2-Hydroxymethyl-18-crown-6 as an efficient organocatalyst for α-aminophosphonates synthesized under eco-friendly conditions, DFT, molecular docking and ADME/T studies

Eco-friendly and simple procedure has been developed for the synthesis of α-aminophosphonates that act as topoisomerase II α-inhibiting anticancer agent, using 2-hydroxymethyl-18-crown-6 as an unexpected homogeneous organocatalyst in multicomponents reaction of aromatic aldehyde, aniline and diethylphosphite in one pot via Kabachnik-Fields reaction. This efficient method proceeds with catalytic amount, transition metal-free, at room temperature within short reaction time, giving the α-aminophosphonates derivatives (4a-r) in high chemical yields (up to 80%). Theoretical DFT calculations of three compounds (4p, 4q and 4r) were carried out in a gas phase at CAM-B3LYP 6-31G (d,p) basis set to predict the molecular geometries and chemical reactivity descriptors. The frontier orbital energies (HOMO/LUMO) were described the charge transfer and used to predict structure-activity relationship study. Molecular electrostatic potential (MEP) has also been analyzed. Molecular docking studies are implemented to analyze the binding energy and compared with Adriamycin against 1ZXM receptor which to be considered as antitumor candidates. In silico pharmacological ADMET properties as Drug likeness and oral activity have been carried out based on Lipinski's rule of five.Communicated by Ramaswamy H. Sarma.

Asymmetric Transfer Hydrogenation as a Key Step in the Synthesis of the Phosphonic Acid Analogs of Aminocarboxylic Acids

α-Aminophosphonic acids have a remarkably broad bioactivity spectrum. They can function as highly efficient transition state mimics for a variety of hydrolytic and angiotensin-converting enzymes, which makes them interesting target structures for synthetic chemists. In particular, the phosphonic acid analogs to α-aminocarboxylic acids (Pa AAs) are potent enzyme inhibitors, but many of them are only available by chiral or enzymatic resolution; sometimes only one enantiomer is accessible, and several have never been prepared in enantiopure form at all. Today, a variety of methods to access enantiopure α-aminophosphonic acids is known but none of the reported approaches can be generally applied for the synthesis of Pa AAs. Here we show that the phosphonic acid analogs of many (proteinogenic) α-amino acids become accessible by the catalytic, stereoselective asymmetric transfer hydrogenation (ATH) of α-oxo-phosphonates. The highly enantioenriched (enantiomeric excess (ee) ≥ 98 %) α-hydroxyphosphonates obtained are important pharmaceutical building blocks in themselves and could be easily converted to α-aminophosphonic acids in most studied cases. Even stereoselectively deuterated analogs became easily accessible from the same α-oxo-phosphonates using deuterated formic acid (DCO2 H).

Evaluation of Antibacterial Activity against Nosocomial Pathogens of an Enzymatically Derived α-Aminophosphonates Possessing Coumarin Scaffold

The purpose of the present study was to evaluate the synergistic effect of two important pharmacophores, coumarin and α-amino dimethyl phosphonate moieties, on antimicrobial activity against selected strains of multidrug-resistant nosocomial pathogenic bacteria. The previously developed enzyme-catalysed Kabachnik-Fields protocol allowed us to obtain the studied compounds with high yields which were free from metal impurities. The structure-activity relationship revealed that inhibitory activity is strongly related to the presence of the trifluoromethyl group (CF3-) in the coumarin scaffold. MIC and MBC studies carried out on six selected pathogenic bacterial strains (Gram-positive pathogenic Staphylococcus aureus (ATCC 23235) strain, as well as on Gram-negative Acinetobacter baumannii (ATCC 17978), Pseudomonas aeruginosa (ATCC 15442), Enterobacter cloacae (ATCC 49141), Porphyromonas gingivalis (ATCC 33277), and Treponema denticola (ATCC 35405)) have shown that tested compounds show a strong bactericidal effect at low concentrations. Among all agents investigated, five exhibit higher antimicrobial activity than those observed for commonly used antibiotics. It should be noted that all the compounds tested showed very high activity against S. aureus, which is the main source of nosocomial infections that cause numerous fatalities. Furthermore, we have shown that the studied coumarin-based α-aminophosphonates, depending on their structural characteristics, are non-selective and act efficiently against various Gram-positive and Gram-negative pathogens, which is of great importance for hospitalised patients.

Enzymatic Synthesis of a Novel Coumarin Aminophosphonates: Antibacterial Effects and Oxidative Stress Modulation on Selected E. coli Strains

The objective of the present study was to evaluate the synergistic effect of two important pharmacophores, coumarin and α-amino dimethyl phosphonate moieties, on antimicrobial activity toward selected LPS-varied E. coli strains. Studied antimicrobial agents were prepared via a Kabachnik-Fields reaction promoted by lipases. The products were provided with an excellent yield (up to 92%) under mild, solvent- and metal-free conditions. A preliminary exploration of coumarin α-amino dimethyl phosphonate analogs as novel antimicrobial agents was carried out to determine the basic features of the structure responsible for the observed biological activity. The structure-activity relationship revealed that an inhibitory activity of the synthesized compounds is strongly related to the type of the substituents located in the phenyl ring. The collected data demonstrated that coumarin-based α-aminophosphonates can be potential antimicrobial drug candidates, which is particularly crucial due to the constantly increasing resistance of bacteria to commonly used antibiotics.

Microbial Lipases and Their Potential in the Production of Pharmaceutical Building Blocks

Processes involving lipases in obtaining active pharmaceutical ingredients (APIs) are crucial to increase the sustainability of the industry. Despite their lower production cost, microbial lipases are striking for their versatile catalyzing reactions beyond their physiological role. In the context of taking advantage of microbial lipases in reactions for the synthesis of API building blocks, this review focuses on: (i) the structural origins of the catalytic properties of microbial lipases, including the results of techniques such as single particle monitoring (SPT) and the description of its selectivity beyond the Kazlauskas rule as the "Mirror-Image Packing" or the "Key Region(s) rule influencing enantioselectivity" (KRIE); (ii) immobilization methods given the conferred operative advantages in industrial applications and their modulating capacity of lipase properties; and (iii) a comprehensive description of microbial lipases use as a conventional or promiscuous catalyst in key reactions in the organic synthesis (Knoevenagel condensation, Morita-Baylis-Hillman (MBH) reactions, Markovnikov additions, Baeyer-Villiger oxidation, racemization, among others). Finally, this review will also focus on a research perspective necessary to increase microbial lipases application development towards a greener industry.

Recent developments in promiscuous enzymatic reactions for carbon-nitrogen bond formation

Biocatalytic promiscuity is a new field of enzyme application in biochemistry, which has received much attention and has developed rapidly in recent years. The promiscuous biocatalysis has been promoted as a useful supplement to traditional strategy for the formation of C-heteroatom bonds. The generation of carbon-nitrogen (CN) bonds is an important issue in synthetic chemistry and is indispensable for the manufacturing of various pharmaceuticals and agrochemicals. Therefore, numerous efficient and reliable synthetic methods for the formation of CN bonds have been developed in recent years. Enzymatic CN bond forming reactions catalyzed by lipases, cytochrome P450 monooxygenases, glycosyltransferases, amine dehydrogenases, proteases, acylases, amylases and halohydrin dehalogenases are well established for synthetic purposes. This review introduces the recent progress in the construction of CN bonds using promiscuous enzymes.

Relationship between Structure and Antibacterial Activity of α-Aminophosphonate Derivatives Obtained via Lipase-Catalyzed Kabachnik-Fields Reaction

We reported a new method dealing with the synthesis of novel pharmacologically relevant α-aminophosphonate derivatives via a lipase-catalyzed Kabachnik−Fields reaction with yields of up to 93%. The advantages of this protocol are excellent yields, mild reaction conditions, low costs, and sustainability. The developed protocol is applicable to a range of H-phosphites and organic amines, providing a wide substrate scope. A new class of α-aminophosphonate analogues possessing P-chiral centers was also synthesized. The synthesized compounds were characterized on the basis of their antimicrobial activities against E. coli. The impact of the various alkoxy groups on antimicrobial activity was demonstrated. The crucial role of the substituents, located at the aromatic rings in the phenylethyloxy and benzyloxy groups, on the inhibitory action against selected pathogenic E. coli strains was revealed. The observed results are especially important because of increasing resistance of bacteria to various drugs and antibiotics.

Promiscuous Lipase-Catalyzed Markovnikov Addition of H-Phosphites to Vinyl Esters for the Synthesis of Cytotoxic α-Acyloxy Phosphonate Derivatives

An enzymatic route for phosphorous-carbon- bond formation is developed by discovering new promiscuous activity of lipase. This biocatalytic transformation of phosphorous-carbon- bond addition leads to biologically and pharmacologically relevant α-acyloxy phosphonates with methyl group in α-position. A series of target compounds were synthesized with yields ranging from 54% to 83% by enzymatic reaction with Candida cylindracea (CcL) lipase via Markovnikov addition of H-phosphites to vinyl esters. We carefully analyzed the best conditions for the given reaction such as the type of enzyme, temperature, and type of solvent. The developed protocol is applicable to a range of H-phosphites and vinyl esters significantly simplifying the preparation of synthetically challenging α-pivaloyloxy phosphonates. Further, the obtained compounds were validated as new potential antimicrobial drugs with characteristic E. coli bacterial strains and DNA modification recognized by the Fpg protein, N-methyl purine glycosylases as new substrates. The impact of the methyl group located in the α-position of the studied α-acyloxy phosphonates on the antimicrobial activity was demonstrated. The pivotal role of this group on inhibitory activity against selected pathogenic E. coli strains was revealed. The observed results are especially important in the case of the increasing resistance of bacteria to various drugs and antibiotics.

Naphthalen-2-yl 1-(benzamido(diethoxyphosphoryl)methyl)-1H-1,2,3-triazole-4-carboxylate

We have previously published new biheterocyclic phospohonic α-amino esters of the 1,2,3-triazole-benzimidazole and 1,2,3-triazole-carbazole type. The aim of the present paper was to describe a new phosponic aminoester bearing a triazole ring substituted in position 5 by an ester group. Thus, according to the same catalytic process used previously, the compound naphthalen-2-yl 1-(benzamido(diethoxyphosphoryl)methyl)-1H-1,2,3-triazole-4-carboxylate was synthesized with an excellent yield and high regioselectivity via the copper (I)-catalyzed alkyne–azide cycloaddition reaction (CuAAC), using diethyl (α-azido(benzamido)methyl)phosphonate (1) as a dipole and 2- naphthyl propiolate as a dipolarophile (2). The structure of the new compound was fully characterized by 1D (31P, 1H-, 13C-) and 2D (1H-1H and 1H-, 13C-) NMR spectroscopy, IR, and HRMS.

Design, synthesis and evaluation of new chromone-derived aminophosphonates as potential acetylcholinesterase inhibitor

A series of novel N-substituted α-aminophosphonates-bearing chromone moiety were synthesized and evaluated for acetylcholinesterase (AChE), butyrylcholinesterase (BuChE) activities and antioxidant properties. Porcine pancreatic lipase was employed as a catalyst. Inhibitory activity against AChE ranged between 0.103 and 5.781 µM, whereas for BuChE, activities ranged between 8.619 and 18.789 µM. The results show that among the various synthesized compounds, strongest AChE inhibition was found for the compound containing aliphatic amine analogs, while in case of BuChE, aromatic amines showed better activity as compared to aliphatic amines. Compound 4j was found to be the most potent inhibitor of AChE with an IC₅₀ value of 0.103 ± 0.24 μM and inhibited AChE through mixed-type inhibition. Compound 4j was twofolds more potent than tacrine, 35-folds potent than galantamine and 50-folds potent than rivastigmine. Also, docking study revealed that compound 4j binds to both the peripheral anionic site and catalytic anionic site of AChE and BuChE. The antioxidant activities of synthesized compounds were performed against 2,2-diphenyl-1-picrylhydrazyl and hydrogen peroxide scavenging. DNA nicking activity of selected compounds also suggested that the compounds do not harm plasmid DNA pBR322. Compound 4j also showed significant DNA damage protection activity. Novel N-substituted α-aminophosphonates bearing chromone moiety were synthesized and evaluated for anti-acetylcholinesterase, anti-butyrylcholinesterase, antioxidant and DNA damage activities.

Novozym 435: the “perfect” lipase immobilized biocatalyst?

Novozym 435 (N435) is a commercially available immobilized lipase produced by Novozymes with its advantages and drawbacks.

Diastereoselective synthesis of bis(α-aminophosphonates) by lipase catalytic promiscuity

New bis(α-aminophosphonates) were directly prepared with high diastereoselectivity by lipase catalytic promiscuity in the presence of immobilized Candida antarctica lipase.

Continuous flow biocatalysis

The continuous flow synthesis of active pharmaceutical ingredients, value-added chemicals, and materials has grown tremendously over the past ten years. This revolution in chemical manufacturing has resulted from innovations in both new methodology and technology. This field, however, has been predominantly focused on synthetic organic chemistry, and the use of biocatalysts in continuous flow systems is only now becoming popular. Although immobilized enzymes and whole cells in batch systems are common, their continuous flow counterparts have grown rapidly over the past two years. With continuous flow systems offering improved mixing, mass transfer, thermal control, pressurized processing, decreased variation, automation, process analytical technology, and in-line purification, the combination of biocatalysis and flow chemistry opens powerful new process windows. This Review explores continuous flow biocatalysts with emphasis on new technology, enzymes, whole cells, co-factor recycling, and immobilization methods for the synthesis of pharmaceuticals, value-added chemicals, and materials.