RESUMO

In this study, the essential oil (EO) from Laurelia sempervirens was analyzed by GC/MS and safrole (1) was identified as the major metabolite 1, was subjected to direct reactions on the oxygenated groups in the aromatic ring and in the side chain, and eight compounds (4 to 12) were obtained by the process. EO and compounds 4-12 were subjected to biological assays on 24 strains of the genus Saprolegnia, specifically of the species 12 S. parasitica and 12 S. australis. EO showed a significant effect against Saprolegnia strains. Compound 6 presents the highest activity against two resistant strains, with minimum inhibitory concentration (MIC) and minimum oomyceticidal concentration (MOC) values of 25 to 100 and 75 to 125 µg/mL, respectively. The results show that compound 6 exhibited superior activities compared to the commercial controls bronopol and azoxystrobin used to combat these pathogens.

Assuntos

RESUMO

Extracellular adenosine triphosphate (ATP) is as key mediator of immune and inflammatory responses. ATP is normally sequestered in the intracellular milieu and released by apoptotic and necrotic cells, where it acts as a pro-inflammatory mediator in the extracellular milieu. A limited number of studies have explored the involvement of purinergic signaling in oomycete infections, including Saprolegnia parasitica; this is a most destructive oomycete pathogen, associated with high mortality and severe economic losses for fish producers. The aim of this study was to determine whether purinergic signaling exerts anti- or pro-inflammatory effects in spleens of grass carp (Ctenopharyngodon idella) naturally infected by S. parasitica. Animals naturally infected with S. parasitica showed typical gross lesions characterized by cotton-wool tufts on the tail and fins, as well as severe histopathological lesions such as necrosis. Spleen ATP and metabolites of nitric oxide (NOx) levels were higher in fish naturally infected by S. parasitica compared to control on day 7 post-infection (PI). Spleen nucleoside triphosphate diphosphohydrolase (NTPDase) activity (ATP as substrate) was greater in fish naturally infected by S. parasitica than in uninfected on day 7 PI, while no significant differences were observed between groups with respect to NTPDase (adenosine diphosphate as substrate) and 5'-nucleotidase activities. Finally, adenosine deaminase (ADA) activity was lower in fish naturally infected by S. parasitica than in uninfected fish on day 7 PI. In summary, spleen tissue necrosis in the context of saprolegniosis provokes an intense release of ATP into the extracellular milieu, where it interacts with the P2X7 purine receptor and leads to a self-sustained pro-inflammatory deleterious cycle, contributing to an intense inflammatory process. In response to excessive ATP levels in the extracellular milieu, ATP and adenosine hydrolysis were modulated in an attempt to restrict the inflammatory process via upregulation of NTPDase and downregulation of ADA activities. We conclude that the purinergic signaling pathway modulates immune and inflammatory responses during natural infection with S. parasitica.

Assuntos

RESUMO

The rapid development of the aquaculture industry has global concerns with health management and control strategies to prevent and/or treat diseases and increase sustainability standards. Saprolegniosis is a disease caused by Saprolegnia parasitica, and is characterized by promoting an immunosuppression in the host. This study evaluated in vitro the extract and one active compound (polygodial) of Drimys winteri, a Chilean medicinal tree as a potential early immunostimulatory aid in Saprolegniosis control. Atlantic salmon (Salmo salar) head kidney cells (ASK-1) were incubated with both extract and pure polygodial before exposure to S. parasitica mycelium, and the expression of the immune-related genes interleukin 1ß (IL-1ß), interferon α (IFNα), and major histocompatibility complex II (MHCII) was evaluated. Both evidenced immunomodulatory capacities by increasing gene expressions. This immunomodulation related to a mitigatory action counteracting the immunosuppressing effects of S. parasitica. Despite that most immune-related genes were up-regulated, the down-regulation of MHCII, characteristic of S. parasitica infection, was lessened by pre-incubation with the compounds. This study provides the first insight on the potential of D. winteri bark extract as a possible immunomodulatory and defensive strategy against this oomycete infection in fish.

Assuntos

RESUMO

Com o aumento da produtividade na piscicultura, os peixes são expostos a altas densidades de estocagem que podem levar ao estresse e imunossupressão. Essa condição favorece a ocorrência de infecções, entre elas a saprolegniose que afeta os peixes e seus ovos, causando sérios prejuízos econômicos aos piscicultores. Dessa forma, compostos químicos eficazes e "ambientalmente amigáveis" são almejados para o controle da doença. O objetivo do presente estudo foi avaliar a suscetibilidade in vitro de 12 isolados de Saprolegnia spp., provenientes dos peixes-rei dulceaquícolas Odontesthes bonariensis e O. humensis. Para isso, testes de suscetibilidade, avaliando a inibição do crescimento micelial de Saprolegnia spp., foram realizados frente a seis químicos (cloreto de sódio, formaldeído, permanganato de potássio, iodopovidona, sal marinho e sal marinho iodado) nas concentrações seriadas de 0 a 10.000ppm. Os resultados obtidos evidenciaram que o formaldeído e o permanganato de potássio, em concentrações a partir de 10 e acima de 100ppm, respectivamente, inibiram o crescimento micelial de isolados Saprolegnia spp.. Já a iodopovidona e os compostos salinos não evidenciaram atividade antimicrobiana em nenhuma das concentrações testadas (0-10.000ppm). Embora os resultados in vitro demonstrem que formaldeído e permanganato de potássio sejam promissores no controle da saprolegniose, estudos futuros deverão avaliar a eficácia e o efeito in vivo desses compostos nos peixes-rei O. bonariensis e O. humensis.

The productivity in fish farming has been increasing and consequently the fish are submitted to high stocking densities which usually cause stress and immunosuppression. These conditions determine the occurrence of a series of infections, including saprolegniosis. This disease affects fish and eggs from freshwater determining relevant economic losses to fish farmers. Thus, to avoid outbreaks, are being sought effective chemical agents that are "environmentally friendly". The aim of this study was to evaluate the in vitro susceptibility of 12 isolates of Saprolegnia spp. from the silversides Odontesthes bonariensis and O. humensis. Susceptibility tests evaluating inhibition of mycelial growth of Saprolegnia spp. were performed using six chemicals (sodium chloride, formaldehyde, potassium permanganate, povidone-iodine, sea salt and iodized sea salt) in concentrations from 0 to 10,000ppm. The results displayed that formaldehyde at the concentration of 10ppm, and potassium permanganate at concentrations above 100ppm, were able to inhibit the mycelial growth of isolates of Saprolegnia spp. However, povidone-iodine and saline compounds exhibited no antimicrobial activity on Saprolegnia spp. Although the in vitro results showed that formaldehyde and potassium permanganate could be promising in controlling saprolegniosis, further studies should be performed to evaluate the in vivo efficacy of these compounds as well as to verify the toxicity of the chemicals to the silversides O. bonariensis and O. humensis.

RESUMO

The productivity in fish farming has been increasing and consequently the fish are submitted to high stocking densities which usually cause stress and immunosuppression. These conditions determine the occurrence of a series of infections, including saprolegniosis. This disease affects fish and eggs from freshwater determining relevant economic losses to fish farmers. Thus, to avoid outbreaks, are being sought effective chemical agents that are "environmentally friendly". The aim of this study was to evaluate the in vitro susceptibility of 12 isolates of Saprolegnia spp. from the silversides Odontesthes bonariensis and O. humensis. Susceptibility tests evaluating inhibition of mycelial growth of Saprolegnia spp. were performed using six chemicals (sodium chloride, formaldehyde, potassium permanganate, povidone-iodine, sea salt and iodized sea salt) in concentrations from 0 to 10,000ppm. The results displayed that formaldehyde at the concentration of 10ppm, and potassium permanganate at concentrations above 100ppm, were able to inhibit the mycelial growth of isolates of Saprolegnia spp. However, povidone-iodine and saline compounds exhibited no antimicrobial activity on Saprolegnia spp. Although the in vitro results showed that formaldehyde and potassium permanganate could be promising in controlling saprolegniosis, further studies should be performed to evaluate the in vivo efficacy of these compounds as well as to verify the toxicity of the chemicals to the silversides O. bonariensis and O. humensis.

Com o aumento da produtividade na piscicultura, os peixes são expostos a altas densidades de estocagem que podem levar ao estresse e imunossupressão. Essa condição favorece a ocorrência de infecções, entre elas a saprolegniose que afeta os peixes e seus ovos, causando sérios prejuízos econômicos aos piscicultores. Dessa forma, compostos químicos eficazes e "ambientalmente amigáveis" são almejados para o controle da doença. O objetivo do presente estudo foi avaliar a suscetibilidade in vitro de 12 isolados de Saprolegnia spp., provenientes dos peixes-rei dulceaquícolas Odontesthes bonariensis e O. humensis. Para isso, testes de suscetibilidade, avaliando a inibição do crescimento micelial de Saprolegnia spp., foram realizados frente a seis químicos (cloreto de sódio, formaldeído, permanganato de potássio, iodopovidona, sal marinho e sal marinho iodado) nas concentrações seriadas de 0 a 10.000ppm. Os resultados obtidos evidenciaram que o formaldeído e o permanganato de potássio, em concentrações a partir de 10 e acima de 100ppm, respectivamente, inibiram o crescimento micelial de isolados Saprolegnia spp.. Já a iodopovidona e os compostos salinos não evidenciaram atividade antimicrobiana em nenhuma das concentrações testadas (0-10.000ppm). Embora os resultados in vitro demonstrem que formaldeído e permanganato de potássio sejam promissores no controle da saprolegniose, estudos futuros deverão avaliar a eficácia e o efeito in vivo desses compostos nos peixes-rei O. bonariensis e O. humensis.

RESUMO

The productivity in fish farming has been increasing and consequently the fish are submitted to high stocking densities which usually cause stress and immunosuppression. These conditions determine the occurrence of a series of infections, including saprolegniosis. This disease affects fish and eggs from freshwater determining relevant economic losses to fish farmers. Thus, to avoid outbreaks, are being sought effective chemical agents that are "environmentally friendly". The aim of this study was to evaluate the in vitro susceptibility of 12 isolates of Saprolegnia spp. from the silversides Odontesthes bonariensis and O. humensis. Susceptibility tests evaluating inhibition of mycelial growth of Saprolegnia spp. were performed using six chemicals (sodium chloride, formaldehyde, potassium permanganate, povidone-iodine, sea salt and iodized sea salt) in concentrations from 0 to 10,000ppm. The results displayed that formaldehyde at the concentration of 10ppm, and potassium permanganate at concentrations above 100ppm, were able to inhibit the mycelial growth of isolates of Saprolegnia spp. However, povidone-iodine and saline compounds exhibited no antimicrobial activity on Saprolegnia spp. Although the in vitro results showed that formaldehyde and potassium permanganate could be promising in controlling saprolegniosis, further studies should be performed to evaluate the in vivo efficacy of these compounds as well as to verify the toxicity of the chemicals to the silversides O. bonariensis and O. humensis.

Com o aumento da produtividade na piscicultura, os peixes são expostos a altas densidades de estocagem que podem levar ao estresse e imunossupressão. Essa condição favorece a ocorrência de infecções, entre elas a saprolegniose que afeta os peixes e seus ovos, causando sérios prejuízos econômicos aos piscicultores. Dessa forma, compostos químicos eficazes e "ambientalmente amigáveis" são almejados para o controle da doença. O objetivo do presente estudo foi avaliar a suscetibilidade in vitro de 12 isolados de Saprolegnia spp., provenientes dos peixes-rei dulceaquícolas Odontesthes bonariensis e O. humensis. Para isso, testes de suscetibilidade, avaliando a inibição do crescimento micelial de Saprolegnia spp., foram realizados frente a seis químicos (cloreto de sódio, formaldeído, permanganato de potássio, iodopovidona, sal marinho e sal marinho iodado) nas concentrações seriadas de 0 a 10.000ppm. Os resultados obtidos evidenciaram que o formaldeído e o permanganato de potássio, em concentrações a partir de 10 e acima de 100ppm, respectivamente, inibiram o crescimento micelial de isolados Saprolegnia spp.. Já a iodopovidona e os compostos salinos não evidenciaram atividade antimicrobiana em nenhuma das concentrações testadas (0-10.000ppm). Embora os resultados in vitro demonstrem que formaldeído e permanganato de potássio sejam promissores no controle da saprolegniose, estudos futuros deverão avaliar a eficácia e o efeito in vivo desses compostos nos peixes-rei O. bonariensis e O. humensis.

RESUMO

The productivity in fish farming has been increasing and consequently the fish are submitted to high stocking densities which usually cause stress and immunosuppression. These conditions determine the occurrence of a series of infections, including saprolegniosis. This disease affects fish and eggs from freshwater determining relevant economic losses to fish farmers. Thus, to avoid outbreaks, are being sought effective chemical agents that are "environmentally friendly". The aim of this study was to evaluate the in vitro susceptibility of 12 isolates of Saprolegnia spp. from the silversides Odontesthes bonariensis and O. humensis. Susceptibility tests evaluating inhibition of mycelial growth of Saprolegnia spp. were performed using six chemicals (sodium chloride, formaldehyde, potassium permanganate, povidone-iodine, sea salt and iodized sea salt) in concentrations from 0 to 10,000ppm. The results displayed that formaldehyde at the concentration of 10ppm, and potassium permanganate at concentrations above 100ppm, were able to inhibit the mycelial growth of isolates of Saprolegnia spp. However, povidone-iodine and saline compounds exhibited no antimicrobial activity on Saprolegnia spp. Although the in vitro results showed that formaldehyde and potassium permanganate could be promising in controlling saprolegniosis, further studies should be performed to evaluate the in vivo efficacy of these compounds as well as to verify the toxicity of the chemicals to the silversides O. bonariensis and O. humensis.

Com o aumento da produtividade na piscicultura, os peixes são expostos a altas densidades de estocagem que podem levar ao estresse e imunossupressão. Essa condição favorece a ocorrência de infecções, entre elas a saprolegniose que afeta os peixes e seus ovos, causando sérios prejuízos econômicos aos piscicultores. Dessa forma, compostos químicos eficazes e "ambientalmente amigáveis" são almejados para o controle da doença. O objetivo do presente estudo foi avaliar a suscetibilidade in vitro de 12 isolados de Saprolegnia spp., provenientes dos peixes-rei dulceaquícolas Odontesthes bonariensis e O. humensis. Para isso, testes de suscetibilidade, avaliando a inibição do crescimento micelial de Saprolegnia spp., foram realizados frente a seis químicos (cloreto de sódio, formaldeído, permanganato de potássio, iodopovidona, sal marinho e sal marinho iodado) nas concentrações seriadas de 0 a 10.000ppm. Os resultados obtidos evidenciaram que o formaldeído e o permanganato de potássio, em concentrações a partir de 10 e acima de 100ppm, respectivamente, inibiram o crescimento micelial de isolados Saprolegnia spp.. Já a iodopovidona e os compostos salinos não evidenciaram atividade antimicrobiana em nenhuma das concentrações testadas (0-10.000ppm). Embora os resultados in vitro demonstrem que formaldeído e permanganato de potássio sejam promissores no controle da saprolegniose, estudos futuros deverão avaliar a eficácia e o efeito in vivo desses compostos nos peixes-rei O. bonariensis e O. humensis.