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Avaliação das propriedades antibacterianas de cianobactérias de água doce para aplicação em antibióticos naturais
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Abstract(s)
A descoberta dos antibióticos revolucionou a medicina, mas a sua eficácia está comprometida
devido à disseminação de mecanismos de resistência a antibióticos, sendo urgente pesquisar novos
compostos antibacterianos. As cianobactérias têm sido estudadas quanto à produção de metabolitos
secundários com atividade antibacteriana.
Este trabalho teve como objetivo avaliar a capacidade antibacteriana de vinte e cinco estirpes
de cianobactérias pertencentes à coleção ESSACC. Para tal, foram produzidos extratos de hexano,
diclorometano:metanol (2:1), metanol 70% e água destas estirpes, em duas extrações sequenciais com
estes solventes: (I) do menos polar para o mais polar; (II) do mais polar para o menos polar. O
fenótipo de suscetibilidade de nove bactérias patogénicas a esses extratos foi avaliado pelos métodos
da Difusão em Disco e da Microdiluição.
Pelo método da Difusão em Disco nenhum dos extratos inibiu totalmente o crescimento
bacteriano. No entanto, houve um decréscimo do crescimento de Pseudomonas aeruginosa ATCC
27853 quando exposta aos extratos de hexano (I) de Aphanizomenon flos-aquae (LMECYA 088),
metanol (II) de Oscillatoria limosa (SAG 42.87), diclorometano:metanol (I)/ metanol (I) de
Arthrospira platensis (SAG 85.79) e diclorometano:metanol (I)/(II) de Nostoc sp. (LMECYA 330).
Pelo teste da Microdiluição verificou-se que o extrato metanólico (I) de A. platensis (SAG 85.79), a
25% v/v, inibiu totalmente o crescimento de P. aeruginosa. Adicionalmente, analisou-se a atividade
adjuvante destes extratos em antibióticos de referência para a P. aeruginosa e observou-se que todos
potenciaram a atividade de aztreonam e piperaciclina/tazobactam, excetuando o extrato de
diclorometano:metanol (I) de A. platensis (SAG 85.79) que apenas potenciou a atividade de
aztreonam. O extrato de diclorometano:metanol (I) de Nostoc sp. (LMECYA 330) apresentou também
atividade sinérgica com o ertapenem.
Os resultados obtidos neste estudo permitiram identificar quatro estirpes cianobacterianas
como potenciais fontes de compostos antibacterianos, o que pode contribuir para a mitigação do
fenómeno da resistência a antibióticos.
The discovery of antibiotics revolutionized the treatment of infectious diseases. However, the efficiency of antibiotics has been compromised by the worldwide spread of antibiotic resistance mechanisms, and the research of new antibacterial compounds is needed. Cyanobacteria have been studied for the production of secondary metabolites with antibacterial activity. The aim of this study was to assess the antibacterial activity of twenty-five cyanobacterial strains belonging to ESSACC collection. In that way, extracts of these cyanobacteria were prepared with hexane, dichloromethane:methanol (2:1), methanol (70%) and water. Two sequential extractions were performed: (I) non-polar to polar solvents; (II) polar to non-polar solvents. The susceptibility phenotype of nine pathogenic bacteria to these extracts was analyzed by the Disk Diffusion and the Microdilution assays. In the Disk Diffusion method, none of the cyanobacterial extracts completely inhibited the growth of the studied bacteria. However, the bacterial growth of P. aeruginosa ATCC 27853 decreased when exposed to the extracts of hexane (I) of Aphanizomenon flos-aquae (LMECYA 088), methanol (II) of Oscillatoria limosa (SAG 42.87), dichlorometane:methanol (I)/ methanol (I) of Arthrospira platensis (SAG 85.79) and dichlorometane:methanol (I)/(II) of Nostoc sp. (LMECYA 330). In the Microdilution method, only the methanolic extract (I) of A. platensis (SAG 85.79), at 25% v/v, fully inhibited the growth of P. aeruginosa ATCC 27853. Additionally, the adjuvant activity of those extracts on standard antibiotics for P. aeruginosa was analyzed, and all the extracts exacerbate the antibacterial activity of aztreonam and piperacillin/tazobactam, except for the dichlorometane:methanol extract (I) of A. platensis (SAG 85.79) that only exacerbate the activity of aztraeonam. Furthermore, the dichlorometane:methanol extract (I) of Nostoc sp. (LMECYA 330) exhibit synergic activity with ertapenem. These results contributed to the identification of four cyanobacterial strains as potential sources of antibacterial compounds, which might be employed to mitigate the current scenario of antibiotic resistance.
The discovery of antibiotics revolutionized the treatment of infectious diseases. However, the efficiency of antibiotics has been compromised by the worldwide spread of antibiotic resistance mechanisms, and the research of new antibacterial compounds is needed. Cyanobacteria have been studied for the production of secondary metabolites with antibacterial activity. The aim of this study was to assess the antibacterial activity of twenty-five cyanobacterial strains belonging to ESSACC collection. In that way, extracts of these cyanobacteria were prepared with hexane, dichloromethane:methanol (2:1), methanol (70%) and water. Two sequential extractions were performed: (I) non-polar to polar solvents; (II) polar to non-polar solvents. The susceptibility phenotype of nine pathogenic bacteria to these extracts was analyzed by the Disk Diffusion and the Microdilution assays. In the Disk Diffusion method, none of the cyanobacterial extracts completely inhibited the growth of the studied bacteria. However, the bacterial growth of P. aeruginosa ATCC 27853 decreased when exposed to the extracts of hexane (I) of Aphanizomenon flos-aquae (LMECYA 088), methanol (II) of Oscillatoria limosa (SAG 42.87), dichlorometane:methanol (I)/ methanol (I) of Arthrospira platensis (SAG 85.79) and dichlorometane:methanol (I)/(II) of Nostoc sp. (LMECYA 330). In the Microdilution method, only the methanolic extract (I) of A. platensis (SAG 85.79), at 25% v/v, fully inhibited the growth of P. aeruginosa ATCC 27853. Additionally, the adjuvant activity of those extracts on standard antibiotics for P. aeruginosa was analyzed, and all the extracts exacerbate the antibacterial activity of aztreonam and piperacillin/tazobactam, except for the dichlorometane:methanol extract (I) of A. platensis (SAG 85.79) that only exacerbate the activity of aztraeonam. Furthermore, the dichlorometane:methanol extract (I) of Nostoc sp. (LMECYA 330) exhibit synergic activity with ertapenem. These results contributed to the identification of four cyanobacterial strains as potential sources of antibacterial compounds, which might be employed to mitigate the current scenario of antibiotic resistance.
Description
Dissertação de mestrado em Biologia Humana e Ambiente, Faculdade de Ciências da Universidade de Lisboa, 2021
Dissertação de mestrado defendida em 15/2/2022
A componente do trabalho que envolveu os testes com as bactérias patogénicas foi realizado no Laboratório Nacional de Referência da Resistência aos Antibióticos e Infeções Associadas aos Cuidados de Saúde (LNR-RA/IACS), Departamento de Doenças Infeciosas do INSA.
Orientadora Elsa Dias (Departamento de Saúde Ambiental, INSA)
Dissertação de mestrado defendida em 15/2/2022
A componente do trabalho que envolveu os testes com as bactérias patogénicas foi realizado no Laboratório Nacional de Referência da Resistência aos Antibióticos e Infeções Associadas aos Cuidados de Saúde (LNR-RA/IACS), Departamento de Doenças Infeciosas do INSA.
Orientadora Elsa Dias (Departamento de Saúde Ambiental, INSA)
Keywords
Resistência a Antibióticos Compostos Bioativos Naturais Cianobactérias Atividade Antibacteriana Adjuvantes Agentes Microbianos e Ambiente Antibiotic Resistance Natural Bbioactive Compounds Cyanobacteria Antibacterial Activity Adjuvant