Matheus D. Baldissera

Trypanocidal activity of the essential oils in their conventional and nanoemulsion forms: in vitro tests.

The aim of this study was to investigate the susceptibility in vitro of Trypanosoma evansi to the essential oils of andiroba (Carapa guaianensis) and aroeira (Schinus molle), in their conventional and nanostructured forms. For that, pure oils at concentrations of 0.5%, 1.0% and 2.0% were used. A negative control (untreated) and a positive control (diminazene aceturate 0.5%) were used as comparative parameters. Later, the same tests were performed, using nanoemulsions oils at concentrations of 0.5% and 1.0%. The tests were carried out in triplicates and the numbers of parasites were quantified on 1, 3 and 6 h from onset of the study. A dose-dependent reduction in the number of parasites to the forms of two oils tested was observed after 1 h. The concentration of parasites was significantly reduced at low concentrations after 3 h, as well as at 6 h no alive parasites were observed for the essential oils tested. Ours findings indicate, for the first time, that oils of andiroba and aroeira (in their conventional and nanoemulsion forms) have high activity against T. evansi in vitro, leading to the suggestion that these oils may be applied as an alternative treatment for this disease.

Treatment with essential oil of Achyrocline satureioides in rats infected with Trypanosoma evansi: relationship between protective effect and tissue damage.

The aim of this study was to evaluate the effects of treatment with free and nanoencapsulated essential oil of Achyrocline satureioides on trypanosomosis and its oxidative/antioxidants variables in liver and kidney of rats infected experimentally with Trypanosoma evansi. For that, 48 rats were divided into six groups (A-F), eight animals each group. Groups A, C and D were composed of uninfected animals, while animals in groups B, E and F were inoculated intraperitoneally with T. evansi. Groups A and B were used as controls, negative and positive, respectively. Groups C and E receive oil (orally), as well as the animals in groups D and F were treated with nanoencapsulated essential oil. The treatment was not able to eliminate the parasites, but it remained the levels of parasitemia low. The carbonyl levels in liver and kidney did not differ between groups. Infected animals (group B) showed an increase in the TBARS levels and a decrease in the CAT activity and NPSH levels in liver and kidney, compared with the same parameters in the control (group A). Treatment with A. satureioides (groups C and D) did not influence the TBARS levels and CAT activity in the liver, but it increased the CAT activity in kidneys of the animals of group C. NPSH levels decreased in liver in the groups treated with nanoencapsulated essential oil (groups D and F). An interesting result observed was that the animals infected and then treated with essential oil of A. satureioides (groups E and F) did not differ from animals of group A for TBARS, CAT and NPSH, unlike what happened with the animals of group B. Therefore, the treatment with essential oil did not eliminate the parasites from the bloodstream, but it reduced the number of trypanosomes, mainly by its nanoencapsulated form. The same occurred with the lipid peroxidation in the liver. However, the treatments reduced the oxidative damage, and it led to the activation of the antioxidant enzymes. We believe that the association of this natural product with a trypanocidal drug may enhance its curative effect.

Trypanocidal action of tea tree oil (Melaleuca alternifolia) against Trypanosoma evansi in vitro and in vivo used mice as experimental model

This study aimed to evaluate the Trypanosoma evansi susceptibility to tea tree oil (TTO - Melaleuca alternifolia) and tea tree oil nanocapsules (TTO nanocapsules) in vitro and in vivo tests. In vitro, we observed a mortality curve of trypomastigotes proportional to dose, i.e., the TTO and TTO nanocapsules have trypanocidal effect. Treatment with TTO in vivo was assessed in experiments (I and II). For Experiment I, T. evansi infected mice were treated with TTO and/or combinations of essential oil with chemotherapy (diminazene aceturate - D.A.). Treatment with TTO at a dose of 1mLkg(-1) was able to extend animal longevity, but had no curative efficacy. However, when TTO was combined with D.A. a disease curative efficacy of 100% for disease was observed, a much better result than the D.A. treatment (33.3%). In Experiment II, T. evansi infected mice were treated with TTO nanocapsules with doses of 0.3, 0.6 and 0.9mLkg(-1). Animals treated with 0.9mLkg(-1) showed higher longevity however without curative effect. Active compounds present in natural products, such as M. alternifolia, may potentiate the treatment of trypanosomosis when associated with other trypanocidal drugs.

Activity of cholinesterases, pyruvate kinase and adenosine deaminase in rats experimentally infected by Fasciola hepatica: Influences of these enzymes on inflammatory response and pathological findings

The aim of this study was to investigate acetylcholinesterase (AChE) in total blood and liver tissue; butyrylcholinesterase (BChE) in serum and liver tissue; adenosine deaminase (ADA) in serum and liver tissue; and pyruvate kinase (PK) in liver tissue of rats experimentally infected by Fasciola hepatica. Animals were divided into two groups with 12 animals each, as follows: group A (uninfected) and group B (infected). Samples were collected at 20 (A1 and B1;n=6 each) and 150 (A2 and B2; n=6 each) days post-infection (PI). Infected animals showed an increase in AChE activity in whole blood and a decrease in AChE activity in liver homogenates (P<0.05) at 20 and 150 days PI. BChE and PK activities were decreased (P<0.05) in serum and liver homogenates of infected animals at 150 days PI. ADA activity was decreased in serum at 20 and 150 days PI, while in liver homogenates it was only decreased at 150 days PI (P<0.05). Aspartate aminotransferase and alanine aminotransferase activities in serum were increased (P<0.05), while concentrations of total protein and albumin were decreased (P<0.05) when compared to control. The histological analysis revealed fibrous perihepatitis and necrosis. Therefore, we conclude that the liver fluke is associated with cholinergic and purinergic dysfunctions, which in turn may influence the pathogenesis of the disease.

In vitro and in vivo action of terpinen-4-ol, γ-terpinene, and α-terpinene against Trypanosoma evansi.

This study aimed to evaluate the susceptibility in vitro and in vivo of Trypanosoma evansi to terpinen-4-ol, γ-terpinene and α-terpinene, the three main compounds of tea tree oil (Melaleuca alternifolia) with known efficacy in the treatment of trypanosomosis. In vitro, a trypanocidal effect of terpinen-4-ol, γ-terpinene, and α-terpinene was observed when used alone or associated at 0.5, 1 and 2% concentrations i.e., the α-terpinene showed a faster trypanocidal effect when compared to chemotherapy (diminazene aceturate - D.A.). In vivo studies were performed in two experiments: I and II where experiment I used T. evansi infected mice treated with terpinen-4-ol, γ-terpinene and α-terpinene alone (at a dose of 1.0 mL kg(-1)) or associated (two compounds, dose of 0.5 mL kg(-1) of each compound; tree compounds, dose of 0.335 mL kg(-1) of each compound); Treatment with α-terpinene was able to extend animal longevity, but showed no curative efficacy. In experiment II, T. evansi infected mice were treated with D.A. associate with α-terpinene, where a curative efficacy of 57.14% was found, a much better result when D.A. was used alone (14.28%). In summary, α-terpinene associated with D.A. can be used as an alternative treatment for T. evansi infection. The compound α-terpinene from M. alternifolia essential oil is the one responsible for the trypanocidal effect, a fact confirmed by in vitro results and the increased longevity observed on treated mice.

Physiological responses of Rhamdia quelen (Siluriformes: Heptapteridae) to anesthesia with essential oils from two different chemotypes of Lippia alba

The aim of this study was to evaluate if Lippia alba has different chemotypes according to the chemical composition of the essential oil (EO) considering collection site, and if the EO may have different effects on blood and plasma parameters in silver catfish, Rhamdia quelen, during and immediately after anesthesia. The citral (EO-C) and linalool (EO-L) chemotypes were identified, and both presented similar anesthetic effects for silver catfish. Fish were exposed to two concentrations of each EO, which induced slow and fast anesthesia (100 and 300 µL L-1, respectively). Blood ions did not change at any time of anesthesia induction and recovery and, therefore, the electrolyte balance was not altered. Blood gases oscillated through all exposure and recovery times, but there was an increase in pO2 after 10 min recovery in fish anesthetized with EO-C. Glucose increased in fish exposed to both EOs when compared with the control group. Overall, exposure to both EOs (except 100 µL L-1 EO-L at most times) reduced plasma cortisol levels compared to the control and/or ethanol groups. However, as plasma creatinine levels in fish anesthetized with EO-C were higher than control fish, the use of EO-L is preferable.

Insecticidal and repellent effects of tea tree and andiroba oils on flies associated with livestock

This study aimed to evaluate the insecticidal and repellent effects of tea tree, Melaleuca alternifolia (Myrtales: Myrtaceae), and andiroba, Carapa guianensis (Sapindales: Meliaceae), essential oils on two species of fly. For in vitro studies, free‐living adult flies were captured and reared in the laboratory. To evaluate the insecticidal effects of the oils, adult flies of Haematobia irritans (L.) and Musca domestica L. (both: Diptera: Muscidae) were separated by species in test cages (n = 10 per group), and subsequently tested with oils at concentrations of 1.0% and 5.0% using a negative control to validate the test. Both oils showed insecticidal activity. Tea tree oil at a concentration of 5.0% was able to kill M. domestica with 100.0% efficacy after 12 h of exposure. However, the effectiveness of andiroba oil at a concentration of 5.0% was only 67.0%. The insecticidal efficacy (100.0%) of both oils against H. irritans was observed at both concentrations for up to 4 h. The repellency effects of the oils at concentrations of 5.0% were tested in vivo on Holstein cows naturally infested by H. irritans. Both oils demonstrated repellency at 24 h, when the numbers of flies on cows treated with tea tree and andiroba oil were 61.6% and 57.7%, respectively, lower than the number of flies on control animals. It is possible to conclude that these essential oils have insecticidal and repellent effects against the species of fly used in this study.

Pseudomonas aeruginosa strain PA01 impairs enzymes of the phosphotransfer network in the gills of Rhamdia quelen

Integration of mitochondria with cytosolic ATP-consuming/ATP-sensing and substrate supply processes is critical for gills bioenergetics, since this tissue plays an important role in the respiratory energy metabolism. The effects of bacterial infection on gills remain poorly understood, limited only to histopathological analyses. Thus, the aim of this study was to investigate whether experimental infection by Pseudomonas aeruginosa strain PA01 alters the enzymes of the phosphoryltransfer network (adenylate kinase (AK), pyruvate kinase (PK) and cytosolic and mitochondrial creatine kinase (CK)) in gills of silver catfish (Rhamdia quelen). The animals were divided into two groups with six fish each: uninfected (negative control) and infected (positive control). On day 7 post-infection (PI), animals were euthanized and the gills collected. AK, PK, and cytosolic and mitochondrial CK activities in gills decreased in infected compared to uninfected animals. Also, severe gill damage and destruction in the primary and secondary lamellae was observed in the infected animals. Therefore, we have demonstrated, for the first time, that experimental infection by P. aeruginosa inhibits key enzymes linked to the production and utilization of metabolic energy in silver catfish, and consequently, impairs cellular energy homeostasis, which may contribute to disease pathogenesis.

Relationship between behavioral alterations and activities of adenylate kinase and creatine kinase in brain of rats infected by Trypanosoma evansi

The aim of this study was to investigate the behavioral assessment and activities of important enzymes involved in the phosphoryl transfer network in rat brains that were experimentally infected with Trypanosoma evansi. Behavioral assessment (cognitive performance), pro-inflammatory cytokines in serum and activities of adenylate kinase (AK), pyruvate kinase (PK), and creatine kinase (CK) in brain were evaluated at 5 and 15 days post-infection (PI). Here we demonstrate a cognitive impairment in the rats infected with T. evansi. At 5 and 15 days PI, a memory deficit and a depressant activity were demonstrated by an inhibition avoidance test and increase in the immobility time in a tail suspension test, respectively. On day 5 PI, a decrease in the CK activity and an increase in the AK activity were observed. On day 15 PI, an increase in the CK activity and a decrease in the AK activity were observed. Considering the importance of energy metabolism for brain functioning, it is possible that the changes in the activity of enzymes involved in the cerebral phosphotransfer network and an increase in the proinflammatory cytokines (TNF and IFN) may be involved at least in part in the cognitive impairment in infected rats with T. evansi.

Melaleuca alternifolia essential oil enhances the non-specific immune system and prevents oxidative damage in Rhamdia quelen experimentally infected by Aeromonas hydrophila: Effects on cholinergic and purinergic systems in liver tissue

Abstract The aim of this study was to evaluate the effects of M. alternifolia essential oil used to treat silver catfish (Rhamdia quelen) experimentally infected by Aeromonas hydrophila on oxidative stress variables, and for the first time, on hepatic enzymes of the cholinergic and adenosinergic systems. For that, fish were divided into six groups (A‐F), each containing seven animals. Groups A, B and C were composed of uninfected animals, while animals in groups D, E and F were intramuscularly inoculated with A. hydrophila. Groups B and E received a prophylactic bath with M. alternifolia essential oil (50 &mgr;L/L, diluted in ethanol) for seven days, while groups C and F were exposed to ethanol. After the prophylactic baths, groups D, E and F were inoculated with 100 &mgr;L of A. hydrophila solution (2.1 × 109 colony‐forming unit). Two days after inoculation, the animals were euthanized and liver samples were collected. Infected animals (the group D) showed increased TBARS and protein carbonylation levels, while CAT, AChE and ADA activities decreased compared to uninfected animals (the group A). The prophylactic treatment with M. alternifolia essential oil (the group E) prevented the alterations caused by A. hydrophila, but it did not change AChE activity. Thus, the prophylactic treatment prevents damage caused by lipids and proteins, as well as alterations of the adenosinergic system, demonstrating that the anti‐inflammatory effect of TTO is mediated by the adenosinergic pathway. In addition, TTO prophylactic treatment might be considered an important approach to prevent the hepatic damage caused by A. hydrophila. HighlightsAeromonas hydrophila cause injury on antioxidant system in liver tissue.Hepatic AChE and ADA activities decrease in infected fish with A. hydrophila.Treatment with TTO prevents the injury on antioxidant system.The anti‐inflammatory effect of TTO is mediated by the adenosinergic pathway.TTO might be considered an important approach to prevent the damage caused by bacteria.