Chemoselective biohydrogenation of α,β- and α,β,γ,δ-unsaturated ketones by the marine-derived fungus Penicillium citrinum CBMAI 1186 in a biphasic system

Marine-derived fungi as biocatalysts

Marine microorganisms account for over 90% of ocean biomass and their diversity is believed to be the result of their ability to adapt to extreme conditions of the marine environment. Biotransformations are used to produce a wide range of high-added value materials, and marine-derived fungi have proven to be a source of new enzymes, even for activities not previously discovered. This review focuses on biotransformations by fungi from marine environments, including bioremediation, from the standpoint of the chemical structure of the substrate, and covers up to September 2022.

The Family Keeps on Growing: Four Novel Fungal OYEs Characterized

Aiming at expanding the portfolio of Old Yellow Enzymes (OYEs), which have been systematically studied to be employed in the chemical and pharmaceutical industries as useful biocatalysts, we decided to explore the immense reservoir of filamentous fungi. We drew from the genome of the two Ascomycetes Aspergillus niger and Botryotinia fuckeliana four new members of the OYE superfamily belonging to the classical and thermophilic-like subfamilies. The two BfOYEs show wider substrate spectra than the AnOYE homologues, which appear as more specialized biocatalysts. According to their mesophilic origins, the new enzymes neither show high thermostability nor extreme pH optimums. The crystal structures of BfOYE4 and AnOYE8 have been determined, revealing the conserved features of the thermophilic-like subclass as well as unique properties, such as a peculiar N-terminal loop involved in dimer surface interactions. For the classical representatives BfOYE1 and AnOYE2, model structures were built and analyzed, showing surprisingly wide open access to the active site cavities due to a shorter β6-loop and a disordered capping subdomain.

Biotransformation of (E)-2-Methyl-3-Phenylacrylaldehyde Using Mycelia of Penicillium citrinum CBMAI 1186, Both Free and Immobilized on Chitosan

This study applied the use of marine-derived fungus Penicillium citrinum CBMAI 1186 in the stereoselective reduction of the C=C double bond of the prochiral (E)-2-methyl-3-phenylacrylaldehyde 1. The fungus immobilized on chitosan, obtained by multistep ultrasound-assisted deacetylation process (Ch-USAD), produced the (S)-(+)-2-methyl-3-phenylpropan-1-ol 3 (c = 49%, 40% ee) isomer and (±)-2-methyl-3-phenylacrilic acid 4 (c = 35%); in contrast, immobilized mycelia on commercial chitosan (Ch-C) yielded the (S)-(+)-2-methyl-3-phenylpropan-1-ol 3 (c = 48%, 10% ee) and (±)-2-methyl-3-phenylpropanal 1a (c = 41%). The reaction using free mycelia gave a 40% yield of (S)-(+)-2-methyl-3-phenylpropan-1-ol 3 with 10% ee. These results showed that the crystallinity form and molecular weight of chitosan (Ch-C or Ch-USAD) used to immobilized mycelia of P. citrinum CBMAI 1186 influenced in the biotransformation of (E)-2-methyl-3-phenylacrylaldehyde 1. Therefore, marine-derived fungus P. citrinum CBMAI 1186 immobilized on chitosan can be a potential alternative in the studies of hydrogenation of the α,β-unsaturated carbon-carbon (α,β-C=C) double bond. Marine-derived fungus Penicillium citrinum CBMAI 1186 immobilized on chitosan in the stereoselective reduction of the C=C double bond of the prochiral (E)-2-methyl-3-phenylacrylaldehyde.

Chemoselective Hydrosilylation of the α,β-Site Double Bond in α,β- and α,β,γ,δ-Unsaturated Ketones Catalyzed by Macrosteric Borane Promoted by Hexafluoro-2-propanol

The B(C₆F₅)₃-catalyzed chemoselective hydrosilylation of α,β- and α,β,γ,δ-unsaturated ketones into the corresponding non-symmetric ketones in mild reaction conditions is developed. Nearly 55 substrates including those bearing reducible functional groups such as alkynyl, alkenyl, cyano, and aromatic heterocycles are chemoselectively hydrosilylated in good to excellent yields. Isotope-labeling studies revealed that hexafluoro-2-propanol also served as a hydrogen source in the process.

Synthesis of Knoevenagel Adducts Under Microwave Irradiation and Biocatalytic Ene-Reduction by the Marine-Derived Fungus Cladosporium sp. CBMAI 1237 for the Production of 2-Cyano-3-Phenylpropanamide Derivatives

The organic synthesis has been driven by the need of sustainable processes, which also requires efficiency and cost-effectiveness. In this work, we described the synthesis of nine Knoevenagel adducts between cyanoacetamide and aromatic aldehydes ((E)-2-cyano-3-(phenyl)acrylamide derivatives), employing triethylamine as catalyst under microwave irradiation in 30 min with excellent yields (93-99% yield). Then, these adducts were employed in the C-C double bond bioreduction by the marine-derived fungus Cladosporium sp. CBMAI 1237 for obtention of 2-cyano-3-phenylpropanamide derivatives in mild conditions and short reaction time for a whole-cells reduction (phosphate buffer pH 7.0, 32 °C, 130 rpm, 8 h) with good yields (48-90%). It is important to emphasize that the experimental conditions, especially the reaction time, should be carefully evaluated for the obtention of high yields. Since a biodegradation process consumed the obtained product in extended periods, probably due to the use of the substrate as carbon and nitrogen source. This approach showed that the use of coupled and greener catalysis methods such as microwave irradiation and biocatalytic reduction, which employs unique biocatalysts like marine-derived fungi, can be an interesting tool for the obtention of organic molecules.

Silver nanoparticle from whole cells of the fungi Trichoderma spp. isolated from Brazilian Amazon

Metal nanoparticles are a promising approach for the development of new antimicrobial systems. Silver nanoparticles (AgNP) have a significant antibacterial activity through bacterial surface adsorption and oxidative stress induction, as indicated by recent observations. This research aimed to use endophytic fungi from the genus Trichoderma spp. isolated from the Bertholletia excelsa (Brazil-nut) seeds and the soil to biosynthesize AgNPs and also test their antibacterial activity. The use of these fungi for this purpose not only valorizes the Amazon biodiversity but it also uses cleaner and cheaper processes, being part of the Green Chemistry concept. The particles were analyzed through Ultraviolet-Visible Spectroscopy and ZetaSizer and the band of absorption at 420 nm was analyzed through Localized Surface Plasmon Resonance. After characterization, the AgNP were tested for antibacterial activity against several bacterial strains, when it was observed that their antibacterial activity was superior in Gram-negative bacteria.

Applications of Marine-Derived Microorganisms and Their Enzymes in Biocatalysis and Biotransformation, the Underexplored Potentials

Biodiversity has been explored in the search for novel enzymes, including forests, savannas, tundras, deserts, and finally the sea. Marine microorganisms and their enzymes are capable of being active in high-salt concentration, large range of temperature, and high incidence of light and pressure, constituting an important source of unique biocatalysts. This review presents studies employing whole-cell processes of marine bacteria and fungi, aiming for new catalysts for different reactions in organic synthesis, such as reduction, oxidation, hydroxylation, hydrolysis, elimination, and conjugation. Genomics and protein engineering studies were also approached, and reactions employing isolated enzymes from different classes (oxidoreductases, hydrolases, lyases, and ligases) were described and summarized. Future biotechnological studies and process development should focus on molecular biology for the obtention of enzymes with interesting, fascinating and enhanced properties, starting from the exploration of microorganisms from the marine environment. This review approaches the literature about the use of marine-derived bacteria, fungi, and their enzymes for biocatalytic reactions of organic compounds, promoting a discussion about the possibilities of these microorganisms in the synthesis of different substances.

The application of safe for humans and the environment Polyversum antifungal agent containing living cells of Pythium oligandrum for biotransformation of prochiral ketones

This report presents the whole-cell biotransformation of benzofuranyl-methyl ketone derivatives with the application of Polyversum antifungal agent containing Pythium oligandrum microorganism. Stereochemistry of the reduction of prochiral substrates was modified by the bioconversion conditions (concentration of reagents, a source of the carbon atom, biotransformation medium). In optimized conditions enantioselective process was noted. Secondary alcohols with excellent enantiomeric purity and high yields were obtained. The enantiomeric excess and conversion degree of 1-(benzofuran-2-yl)ethanol, 1-(7-ethylbenzofuran-2-yl)ethanol and 1-(3,7-dimethylbenzofuran-2-yl)ethanol were 99%/98.1%, 94%/94.4% and 99%/72.6%, respectively. In the presence of P. oligandrum, one of the enantiotopic hydrides of the dihydropyridine ring coenzyme is selectively transferred to a re side of the prochiral carbonyl group to give products with S configuration. This study demonstrates an inexpensive, eco-friendly approach in synthesis of optically pure benzofuran derivatives and can be an interesting alternative to organocatalysis. Furthermore, this method can be used in biotechnology processes due to its good chemical performance and a high degree of product isolation.

Enantioselective ene-reduction of E-2-cyano-3-(furan-2-yl) acrylamide by marine and terrestrial fungi and absolute configuration of (R)-2-cyano-3-(furan-2-yl) propanamide determined by calculations of electronic circular dichroism (ECD) spectra

This work reports the green organic chemistry synthesis of E-2-cyano-3(furan-2-yl) acrylamide under microwave radiation (55 W), as well as the use of filamentous marine and terrestrial-derived fungi, in the first ene-reduction of 2-cyano-3-(furan-2-yl) acrylamide to (R)-2-cyano-3-(furan-2-yl)propanamide. The fungal strains screened included Penicillium citrinum CBMAI 1186, Trichoderma sp. CBMAI 932 and Aspergillus sydowii CBMAI 935, and the filamentous terrestrial fungi Aspergillus sp. FPZSP 146 and Aspergillus sp. FPZSP 152. A compound with an uncommon CN-bearing stereogenic center at the α-C position was obtained by enantioselective reactions mediated in the presence of the microorganisms yielding the (R)-2-cyano-3-(furan-2-yl) propanamide 3a. Its isolated yield and e.e. ranged from 86% to 98% and 39% to 99%, respectively. The absolute configuration of the biotransformation products was determined by time-dependent density functional theory (TD-DFT) calculations of electronic circular dichroism (ECD) spectra. Finally, the tautomerization of 2-cyano-3-(furan-2-yl) propanamide 3a to form an achiral ketenimine was observed and investigated in presence of protic solvents.

Discovery, Characterisation, Engineering and Applications of Ene Reductases for Industrial Biocatalysis

Recent studies of multiple enzyme families collectively referred to as ene-reductases (ERs) have highlighted potential industrial application of these biocatalysts in the production of fine and speciality chemicals. Processes have been developed whereby ERs contribute to synthetic routes as isolated enzymes, components of multi-enzyme cascades, and more recently in metabolic engineering and synthetic biology programmes using microbial cell factories to support chemicals production. The discovery of ERs from previously untapped sources and the expansion of directed evolution screening programmes, coupled to deeper mechanistic understanding of ER reactions, have driven their use in natural product and chemicals synthesis. Here we review developments, challenges and opportunities for the use of ERs in fine and speciality chemicals manufacture. The ER research field is rapidly expanding and the focus of this review is on developments that have emerged predominantly over the last 4 years.

Whole Cells as Biocatalysts in Organic Transformations

Currently, the power and usefulness of biocatalysis in organic synthesis is undeniable, mainly due to the very high enantiomeric excess reached using enzymes, in an attempt to emulate natural processes. However, the use of isolated enzymes has some significant drawbacks, the most important of which is cost. The use of whole cells has emerged as a useful strategy with several advantages over isolated enzymes; for this reason, modern research in this field is increasing, and various reports have been published recently. This review surveys the most recent developments in the enantioselective reduction of carbon-carbon double bonds and prochiral ketones and the oxidation of prochiral sulfides using whole cells as biocatalytic systems.

Recent Advances in Marine Enzymes for Biotechnological Processes

In the last decade, new trends in the food and pharmaceutical industries have increased concern for the quality and safety of products. The use of biocatalytic processes using marine enzymes has become an important and useful natural product for biotechnological applications. Bioprocesses using biocatalysts like marine enzymes (fungi, bacteria, plants, animals, algae, etc.) offer hyperthermostability, salt tolerance, barophilicity, cold adaptability, chemoselectivity, regioselectivity, and stereoselectivity. Currently, enzymatic methods are used to produce a large variety of products that humans consume, and the specific nature of the enzymes including processing under mild pH and temperature conditions result in fewer unwanted side-effects and by-products. This offers high selectivity in industrial processes. The marine habitat has been become increasingly studied because it represents a huge source potential biocatalysts. Enzymes include oxidoreductases, hydrolases, transferases, isomerases, ligases, and lyases that can be used in food and pharmaceutical applications. Finally, recent advances in biotechnological processes using enzymes of marine organisms (bacterial, fungi, algal, and sponges) are described and also our work on marine organisms from South America, especially marine-derived fungi and bacteria involved in biotransformations and biodegradation of organic compounds.