Aldilene da Silva Lima

Acaricidal activity of essential oils from Lippia alba genotypes and its major components carvone, limonene, and citral against Rhipicephalus microplus

The goal of the present study was to evaluate the acaricidal potential of Lippia alba essential oil, citral chemotypes (LA-10 and LA-44 genotypes) and carvone chemotypes (LA-13 and LA-57 genotypes), as well as purified citral and enantiomers of carvone and limonene. Efficacy against Rhipicephalus microplus was assessed by the larval packet and the engorged female immersion tests. Citral chemotypes had greater larvicidal activity than carvone chemotypes, and this was further supported by larvicidal and adulticidal activity of purified citral with LC50 values of 7.0 and 29.8 mg/mL, respectively. While purified enantiomers of carvone exhibited greater larvicidal activity than those of limonene, enantioselectivity of limonene was observed with R-(+) displaying significantly higher efficacy (LC50 of 31.2mg/mL) than S-(-) (LC50 of 54.5mg/mL). The essential oils and purified compounds were much less toxic toward engorged adult females, with the exception of citral, and this may be due to limited cuticular penetration.

Acaricide activity of different extracts from Piper tuberculatum fruits against Rhipicephalus microplus

Rhipicephalus microplus is the main tick that affects cattle. Plant bioactive molecules can be used to control this ectoparasite. The aim of this study was to evaluate the in vitro efficacy of Piper tuberculatum fruit extracts obtained with different solvents on R. microplus larvae and engorged females. Hexane, ethyl ether, ethanolic, and methanolic extracts of P. tuberculatum fruits were evaluated. After extraction, all of the extracts were dried. Adult immersion tests and larval packet tests were performed with five different concentrations of each of the extracts. The hexane extracts of P. tuberculatum showed the highest larvicidal activity against R. microplus (lethal concentration (LC50u2009=u20090.04xa0mg/mL), followed by the ethyl ether (LC50u2009=u20090.08xa0mg/mL), ethanolic (LC50u2009=u20092.73xa0mg/mL), and methanolic (LC50u2009=u20094.49xa0mg/mL) extracts. The P. tuberculatum fruit extracts were also effective against R. microplus-engorged females. Ethyl acetate extracts showed the highest efficiency (LC50u2009=u200918.4xa0mg/mL), followed by the methanolic (LC50u2009=u2009105.6xa0mg/mL), ethanolic (LC50u2009=u2009140.0xa0mg/mL), and hexane (LC50u2009=u2009297.4xa0mg/mL) extracts. All of the extracts showed similar chromatographic profiles containing 24xa0% piperine. The P. tuberculatum fruit extracts contain bioactive compounds with great potential to improve the standard formulations of acaricides for the control of R. microplus.Rhipicephalus microplus is the main tick that affects cattle. Plant bioactive molecules can be used to control this ectoparasite. The aim of this study was to evaluate the in vitro efficacy of Piper tuberculatum fruit extracts obtained with different solvents on R. microplus larvae and engorged females. Hexane, ethyl ether, ethanolic, and methanolic extracts of P. tuberculatum fruits were evaluated. After extraction, all of the extracts were dried. Adult immersion tests and larval packet tests were performed with five different concentrations of each of the extracts. The hexane extracts of P. tuberculatum showed the highest larvicidal activity against R. microplus (lethal concentration (LC50u2009=u20090.04xa0mg/mL), followed by the ethyl ether (LC50u2009=u20090.08xa0mg/mL), ethanolic (LC50u2009=u20092.73xa0mg/mL), and methanolic (LC50u2009=u20094.49xa0mg/mL) extracts. The P. tuberculatum fruit extracts were also effective against R. microplus-engorged females. Ethyl acetate extracts showed the highest efficiency (LC50u2009=u200918.4xa0mg/mL), followed by the methanolic (LC50u2009=u2009105.6xa0mg/mL), ethanolic (LC50u2009=u2009140.0xa0mg/mL), and hexane (LC50u2009=u2009297.4xa0mg/mL) extracts. All of the extracts showed similar chromatographic profiles containing 24xa0% piperine. The P. tuberculatum fruit extracts contain bioactive compounds with great potential to improve the standard formulations of acaricides for the control of R. microplus.

An ethnopharmacological assessment of the use of plants against parasitic diseases in humans and animals.

ETHNOPHARMACOLOGICAL RELEVANCEnEthnobotanical surveys are detecting an increasing frequency of exotic plant species in pharmacopeias, which has led researchers to investigate the role of such species in traditional medical systems. According to the diversification hypothesis, exotic species are included to complete pharmacopeias, i.e., to treat diseases for which no native species are known, thus broadening the scope of the plant repertoire.nnnMATERIALS AND METHODSnThe present study was conducted at two rural communities in northeastern Brazil aiming at a survey of the plants known or used by the population to treat endo- and ectoparasitic diseases in humans and animals. In addition, plant extracts exhibiting acaricide activity were assessed using the engorged female immersion and larval packet tests (LPT).nnnRESULTSnThe results of the present study showed a tendency for native species to be used against ectoparasites and exhibit a broader scope of use compared to exotic species. In turn, exotic species were predominantly indicated to treat diseases caused by endoparasites, although there was an overlap of native and exotic species relative to some therapeutic purpose, e.g., ticks. Only two of the plant species tested exhibited acaricide activity (Nicotiana glauca Graham and Croton blanchetianus Baill.), and in both cases, the activity was weak.nnnCONCLUSIONnThe ethnobotanical data do not fully support the suggested hypothesis. Overall, the wide versatility of exotic species was not exclusively used to treat parasitic diseases in humans and animals. In addition, the selection of acaricide plants based on the ethnopharmacological study generated uninteresting results.

Chemical composition and acaricide activity of an essential oil from a rare chemotype of Cinnamomum verum Presl on Rhipicephalus microplus (Acari: Ixodidae)

The Essential Oils (EOs) from the leaves of species Cinnamomum verum J. Presl are used in the pharmaceutical industry for their numerous biological activities. Currently, the main compound of C. verum EO is eugenol which has acaricidal activity; however, a rare chemotype with benzyl benzoate as the main component can be found. Benzyl benzoate is recognized as an acaricide; however, studies of the C. verum EOs benzyl benzoate chemotype on Rhipicephalus microplus were not reported. The aim of this study was to evaluate the acaricide activity of an EO from a rare chemotype of C. verum, as well as purified benzyl benzoate, against larvae and engorged females of R. microplus resistant to amidines and pyrethroids. The EO was extracted from C. verum leaves and the compounds present were identified using a gas phase chromatograph coupled to a mass spectrometer. Efficacy against R. microplus was assessed by the larval packet and the engorged female immersion tests. A rare chemotype of C. verum was found to produce EOs with benzyl benzoate (65.4%) as the main compound. The C. verum essential oil was 3.3 times more efficient on the R. microplus larvae than was benzyl benzoate. However, no differences were found on the R. microplus engorged females. This is the first report regarding the acaricidal activity of C. verum with chemotype benzyl benzoate, and this compound showed acaricidal activity on R. microplus larvae.

Seasonal analysis and acaricidal activity of the thymol-type essential oil of Ocimum gratissimum and its major constituents against Rhipicephalus microplus (Acari: Ixodidae)

The tick Rhipicephalus microplus affects cattle health, with production loss in tropical and subtropical regions. Moreover, the use of commercial acaricides has been reduced due to the resistance of this parasite. Although alternatives such as plant bioactive molecules have been sought, essential oils present variations in their chemical constituents due to environmental factors, which can interfere with their acaricidal activity. The objective of the present study was to evaluate the seasonal influence of the essential oil of Ocimum gratissimum and its major constituents on acaricidal activity against R. microplus larvae. A high-yield essential oil of O. gratissimum and its major constituents were used, and a plant with a thymol-type oil was selected for seasonal analysis and acaricidal activity against R. microplus. Gas chromatography (GC) and GC-mass spectrometry (MS) were employed to identify 31 oil constituents (average yield of 6.26%). The main compounds were found to be thymol (33.4 to 47.9%), γ-terpinene (26.2 to 36.8%), and p-cymene (4.3 to 17.0%). Concerning acaricidal activity, the December (LC50 0.84xa0mg/mL) and September (LC50 1.58xa0mg/mL) oils obtained in the dry season were the most active, and assays performed with commercial standards revealed LC50 values of p-cymene, thymol, and γ-terpinene of 1.41, 1.81, and 3.08xa0mg/mL, respectively. Overall, lower acaricidal activities were found for oils produced from plants harvested in the rainy season. The results showed that seasonal variation in the chemical composition of the O. gratissimum essential oil influences its acaricidal activity. The seasonal variations in the thymol-type essential oil of O. gratissimum can represent an important strategy for the control of R. microplus.

Anthelmintic activity of plant extracts from Brazilian savanna

Helminth infections represent a serious problem for the production of small ruminants that is currently aggravated by resistance to anthelmintic products and has induced a search for control alternatives, such as natural products. In this study, extracts of Turnera ulmifolia L. (leaves and roots), Parkia platycephala Benth. (leaves and seeds) and Dimorphandra gardneriana Tul. (leaves and bark), which have been cited in ethnoveterinary studies and selected naturally by goats in the cerrado (Brazilian savanna), were tested in vitro against Haemonchus contortus. Hydroacetonic (ACT) and hydroalcoholic (ETH) extracts were evaluated using an Egg Hatching Assay (EHA), a Larval Exsheathment Inhibition Assay (LEIA) and a Larval Development Assay (LDA). A second set of incubations was performed using polyvinylpolypyrrolidone (PVPP) to determine the influence of polyphenols on the anthelmintic effects of EHA and LEIA. Data from each extract were used to calculate inhibition concentrations (IC50). All tested extracts showed activity against at least one life stage of H. contortus. The use of PVPP revealed that the tannins are not the only extracts of secondary metabolites responsible for the anthelmintic effects. The results showed clear in vitro anthelmintic activities against H. contortus at different stages and indicated the potential use of these species as a promising alternative approach to control helminthic infections of small ruminants.

In vitro and in vivo activity of hydrolyzed Saccharomyces cerevisiae against goat nematodes

Haemonchus contortus is the most prevalent nematode in tropical and subtropical regions and is responsible for significant losses in small ruminant production systems. Control of this parasite is based on the use of synthetic anthelmintics; although effective, prolonged and indiscriminate use can select for populations of resistant nematodes. Hydrolyzed yeast can help prevent populations of nematodes and is low in cost. The present study aimed to evaluate the preventive effect of hydrolyzed yeast on H. contortus through in vitro and in vivo assays. In in vitro experiments, the yeast preparation was tested at different stages of the H. contortus life cycle via tests of egg hatchability, larval development, larval exsheathment and larval migration. Both eggs and L3 larvae were obtained from sheep artificially infected with a monospecific strain of H. contortus. In in vivo experiments, animals were treated with hydrolyzed yeast (53.4u202fmg/kg/BW), and fecal egg counts (FECs), feces culture and Famacha were performed. The yeast preparation inhibited larval exsheathment in a dose-dependent manner (IC95 of 0.46u202fmg/mL), though no activity at the other stages of the H. contortus life cycle was observed. The hydrolyzed yeast preparation was able to reduce FECs in treated animals from D40 to D54 (pu202f<u202f0.05), showing an average efficiency of 60%. The yeast exhibited preventive properties, and the IC95 value suggests that H. contortus is highly susceptible. Our results indicate that administration of hydrolyzed yeast, which is already used commercially in ruminant nutrition, is an alternative method for the control of nematodes, mainly H. contortus.