Cananga odorata L., Illicium verum, and Foeniculum vulgare essential oils impair the reproduction of the cattle tick Rhipicephalus microplus (Acari: Ixodidae).

This study aimed to evaluate the acaricidal potential of the essential oils of Cananga odorata L. (ylang-ylang), Illicium verum (star anise), and Foeniculum vulgare (sweet fennel) in Rhipicephalus microplus engorged females. The essential oils were extracted by hydrodistillation, and the females were immersed in each essential oil at concentrations ranging from 10 µL/mL to 50 µL/mL, using 10% dimethyl sulfoxide as a solvent. Tick mortality was evaluated after seven and 14 days, and the following parameters were determined: female weight before oviposition, preoviposition period, egg mass weight, egg production index, incubation period, hatching rate, fecundity, percentage of reduction in oviposition, percentage of reduction in hatching and product efficacy. Lethal concentration (LC50) values were 34.42 µL/mL (28.34-40.86) for C. odorata and 40.60 µL/mL (32.58-58.21) for F. vulgare. This parameter was not calculated for I. verum because there was insufficient mortality at the concentrations evaluated. The greatest efficacy was observed in the group treated with 40 µL/mL F. vulgare essential oil (97.17%), followed by I. verum (91.35%) and C. odorata (86.19%) at the same concentration. Efficacy results were associated with a greater reduction in egg mass weight and lower hatching rates. Although the essential oils caused a slight acaricidal impact, they showed significant effects on the reproductive performance of R. microplus engorged females. Thus, the results of this study indicate that these essential oils can be used in the development of new acaricidal formulations.

Diet with different concentrations of lychee peel flour modulates oxidative stress parameters and antioxidant activity in zebrafish.

The agri-food industry generates substantial waste, leading to significant environmental impacts. Lychee (Litchi chinensis Sonnerat), which is rich in bioactive compounds in its peel, pulp, and seeds, offers an opportunity for waste use. This study aimed to evaluate the effects of supplementing a high-carbohydrate diet with varying levels of lychee peel flour on lipid metabolism biomarkers and oxidative stress in a zebrafish (Danio rerio) model. A total of 225 zebrafish, approximately four months old, were divided into five groups: control, high-carbohydrate (HC), HC2%, HC4%, and HC6%. The study did not find significant differences in the growth performance of zebrafish in any group. However, the HC6% group exhibited a significant decrease in glucose and triglyceride levels compared with the HC group. Furthermore, this group showed enhanced activities of the antioxidant enzymes catalase (CAT) and superoxide dismutase (SOD), along with reduced levels of malondialdehyde (MDA). Increased antioxidant activity was also evidenced by DPPH-, ABTS+, and ß-carotene/Linoleic acid assays in the HC6% group. A positive correlation was identified between SOD/CAT activity and in vitro antioxidant assays. These findings suggest that dietary supplementation with 6% lychee peel flour can significantly modulate glucose homeostasis, lipid metabolism, and antioxidant activity in zebrafish.

Intense Caloric Restriction from Birth Prevents Cardiovascular Aging in Rats.

We previously demonstrated that a 50% caloric restriction (CR) from birth improves several cardiometabolic risk factors in young rats. In this study, we investigated in middle-aged rats the consequences of a 50% CR from birth on cardiometabolic risk factors, heart function/morphology, ventricular arrhythmia, and fibrillation incidence, and cardiac intracellular proteins involved with redox status and cell survival. From birth to the age of 18 months, rats were divided into an Ad Libitum (AL18) group, which had free access to food, and a CR18 group, which had food limited to 50% of that consumed by the AL18. Resting metabolic rate, blood pressure, and heart rate were recorded, and oral glucose and intraperitoneal insulin tolerance tests were performed. Blood was collected for biochemical analyses, and visceral fat and liver were harvested and weighed. Hearts were harvested for cardiac function, histological, redox status, and western blot analyses. The 50% CR from birth potentially reduced several cardiometabolic risk factors in 18-month-old rats. Moreover, compared with AL18, the CR18 group showed a ∼50% increase in cardiac contractility and relaxation, nearly three to five times less incidence of ventricular arrhythmia and fibrillation, ∼18% lower cardiomyocyte diameter, and ∼60% lower cardiac fibrosis. CR18 hearts also improved biomarkers of antioxidant defense and cell survival. Collectively, these results reveal several metabolic and cardiac antiaging effects of a 50% CR from birth in middle-aged rats.

Toxic effect of Callistemon viminalis essential oil on the ovary of engorged Rhipicephalus microplus female ticks (Acari: Ixodidae).

Rhipicephalus microplus is the main ectoparasite of cattle and its parasitism can reduce weight gain of hosts, in addition to causing anemia, increasing the risk of myiasis, and resulting in the transmission of Babesia bovis and Anaplasma marginale, among other pathogens. The use of synthetic chemicals plays an important role in controlling these ticks. However, its frequent and indiscriminate use has contributed to the selection of resistant strains, resulting in greater interest in the search for natural-origin products. The shrub Callistemon viminalis (Myrtaceae), also known as weeping bottlebrush, is known for its antibacterial, acaricidal, repellent, and antifungal activities, but there are no reports in the literature about its effects on the internal morphology of ticks. This study aimed to extract and characterize the essential oil obtained from the leaves of C. viminalis. Additionally, its effects on the ovary morphology of engorged R. microplus were assessed through histological, histochemical, and morphometric techniques. Exposure to C. viminalis caused dose-dependent morphological changes, such as cellular alterations in the epithelial layer lining the ovary lumen and the pedicel, irregularity of the chorion and oocyte shape, changes in protein and carbohydrate content, decrease in oocyte size, reduction in the size of the nucleus as well as cytoplasmic and nucleolar vacuolation. Thus, C. viminalis essential oil exhibited a toxic effect on the reproductive system of R. microplus, which may result in the reproductive impairment of this tick species.

Comparative toxicological evaluation of carvacrol, acetylcarvacrol anda fipronil-based pesticide in human blood cells.

Plant-derived chemicals are promising substances to control arthropod pests, although synthetic ones are still the most frequently used. Thus, comparative toxicological studies are needed to determine if natural substances are safe alternatives to replace the use of synthetic chemicals. This study aimed to compare the toxicity of carvacrol (natural origin), acetylcarvacrol (semi-synthetic) and a fipronil-based pesticide (synthetic). We assessed the effects of these chemicals on hemolytic activity, erythrocytes morphology and leucocyte viability using whole blood from human subjects. Additionally, DNA damage was evaluated through comet and DNA fragmentation assays. Fipronil and carvacrol caused hemolysis at concentrations ranging from 0.5 to 2.0%, whereas acetylcarvacrol did not cause hemolysis at 0.5 and 0.75%. Fipronil and carvacrol caused severe alterations in erythrocytes' morphology at 2%, such as ghost erythrocytes, elliptocyte-like shape and rouleau-like shape, presenting only 3.3 and 8.3% normal cells, respectively, at this concentration. However, 73.3% erythrocytes incubated with 2% acetylcarvacrol exhibited normal morphology. Fipronil considerably reduced leucocytes viability, decreasing it to 78% at 2%. Carvacrol and acetylcarvacrol showed no differences in leucocyte viability for 0.5 to 1.0%, but a decrease was observed for 2% carvacrol. The comet assay showed similar DNA damage for fipronil and carvacrol, but it was significantly lower for 1 and 2% acetylcarvacrol. Incubation with genomic DNA showed that only fipronil caused fragmentation of this molecule. Thus, we conclude that carvacrol and fipronil can present similar toxicity at higher concentrations. However, acetylation of carvacrol significantly reduced its toxicity to human blood cells compared with the other chemicals.

Use of Tribulus terrestris and Lepidium meyenii extract in rats: reproductive, biochemical and body parameters.

The oral administration of Tribulus terrestris and Lepidium meyenii extracts on reproductive, biochemical and body parameters was evaluated in rats. Thirty-six male Wistar rats weighting 210 ± 18 g were divided into six experimental groups (n = 6). Each group received, daily for 28 days, different solutions: T. terrestris (100 mg/kg), L. meyenii (1 g/kg) and T. terrestris at doses of 75, 50 and 25 mg/kg combined with L. meyenii at doses of 0.25, 0.5 and 0.75 g/kg, respectively, and distilled water (control). T. terrestris increased (p < 0.05) the serum testosterone, regardless of dose. Combined use of the extracts increased (p < 0.05) the diameter of the epididymal duct and epididymis lumen. The combinations of T. terrestris (75 and 50 mg/kg) with L. meyenii increased (p < 0.05) the sperm concentration. There were no differences (p > 0.05) in the other semen characteristics; relative weight of organs; and serum levels of urea, creatinine, alanine and aspartate transaminase, gamma glutamyl transferase, cholesterol, triglycerides, glucose, follicle-stimulating hormone and luteinizing hormone. No histopathological changes were observed (p > 0.05). It is concluded that the association of T. terrestris and L. meyenii has positive effects on serum testosterone, sperm concentration and epididymal morphology, with no evidence of effects in the testis, liver, spleen and kidneys.

Acaricidal and repellent activity of the essential oils of Backhousia citriodora, Callistemon viminalis and Cinnamodendron dinisii against Rhipicephalus spp.

The ticks Rhipicephalus microplus and Rhipicephalus sanguineus sensu lato (s.l) are of great importance to agriculture, veterinary medicine and public health. Due to a number of problems related to the use of synthetic acaricides, natural products emerge as promising substances for alternative tick control. In the present study, essential oils of Backhousia citriodora, Callistemon viminalis and Cinnamodendron dinisii were extracted by hydrodistillation, characterized by GC-MS and GC-FID and biologically evaluated for acaricidal activity against R. microplus and repellent activity against R. sanguineus s.l. Inhibition of acetylcholinesterase (AChe) by the essential oils was also evaluated. The major constituent of B. citriodora is citral (98.9 %), whereas the essential oil from C. viminalis is rich in 1.8-cineole (78.1 %), α-pinene (12.5 %) and limonene (3.36 %), and that from C. dinisii contains α-pinene (30.8 %), ß-pinene (12.5 %) and sabinene (11.3 %) as the principal constituents. The median lethal concentrations (LC 50) estimated for the essential oils on engorged R. microplus females were 3.276 µL.mL-1 for B. citriodora, 8.195 µL.mL-1 for C. dinisii and 8.936 µL.mL-1 for C. viminalis. The essential oil of B. citriodora showed the best repellent effect against unfed R. sanguineus s.l. adults, demonstrating repellent action up to 3 h after application. The essential oil of C. viminalis was able to reduce AChe activity, with an average inhibitory concentration (IC 50) of 0.33 µg mL-1. Thus, these oils can be considered as sources of bioactive compounds for tick control.

Repellent activity of acetylcarvacrol and its effects on salivary gland morphology in unfed Rhipicephalus sanguineus sensu lato ticks (Acari: Ixodidae).

Rhipicephalus sanguineus sensu lato (s.l.), commonly known as brown dog tick, is a widely distributed tick species that is substantially important for human and veterinary medicine. Therefore, it is the target of different control methods. Carvacrol and its semisynthetic derivative, acetylcarvacrol, are promising chemical compounds for alternative tick control. Thus, this study aimed to compare the repellent activities of carvacrol and acetylcarvacrol at different concentrations and drying times. Additionally, morphological alterations found in salivary glands were evaluated through histological techniques after exposure to acetylcarvacrol. The impact of the morphological changes on the development and survival of acini/cells in salivary glands was measured by a semiquantitative analysis. The repellent action of both compounds did not differ when evaluated at different concentrations, although acetylcarvacrol increased its effects as the concentration raised. Regarding the different drying times, acetylcarvacrol maintained its effects after 3 hours of exposure, while the efficacy of carvacrol decreased during this time period. Salivary glands of unfed R. sanguineus s.l. females showed dose-dependent alterations in the size and shape of acini as well as cytoplasmic vacuolization. Loss of the acinar cell limit, rupture of secretory granules and nuclear changes in the cells were also observed in the treated groups. Thus, our results demonstrated the potential of acetylcarvacrol to act as repellent against R. sanguineus s.l. Additionally, the morphological alterations found in salivary glands may interfere with the feeding process of ticks, which contributes to mitigate infestation by this species.

Cytotoxic effects of Satureja montana L. essential oil on oocytes of engorged Rhipicephalus microplus female ticks (Acari: Ixodidae).

In addition to pesticidal activity, the capacity of natural compounds to inhibit the reproduction of parasites emerge as an important alternative tick control method. In this context, Satureja spp. stand out due to their recognized pesticidal properties. Among parasites of veterinary importance, the cattle tick, Rhipicephalus microplus, is responsible for great economic losses in livestock and transmission of relevant pathogens. Thus, the aim of this study was to evaluate the effects of different concentrations of the essential oil of Satureja montana L. on the ovary morphology of R. microplus engorged females through histological and histochemical techniques. The most remarkable morphological changes found were: cytoplasmic vacuolation of germ cells, irregular and thicker chorion, irregular oocyte shape, ring-shaped nucleolus, decrease in protein and carbohydrate content in oocytes, in addition to cellular changes in the oviduct and pedicel. All morphological changes were assessed using a semiquantitative method already established in the literature. Ticks exposed to 5.0 µl/ml of essential oil showed the most significant changes when compared to control groups. Thus, the essential oil of S. montana L. damaged the reproductive system of R. microplus, which may impair ticks' offspring production and promote a long-term control of this species. HIGHLIGHTS: The essential oil of Satureja montana L. affects the ovary morphology of the cattle tick. The main morphological alterations found were cytoplasmic vacuolation, irregular and thicker chorion and irregular oocyte shape. These alterations may impair the development of eggs.

Acetylation of carvacrol raises its efficacy against engorged cattle ticks Rhipicephalus (Boophilus) microplus (Acari: Ixodidae).

The effects of acetylcarvacrol on the reproductive performance of engorged female R. microplus were evaluated. Carvacrol was acetylated by a reaction with acetic anhydride, confirmed by the identification of its melting point and by infrared spectroscopy. Based on the median lethal concentration, females were exposed to sublethal concentrations (3.7, 4.6 and 5.0 µL/mL) of acetylcarvacrol by means of the adult immersion test. The following parameters were evaluated: female weight before oviposition, pre-oviposition period, egg mass weight, egg production index, incubation period, hatching rate, fecundity rate, percentage of reduction in oviposition, percentage of reduction in hatching and product efficacy. The greatest efficacy was observed in the group treated with the highest concentration (91.69%) due to the greater weight reduction in egg mass (34.91 ± 0.02 mg) and the lower hatching rate (7.23 ± 15.50%). Therefore, this compound is a promising alternative for the control of R. microplus infestations.

Effects of Moro orange juice (Citrus sinensis (l.) Osbeck) on some metabolic and morphological parameters in obese and diabetic rats.

BACKGROUND: Nutritional intervention with the use of phytochemicals is an important method for the treatment and prevention of a metabolic syndrome. The objective of this study was to chemically characterize Moro orange juice. The influence of juice intake on metabolic parameters of rats that were obese, diabetic or both by means of body mass management after the activation of anthocyanins during refrigerated storage was also assessed. RESULTS: Juice intake reversed most of the metabolic abnormalities exhibited by obese rats, including reduction of body mass and improvement of the biochemical profile. The loss of body mass by diabetic animals and obese and diabetic animals was not attributed to juice intake, but to type I diabetes mellitus. In these animals, no improvement was observed in the biochemical profile, liver enzymes and glycemia, so this treatment model was deemed unfeasible. CONCLUSION: The beneficial effects cannot be explained only by the anthocyanin C3G present in the juice, but rather, by the synergism between all the components. Studies in humans are needed to determine whether the ingestion of this orange can be recommended as an effective strategy to prevent or ameliorate complications of obesity. © 2020 Society of Chemical Industry.

Therapeutic effects of different doses of prebiotic (isolated from Saccharomyces cerevisiae) in comparison to n-3 supplement on glycemic control, lipid profiles and immunological response in diabetic rats.

BACKGROUND: The regular intake of fiber generates numerous health benefits. However, the efficacy depends on the duration of consumption and the ingested dose. Studies investigating the optimal dose are of interest to enable the inclusion of fiber in the routine treatment of diabetic patients. OBJECTIVE: We aimed to evaluate the effects of different doses of ß-glucan (BG-isolated from Saccharomyces cerevisiae), in comparison to n-3 supplement, on the inflammatory and metabolic parameters of Wistar rats induced to diabetes by streptozotocin. METHODS: Forty animals were randomly divided into six groups receiving 0 mg/kg, 10 mg/kg, 20 mg/kg, or 40 mg/kg BG daily for 4 weeks or fish oil derivative [1000 mg/kg of omega-3 fatty acids (n-3)] for the same period. One additional group was composed of healthy controls. Serum metabolic and immunological parameters were evaluated by colorimetric and ELISA assays respectively. Histopathological analysis of the liver, small intestine and pancreas were also conducted. Significant changes due to BG intake were set into regression models with second-degree fit in order to estimate the optimal BG dose to achieve health benefits. RESULTS: The animals that ingested BG had lower food and water intake (p < 0.05) than the negative control group (0 mg/kg). However, consumption was still elevated in comparison to healthy controls. Blood glucose and serum levels of total cholesterol, LDL-c, and TG (p < 0.05) reduced in comparison to diabetic animals without treatment (better or similar to n-3 group depending on dose), but did not reach normal levels (in comparison to healthy controls). HDL-c was not different (p > 0.05) among all groups. These reductions were already seen with the lowest dose of 10 mg/kg. On average, the serum levels of the hepatic enzymes ALT and AST were 40% and 60% lower in the BG groups in comparison to diabetic animals without treatment (better results than n-3 group). The group receiving 40 mg/kg reached similar values of healthy controls for ALT; whereas the same result occurred from the dose of 10 mg/kg for AST. The ideal dose, estimated from the mean of all metabolic parameters was approximately 30 mg/kg/day. Regarding the immunological profile, TNF-α significantly decreased in the BG groups compared to controls (p < 0.05), reaching better values than n-3 group and similar to healthy controls. No significant differences were found between the groups in IL-1ß or IL-10 (p > 0.05). No histological changes were found in the pancreas, liver, or intestine due to treatment among diabetic animals. CONCLUSIONS: BG significantly reduced blood glucose as well as serum total cholesterol, LDL-c and TG. There was a hepatoprotective effect due to the reduction in ALT and AST and a reduction in TNF-α, indicating a modulation of the immune response. In general, BG effects were better than n-3 supplement (or at least comparable) depending on the dose.

Sublethal concentrations of acetylcarvacrol affect reproduction and integument morphology in the brown dog tick Rhipicephalus sanguineus sensu lato (Acari: Ixodidae).

Rhipicephalus sanguineus sensu lato (s.l.), also known as the brown dog tick, is among the main tick species involved in the transmission of pathogens to humans and other animals and, therefore, the target of numerous control methods. However, due to the disadvantages of synthetic acaricides, the use of alternative products such as plant derivatives has been encouraged. This study aimed to evaluate the acaricidal potential of acetylcarvacrol and to determine its efficacy at sublethal doses for the control of R. sanguineus s.l. female ticks. In addition, as acetylcarvacrol was applied topically, morphological alterations in the integument were assessed. Acetylation of carvacrol was performed by reaction with acetic anhydride in a sodium hydroxide solution, being confirmed by infrared spectroscopy. The lethal concentration for 50 and 90% (LC50 and LC90) of unfed ticks and the efficacy of acetylcarvacrol in engorged females were determined after the Adult Immersion Test (AIT). For the evaluation of effects of acetylcarvacrol in the integument, routine histological techniques were employed after the AIT. The LC50 and LC90 in unfed females were 2.8 and 7.2 µL/mL, respectively. Regarding reproductive performance, after treatment with 8.0 µL/mL acetylcarvacrol 90.9% control was achieved, as ticks showed the lowest egg production index (EPI), hatching rate (HR), and fecundity rate (FR). In the integument, considerable morphological alterations were observed both in cuticle and epithelium. Thus, acetylcarvacrol affected R. sanguineus s.l. external coating and reproduction when applied at sublethal concentrations, probably contributing to a long-term control.

Low concentrations of acetylcarvacrol induce drastic morphological damages in ovaries of surviving Rhipicephalus sanguineus sensu lato ticks (Acari: Ixodidae).

Rhipicephalus sanguineus sensu lato (s. l.) ticks are targets of acaricidal treatments due to their great veterinary and medical importance. Acetylcarvacrol stands out as a promising acaricidal substance for its increased biocidal activity and stability. Additionally, its toxicity to mammals is reduced when compared to the parent molecule, carvacrol. The present study aimed to evaluate the effects of acetylcarvacrol on the morphology of ovaries of engorged R. sanguineus s. l. ticks. The animals were subjected to the Adult Immersion Test to calculate the lethal concentrations (LC50 and LC90) of acetylcarvacrol. Subsequently, the surviving ticks were dissected for collection of the ovaries. The samples were processed through routine histological techniques. The histological sections were stained with hematoxylin and eosin, bromophenol blue (protein detection) and PAS (polysaccharide detection). The alterations found in the ovaries were evaluated by morphometric and semiquantitative analysis. The LC50 and LC90 were 17.805 and 26.164 µL/mL, respectively. The most severe morphological alterations were disappearance of the female germ cells (oocytes), nucleolus vacuolization, thicker and irregular chorion, and decrease in size of the oocytes. Also, the content of proteins and carbohydrates in the oocytes were heavily affected by the chemical, as evidenced by a non-homogeneous staining pattern. The group exposed to the highest concentration of acetylcarvacrol (20 µL/mL) exhibited a statistically greater score in the semiquantitative analysis when compared to the other groups. The morphological changes in the ovaries may reduce the ticks' offspring production or generate descendants that will struggle to carry out essential biochemical processes during their lives. Thus, acetylcarvacrol may be a promising alternative to control tick infestation by impairing the reproduction of this parasite.