In vitro activity of usnic acid potassium salt against different developmental stages of Schistosoma mansoni: An ultrastructural study.

Currently, the control of schistosomiasis is based on a single drug, praziquantel, which is effective against all species of Schistosoma but only in the adult stage, presenting a schistosomicidal deficit at the other developmental stages of the parasites. Recently our research group has demonstrated that the potassium salt of usnic acid (PS-UA) presented schistosomicidal property against couples of adult worms of S. mansoni. Thus, the present study seeks to report for the first time the in vitro activity of PS-UA against different developmental stages of S. mansoni (schistosomules and young worms). As schistosomicide parameters, we evaluated motility, mortality, cell viability of the worms and tegument changes by scanning electron microscopy (SEM). After 3 h exposure, PS-UA was lethal to schistosomules at concentrations of 100 and 50 µM, whereas for concentrations 25 and 12.5 µM, 38 and 18% of mortality and 62 and 24% changes in motility, respectively, were reached. Yet for schistosomules, concentration of 25 µM caused 90 and 100% of death after 6 and 12 h, respectively. In the concentration of 12.5 µM at intervals of 12 and 24 h mortality was 68 and 100%, respectively. For young worms, after 3 h of exposure at concentrations of 200 and 100 µM caused 57 and 27% mortality, respectively. After 12 and 24 h, these concentrations caused mortality of 90 and 100% and 47 and 60% respectively. After 24 h, concentrations of 50 and 25 µM caused 80 and 30% change in motility, respectively. However, at the 12.5 µM concentration no change was observed. In addition, PS-UA reduced the cellular viability of young worms by 50.98% and 85.87% at concentrations of 100 and 200 µM, respectively. In both stages of worms and at different exposure intervals, PS-UA caused alterations such as: dorsoventral contraction, peeling, swelling, blisters, erosion, exposure of subtegumental tissue and disintegration of tegument. According to the results, changes in motility and mortality caused by PS-UA against schistosomules and young worms were concentration and time-dependents, also PS-UA even at low concentration, was able to cause profound ultrastructural changes in the integument of the worms. PS-UA is a promising candidate as prophylactic agent in the control of schistosomiasis mansoni.

Potassium usnate, a water-soluble usnic acid salt, shows enhanced activity against Schistosoma mansoni in vitro.

Here, we report enhanced the in vitro effect of potassium usnate on coupled adult Schistosoma mansoni worms at different time intervals and concentrations. The evaluated schistosomicidal parameters were the following: motility, mortality, fecundity and integumentary changes, as viewed in photomicrographs. Potassium usnate was able to cause 100 and 50% mortality at 100 and 50 µM concentrations, respectively, after 24 h of exposure, while 25 and 12.5 µM concentrations caused changes in motility at 48 and 72 h, and lethality at 96 and 120 h respectively. Eggs were not detected at any of the concentrations analyzed. Photomicrographs revealed morphological tegument alterations within all periods of observation, such as swelling, blisters, dorsoventral contraction, short and curved worms. In conclusion, our results indicate that potassium usnate represents a possible candidate for a new drug in the control of schistosomiasis.

Usnic Acid Potassium Salt: Evaluation of the Acute Toxicity and Antinociceptive Effect in Murine Model.

To obtain usnic acid potassium salt (PS-UA), the usnic acid (UA) was extracted and purified from the lichen Cladonia substellata, and modified to produce PS-UA. The structure was determined by 1H-NMR, IR and elemental analysis, ratified through computational models, as well as identification the site of K+ insertion in the molecule. Antinociceptive activity was detected through contortions in mice induced by acetic acid and formalin (phases I and II) after treatments with 10 and 20 mg/kg of PS-UA, indicating interference in both non-inflammatory and inflammatory pain. After oral administration at doses of 500, 1000 and 2000 mg/kg, no deaths of mice with treatments below 2000 mg/kg were observed. Except for body weight gain, food and water consumption decreased with treatments of 1000 and 2000 mg/kg, and the number of segmented leukocytes was higher for both treatments. Regarding serum levels, cholesterol and triglycerides decreased, however, there was an increase in hepatic transaminases with both treatments. Liver and kidney histological changes were detected in treatments of 2000 mg/kg, while the spleen was preserved. The PS-UA demonstrated antinociceptive activity while the acute toxicity at the concentration of 2000 mg/kg was the only dose that presented morphological changes in the liver and kidney.

In vitro antimicrobial activity of the organic extract of Cladonia substellata Vainio and usnic acid against Staphylococcus spp. obtained from cats and dogs / Atividade antimicrobiana in vitro do extrato orgânico de Cladonia substellata Vainio e ácido úsnico frente Staphylococcus spp. obtidos de cães e gatos

ladonia substellata Vainio is a lichen found in different regions of the world, including the Northeast of Brazil. It contains several secondary metabolites with biological activity, including usnic acid, which has exhibited a wide range of biological activities. The aim of this study was to evaluate the in vitro antimicrobial activity of the organic extract of C. substellata and purified usnic acid. Initially, Staphylococcus spp., derived from samples of skin and ears of dogs and cats with suspected pyoderma and otitis, were isolated and analyzed. In antimicrobial susceptibility testing against Staphylococcus spp., 77% (105/136) of the isolates were resistant to the antimicrobials tested. In the assessment of biofilm production, 83% (113/136) were classified as producing biofilm. In genetic characterization, 32% (44/136) were positive for blaZ, no isolate (0/136) was positive for the mecA gene, and 2% (3/136) were positive for the icaD gene. The in vitro antimicrobial activity of the organic extract of C. substellata and purified usnic acid against Staphylococcus spp. ranged from 0.25mg/mL to 0.0019mg/mL, inhibiting bacterial growth at low concentrations. The substances were more effective against biofilm-producing bacteria (0.65mg/mL-0.42mg/mL) when compared to non-biofilm producing bacteria (2.52mg/mL-2.71mg/mL). Usnic acid and the organic extract of C. substellata can be effective in the treatment of pyoderma and otitis in dogs and cats caused by Staphylococcus spp.(AU)

Cladonia substellata Vainio é um líquen encontrado em diversos continentes do mundo, inclusive no nordeste do Brasil, possui vários metabólitos secundários com atividade biológica, entre eles, o ácido úsnico, que tem apresentado uma vasta gama de atividades biológicas. O objetivo deste trabalho foi avaliar a atividade antimicrobiana in vitro do extrato orgânico de C. substellata e do ácido úsnico purificado. Para isto, foram isolados Staphylococcus spp. de amostras de pele e orelha de cães e gatos com suspeita de piodermatite e otite. No teste de sensibilidade aos antimicrobianos frente Staphylococcus spp., 77% (105/136) foram resistentes. Na avaliação da produção de biofilme 83% (113/136) foram classificadas como produtoras de biofilme. Na caracterização genotípica, 32% (44/136) foram positivos para o gene blaZ, nenhum isolado (n=136) foi positivo para o gene mecA, e 2% (3/136) foram positivos para o gene icaD. A atividade antimicrobiana in vitro do extrato orgânico de C. substellata e do ácido úsnico purificado para Staphylococcus spp. variou de 0,25mg/ml a 0,0019mg/ml, inibindo o crescimento bacteriano em baixas concentrações. Foram mais eficazes contra bactérias produtoras de biofilme (0,65mg/ml-0,42mg/ml) quando comparadas às não produtoras de biofilme (2,52mg/ml-2,71mg/ml). Viabilizando a utilização do ácido úsnico e do extrato orgânico de C. substellata, no tratamento de otite e piodermatite em cães e gatos com o envolvimento de Staphylococcus spp.(AU)