Atividade antimicrobiana de tripodanthus acutifolius von thieg em cepas de mycobacterium spp.

Abstract

Introduction: The genus Mycobacterium can be subdivided into two groups: slow-growing and fast-growing bacteria, which cause several lung diseases, such as Tuberculosis (TB), and opportunistic diseases such as infections of the skin and other tissues. A characteristic shared by several species of this genus is the intrinsic or acquired resistance to several antibiotics, becoming a public health problem. Among the alternatives to this problem are research with natural products based on medicinal plants, a species that has shown promising results is Tripodanthus acutifolius von Thieg, a mistletoe endemic to South America, which has shown antimicrobial activity against some strains of Gram-positive and Gram-negative bacteria in addition to antifungal action.. Objective: To evaluate the antimicrobial activity of T. acutifolius von Thieg extracts on Mycobacterium spp. Manuscript I: Objective: to investigate which plant species have already been tested and which main secondary metabolites are active against Mycobacterium tuberculosis. Methodology: An integrative review was carried out with the following guiding questions to guide this study: which plant species have already shown potential antimycobacterial activity against Mycobacterium tuberculosis? And which groups of secondary metabolites stood out among the investigated species as possible antimycobacterial agents? The works included in this review were in vitro experimental studies, carried out all over the world, that used extracts of medicinal plants in order to evaluate the antimycobacterial action, in vitro, by microdilution method, with identification of major compounds, against Mycobacterium tuberculosis , published between 2011 and 2021, open access and in Portuguese and English. For the research, the electronic databases Web of Science and PubMed were used. The search was carried out using the descriptors: “medicinal plants AND against AND Mycobacterium tuberculosis” Results: 12 articles were found, in which they report the antimicrobial activities of 20 species of plants, using seven different solvents: methanol, ethanol, ethyl acetate, hexane, dichloromethane and chloroform among the studied species, four of them stood out with MIC<10 µg/mL, they were Artemisia abyssinica, Duroia macrophylla Huber, Uvaria rufa, Bridelia micrantha (Berth), being the variety of secondary metabolites preponderant for the action antimycobacterial activity, highlighting alkaloids, terpenes and phenolic compounds as the main compounds isolated from these species. Conclusion: the number of secondary metabolites obtained in the extraction is decisive in the antimycobacterial action, with the combination of two or more classes of these compounds being more effective in the antimycobacterial action. Manuscript II: Objective: To evaluate the antimicrobial activity of Tripodanthus acutifolius against nontuberculous mycobacteria of clinical importance. Methodology: experimental study, in vitro. The aerial parts of Tripodanthus acutifolius were harvested in January 2022, dried and separated into leaves and flowers, extraction being carried out by maceration of the crude aqueous extract, which were fractionated with 3 solvents of different polarities: hexane, ethyl acetate and methanol. Subsequently, the extracts were lyophilized and MIC tested with them, using the technique of microdilution with Resazurin (REMA). The mycobacteria selected were those with rapid/intermediate growth, causing opportunistic infections, namely: Mycobacterium boletii, Mycobacterium abscessus, Mycobacterium chelonae, Mycobacterium fortuitum and Mycobacterium marinum Results: Among the tested strains, the growth of the M. marinum species was inhibited by the crude aqueous extract of the flowers and by the ethyl acetate fraction of the leaves of T. acutifolius, with a MIC of 200 µg/mL, with the extracts not antagonistic to the antibiotic Ciprofloxacin when tested, the hexane fraction of the flowers showed synergistic activity to the antibiotic, the presence of phenolic compounds in the extract fractions was verified. Conclusion: the crude aqueous extract of the flowers and the ethyl acetate fraction of the leaves of Tripodanthus acutifolius have antimycobacterial potential against Mycobacterium marinum General conclusions: Secondary metabolites are crucial for the in vitro antimycobacterial capacity of extracts obtained from medicinal plants. Several plants have already been analyzed for antimycobacterial action and some of them have shown promise in the discovery of new compounds. The species Tripodanthus acutifolius demonstrated antimycobacterial power against one of the studied strains; Mycobacterium marinum was the pathogen that showed sensitivity to two of the extracts obtained in our study. The crude aqueous extract of the flowers and the ethyl acetate fraction of the leaves of Tripodanthus acutifolius showed the best results.