Anxiolytic and Antidepressant-like Effects of Monoterpene Tetrahydrolinalool and In silico Approach of new Potential Targets.

INTRODUCTION: Although drugs currently available for the treatment of anxiety and depression act through modulation of the neurotransmission systems involved in the neurobiology of the disorder, yet they often present side effects, which can impair patient adherence to treatment. METHODS: This has driven the search for new molecules with anxiolytic and antidepressant potential. Aromatic plants are rich in essential oils, and their chemical constituents, such as monoterpenes, are being studied for these disorders. This study aims to evaluate the anxiolytic and antidepressant-like potential of the monoterpene tetrahydrolinalool in in vivo animal models and review pharmacological targets with validation through molecular docking. Male Swiss mice (Mus musculus) were treated with THL (37.5-600 mg kg-1 p.o.) and submitted to the elevated plus maze, open field, rotarod, and forced swim tests. In the elevated plus-maze, THL at doses of 37.5 and 75 mg kg-1 induced a significant increase in the percentage of entries (72.7 and 64.3% respectively), and lengths of stay (80.3 and 76.8% respectively) in the open arms tests. RESULTS: These doses did not compromise locomotor activity or motor coordination in the animals. In the open field, rotarod tests, and the forced swimming model, treatment with THL significantly reduced immobility times at doses of 150, 300, and 600 mg kg-1, and by respective percentages of 69.3, 60.9 and 68.7%. CONCLUSION: In molecular docking assay, which investigated potential targets, THL presented satisfactory energy values for: nNOs, SGC, IL-6, 5-HT1A, NMDAr, and D1. These demonstrate the potential of THL (a derivative of natural origin) in in vivo and in silico models, making it a drug candidate.

Antinociceptive, anti-inflammatory and antioxidant activities of the crude ethanolic extract and alkaloid fraction of Waltheria viscosissima A. St. - Hil. (Malvaceae).

ETHNOPHARMACOLOGICAL RELEVANCE: The Waltheria viscosissima A. St.- Hil (Malvaceae) is also known as 'Malva branca', has been reported as ethnopharmacologically useful plant containing antinociceptive and anti-inflammatory properties, but scientific evidence is absent. AIM OF THE STUDY: Elucidate the antinociceptive, anti-inflammatory and antioxidant activity of the crude ethanol extract (EEBWa.v) and alkaloid fraction (FAWa.v) of aerial parts of the W. viscosissima in healthy mice with induced inflammation. MATERIALS AND METHODS: EEBWa.v and FAWa.v (50, 100 and 200 mg/kg) and morphine (10 mg/kg) were used in vivo tests of chemical nociception induced by acetic acid (0.6%; 10 mg/kg) and formalin (2.5%) in Swiss male mice. Acute inflammation was induced by carrageenan (1%) in vivo tests and there were several groups tested. The control (inflammation induced without treatment) and the groups treated with EEBWa.v (100 mg/kg), FAWa.v (100 mg/kg) and dexamethasone (2 mg/kg). After this procedure, the animals were euthanized and the peritoneal fluid was collected to evaluate cell migration and redox balance (malondialdehyde - MDA and Total Antioxidant Capacity - TAC). RESULTS: The morphine, EEBWa.v (50 and 100 mg/kg) and FAWa.v (100 mg/kg) significantly reduced the number of abdominal writhes compared to the control group. FAWa.v (100 mg/kg) was superior to FAWa.v (200 mg/kg). In the formalin-induced nociception model (neurogenic phase) EEBWa.v (50 and 200 mg/kg) significantly reduced the number of paw licks. In the inflammatory phase with peripheral action, FAWa.v (100 mg/kg) was superior to EEBWa.v (200 mg/kg). EEBWa.v and FAWa.v (100 mg/kg) proved to be significant for the next experiments. Both samples showed reduction in cell migration, as well as those treated with dexamethasone, in animals with inflammation induced by carrageenan, compared to the untreated group. The redox balance (TAC and MDA) revealed that only EEBWa.v (100 mg/kg) had higher antioxidant potential than the untreated group and the dexamethasone group, p < 0.005 and p < 0.001, respectively. FAWa.v (100 mg/kg) did not show antioxidant activity superior to EEBWa.v. It was also detected that EEBWa.v and FAWa.v (100 mg/kg) failed to inhibit lipid peroxidation. CONCLUSIONS: The W. viscosissima stimulates pain control, which can be mediated by both central and peripheral action. These bioactive compounds showed promising and potential to replace standard medicines. This bioactive effect is statistically similar to morphine and dexamethasone, standard medicines on the market, but with the advantage of antioxidant activity.

COVID-19: Is reinfection possible?

The COVID-19 pandemic has spread rapidly in many countries, overburdening health systems and causing numerous economic and social impacts. Most studies on the subject have focused on epidemiology, diagnosis, and treatment, however, there remains a scientific gap concerning the possibility of reinfection. The purpose of this bibliographic review is to gather information from studies aimed at this possibility, and to clarify what we know so far. It was found that in many situations cured patients are being released from hospitals, however, in some cases, the discharge criteria are not effective. Patients are presenting positive RT-PCR tests. There are several factors that might interfere so that patients cured of COVID-19 continue to test positive, and this would not necessarily represent a case of recurrence, as the test cannot differentiate the viral RNA from the complete virus, which alone is capable of causing the active infection. This review demonstrates that in order to rule out the possibility of COVID-19 reinfection in cured patients, more robust methods need to be adopted as criteria for both clinical discharge and post-hospital follow-up.

Psychopharmacological effects of riparin III from Aniba riparia (Nees) Mez. (Lauraceae) supported by metabolic approach and multivariate data analysis.

BACKGROUND: Currently there is a high prevalence of humor disorders such as anxiety and depression throughout the world, especially concerning advanced age patients. Aniba riparia (Nees) Mez. (Lauraceae), popular known as "louro", can be found from the Amazon through Guianas until the Andes. Previous studies have already reported the isolation of alkamide-type alkaloids such as riparin III (O-methyl-N-2,6-dyhydroxy-benzoyl tyramine) which has demonstrated anxiolytic and antidepressant-like effects in high doses by intraperitoneal administration. METHODS: Experimental protocol was conducted in order to analyze the anxiolytic-like effect of riparin III at lower doses by intravenous administration to Wistar rats (Rattus norvegicus) (n = 5). The experimental approach was designed to last 15 days, divided in 3 distinct periods of five days: control, anxiogenic and treatment periods. The anxiolytic-like effect was evaluated by experimental behavior tests such as open field and elevated plus-maze test, combined with urine metabolic footprint analysis. The urine was collected daily and analyzed by 1H NMR. Generated data were statistically treated by Principal Component Analysis in order to detect patterns among the distinct periods evaluated as well as biomarkers responsible for its distinction. RESULTS: It was observed on treatment group that cortisol, biomarker related to physiological stress was reduced, indicating anxiolytic-like effect of riparin III, probably through activation of 5-HT2A receptors, which was corroborated by behavioral tests. CONCLUSION: 1H NMR urine metabolic footprint combined with multivariate data analysis have demonstrated to be an important diagnostic tool to prove the anxiolytic-like effect of riparin III in a more efficient and pragmatic way.

Antinociceptive activity of the extract of Erythroxylum caatingae / Actividad antinociceptiva del extracto de Erythroxylum caatingae

The genus Erythoxylum plants are popularly used as anti-inflammatory, anti-bacterial, and diuretic agentes, and for treating of respiratory problems. This study investigated the antinociceptive activity of methanolic extract of Erythroxylum caatingae (EcME) in chemical (formalin test and acetic acid test) and thermal models (hot plate test) of nociception. Intraperitoneal pre-treatment with EcME reduced the number of abdominal contortions and the licking time in the second phase of the formalin test. EcME did not show a significant effect in the hot plate test, rota-rod test, and the elevated plus maze test. These findings indicate that the antinociceptive activity of EcME is not because of a depressor effect on the central nervous system, and EcME is not a muscle relaxant. Nevertheless, Erythroxylum caatingae demonstrated peripheral antinociceptive activity, which confirms its popular use and contributes to the scientific knowledge of the species.

El género Erythoxylum es popularmente utilizado como agente anti-inflamatorio, antibacteriano y para el tratamiento de problemas respiratorios. Este estudio tiene como objetivo investigar la actividad antinociceptiva del extracto metanólico Erythroxylum caatingae (EcME), utilizando modelos químicos (prueba de la formalina y prueba de ácido acético) y térmico (prueba de la placa caliente) de nocicepción. El pretratamiento EcME por la vía intraperitoneal (i.p.), fue capaz de reducir el número de contorsiones abdominales y el tiempo de lamida en la segunda fase del test de formalina. EcME no tuvo efecto significativo en el test de la placa caliente, Rota-Rod y Laberinto en Cruz Elevado, mostrando que el efecto antinociceptivo no está relacionado con un efecto depresor del sistema nervioso central o miorelajante. Los datos experimentales muestran que Erythroxylum caatingae posee una actividad antinociceptiva periférica que confirma su uso popular, contribuyendo para el conocimiento científico de la especie.

Total Phenolic Content and Antioxidant Activity of Some Malvaceae Family Species.

The antioxidant activity of four species of the Malvaceae family (Sidastrum micranthum (A. St.-Hil.) Fryxell, Wissadula periplocifolia (L.) C. Presl, Sida rhombifolia (L.) E. H. L and Herissantia crispa L. (Brizicky)) were studied using the total phenolic content, DPPH radical scavenging activity and Trolox equivalent antioxidant capacity (TEAC) assays. The antioxidant activity of the crude extract, phases and two isolated flavonoids, kaempferol 3,7-di-O-α-l-rhamnopyranoside (lespedin) and kaempferol 3-O-ß-d-(6''-E-p-coumaroil) glucopyranoside (tiliroside) was determined. The results showed that there is a strong correlation between total polyphenol contents and antioxidant activity of the crude extract of Sidastrum micranthum and Wissadula periplocifolia; however, this was not observed between Sida rhombifolia and Herissantia crispa. The ethyl acetate (EaF) phase showed the best antioxidant effect in the total phenolics, DPPH and TEAC assays, followed by the chloroform (CfF) phase, in most species tested. Lespedin, isolated from the EaF phase of W. periplocifolia and H. crispa may not be responsible for the antioxidant activity due to its low antioxidant activity (IC50: DPPH: 1,019.92 ± 68.99 mg/mL; TEAC: 52.70 ± 0.47 mg/mL); whereas tiliroside, isolated from W. periplocifolia, H. crispa and S. micrantum presented a low IC50 value (1.63 ± 0.86 mg/mL) compared to ascorbic acid in the TEAC assay.