Activity of essential oil of Lippia triplinervis Gardner (Verbenaceae) on Rhipicephalus microplus (Acari: Ixodidae).

The objective of this work was to characterize and investigate the acaricidal activity of the essential oil of the aerial parts of Lippia triplinervis at different concentrations on unengorged larvae and engorged females of Rhipicephalus microplus. The essential oil yielded 2.21 % (w/w to dry matter) and was composed mainly of carvacrol (31.9 %), thymol (30.6 %), and p-cymene (12.3 %). Two tests were performed to assess the acaricidal activity: the modified larval packet test, with concentrations of 2.5, 5.0, 10.0, 15.0, and 20.0 mg/mL and the female immersion test, with concentrations of 10.0, 20.0, 30.0, 40.0, and 50.0 mg/mL. There were ten repetitions for each concentration, and for each test, a control group was formed in which the ticks were treated with Tween 80 (20 mg/mL). The experimental groups were kept in a climate-controlled chamber (27 ± 1 °C and RH >80 %). The mortality of the larvae was above 95 % in all the groups tested and reached 100 % as of the 5.0 mg/mL concentration, while the control group exhibited 0 % mortality. In the female immersion test, there was a significant decline (p < 0.05) in the egg mass weight, egg production index, and hatching percentage starting at the concentration of 30.0, 40.0, and 20.0 mg/mL, respectively, and the control percentage at the concentrations of 40.0 and 50.0 mg/mL were above 90 and 95 %. The L. triplinervis oil as thus an alternative source of the monoterpenes thymol, carvacrol, and p-cymene, and its toxicity on R. microplus larvae and females makes it promising possibility for control of this tick.

Combination of entomopathogenic nematodes with acaricides or essential oil of Lippia triplinervis against Rhipicephalus microplus (Acari: Ixodidae).

This study aimed to evaluate the combination effect of Heterorhabditis bacteriophora HP88 and H. indica LPP1, with the acaricides deltamethrin, amitraz and chlorfenvinphos, and the essential oil (EO) of Lippia triplinervis, against engorged females of Rhipicephalus microplus. In order to verify the effect of acaricides and EO, the adult immersion test was used, and in the groups treated only with entomopathogenic nematodes (EPNs), 150 infective juveniles were used per female. In the treatments with nematodes in combination with the acaricides or EO, the females were immersed in the solutions (acaricide or EO) and then transferred to Petri dishes for application of the nematodes. The treatment with acaricides resulted in a control percentage lower than 70%, except in the group treated with chlorfenvinphos in the second experiment (84.3%). The control percentage was 73% for L. triplinervis EO, and greater than 90% in all the groups treated with nematodes. For treatments with EPNs combined with the acaricides or EO, the efficacy was greater than 95% (except for deltamethrin + HP88), and reached 100% in the treatment with LPP1 + amitraz. It can be concluded that the EPNs at the concentrations tested were compatible with the acaricides deltamethrin, amitraz and chlorfenvinphos, and with the EO of L. triplinervis. These combinations enhance the effect of these control agents.

Usnic acid enantiomers restore cognitive deficits and neurochemical alterations induced by Aß1-42 in mice.

Alzheimer's disease (AD) is the most prevalent form of dementia with a complex pathophysiology not fully elucidated but with limited pharmacological treatment. The Usnic acid (UA) is a lichen secondary metabolite found in two enantiomeric forms: (R)-(+)-UA or (S)-(-)-UA, with antioxidant and anti-inflammatory potential. Thus, given the role of neuroinflammation and oxidative injury in the AD, this study aimed to investigate experimentally the cognitive enhancing and anti-neuroinflammatory effects of UA enantiomers. First, the interactions of UA on acetylcholinesterase (AChE) was assessed by molecular docking and its inhibitory capability on AChE was assessed in vitro. In vivo trials investigated the effects of UA enantiomers in mice exposed to Aß1-42 peptide (400 pmol/mice) intracerebroventricularly (i.c.v.). For this, mice were treated orally during 24 days with (R)-(+)-UA or (S)-(-)-UA at 25, 50, or 100 mg/kg, vehicle, or donepezil (2 mg/kg). Animals were submitted to the novel object recognized, Morris water maze, and inhibitory-avoidance task to assess the cognitive deficits. Additionally, UA antioxidant capacity and neuroinflammatory biomarkers were measured at the cortex and hippocampus from mice. Our results indicated that UA enantiomers evoked complex-receptor interaction with AChE like galantamine in silico. Also, UA enantiomers improved the learning and memory of the animals and in parallel decreased the myeloperoxidase activity and the lipid hydroperoxides (LOOH) on the cortex and hippocampus and reduced the IL-1ß levels on the hippocampus. In summary, UA restored the cognitive deficits, as well as the signs of LOOH and neuroinflammation induced by Aß1-42 administration in mice.