DHF, DFX, ERM or SEL or 1 mg/kg diazepam. Locomotion and ethological parameters in the open field (OF) and elevated plus maze (EPM) were recorded. We also examined the effect of DFX, ERM and SEL on the membrane potential and calcium influx in synaptosomes, and the presence of the compounds in the cortical tissue using gas chromatography. EOs and isolated compounds reduced anxiety-related parameters in the EPM (open arms time and entries, end activity, head dipping) and OF (center time and entries, total rearing, unprotected rearing, sniffing, grooming) without alter ambulation or induce sedation. Flumazenil (2 mg/kg, i.p.) altered the anxiolytic-like effect of all treatments and vanished the DFX, ERM and SEL-induced changes in membrane potential. However, FMZ did not blocked the DFX-, ERM- and SEL-induced inhibition of calcium influx. Therefore, our results suggest that N. grandiflora EO and isolated compounds induced anxiolytic-like effect in mice due to positive modulation of GABAa receptors and/or inhibition of neuronal calcium influx.

Effect of meteorological elements on the content and composition of Aloysia triphylla (L´Hérit) Britton essential oil / Efecto de los elementos meteorológicos sobre el contenido y la composición del aceite esencial de Aloysia triphylla (L´Hérit) Britton

The concentration and composition of an essential oil can vary according to environmental variations and seasonal periods. The objective of this study was to correlate meteorological elements with the content and concentration of components of Aloysia triphylla essential oil, for the four seasons of the year. The experiment was conducted in a plastic greenhouse of the UFSM, Frederico Westphalen campus ­ RS, Brazil, in a complete randomized blocks design during the four seasons, with three repetitions. The meteorological data were collected with the aid of a compact meteorological station, in order to characterize the environment in which the species was conducted. The evaluations were carried out at the middle date of each season. It was observed a correlation between the meteorological variables with the essential oil production and its components. According to the analysis, there influence of the temperature on the essential oil contents, considering that the maximum temperature shows a direct positive influence on the concentration of limonene and negative for spathulenol.

El contenido y la composición de un aceite esencial pueden variar según las variaciones ambientales y los períodos estacionales. El objetivo de este estudio fue correlacionar los elementos meteorológicos con el contenido y la concentración de los componentes del aceite esencial de Aloysia triphylla, para las cuatro estaciones del año. El experimento se realizó en un invernadero de plástico de la UFSM, campus de Frederico Westphalen - RS, Brasil, en un diseño completo de bloques al azar durante las cuatro estaciones, con tres repeticiones. Los datos meteorológicos se recopilaron con la ayuda de una estación meteorológica compacta, para caracterizar el entorno en el que se realizó la especie. Las evaluaciones se llevaron a cabo en la fecha media de cada temporada. Se observó una correlación entre las variables meteorológicas con la producción de aceites esenciales y sus componentes. De acuerdo con el análisis, existe una influencia de la temperatura en los contenidos de aceites esenciales, considerando que la temperatura máxima muestra una influencia positiva directa sobre la concentración de limoneno y negativa para el espatulenol.

Antiproliferative potential and phenolic compounds of infusions and essential oil of chamomile cultivated with homeopathy.

ETHNOPHARMACOLOGICAL RELEVANCE: Chamomilla recutita (Asteraceae) is used worldwide as a soothing, anti-inflammatory and aromatherapy. In Brazil, it is one of the most cultivated medicinal species. However, the cultivation form may alter the production of compounds in the secondary metabolism and compromise the therapeutic purpose of this species. AIM OF THE STUDY: Evaluation of antiproliferative and genotoxic effects of infusions and essential oil of chamomile, cultivated with homeopathy, on the cell cycle of Allium cepa, as well as the determination of the phenolic compounds present in the infusions of the chamomile inflorescences. MATERIAL AND METHODS: For the Allium cepa test, two concentrations of 10 and 40 g L-1 of inflorescences of chamomile were used for the preparation of the infusions and essential oil diluted to 0.10%, referring to the six treatments obtained in field cultivation, in which were carried out the applications of homeopathy from the emergence to the harvest of the plants. Distilled water and ethanol were used as negative control and glyphosate 2% as a positive control. The determination of phenolic compounds present in the infusions was carried by liquid chromatography in a UHPLC apparatus. RESULTS: Chamomile infusions at concentrations of 10 and 40 g L-1 of inflorescence reduced mitotic index and emphasized antiproliferative activity on the cell cycle of Allium cepa. However, the treatments related to essential oil diluted to 0.10% showed a response variation dependent on the dynamization used, as well as for apigenin concentration. CONCLUSIONS: Therefore, cultivation with homeopathy does not induce a genotoxic effect in the use of infusions and essential oil of chamomile and it emphasize antiproliferative activity on the cell cycle of Allium cepa, favoring the sustainable cultivation and the safe use of this medicinal species when cultivated with homeopathy.

Involvement of HPI-axis in anesthesia with Lippia alba essential oil citral and linalool chemotypes: gene expression in the secondary responses in silver catfish.

In teleost fish, stress initiates a hormone cascade along the hypothalamus-pituitary-interrenal (HPI) axis to provoke several physiological reactions in order to maintain homeostasis. In aquaculture, a number of factors induce stress in fish, such as handling and transport, and in order to reduce the consequences of this, the use of anesthetics has been an interesting alternative. Essential oil (EO) of Lippia alba is considered to be a good anesthetic; however, its distinct chemotypes have different side effects. Therefore, the present study aimed to investigate, in detail, the expression of genes involved with the HPI axis and the effects of anesthesia with the EOs of two chemotypes of L. alba (citral EO-C and linalool EO-L) on this expression in silver catfish, Rhamdia quelen. Anesthesia with the EO-C is stressful for silver catfish because there was an upregulation of the genes directly related to stress: slc6a2, crh, hsd20b, hspa12a, and hsp90. In this study, it was also possible to observe the importance of the hsd11b2 gene in the response to stress by handling. The use of EO-C as anesthetics for fish is not recommended, but, the use of OE-L is indicated for silver catfish as it does not cause major changes in the HPI axis.