Antifungal effect of Arnica montana and Hamamelis virginiana against Candida species

Objetivo ­ Avaliar a atividade antifúngica dos extratos glicólicos de Arnica montana e Hamamelis virginiana contra cepas de Candida spp. A candidíase é uma infecção fúngica comum, portanto, a pesquisa de novos agentes antifúngicos tem sido um alvo interessante. Várias plantas apresentaram atividades biológicas e, portanto, podem ser fontes promissoras de produtos naturais com atividades an-tifúngicas. Métodos ­ As atividades antifúngicas dos extratos glicólicos foram avaliadas por meio da determinação da concentração inibitória mínima (CIM) de acordo com o protocolo M27-S3 do Clinical and Laboratory Standards Institute (2008). Resultados ­ O ex-trato glicólico de A. montana apresentou a atividade antifúngica mais forte contra C. tropicalis, com concentração inibitória mínima (CIM) de 10% v/v e concentração fungicida mínima (MFC) de 80% v/v, seguido por C. krusei e C. glabrata, com valores de MIC e MFC de 20% v/v. Além disso, avaliamos a toxicidade dos dois extratos glicólicos no modelo Galleria mellonella usando as curvas de sobre-vivência de larvas tratadas com os extratos. Nossos resultados demonstraram que os extratos glicólicos de A. montana e H. virginiana não exibiram toxicidade contra larvas de G. mellonella e demonstraram atividade antifúngica contra espécies de Candida spp. Con-clusão ­ Assim, ambos os extratos são candidatos promissores para o desenvolvimento de novos agentes antifúngicos.

Objective ­ To evaluate the antifungal activity of Arnica montana and Hamamelis virginiana glycolic extracts against Candida strains. Methods ­ The antifungal activities of glycolic extracts were investigated by determination of the minimum inhibitory concentration (MIC) according to protocol M27-S3 of Clinical and Laboratory Standards Institute (2008). Results ­ A. montana glycolic extract showed the strongest antifungal activity against C. tropicalis, with a minimum inhibitory concentration (MIC) of 10% v/v and a minimum fungicidal concentration (MFC) of 80% v/v, then C. krusei and C. glabrata, with MIC and MFC values of 20% v/v. H. virginiana glycolic extract ex-hibited stronger activity against C. albicans and C. tropicalis, with MIC and MFC values of 10% v/v, than against C. glabrata, C. krusei, and C. parapsilosis, with MIC and MFC values of 20% v/v. Moreover, we evaluated the toxicity of the two glycolic extracts in the Galleria mellonella model using the survival curves of larvae treated with the two extracts. Our results demonstrated that the glycolic extracts of A. montana and H. virginiana exhibited no toxicity against G. mellonella larvae and demonstrated antifungal activity against Candida spe-cies. Conclusion ­ Thus, both extracts are promising candidates for the development of novel antifungal agents.

Assessment of neuropharmacological potential of low molecular weight components extracted from Rhinella schneideri toad poison

Studies on toad poison are relevant since they are considered a good source of toxins that act on different biological systems. Among the molecules found in the toad poison, it can be highlighted the cardiotonic heterosides, which have a known mechanism that inhibit Na+/K+-ATPase enzyme. However, these poisons have many other molecules that may have important biological actions. Therefore, this work evaluated the action of the low molecular weight components from Rhinella schneideri toad poison on Na+/K+-ATPase and their anticonvulsive and / or neurotoxic effects, in order to detect molecules with actions of biotechnological interest. Methods: Rhinella schneideri toad (male and female) poison was collected by pressuring their parotoid glands and immediately dried and stored at -20 °C. The poison was dialysed and the water containing the low molecular mass molecules (< 8 kDa) that permeate the dialysis membrane was collected, frozen and lyophilized, resulting in the sample used in the assays, named low molecular weight fraction (LMWF). Na+/K+ ATPase was isolated from rabbit kidneys and enzyme activity assays performed by the quantification of phosphate released due to enzyme activity in the presence of LMWF (1.0; 10; 50 and 100 µg/mL) from Rhinella schneideri poison. Evaluation of the L-Glutamate (L-Glu) excitatory amino acid uptake in brain-cortical synaptosomes of Wistar rats was performed using [3H]L-glutamate and different concentration of LMWF (10-5 to 10 µg/µL). Anticonvulsant assays were performed using pentylenetetrazole (PTZ) and N-methyl-D-aspartate (NMDA) to induce seizures in Wistar rats (n= 6), which were cannulated in the lateral ventricle and treated with different concentration of LMWF (0.25; 0.5; 1.0; 2.0; 3.0 and 4.0 µg/µL) 15 min prior to the injection of the seizure agent. Results: LMWF induced a concentration-dependent inhibition of Na+/K+-ATPase (IC50% = 107.5 μg/mL). The poison induces an increased uptake of the amino acid L-glutamate in brain-cortical synaptosomes of Wistar rats. This increase in the L-glutamate uptake was observed mainly at the lowest concentrations tested (10-5 to 10-2 µg/µL). In addition, this fraction showed a very relevant central neuroprotection on seizures induced by PTZ and NMDA. Conclusions: LMWF from Rhinella schneideri poison has low molecular weight compounds, which were able to inhibit Na+/K+-ATPase activity, increase the L-glutamate uptake and reduced seizures induced by PTZ and NMDA. These results showed that LMWF is a rich source of components with biological functions of high medical and scientific interest.(AU)