Potencial leishmanicida de extratos de bactérias isoladas de liquens da Antártica

Abstract

Leishmaniasis is an infectious parasitic disease, neglected and widely distributed geographically, affecting millions of individuals on all continents of the planet. The pharmacological list available for the treatment of infections caused by leishmania is limited and has high toxicity. Therefore, there is a relentless search for new, safer and more effective therapeutic options for the treatment of leishmaniasis. This study aimed to investigate the activity of candidates for prototype leishmanicidal drugs based on bacterial extracts isolated from Antarctic lichens that constitute safer therapeutic options for the treatment of leishmaniasis. The pigment-producing bacteria were reactivated in Nutrient Agar medium at 15ºC for 7 days and the inocula were standardized and seeded in 50ml of nutrient broth. The metabolites were extracted by centrifugation and pellet separation, which was subjected to cell lysis with methanol followed by vortexing and centrifugation to obtain intracellular pigments. The MTT colorimetric assay was used to assess the cytotoxicity effect on J774.A1 lineage macrophages. The extracts 8LB19, 5LB35, 23LB3, 7LB4, 10AUVB14, 6AUVB13 did not show cytotoxicity to macrophages, except for 5AUVB13 which presented cytotoxicity to the host cell with maximum observed effect of 38.2 ± 3.7%. Promastigote cultures of L. chagasi and L. amazonensis were counted directly under an optical microscope to verify the leishmanicidal activity. Statistical calculations were obtained using the GraphPad Prism program. Of the methanol extracts tested to date on L. chagasi, 5AUVB13 and 6AUVB13 exhibited potent activity with a maximum effect of 97.93 ± 1.88%, 96.10 ± 0.01% and IC50 of 18. 31 µg/ml (11.22 - 30.47) 22.05 µg/ml (13.51 - 30.59), 7LB4 and 23LB3 demonstrated activity below 50%, with a maximum effect of 32.47 ± 5.19, 16.30 ± 1.88 respectively. 8LB19, 5LB35 and 10AUVB14 were not active. Against L. amazonensis, 8 LB 19, 5LB35 and 10 AUVB 14 were not active; 23LB3 and 7LB4, however, exhibited moderate activity with a maximum effect of 37.50 ± 1.80 and 39.58 ± 4.54, respectively. 5AUVB13 and 6AUVB13 exhibited activity greater than 50% with the respective maximum effects of 65.63 ± 1.80 and 60.42 ± 1.04 and IC50 of 52.72 (37.14 - 68.29) and 44.63 (33.61-55.65), with emphasis on 5 AUVB 13 and 6 AUVB 13 that were active in both species.