This updated review article covers the literature between 2011 and 2021 on the antibacterial activity of EOs against the main bacteria that cause caries and periodontal diseases. The criteria to classify the in vitro antibacterial activity of EOs is updated and the most promising results are addressed.
Abstract::
There is great interest in developing chemical technologies to achieve regioselective and stereoselective reactions since only one enantiomer is required for producing the chiral leads for drug development. These selective reactions are dif-ficultly provided by traditional chemical synthetic methods, even under expensive catalysts and long reaction times. Fila-mentous fungi are efficient biocatalysts capable of catalyzing a wide variety of reactions with significant contributions to the development of clean and selective processes. Although some enzymes have already been employed in isolated forms or as crude protein extracts as catalysts for conducting selective reactions, the use of whole-cell provides advantages regarding cofactor regenerations. It is also possible to carry out conversions at chemically unreactive positions and to perform racemic resolution through microbial transformation. The current literature contains several reports on the biotransformation of dif-ferent compounds by fungi, which generated chemical analogs with high selectivity, using mild and eco-friendly conditions. Prompted by the enormous pharmacological interest in the development of stereoselective chemical technologies, this re-view covers the biotransformations catalyzed by fungi that yielded chiral products with enantiomeric excesses published over the period 2010-2020. This work highlights new approaches for the achievement of a variety of bioactive chiral build-ing blocks, which can be a good starting point for the synthesis of new compounds combining biotransformation and syn-thetic organic chemistry.
Natural coumarins are present in remarkable amounts as secondary metabolites in edible and medicinal plants, where they display interesting bioactivities. Considering the wide enzymatic arsenal of filamentous fungi, studies on the biotransformation of coumarins using these microorganisms have great importance in green chemical derivatization. Several reports on the biotransformation of coumarins using fungi have highlighted the achievement of chemical analogs with high selectivity by using mild and ecofriendly conditions. Prompted by the enormous pharmacological, alimentary, and chemical interest in coumarin-like compounds, this study evaluated the biotransformation of nine coumarin scaffolds using Cunninghamella elegans ATCC 10028b and Aspergillus brasiliensis ATCC 16404. The chemical reactions which were catalyzed by the microorganisms were highly selective. Among the nine studied coumarins, only two of them were biotransformed. One of the coumarins, 7-hydroxy-2,3-dihydrocyclopenta[c]chromen-4(1H)-one, was biotransformed into the new 7,9-dihydroxy-2,3-dihydrocyclopenta[c]chromen-4(1H)-one, which was generated by selective hydroxylation in an unactivated carbon. Our results highlight some chemical features of coumarin cores that are important to biotransformation using filamentous fungi.
The biotransformation reactions are used as a successful alternative to derivatization by the traditional chemistry because they conduct to uncommon reactions, which would hardly be carried out by chemical synthesis. A wide diversity of compounds may be metabolized by fungi, leading to chemical derivatives through selective reactions that work under ecofriendly conditions. Endophytic fungi live in symbiosis with health tissues of plants. The employment of endophytic fungi as enzymatic sources to biotransformation reactions is very promising since these microorganisms came from uncommon and underexplored habitat. The environmental conditions directly influence the composition of the endophytic microbiota and its genetic expression, which could change also the production of the enzymes. The extraordinary richness of the Brazilian biodiversity is a key factor in the diversification of the endophytic community. The present review presents a mapping of the biotransformation reactions catalyzed by Brazilian endophytic fungi. Our findings contribute both to the appreciation of these fungi in the chemical derivatization and for the preservation of the Brazilian species.
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