Investigation of the Anticancer Effect of α-Aminophosphonates and Arylidine Derivatives of 3-Acetyl-1-aminoquinolin-2(1H)-one on the DMBA Model of Breast Cancer in Albino Rats with In Silico Prediction of Their Thymidylate Synthase Inhibitory Effect.

Breast cancer is a major cause of death in women worldwide. In this study, 60 female rats were classified into 6 groups; negative control, α-aminophosphonates, arylidine derivatives of 3-acetyl-1-aminoquinolin-2(1H)-one, DMBA, DMBA & α-aminophosphonates, and DMBA & arylidine derivatives of 3-acetyl-1-aminoquinolin-2(1H)-one. New α-aminophosphonates and arylidine derivatives of 3-acetyl-1-aminoquinolin-2(1H)-one were synthesized and elucidated by different spectroscopic and elemental analysis. Histopathological examination showed marked proliferation of cancer cells in the DMBA group. Treatment with α-aminophosphonates mainly decreased tumor mass. Bcl2 expression increased in DMBA-administered rats and then declined in the treated groups, mostly with α-aminophosphonates. The level of CA15-3 markedly declined in DMBA groups treated with α-aminophosphonates and arylidine derivatives of 3-acetyl-1-aminoquinolin-2(1H)-one. Gene expression of GST-P, PCNA, PDK, and PIK3CA decreased in the DMBA group treated with α-aminophosphonates and arylidine derivatives of 3-acetyl-1-aminoquinolin-2(1H)-one, whereas PIK3R1 and BAX increased in the DMBA group treated with α-aminophosphonates and arylidine derivatives of 3-acetyl-1-aminoquinolin-2(1H)-one. The molecular docking postulated that the investigated compounds can inhibt the Thymidylate synthase TM due to high hydrophobicity charachter.

Asymmetric Synthesis of Tetrasubstituted α-Aminophosphonic Acid Derivatives.

Due to their structural similarity with natural α-amino acids, α-aminophosphonic acid derivatives are known biologically active molecules. In view of the relevance of tetrasubstituted carbons in nature and medicine and the strong dependence of the biological activity of chiral molecules into their absolute configuration, the synthesis of α-aminophosphonates bearing tetrasubstituted carbons in an asymmetric fashion has grown in interest in the past few decades. In the following lines, the existing literatures for the synthesis of optically active tetrasubstituted α-aminophosphonates are summarized, comprising diastereoselective and enantioselective approaches.

A greener protocol for the synthesis of phosphorochalcogenoates: Antioxidant and free radical scavenging activities.

In this contribution, a metal- and base-free protocol has been developed for the synthesis of phosphorochalcogenoates (Se and Te) by using DMSO as solvent at 50 °C. A variety of phosphorochalcogenoates were prepared from diorganyl dichalcogenides and H-phosphonates, leading to the formation of a Chal-P(O) bond, in a rapid procedure with good to excellent yields. A full structural elucidation of products was accessed by 1D and 2D NMR, IR, CGMS, and HRMS analyses, and a stability evaluation of the phosphorochalcogenoates was performed for an effective operational description of this simple and feasible method. Typical 77Se{1H} (δSe = 866.0 ppm), 125Te{1H} (δTe = 422.0 ppm) and 31P{1H} (δP = -1.0, -13.0 and -15.0 ppm) NMR chemical shifts were imperative to confirm the byproducts, in which this stability study was also important to select some products for pharmacological screening. The phosphorochalcogenoates were screened in vitro and ex vivo tests for the antioxidant potential and free radical scavenging activity, as well as to investigation toxicity in mice through of the plasma levels of markers of renal and hepatic damage. The pharmacological screening of phosphorochalcogenoates indicated that compounds have antioxidant propriety in different assays and not changes plasma levels of markers of renal and hepatic damage, with excision of 3g compound that increased plasma creatinine levels and decreased plasma urea levels when compared to control group in the blood mice. Thus, these compounds can be promising synthetic antioxidants that provide protection against oxidative diseases.

Challenges and Hallmarks of Establishing Alkylacetylphosphonates as Probes of Bacterial 1-Deoxy-d-xylulose 5-Phosphate Synthase.

1-Deoxy-d-xylulose 5-phosphate (DXP) synthase catalyzes the thiamin diphosphate (ThDP)-dependent formation of DXP from pyruvate and d-glyceraldehyde 3-phosphate. DXP is at a metabolic branch point in bacteria, feeding into the methylerythritol phosphate pathway to indispensable isoprenoids and acting as a precursor for biosynthesis of essential cofactors in central metabolism, pyridoxal phosphate and ThDP, the latter of which is also required for DXP synthase catalysis. DXP synthase follows a unique random sequential mechanism and possesses an unusually large active site. These features have guided the design of sterically demanding alkylacetylphosphonates (alkylAPs) toward the development of selective DXP synthase inhibitors. alkylAPs studied here display selective, low µM inhibitory activity against DXP synthase. They are weak inhibitors of bacterial growth in standard nutrient rich conditions. However, bacteria are significantly sensitized to most alkylAPs in defined minimal growth medium, with minimal inhibitory concentrations (MICs) ranging from low µM to low mM and influenced by alkyl-chain length. The longest analog (C8) displays the weakest antimicrobial activity and is a substrate for efflux via AcrAB-TolC. The dependence of inhibitor potency on growth environment emphasizes the need for antimicrobial screening conditions that are relevant to the in vivo microbial microenvironment during infection. DXP synthase expression and thiamin supplementation studies offer support for DXP synthase as an intracellular target for some alkylAPs and reveal both the challenges and intriguing aspects of these approaches to study target engagement.

Advances in Green Organic Sonochemistry.

Over the past 15 years, sustainable chemistry has emerged as a new paradigm in the development of chemistry. In the field of organic synthesis, green chemistry rhymes with relevant choice of starting materials, atom economy, methodologies that minimize the number of chemical steps, appropriate use of benign solvents and reagents, efficient strategies for product isolation and purification and energy minimization. In that context, unconventional methods, and especially ultrasound, can be a fine addition towards achieving these green requirements. Undoubtedly, sonochemistry is considered as being one of the most promising green chemical methods (Cravotto et al. Catal Commun 63: 2-9, 2015). This review is devoted to the most striking results obtained in green organic sonochemistry between 2006 and 2016. Furthermore, among catalytic transformations, oxidation reactions are the most polluting reactions in the chemical industry; thus, we have focused a part of our review on the very promising catalytic activity of ultrasound for oxidative purposes.

N-Branched acyclic nucleoside phosphonates as monomers for the synthesis of modified oligonucleotides.

Protected N-branched nucleoside phosphonates containing adenine and thymine bases were prepared as the monomers for the introduction of aza-acyclic nucleotide units into modified oligonucleotides. The phosphotriester and phosphoramidite methods were used for the incorporation of modified and natural units, respectively. The solid phase synthesis of a series of nonamers containing one central modified unit was successfully performed in both 3'→5' and 5'→3' directions. Hybridization properties of the prepared oligoribonucleotides and oligodeoxyribonucleotides were evaluated. The measurement of thermal characteristics of the complexes of modified nonamers with the complementary strand revealed a considerable destabilizing effect of the introduced units. We also examined the substrate/inhibitory properties of aza-acyclic nucleoside phosphono-diphosphate derivatives (analogues of nucleoside triphosphates) but neither inhibition of human and bacterial DNA polymerases nor polymerase-mediated incorporation of these triphosphate analogues into short DNA was observed.

Recent advances in H-phosphonate chemistry. Part 1. H-phosphonate esters: synthesis and basic reactions.

This review covers recent progress in the preparation of H-phosphonate mono- and diesters, basic studies on mechanistic and stereochemical aspects of this class of phosphorus compounds, and their fundamental chemistry in terms of transformation of P-H bonds into P-heteroatom bonds. Selected recent applications of H-phosphonate derivatives in basic organic phosphorus chemistry and in the synthesis of biologically important phosphorus compounds are also discussed.

Multistage screening reveals chameleon ligands of the human farnesyl pyrophosphate synthase: implications to drug discovery for neurodegenerative diseases.

Human farnesyl pyrophosphate synthase (hFPPS) is the gate-keeper of mammalian isoprenoids and the key target of bisphosphonate drugs. Bisphosphonates suffer from poor "drug-like" properties and are mainly effective in treating skeletal diseases. Recent investigations have implicated hFPPS in various nonskeletal diseases, including Alzheimer's disease (AD). Analysis of single nucleotide polymorphisms in the hFPPS gene and mRNA levels in autopsy-confirmed AD subjects was undertaken, and a genetic link between hFPPS and phosphorylated tau (P-Tau) levels in the human brain was identified. Elevated P-Tau levels are strongly implicated in AD progression. The development of nonbisphosphonate inhibitors can provide molecular tools for validating hFPPS as a therapeutic target for tauopathy-associated neurodegeneration. A multistage screening protocol led to the identification of a new monophosphonate chemotype that bind in an allosteric pocket of hFPPS. Optimization of these compounds could lead to human therapeutics that block tau metabolism and arrest the progression of neurodegeneration.

Design, synthesis, antiviral and cytostatic activity of ω-(1H-1,2,3-triazol-1-yl)(polyhydroxy)alkylphosphonates as acyclic nucleotide analogues.

The efficient synthesis of a new series of polyhydroxylated dibenzyl ω-(1H-1,2,3-triazol-1-yl)alkylphosphonates as acyclic nucleotide analogues is described starting from dibenzyl ω-azido(polyhydroxy)alkylphosphonates and selected alkynes under microwave irradiation. Selected O,O-dibenzylphosphonate acyclonucleotides were transformed into the respective phosphonic acids. All compounds were evaluated in vitro for activity against a broad variety of DNA and RNA viruses and for cytostatic activity against murine leukemia L1210, human T-lymphocyte CEM and human cervix carcinoma HeLa cells. Compound (1S,2S)-16b exhibited antiviral activity against Influenza A H3N2 subtype (EC50=20µM-visual CPE score; EC50=18µM-MTS method; MCC >100µM, CC50 >100µM) in Madin Darby canine kidney cell cultures (MDCK), and (1S,2S)-16k was active against vesicular stomatitis virus and respiratory syncytial virus in HeLa cells (EC50=9 and 12µM, respectively). Moreover, compound (1R,2S)-16l showed activity against both herpes simplex viruses (HSV-1, HSV-2) in HEL cell cultures (EC50=2.9 and 4µM, respectively) and feline herpes virus in CRFK cells (EC50=4µM) but at the same time it exhibited cytotoxicity toward uninfected cell (MCC⩾4µM). Several other compounds have been found to inhibit proliferation of L1210, CEM as well as HeLa cells with IC50 in the 4-50µM range. Among them compounds (1S,2S)- and (1R,2S)-16l were the most active (IC50 in the 4-7µM range).

PMPA and PMEA prodrugs for the treatment of HIV infections and human papillomavirus (HPV) associated neoplasia and cancer.

The synthesis and in vitro biological evaluation of novel phosphonamidate and phosphonodiamidate prodrugs of adefovir and tenofovir are reported. The selected synthetic approach from free phosphonic acid via bis-trimethylsilyl ester intermediates affords (L)-alanine ester derivatives in 10-70% yields. When assessed for their anti-HIV activity, all the prodrugs showed submicromolar activity. Noteworthy, the most potent derivative in the adefovir series contained a 5,6,7,8-tetrahydronaphtyl group, herein reported for the first time as an aryl moiety in a ProTide. A pronounced cytostatic activity of the above prodrugs is also reported. Selected compounds were tested for their antiproliferative activity against HPV-transformed cells and they were found significantly more active in comparison to their parent compounds. In this study a slightly improved activity of the adefovir derivatives over those of tenofovir was also noticed. However, no specificity for naturally HPV-transformed cell lines was observed.

Pnicogen bonds between X═PH3 (X = O, S, NH, CH2) and phosphorus and nitrogen bases.

Ab initio MP2/aug'-cc-pVTZ calculations have been carried out to investigate the pnicogen bonded complexes formed between the acids O═PH3, S═PH3, HN═PH3, and H2C═PH3 and the bases NH3, NCH, N2, PH3, and PCH. All nitrogen and phosphorus bases form complexes in which the bases are lone pair electron donors. The binding energies of complexes involving the stronger bases NH3, NCH, and PH3 differentiate among the acids, but the binding energies of complexes with the weaker bases do not. These complexes are stabilized by charge transfer from the lone pair orbital of N or P to the σ*P═A orbital of X═PH3, where A is the atom of X directly bonded to P. PCH also forms complexes with the X═PH3 acids as a π electron donor to the σ*P═A orbital. The binding energies and the charge-transfer energies of the π complexes are greater than those of the complexes in which PCH is a lone pair donor. Whether the positive charge on P increases, decreases, or remains the same upon complex formation, the chemical shieldings of (31)P decrease in the complexes relative to the corresponding monomers. (1p)J(P-N) and (1p)J(P-P) values correlate best with the corresponding P-N and P-P distances as a function of the nature of the base. (1)J(P-A) values do not correlate with P-A distances. Rather, the absolute values of (1)J(P-O), (1)J(P-S), and (1)J(P-N) decrease upon complexation. Decreasing (1)J(P-A) values correlate linearly with increasing complex binding energies. In contrast, (1)J(P-C) values increase upon complexation and correlate linearly with increasing binding energies.

In vitro evaluation of 9-(2-phosphonylmethoxyethyl)adenine ester analogues, a series of anti-HBV structures with improved plasma stability and liver release.

Chronic hepatitis B virus (HBV) infection may lead to liver cirrhosis and hepatocellular carcinoma, but few drugs are available for its treatment. Acyclic nucleoside phosphonates (ANPs) have remarkable antivirus activities but are not easily absorbed from the gastrointestinal tract and accumulate in the kidneys, resulting in nephrotoxicity. Therefore, there is a need to find effective liver site-specific prodrugs. The dipivaloyloxymethyl ester of 9-(2-phosphonylmethoxyethyl)adenine (PMEA)-adefovir dipivoxil (ADV)-is a first-line therapy drug for chronic hepatitis B with a low therapeutic index because of renal toxicity and low hepatic uptake. In this study, a series of PMEA derivatives were synthesized to enhance plasma stability and liver release. The metabolic stability of ADV (Chemical I) and its two analogues (Chemicals II and III) was evaluated in rat plasma and liver homogenate in vitro. An ion-pair reverse-phase HPLC-UV method and a hybrid ion trap and high-resolution time-of-flight mass spectrometry (LC-IT-TOF-MS) were used to evaluate the degradation rate of the analogues and to identify their intermediate metabolites, respectively. Chemicals I and II were hydrolyzed by cleavage of the C-O bond to give monoesters. Sufficient enzymatic activation in the liver homogenate through a relatively simple metabolic pathway, in addition to a favorable stability profile in rat plasma, made Chemical II an optimal candidate. Next, six analogues based on the structure of Chemical II were synthesized and evaluated in plasma and liver homogenate. Compared to Chemical II, these compounds generated less active PMEA levels in rat liver homogenate. Therefore, chemical modification of Chemical II may lead to new promising PMEA derivatives with enhanced plasma stability and liver activation.

Synthesis and antitumor activities of novel α-aminophosphonates dehydroabietic acid derivatives.

A series of novel α-aminophosphonate derivatives containing DHA structure were designed and synthesized as antitumor agents. In vitro antitumor activities of these compounds against the NCI-H460 (human lung cancer cell), A549 (human lung adenocarcinoma cell), HepG2 (human liver cancer cell) and SKOV3 (human ovarian cancer cell) human cancer cell lines were evaluated and compared with commercial anticancer drug 5-fluorouracil (5-FU), employing standard MTT assay. The pharmacological screening results revealed that many compounds exhibited moderate to high levels of antitumor activities against the tested cancer cell lines and that most demonstrated more potent inhibitory activities compared with the commercial anticancer drug 5-FU. The action mechanism of representative compound 7c was preliminarily investigated by acridine orange/ethidium bromide staining, Hoechst 33258 staining, JC-1 mitochondrial membrane potential staining and flow cytometry, which indicated that the compound can induce cell apoptosis in NCI-H460 cells. Cell cycle analysis showed that compound 7c mainly arrested NCI-H460 cells in G1 stage.

Evaluation of 2'-α-fluorine modified nucleoside phosphonates as potential inhibitors of HCV polymerase.

Ribonucleoside phosphonate analogues containing 2'-α-fluoro modifications were synthesized and their potency evaluated against HCV RNA polymerase. The diphosphophosphonate (triphosphate equivalent) adenine and cytidine analogues displayed potent inhibition of the HCV polymerase in the range of 1.9-2.1 µM, but only modest cell-based activity in the HCV replicon. Pro-drugs of the parent nucleoside phosphonates improved the cell-based activity.

Design and synthesis of small molecule glycerol 3-phosphate acyltransferase inhibitors.

The incidence of obesity and other diseases associated with an increased triacylglycerol mass is growing rapidly, particularly in the United States. Glycerol 3-phosphate acyltransferase (GPAT) catalyzes the rate-limiting step of glycerolipid biosynthesis, the acylation of glycerol 3-phosphate with saturated long-chain acyl-CoAs. In an effort to produce small molecule inhibitors of this enzyme, a series of benzoic and phosphonic acids was designed and synthesized. In vitro testing of this series has led to the identification of several compounds, in particular 2-(nonylsulfonamido)benzoic acid (15g), possessing moderate GPAT inhibitory activity in an intact mitochondrial assay.

Synthesis and biological evaluation of a series of liver-selective phosphonic acid thyroid hormone receptor agonists and their prodrugs.

Phosphonic acid (PA) thyroid hormone receptor (TR) agonists were synthesized to exploit the poor distribution of PA-based drugs to extrahepatic tissues and thereby to improve the therapeutic index. Nine PAs showed excellent TR binding affinities (TRbeta(1), K(i) < 10 nM), and most of them demonstrated significant cholesterol lowering effects in a cholesterol-fed rat (CFR) model. Unlike the corresponding carboxylic acid analogue and T(3), PA 22c demonstrated liver-selective effects by inducing maximal mitochondrial glycerol-3-phosphate dehydrogenase activity in rat liver while having no effect in the heart. Because of the low oral bioavailability of PA 22c, a series of prodrugs was synthesized and screened for oral efficacy in the CFR assay. The liver-activated cyclic 1-(3-chlorophenyl)-1,3-propanyl prodrug (MB07811) showed potent lipid lowering activity in the CFR (ED(50) 0.4 mg/kg, po) and good oral bioavailability (40%, rat) and was selected for development for the treatment of hypercholesterolemia.

Activity-based proteomics of lipolytic enzymes.

Lipases play fundamental roles in biological processes since hydrolysis of triacylglycerols and cholesteryl esters is a key event in energy homeostasis of animals. Perturbations in the metabolism and the cellular retention of lipids result in common diseases such as obesity, type 2 diabetes, and atherosclerosis. The introduction of active site-directed chemical probes for enzymatic activity profiling in complex mixtures, known as activity-based proteomics, has greatly facilitated and accelerated global analysis and functional annotation of lipolytic proteins. Here we review probe design and application for discovery and discrimination of lipolytic and esterolytic enzymes. These probes are usually detected by their fluorescent or affinity tags and their protein targets are analyzed using established proteomics techniques. Moreover, microarray technologies can be applied for higher throughput screenings of enzyme or probe specificity.

Inhibitors of phenylalanine ammonia-lyase: substituted derivatives of 2-aminoindane-2-phosphonic acid and 1-aminobenzylphosphonic acid.

Six derivatives of 2-aminoindane-2-phosphonic acid and 1-aminobenzylphosphonic acid were synthesized. The compounds were tested both as inhibitors of buckwheat phenylalanine ammonia-lyase (in vitro) and as inhibitors of anthocyanin biosynthesis (in vivo). (+/-)-2-Amino-4-bromoindane-2-phosphonic acid was found to be the strongest inhibitor from investigated compounds. The results obtained are a basis for design of phenylalanine ammonia-lyase inhibitors useful in the enzyme structure studies in photo labelling experiments.

Synthesis and evaluation of ketophosph(on)ates as beta-lactamase inhibitors.

A series of amidoketophosph(on)ates of general structure PhCH2OCONHCH(R)COCHR'(CH2)n(O)P(O2-)(O)R'' (R = H, CH3; R' = H, CH3; n = 0, 1; R'' = H, CH3, Et, Ph) have been prepared as a potential source of beta-lactamase inhibitors. The phosphonates (n = 0) were obtained by means of the Arbuzov reaction while most of the phosphates were achieved from reaction of phosph(or/on)ic acids with the appropriate diazoketone PhCH2OCONHCH(R)COCR'N2. The electrophilicity of the carbonyl group in the resulting phosph(on)ates was assessed by the degree of hydration in aqueous solution, determined from NMR spectra. These compounds inhibited typical class C and class D beta-lactamases, particularly the latter group, but showed no activity against class A enzymes. To enhance the carbonyl electrophilicity, an alpha-difluorinated analogue (R = H, CHR' = CF2, n = 0, R'' = Et) was also prepared, but no enhanced inhibitory activity was observed. All evidence suggested that these compounds inhibited in the carbonyl form rather than by formation of tetrahedral adducts at the beta-lactamase active site. They show promise as leads to specific class D beta-lactamase inhibitors.