Enzymic catalysis in heterogeneous eutectic mixtures of substrates

Insight into the influence of natural deep eutectic solvents on the extraction of phenolic compounds from poplar type propolis: Composition and in vitro biological activity

Natural deep eutectic solvents (NADESs) have been considered promising to replace traditional volatile and toxic organic solvents for the extraction of biologically active substances from natural sources. This work applied an efficient and ethanol-exclusion strategy for extraction of phenolic compounds from poplar type propolis using five known NADESs (lactic acid:1,2-propanediol 1:1, lactic acid:fructose 5:1, choline chloride:1,2-propanediol 1:3, choline chloride:1,2-propanediol:water 1:1:1 and betaine:malic acid:water 1:1:6). The selected NADESs' extractability was evaluated by measuring the concentrations of total phenolics and total flavones and flavonols in the propolis extracts obtained, which qualitative chemical composition was further determined in detail by gas chromatography-mass spectrometry (GC-MS) analysis. It demonstrated that the chemical profiles of NADES and 70% ethanolic propolis extracts are similar. To expand the knowledge about the role of the applied solvents in the poplar propolis extraction process, the in vitro antimicrobial, cytotoxic and genotoxic activity of both NADESs and liquid NADES extracts were evaluated. The results revealed that the use of the selected NADESs as an extraction media for phenolic compounds from poplar propolis not only delivered a good extraction yield in some cases, but generally led to the preservation of propolis extracts' biological activity and even to the enhancement of their antimicrobial effect in comparison with the hydroethanolic one. Besides, the tested NADESs except for lactic acid:fructose and betaine:malic acid:water exerted low to negligible toxicity against normal cells treated and apart from lactic acid:fructose the remaining solvents demonstrated concentration-dependent moderate to subtle genotoxicity. There is a probability that not the supramolecular structure of the NADESs, but their components, played a key role for the observed biological effects. The present study has demonstrated an alternative approach for extracting the biologically active complex from poplar type propolis using NADESs, which could be useful for further pharmaceutical and cosmeceutical applications.

From Nature to Innovation: The Uncharted Potential of Natural Deep Eutectic Solvents

This review discusses the significance of natural deep eutectic solvents (NaDESs) as a promising green extraction technology. It employs the consolidated meta-analytic approach theory methodology, using the Web of Science and Scopus databases to analyze 2091 articles as the basis of the review. This review explores NaDESs by examining their properties, challenges, and limitations. It underscores the broad applications of NaDESs, some of which remain unexplored, with a focus on their roles as solvents and preservatives. NaDESs' connections with nanocarriers and their use in the food, cosmetics, and pharmaceutical sectors are highlighted. This article suggests that biomimicry could inspire researchers to develop technologies that are less harmful to the human body by emulating natural processes. This approach challenges the notion that green science is inferior. This review presents numerous successful studies and applications of NaDESs, concluding that they represent a viable and promising avenue for research in the field of green chemistry.

Preclinical safety evaluation of Lipase OF from Candida cylindracea

Triacylglycerol lipases are enzymes commonly used to process foods and beverages such as oils, wines, and cheeses through catalyzation of long-chain triglyceride hydrolysis. Lipase OF derived from Candida cylindracea (strain MS-5-OF) is only intended for use as a processing aid in food production applications; however, it may be present at trace levels in some products. As such, the safety of Lipase OF was evaluated in this study that included a bacterial reverse mutation assay, an in vitro chromosome aberration test, and a 90-day subchronic toxicity study in rats. In the in vitro bacterial reverse mutation and chromosome aberration assays, Lipase OF was not observed to be mutagenic at concentrations up to 5000 μg/plate and 50 μg/ml, respectively, in the presence or absence of metabolic activation. Results from the 90-day subchronic toxicity study indicated only minimal adverse effects (i.e., increased platelet count and prothrombin time) in male rats from the high-dose group following administration of Lipase OF via the diet at levels of 0, 1.0, 2.5, and 5.0 w/w%. The no-observed-adverse-effect level (NOAEL) for Lipase OF was therefore considered 2.5 w/w% (1597.6 mg/kg body weight/day [1027.3 mg TOS/kg body weight/day]) in males and 5.0 w/w% (3700.4 mg/kg body weight/day [2379.4 mg TOS/kg body weight/day]) in females under the test conditions. Thus, the evidence presented within this study supports the safe use of Lipase OF as a processing aid in various food production applications for human consumption.

Are deep eutectic solvents useful in chromatography? A short review

A literature update has been done concerning Deep Eutectic Solvents (DES) use in chromatography applications. The literature survey was based on the period from 2010 till 2020 and manuscripts reported in the data bases Web of Science and Scopus. The use of DES as mobile phase and mobile phase additives, stationary phases and solid phase modifiers and the use of DES as reaction solvents for chromatography use, were evaluated. Emphasis was placed on the differentiation of DES and Ionic Liquids (ILs) and the advanced green characteristics of the new solvents as compared with traditional organic solvents and ILs with a look into the drawbacks and future perspectives in the field of separation methods.

Water-mediated catalyst-free synthesis of lysine-based ampholytic amphiphiles for multipurpose applications: Characterization and pH-responsive emulsifying properties

A novel series of lysine-based ampholytic amphiphiles, with alkylsuccinic anhydrides of varying chain lengths as hydrophobic acylating agents, were synthesized in medium to high yield (50.23-90.15%) based on a facile, catalyst-free method in water medium; and structurally confirmed by mass spectrometry (MS), Fourier transform infra-red (FTIR) spectroscopy, and ¹H/¹³C nuclear magnetic resonances (NMR) analysis. The resulting compounds were subjected to pH-dependent amphiphilic property, ferrous ion chelating, DPPH antioxidant capacity, and cytotoxicity analyses. Results showed that CMC values decrease, γ value increase, and emulsion stability increase with the increase of medium pH, suggesting that the surface activity of synthetic compounds at air/water and oil/water interface under neutral and alkaline conditions was remarkably higher than that under acidic condition. Lauryl O-acylated malic lysine (compound 4b) presented excellent foaming ability close to commercial detergent sodium dodecyl sulphate; dodecyl succinic lysine (compound 4a) afforded highly stable o/w nanoemulsion. Moreover, compound 4b displayed comparable ferrous ion chelating property to lysine and 2,2-diphenyl-1-picrylhydrazyl (DPPH) antioxidative capacity similar to a commercial food ingredient, diacetyl tartaric acid esters of mono- and di-glycerides (DATEM), indicating its multi-faceted functionalities. A cytotoxicity study of compounds 3b &4b showed that they were non-toxic. Thus, these novel ampholytic amphiphiles may find multi-purpose applications in food, detergent, pharmaceutical, and cosmetic industry.

Natural Deep Eutectic Solvents: Properties, Applications, and Perspectives

As functional liquid media, natural deep eutectic solvent (NADES) species can dissolve natural or synthetic chemicals of low water solubility. Moreover, the special properties of NADES, such as biodegradability and biocompatibility, suggest that they are alternative candidates for concepts and applications involving some organic solvents and ionic liquids. Owing to the growing comprehension of the eutectic mechanisms and the advancing interest in the natural eutectic phenomenon, many NADES applications have been developed in the past several years. However, unlike organic solvents, the basic structural unit of NADES media primarily depends on the intermolecular interactions among their components. This makes NADES matrices readily influenced by various factors, such as water content, temperature, and component ratio and, thus, extends the metabolomic challenge of natural products (NPs). To enhance the understanding of the importance of NADES in biological systems, this review focuses on NADES properties and applications in NP research. The present thorough chronological and statistical analysis of existing report adds to the recognition of the distinctiveness of (NA)DES, involves a discussion of NADES-related observations in NP research, and reportes applications of these eutectic mixtures. The work identifies potential areas for future studies of (NA)DES by evaluating relevant applications, including their use as extraction and chromatographic media as well as their biomedical relevance. The chemical diversity of natural metabolites that generate or participate in NADES formation highlights the growing insight that biosynthetically primordial metabolites (PRIMs) are as essential to the biological function and bioactivity of unrefined natural products as the biosynthetically more highly evolutionary metabolites (HEVOs) that can be isolated from crude mixtures.

Natural Deep Eutectic Solvents in Extraction Process

Developing new, eco-friendly solvents which would meet technological and economic demands is perhaps the most popular aspects of Green Chemistry. Natural deep eutectic solvents (NADES) fully meet green chemistry principles. These solvents offer many advantages including biodegradability, low toxicity, sustainability, low costs and simple preparation. This paper provides an overview of knowledge regarding NADES with special emphasis on extraction applications and further perspectives as truly sustainable solvents.

Applications of deep eutectic solvents in biotechnology and bioengineering-Promises and challenges

Deep eutectic solvents (DESs) have been touted recently as potential alternatives to ionic liquids (ILs). Although they possess core characteristics that are similar to those of ILs (e.g., low volatility, non-flammability, low melting points, low vapor pressure, dipolar nature, chemical and thermal stability, high solubility, and tuneability), DESs are superior in terms of the availability of raw materials, the ease of storage and synthesis, and the low cost of their starting materials. As such, they have become the subject of intensive research in various sectors, notably the chemical, electrochemical, and biological sectors. To date, the applications of DESs have shown great promise, especially in the medical and biotechnological fields. In spite of these various achievements, the safety concern for these mixtures must be sufficiently addressed. Indeed, in order to exploit the vast array of opportunities that DESs offer to the biological industry, first, they must be established as safe mixtures. Hence, the biotechnological applications of DESs only can be implemented if they are proven to have negligible or low toxicity profiles. This review is the first of its kind, and it discusses two current aspects of DES-based research. First, it describes the properties of these mixtures with ample focus on their toxicity profiles. Second, it provides an overview of the breakthroughs that have occurred and the foreseeable prospects of the use of DESs in various biotechnological and biological applications.

Eutectic Formation Analysis of Amino Acid Mixtures Using Molecular Dynamics Simulations

The mechanism of eutectic formation was investigated via computer-aided molecular dynamics techniques based on experimental results. The CBZ group mixtures CBZ-l-Asp/d-AlaNH2 x HCl/methanol, CBZ-l-Asp/l-PheOMe x HCl/methanol, and CBZ-l-Tyr/l-ArgNH2 x 2HCl/methanol formed transparent eutectic melts. The non-CBZ group mixtures l-Asp/d-AlaNH2 x HCl/methanol, l-Asp/l-PheOMe x HCl/methanol, and l-Tyr/l-ArgNH2 x 2HCl/methanol did not form eutectic melts. According to molecular dynamics simulation results, increase in the kinetic energy values of eutectic forming mixtures was much larger than the increase in potential energy over a temperature shift from 298 to 333 K. However, the results for non-eutectic forming mixtures were reversed. The Coulomb interaction energies of eutectic forming mixtures significantly decreased, because eutectic melting can increase the mobility of molecules in the mixtures. The enhancement of molecular mobility was confirmed by increased self-diffusion constant values, and the change of solid-to-liquid phase was detected by radial distribution function results. The periodic boundary conditions for calculation of molecular dynamics were found to be reliable.

Lipase-catalyzed synthesis of sorbitol-fatty acid esters at extremely high substrate concentrations

Lipase-catalyzed synthesis of sorbitol-fatty acid esters was performed in eutectic media with extremely high substrate concentrations. Homogeneous eutectic melts of sorbitol and fatty acids of C6-C16 were prepared using an adjuvant mixture. Enhanced homogeneity of mixtures was confirmed by X-ray diffraction analysis. The substrate concentration was 3.63-6.67 M in the eutectic media, whereas in organic media the concentration was below 0.10 M. Esters were synthesized with an immobilized Candida antarctica lipase, and optimum conditions were analyzed. Compared to reactions in organic media, the initial reaction rate of ester synthesis and the overall productivity were significantly enhanced in eutectic media while the conversion yields were similar. Based on the kinetic analysis, highly viscous eutectic media were shown to influence the initial reaction rate and the apparent activation energy resulting in diffusion limitations.

Microbial proteases in peptide synthesis: approaches and applications

Enzymatic synthesis of peptides has attracted a great deal of attention in recent years. The proteases from bacterial, fungal, plant, and animal sources have been successfully applied to the synthesis of several small peptides, mainly dipeptides and tripeptides. Peptide bonds can be synthesized using proteases in either a thermodynamically controlled or a kinetically controlled manner. The development of new methods suitable for the large-scale production of biologically active peptides has been actively pursued over the last decade due to their bioactive nature as well as better understanding of their biological functions and properties. The aim of this study was to review the basic techniques of peptide synthesis and some advancement in biotechnological methods for their production.

Enzymatic synthesis of beta-lactam antibiotics via direct condensation

In this paper, the feasibility of precipitation driven synthesis of acidic and zwitterionic beta-lactam antibiotics is studied. As an example of the first type, penicillin G was produced in good yield (160 mmol kg(-1)) directly from the free acid and amine aqueous substrate suspension, where the synthesis product precipitated. Such a precipitation driven synthesis via direct reversal of the hydrolytic reaction is thermodynamically unfavourable for zwitterionic beta-lactam antibiotics, such as amoxicillin. In this paper, a novel method is suggested to help favour precipitation of (poorly soluble) product salts by deliberate addition of certain counter-ions. After screening a number of different counter-ions, it was found that the amoxicillin anion forms a poorly soluble salt with Zn(2+). Despite increased beta-lactam degradation due to the presence of zinc ions, in a synthetic reaction with 0.1 M ZnSO(4) present the synthetic yield could be increased at least 30-fold.

Solvent-free enzymatic synthesis of alitame precursor using eutectic substrate mixtures

N-benzyloxycarbonyl-L-aspartic acid ethyl ester-D-alanine amide, a derivative of alitame, was synthesized from a eutectic mixture of the substrates N-benzyloxycarbonyl-L-aspartic acid diethyl ester and D-alanine amide using alpha-chymotrypsin. The hydrophilic solvents DMSO and MEA were found to be the best adjuvants for formation of a eutectic substrate mixture. A low eutectic temperature of 27 degrees C was obtained for the substrate mixture containing 9% DMSO, 18% MEA, and 12% water. Under these conditions a conversion yield of 70.3% (mol/mol) was obtained at 37 degrees C. The optimum molar ratio of the acyl acceptor D-alanine amide and the acyl donor N-benzyloxycarbonyl-L-aspartic acid diethyl ester was 1:1.

Improving enzymes by using them in organic solvents

The technological utility of enzymes can be enhanced greatly by using them in organic solvents rather than their natural aqueous reaction media. Studies over the past 15 years have revealed not only that this change in solvent is feasible, but also that in such seemingly hostile environments enzymes can catalyse reactions impossible in water, become more stable, and exhibit new behaviour such as 'molecular memory'. Of particular importance has been the discovery that enzymatic selectivity, including substrate, stereo-, regio- and chemoselectivity, can be markedly affected, and sometimes even inverted, by the solvent. Enzyme-catalysed reactions in organic solvents, and even in supercritical fluids and the gas phase, have found numerous potential applications, some of which are already commercialized.

Effect of water and enzyme concentration on thermolysin-catalyzed solid-to-solid peptide synthesis

We have studied a thermolysin-catalyzed solid-to-solid dipeptide synthesis using equimolar amounts of Z-Gln-OH and H-Leu-NH2 as model substrates. The high substrate concentrations make this an effective alternative to enzymatic peptide synthesis in organic solvents. Water content was varied in the range of 0 to 600 mL water per mol substrate and enzyme concentration in the range of 0.5 to 10 g/mol of substrates. High yields around 80% conversion and initial rates from 5 to 20 mmol s-1 kg-1 were achieved. The initial rate increases 10-fold on reducing the water content, to reach a pronounced optimum at 40 mL water per mol substrate. Below this, the rate falls to much lower values in a system with no added water, and to zero in a rigorously dried system. This behavior is discussed in terms of two factors: At higher water contents the system is mass transfer limited (as shown by varying enzyme content), and the diffusion distances required vary. At low water levels, effects reflect the stimulation of the enzymatic activity by water.

Biologically active peptides and enzymatic approaches to their production

This review briefly surveys various classes of biologically active and flavor peptides that have been isolated and characterized in recent years, and analyzes emerging trends and advances in biotechnological methods for their production.