Respuesta de Aedes aegypti L. (Diptera: Culicidae) a transflutrina y linalol impregnados en diferentes tipos de tela / Response of Aedes aegypti L. (Diptera: Culicidae) to transfluthrin and linalool impregnated in different of fabric types

Resumen: Objetivo: Evaluar el efecto de repelencia espacial contra Ae. aegypti de dos compuestos químicos impregnados en diferentes tipos de telas. Material y métodos: El estudio se realizó en el periodo 2015-2016 en el Centro Regional de Investigación en Salud Pública, del Instituto Nacional de Salud Pública. Se utilizó el Sistema de Procesamiento de Alto-rendimiento para evaluar la respuesta de Ae. aegypti a transflutrina y linalol, impregnados individualmente a diferentes concentraciones en popelina, algodón y poliéster. También se determinó el efecto de sus mezclas, lavado sobre la residualidad y porcentaje de protección. Resultados: La mayor respuesta de repelencia espacial fue para el tratamiento linalol-algodón al 0.1% (RE= 70 ± 5.77%). La mezcla de linalol 0.1% y transflutrina 0.001% presentó un porcentaje de repelencia espacial similar para los tres tipos de tela. El tratamiento transflutrina-popelina 0.001% mantuvo una residualidad de cinco días. El linalol al 0.1% produjo 62.50% de protección en presencia de un estímulo de atracción. Conclusión: Se sugiere la impregnación de linalol al 0.1% en ropa como medida de protección de las picaduras de Ae. aegypti.

Abstract: Objective: Evaluate the effect of spatial repellency against Ae. aegypti of two chemical compounds impregnated in different types of fabrics. Materials and methods: The study was carried out in the year 2015-2016 in the Centro Regional de Investigación en Salud Pública, del Instituto Nacional de Salud Pública. The high-throughput screening system was used to evaluate the response of Ae. aegypti to transfluthrin and linalool, impregnated individually at different concentrations in poplin, cotton and polyester. The effect of their mixtures was also determined, washing on residuality and percentage of protection. Results: The highest spatial repellency response was for 0.1% linalool-cotton treatment (RE = 70 ± 5.77%). The mixture of 0.1% linalool and 0.001% transfluthrin presented a similar spatial repellence percentage for the three types of fabric. The transfluthrin-poplin treatment 0.001% maintained a residual of five days. 0.1% linalool produced a 62.50% protection in the presence of an attraction stimulus. Conclusion: It is suggested the impregnation of 0.1% linalool in clothing as a protection measure for Ae. aegypti.

Orofacial antinociceptive activity and anchorage molecular mechanism in silico of geraniol

Abstract We aimed to evaluate the orofacial antinociceptive effect of geraniol in mice and its molecular anchorage mechanism. Seven mice per group (probabilistic sample) were treated with geraniol (12.5, 25 and 50 mg/kg, i.p.), morphine (6 mg/kg, i.p.) and vehicle (saline + Tween 80 at 0.2%, i.p.) 30 minutes prior to the beginning of the experiment. Injecting glutamate (25 μM), capsaicin (2.5 μg) and formalin (2%) into the right upper lip (perinasal) of the mouse induced nociception. Behavioral analysis of the animals considered the friction time (in seconds) of the mentioned region using hind or front paws by a researcher blinded to the treatment groups. The statistical analysis was performed blindly, considering α = 5%. The results showed that in the glutamate and capsaicin tests, concentrations of 25 mg/kg and 50 mg/kg presented antinociceptive activity (p < 0.005, power> 80%). In the formalin test, geraniol was able to reduce nociception at a concentration of 50 mg/kg (p < 0.005, power> 80%). In the molecular anchorage study, high values of binding between the evaluated substance and receptors of glutamate were observed (metabotropic glutamate receptor, -87.8501 Kcal/mol; N-methyl-D-aspartate, -86.4451 Kcal/mol; α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid, -85.6755 Kcal/mol). Geraniol presented orofacial antinociceptive activity, probably by interacting with glutamate-related receptors.

Susceptibility of cariogenic microorganisms to phytoconstituents / Susceptibilidade de microrganismos cariogênicos a fitoconstituintes

Abstract This study aimed to evaluate the in vitro antibacterial activity of the phytochemicals thymol, linalool, and citronellol against Streptococcus mutans, Streptococcus salivarius and Streptococcus oralis. Disk diffusion screening on solid medium and measurement of the diameter of the bacterial growth inhibition halos was the technique utilized. The Minimum Inhibitory Concentration (MIC) of the substances was determined using serial substance dilutions and microdilution technique in Brain Heart Infusion culture medium. After incubation for 24 hours in an oven at 37 °C, plate reading was completed and confirmed by visual method using 2,3,5 triphenyl tetrazolium chloride dye. The Minimum Bactericidal Concentration (MBC) was determined from MIC subcultures. Assays were performed in triplicate, and chlorhexidine was used as a positive control. The diameters in mm of the growth inhibition halos ranged between 7.3 and 10.7 for S. mutans, 7.3 and 10.0 for S. oralis, and 8.2 and 9.8 for S. salivarius. The MIC and MBC values obtained converged, ranging from maximum values in the presence of Linalool (1,250.0 mg/mL, 2,500.0 mg/mL and 2,500.0 mg/mL, respectively, for S. mutans, S. oralis, and S. salivarius); and minimum values with Thymol (312.5 μg/ml, 156.2 μg/mL and 156.2 μg/ml, respectively for S. mutans, S. oralis, and S. salivarius). All the tested phytochemicals displayed antibacterial activity, thus representing substances with potential applications in preventing tooth decay.

Resumo Este estudo objetivou avaliar a atividade antibacteriana in vitro dos fitoquímicos timol, linalol e citronelol sobre Streptococcus mutans, Streptococcus salivaris e Streptococcus oralis. Utilizou-se a técnica de discos de difusão em meio sólido e medição do diâmetro dos halos de inibição. A concentração inibitória mínima (CIM) das substâncias foi determinada utilizando diluições em série das substâncias e técnica de microdiluição em meio de cultura de Brain Heart Infusion. Após incubação durante 24 horas em estufa a 37 °C, a leitura da placa foi confirmada pelo método visual usando o corante 2,3,5 trifenil cloreto de tetrazólio. A concentração bactericida mínima (CBM) foi determinada a partir de subculturas de MIC. Os ensaios foram realizados em triplicata, e clorexidina foi usada como um controle positivo. Os diâmetros dos halos de inibição do crescimento variaram entre 7,3 e 10,7 por S. mutans, 7,3 e 10,0 por S. oralis, e 8,2 e 9,8 para S. salivaris. Os valores de CIM e CBM obtidos variaram de valores máximos na presença de linalol (1.250,0 mg/mL, 2.500.0 mg/mL e 2.500.0 mg/mL, respectivamente, para o S. mutans, S oralis e S. salivaris); a valores mínimos com timol (312,5 μg/ml, 156,2 μg/mL e 156,2 μg/ml, respectivamente para S. mutans, S. oralis e S. salivaris). Todos os fitoquímicos testados apresentaram atividade antibacteriana, representando, assim, substâncias com potencial de aplicações na prevenção da cárie dentária.

Antifungal activity of linalool in cases of Candida spp. isolated from individuals with oral candidiasis / Atividade antifúngica do linalol em casos de Candida spp. isolados de indivíduos com candidíase oral

Abstract This study analyzed the antifungal activity of phytoconstituents from linalool on Candida spp. strains, in vitro, isolated from patients with clinical diagnoses of oral candidiasis associated with the use of a dental prosthesis. Biological samples were collected from 12 patients using complete dentures or removable partial dentures and who presented mucous with diffuse erythematous or stippled features, indicating a clinical diagnosis of candidiasis. To identify fungal colonies of the genus Candida, samples were plated onto CHROMagar Candida®. The antifungal activity of linalool, a monoterpene unsaturated constituent of basil oil, was performed using the broth microdilution technique. Then, the minimum inhibitory concentration (MIC), the two subsequent stronger concentrations and the positive controls were subcultured on Sabouraud Dextrose Agar plates to determine the minimum fungicidal concentration (MFC). The experiments were performed in triplicate and nystatin was used as a positive control in all tests. Diagnoses of oral candidiasis were verified in eight patients (66.6%) and the most prevalent fungal species was Candida albicans (37.5%), followed by Candida krusei (25.0%); and Candida tropicalis (4.2%). The best antifungal activity of linalool was observed on Candida tropicalis (MIC = 500 mg/mL), followed by Candida albicans (MIC = 1.000 mg/mL), and Candida krusei (MIC = 2.000 mg/mL).Under the study conditions and based on the results obtained, it can be concluded that the Candida strains tested were susceptible to linalool.

Resumo Este estudo analisou a atividade antifúngica do fitoconstituinte linalol em cepas de Candida ssp, in vitro, isolados de pacientes com o diagnóstico clínico de candidíase oral associado ao uso de prótese dentária. As amostras biológicas foram coletadas de 12 pacientes portadores de próteses totais ou próteses parciais removíveis e que apresentavam características de mucosa eritematosa difusa ou pontilhadas, indicando um diagnóstico clínico de candidíase. Para identificar colônias de fungos do gênero Candida, as amostras foram semeadas em CHROMagar Candida®. A atividade antifúngica do linalol, um componente insaturado monoterpene de óleo de manjericão, foi realizada através da técnica de microdiluição em caldo. Em seguida, a concentração inibitória mínima (MIC), as duas concentrações consecutivas mais fortes e os controles positivos foram subcultivados em placas de Agar Sabouraud Dextrose para determinar a concentração fungicida mínima (MFC). Os experimentos foram realizados em triplicata e a nistatina foi usada como controle positivo em todos os testes. O diagnóstico de candidíase oral foi comprovado em oito pacientes (66,6%) e as espécies de fungos mais prevalentes foram Candida albicans (37,5%), seguido por Candida krusei (25,0%); e Candida tropicalis (4,2%). A melhor atividade antifúngica do linalol foi observada em Candida tropicalis (MIC = 500 mg/ml), seguido por Candida albicans (CIM = 1,000 mg/mL), e Candida krusei (CIM = 2,000 mg/mL). Sob as condições do estudo e com base nos resultados obtidos, pode-se concluir que as estirpes de Candida testadas foram susceptíveis a linalol.

Insights into the intracellular mechanisms of citronellal in Candida albicans: implications for reactive oxygen species-mediated necrosis, mitochondrial dysfunction, and DNA damage

Abstract INTRODUCTION Citronellal (Cit) possesses antifungal activity and has possible implications for reactive oxygen species (ROS) generation in Candida albicans. In this study, the effects of Cit on ROS generation and the mechanisms by which Cit exerts anti-Candida effects were examined. METHODS A 2′,7′-dichlorodihydrofluorescein diacetate assay was used to assess oxidative damage. Cell necrosis was determined by flow cytometry after FITC-Annexin V staining. Mitochondrial function was studied based on mitochondrial potential, metabolic activity (MTT assay), and phenotypic susceptibility on a non-fermentable carbon source. Membrane intactness and DNA damage were estimated by a propidium iodide (PI) uptake assay and 4',6-diamidino-2-phenylindole (DAPI) staining. RESULTS ROS generation was enhanced in response to Cit, leading to necrosis (2%). Additional hallmarks of cell death in response to Cit, such as mitochondrial membrane depolarization and DNA damage, were also observed. Cit treatment resulted in dysfunctional mitochondria, as evidenced by poor labeling with the mitochondrial membrane potential-sensitive probe rhodamine B, reduced metabolic activity (61.5%), and inhibited growth on a non-fermentable carbon source. Furthermore, Cit induced DNA damage based on DAPI staining. These phenotypes were reinforced by RT-PCR showing differences in gene expression (30-60%) between control and Cit-treated cells. Finally, PI uptake in the presence of sodium azide confirmed non-intact membranes and suggested that Cit activity is independent of the energy status of the cell. CONCLUSIONS Cit possesses dual anticandidal mechanisms, including membrane-disruptive and oxidative damage. Taken together, our data demonstrated that cit could be used as a prominent antifungal drug.

S-(+)- and R-(-)-linalool: a comparison of the in vitro anti-Aeromonas hydrophila activity and anesthetic properties in fish

ABSTRACT Linalool is the main compound of many essential oils and occurs in two isomeric forms: S-(+)- and R-(-)-linalool. This study aimed to determine if linalool isomers have different antimicrobial and anesthetic properties in fish. For this purpose, these compounds were previously isolated from Lippia alba (Mill.)N. E. Brown and Ocimum americanum L. essential oils. Antimicrobial effects were evaluated through the microdilution test against Aeromonas hydrophila, an important fish disease etiologic agent. Induction time until sedation, anesthesia and recovery time were determined in silver catfish (Rhamdia quelen) through bath exposure (60, 180, 300 or 500 μL L-1). The results showed different biological properties for the isomers being S-(+)-linalool the only active against A. hydrophila at 3.2 mg mL-1. The sedation was induced without differences between the compounds, however R-(-)-linalool promoted faster anesthesia. There were no differences regarding the recovery time of the animals exposed to the linalool isomers. Although both S-(+)- and R-(-)-linalool can be used for sedative purposes, their use in A. hydrophila infection is inadvisable due to the high effective concentration. Considering anesthesia as the main objective, the R-(-)-linalool demonstrated clear advantages at lower concentration.

Citronellal-induced disruption of membrane homeostasis in candida albicans and attenuation of its virulence attributes

Abstract: INTRODUCTION There is an increasing burden of multidrug resistance. As a result, deciphering the mechanisms of action of natural compounds with antifungal activity has gained considerable prominence. We aimed to elucidate the probable mechanism of action of citronellal, a monoterpenoid found in the essential oil extracted from Cymbopogon plants, against Candida albicans. METHODS Drug susceptibility was measured by broth microdilution and spot assays. Ergosterol levels were estimated using the alcoholic potassium hydroxide method and H+ extrusion was assessed by monitoring the glucose-induced acidification of the external medium. Virulence traits were studied by hyphal morphogenesis and biofilm formation, along with fungal cell adherence to polystyrene surface and human oral epithelial cells. RESULTS Citronellal showed anticandidal activity against C. albicans and non-albicans species of Candida at a minimum inhibitory concentration of 1 mg/ml. Citronellal interfered with membrane homeostasis, which is the major target of known antifungal drugs, by increasing the hypersensitivity of the fungi to membrane-perturbing agents, reducing ergosterol levels, and diminishing glucose-induced H+ extrusion. In addition, oxidative and genotoxic stresses were induced via an increased production of reactive oxygen species. Furthermore, citronellal inhibited the virulent attributes of yeast-to-hypha transition and biofilm formation. It also reduced cell adherence to polystyrene surface and the human oral epithelial cells. CONCLUSIONS This is the first study to propose the cell membrane, morphogenetic switching, biofilm formation, and cell adherence of Candida albicans as potential targets for the anticandidal activity of citronellal. However, clinical investigations on the therapeutic applications of citronellal are required.

Anthelmintic activity of Cymbopogon citratus against Haemonchus contortus / Atividade anti-helmíntica de Cymbopogon citratussobre Haemonchus contortus

Parasitic nematodes are of major economic importance in livestock. An alternative for the control of parasites is phytotherapy. This study evaluated the efficacy of Cymbopogon citratus decoction (CcD), C. citratus essential oil (CcEo) and citral against Haemonchus contortus using in vitro egg hatch test (EHT) and larval development test (LDT) and an in vivo test using a Meriones unguiculatus (gerbil) model. The effect of 800 mg/kg CcEo was evaluated in gerbils that had been artificially infected with 5,000 third-stage H. contortus larvae. The effective concentrations required to inhibit 50% (EC50) of egg hatching were 0.46, 0.14 and 0.13 mg/mL for CcD, CcEo and citral, respectively. The EC50 values in the LDT were 5.04, 1.92 and 1.37 mg/mL for CcD, CcEo and citral, respectively. H. contortus population in the group treated with C. citratus essential oil was reduced by 38.5% (P< 0.05) in comparison to the control group. These results suggest that it may be possible to use C. citratusessential oil to control of H. contortus parasite of small ruminant.

O parasitismo por nematoides tem grande importância econômica no rebanho. Uma alternativa para o controle de parasitas é a fitoterapia. Este estudo avaliou a eficácia do decocto de Cymbopogon citratus (DCc), do óleo essencial de C. citratus (OECc) e do citral contra Haemonchus contortus utilizando o teste in vitro de eclosão dos ovos (TEO) e o teste de desenvolvimento larval (TDL) e um teste in vivo com modelo Meriones unguiculatus (gerbil). O efeito de 800 mg/kg de OECc foi avaliado em gerbils infectados artificialmente com 5000 larvas de terceira fase de H. contortus. As concentrações efetivas necessárias para inibir 50% (CE50) da eclosão dos ovos foram 0,46; 0,14 e 0,13 mg/mL para DCc, OECc e citral, respectivamente. Os valores da CE50 no TDL foram de 5,04; 1,92 e 1,37 mg/mL para DCc, OECc e citral, respectivamente. No grupo tratado com óleo de C. citratus a população H. contortus foi reduzida em 38,5% (P < 0,05) em comparação com o grupo controle. Estes resultados sugerem que pode ser possível a utilização de óleo essencial de C. citratus para controle de H. contortus, parasita de pequenos ruminantes.