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BackgroundInfections of sheep with gastrointestinal parasites, especially Haemonchus contortus, have caused serious losses in livestock production, particularly after the emergence of resistance to conventional anthelmintics. The search for new anthelmintic agents, especially those of botanical origin, has grown substantially due to the perspective of less contamination of meat and milk, as well as other advantages related to their cost and accessibility in less developed countries. The aim of this study was to evaluate the in vitro anthelmintic activity of essential oils of the plant species Citrus aurantifolia, Anthemis nobile and Lavandula officinalis against the main developmental stages of the parasite H. contortus.ResultsPlant species were selected based on substantial ethnopharmacological information. Analysis of the composition of each oil by gas chromatography coupled to mass spectrometry (GC-MS) demonstrated the presence of limonene (56.37%), isobutyl angelate (29.26%) and linalool acetate (35.97%) as the major constituents in C. aurantifolia, A. nobile and L. officinalis, respectively. Different concentrations of each oil were tested in vitro for their capacity to inhibit egg hatching (EHT), larval development (LDT) and adult worm motility (AWMT) using a multidrug-resistant strain of H. contortus (Embrapa 2010). The IC50 values obtained for the oils of C. aurantifolia, A. nobile and L. officinalis were 0.694, 0.842 and 0.316 mg/ml in the EHT and 0.044, 0.117 and 0.280 mg/ml in the LDT, respectively. The three oils were able to inhibit adult worm motility completely within the first 8–12 h of observation in the AWMT.ConclusionsThe present results demonstrate significant anthelmintic activity of the three oils against the different developmental stages of H. contortus. Furthermore, this study is of ethnopharmacological importance by validating the anthelmintic activity of the oils studied. Although new experiments are necessary, these data contribute to the development of pharmaceutical-veterinary products for sheep farming by opening up new therapeutic possibilities against gastrointestinal infections caused by H. contortus.

Depression and anxiety are common neuropsychiatric disorders that usually appear as comorbidities. The development of new drugs is crucial for safer and more effective clinical management of both disorders. Riparin A is a synthetic chemical analog of riparins that naturally occur in several medicinal plants. Marked pharmacological effects such as anxiolytic and antidepressant properties characterize this class of compounds. However, little is known about the potential anxiolytic and antidepressant effects of Riparin A. In this work, we showed that, unlike other riparins, Riparin A exerts only a very mild anxiolyticlike effect as demonstrated by the results of classical behavioral tests such as the elevated plus-maze, lightdark box and open-field tests in rats. However, all doses of Riparin A (2.5; 5.0 and 10 mg/kg; intraperitoneal) have shown significant antidepressant activity in rats submitted to forced swimming test. In addition to this interesting pharmacological property, Riparin A did not promote any important alterations in the locomotor performance of the animals as specifically demonstrated by the rotarod test. Furthermore, Riparin A did not induce sedation in treated animals; instead, this compound appears to increase the animal's state of alertness as measured by the latency time to loss of reflexes and time to recovery from sleep in rats submitted to the pentobarbital-induced sleep time test. The present results point to an antidepressant effect of Riparin A and reinforce the pharmaceutical interest in the group of riparins, particularly their high potential for use in new studies investigating the structure-activity relationships between member compounds. Behavioural