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A practical and facile strategy for the synthesis ofiortho/i-phosphated (hetero)arylamines from readily available arylhydroxylamines and dialkyl phosphites via cascade Atherton-Todd reaction/[3,3]-rearrangement was developed. This method is amenable to various arylhydroxylamines such as phenylhydroxylamines, naphthylhydroxylamines, and pyridylhydroxylamines, has mild reaction conditions, is oxidant-free, and has good functional-group compatibility and excellent regioselectivity.

Biocontainment is a key methodology to reduce environmental risk through the deliberate release of genetically modified microorganisms. Previously, we developed a phosphite (HPO

The oxidative α-functionalization of 2-aryl-1,2,3,4-tetrahydroisoquinolines (THIQs) promoted by a versatile heterogeneous nanocatalyst consisting of copper nanoparticles immobilized on silica-coated maghemite (CuNPs/MagSilica) has been accomplished. The methodology was successfully applied in the cross-dehydrogenative coupling (CDC) reaction of

A convenient, efficient, and inexpensive method has been developed for the synthesis of 1,2,3-triazine derivatives via deoxygenation of 1,2,3-triazine 1-oxide using trialkyl phosphites. Triethyl phosphite is more reactive than trimethyl phosphite, and both phosphites form their corresponding phosphates in these reactions. This procedure provides a range of aromatic and aliphatic substituted 1,2,3-triazine-4-carboxylate derivatives cleanly in high yields. Unexpected 1,2,4-triazine derivatives were also obtained as minor products during deoxygenation of 1,2,3-triazine-4-carboxylate 1-oxides having an aliphatic substituent at the 5-position.

α-Aminophosphonate analogues containing a phthalazine skeleton were efficiently obtained by a new transition-metal-free addition of dialkyl phosphites to phthalazin-2-ium bromide under mild conditions. A mechanistic study using isotope labeling and radical inhibition experiment revealed that the present transformation passes through a nucleophilic addition of dialkyl phosphates, rather than an insertion of

The binding of adenosine 5’-triphosphate (ATP) and adenosine 5’-monophosphate (AMP) to adenylate kinase (AdK) drives closure of lids over the substrate adenosyl groups. We test the hypothesis that this conformational change activates AdK for catalysis. The rate constants for Homo sapiens adenylate kinase 1 (HsAdK1)-catalyzed phosphoryl group transfer to AMP, k(cat)/K(m) = 7.0 x 10(6) M(−1) s(−1), and phosphite dianion, (k(HPi))(obs) ≤ 1 x 10(−4) M(−1) s(−1), show that the binding energy of the adenosyl group effects a ≥7.0 x 10(10)-fold rate acceleration of phosphoryl transfer from ATP. The third-order rate constant of k(cat)/K(HPi)K(EA) = 260 M(−2) s(−1) for 1-(β-d-erythrofuranosyl)adenine (EA)-activated phosphoryl transfer to phosphite dianion was determined, and the isohypophosphate reaction product characterized by (31)P NMR. The results demonstrate: (i) a ≥14.7 kcal/mol stabilization of the transition state for phosphoryl transfer by the adenosyl group of AMP and a ≥2.6 x 10(6)-fold rate acceleration from the EA-driven conformational change, and (ii) the recovery of ≥8.7 kcal/mol of this transition state stabilization for EA-activated phosphoryl transfer from ATP to phosphite.

Azido nucleosides couple with phosphoramidites via an initial iminophosphorane, which eliminates acrylonitrile to generate the coupled dimer P(V) product. The vulnerable phosphite triester intermediate is bypassed entirely, making the methodology very suitable to solution-phase synthesis. This new coupling protocol requires no protection of the 5'-OH function and provides a new method of installing internucleosidic phosphorodiamidate bonds with near quantitative yields.

A highly efficient and environmentally-friendly base-mediated transition metal-free direct thiophilic catalytic approach is reported for the synthesis of

A practical approach to α-aminophosphonates has been developed through an In(OTf)

The study was conducted with C31 and C80 genotypes of the potato (

Di-tert-butyl oxymethyl phosphonates were investigated regarding their suitability for preparing the active pharmaceutical ingredient tenofovir (PMPA). First, an efficient and simple access to the crystalline di-tert-butyl(hydroxymethyl)phosphonate was developed. O-Mesylation gave high yields of the active phosphonomethylation reagent. For the synthesis of tenofovir, a two-step sequence was developed using Mg(OtBu)2 as the base for the alkylation of (R)-9-(2-hydroxypropyl)adenine. Subsequent deprotection could be achieved with aqueous acids. (Di-tert-butoxyphosphoryl)methyl methanesulfonate showed to be the most efficient electrophile tested, affording PMPA in 72% yield on a 5 g scale. The developed protocol could also be applied for the preparation of the hepatitis B drug adefovir (64% yield/1 g scale).

The activation barriers ΔG⧧ for kcat/Km for the reactions of whole substrates catalyzed by 6-phosphogluconate dehydrogenase, glucose 6-phosphate dehydrogenase, and glucose 6-phosphate isomerase are reduced by 11-13 kcal/mol by interactions between the protein and the substrate phosphodianion. Between 4 and 6 kcal/mol of this dianion binding energy is expressed at the transition state for phosphite dianion activation of the respective enzyme-catalyzed reactions of truncated substrates d-xylonate or d-xylose. These and earlier results from studies on β-phosphoglucomutase, triosephosphate isomerase, and glycerol 3-phosphate dehydrogenase define a cluster of six enzymes that catalyze reactions in glycolysis or of glycolytic intermediates, and which utilize substrate dianion binding energy for enzyme activation. Dianion-driven conformational changes, which convert flexible open proteins to tight protein cages for the phosphorylated substrate, have been thoroughly documented for five of these six enzymes. The clustering of metabolic enzymes which couple phosphodianion-driven conformational changes to enzyme activation suggests that this catalytic motif has been widely propagated in the proteome.

Currently available fungicides against potato late blight are effective but there are concerns about the sustainability of frequent applications and the risks of fungicide resistance. Therefore, we investigated how potassium phosphite can be integrated into late blight control programs with reduced fungicides in field trials. Phosphite was somewhat less effective than the conventional fungicides at suppressing late blight in the foliage, and the tubers contained less starch. However, when we reduced the amount of phosphite and combined it with reduced amounts of conventional fungicides, we observed no differences in disease suppression, total yields, and tuber starch contents compared with the full treatments with conventional fungicides. The amount of phosphite detected in the harvested tubers was linearly associated with the amount of phosphite applied to the foliage. Our analyses indicate that phosphite could replace some fungicides without exceeding the current European Union standards for the maximum residue levels in potato tubers. No phosphite was detected in the starch from the tubers. In 1 of 2 years, early blight (caused by Alternaria solani) was less severe in the phosphite treatments than in the treatments without phosphite. The integration of phosphite into current treatment strategies would reduce the dependence on conventional fungicides.

The inhibiting effect of the secondary phosphite antioxidant degradation product bis(2,4-di-tert-butylphenyl)phosphate (bDtBPP) on cell growth is well-known. The present study describes structurally related compounds which are likely to be formed from similar widely used phosphite antioxidants used in materials for the manufacturing of single-use (SU) equipment. Two potential candidates of such compounds-3,3',5,5'-tetra-tert-butyl-2,2'-dihydroxybiphenylphosphate (TtBBP) and bis(p-nonylphenyl)phosphate (bNPP)-were identified by chromatography and mass spectrometry followed by synthesis and X-ray structure elucidation. Additionally, the formation of TtBBP was confirmed in an analytical degradation study and its migration from SU bioprocessing material was estimated. The cytotoxicity evaluation by means of cell culture spiking experiments and flow cytometry analysis revealed that' even if cell growth was inhibited by all the compounds to some extent, bDtBPP showed the most severe effect and stoods out from the other two degradants investigated. Graphical abstract.

In situ synthesis of a deep eutectic solvent and homogeneous liquid-liquid microextraction performed in a narrow bore tube was developed for efficient extraction of irgaphos 168 and irganox 1010 in doogh and water samples packed in polypropylene packages. First, pH of the aqueous sample solutions containing the analytes is adjusted at 9. Then a hydrogen bond acceptor (choline chloride) and a hydrogen bond donor (oleic acid) are dissolved in the solution and vortexed to obtain a homogeneous solution. The solution is filled into a narrow bore tube, in which its bottom was clogged by a septum. Then hydrochloric acid solution is injected into the solution by a syringe. The tube is placed in an ultrasonic bath. During this step, the droplets of choline chloride:oleic acid deep eutectic solvent are produced. The method indicated high enrichment factor (435 for irgaphos 168 and 488 for irganox 1010), low limits of detection (0.03 and 0.09 ng/mL for irgaphos 168 and irganox 1010, respectively) and quantification (0.13 and 0.29 ng/mL for irgaphos 168 and irganox 1010), good recovery (74 and 83% for irgaphos 168 and irganox 1010, respectively), and satisfactory repeatabilities (relative standard deviations ≤12%) can be obtained using the developed method.

While the Staudinger reaction has first been described a hundred years ago in 1919, the ligation reaction became one of the most important and efficient bioconjugation techniques in the 1990s and this century. It holds the crucial characteristics for bioorthogonal chemistry: biocompatibility, selectivity, and a rapid and high-yielding turnover for a wide variety of applications. In the past years, it has been used especially in chemical biology for peptide/protein synthesis, posttranslational modifications, and DNA labeling. Furthermore, it can be used for cell-surface engineering, development of microarrays, and drug delivery systems. However, it is also possible to use the reaction in synthetic chemistry for general formation of amide bonds. In this review, the three major types, traceless and nontraceless Staudinger Ligation as well as the Staudinger phosphite reaction, are described in detail. We will further illustrate each reaction mechanism and describe characteristic substrates, intermediates, and products. In addition, not only its advantages but also stereochemical aspects, scope, and limitations, in particular side reactions, are discussed. Finally, the method is compared to other bioorthogonal labeling methods.

A genetically modified (GM) strain of the diatom Chaetoceros gracilis expressing the phosphite dehydrogenase gene (ptxD), which is a useful gene both for the biological containment and the avoidance of microbial contamination, was characterized to estimate the risk against the biodiversity by laboratory experiments. GM strain could grow in the medium containing phosphite as a sole source of phosphorus, while its general characteristics such as growth, salt tolerance, heat and dehydration resistance in the normal phosphate-containing medium were equivalent to those of wild type (WT) strain. The increase in potential toxicity of GM strain against plant, crustacean, fish and mammal was also disproved. The dispersal ability of WT strain cultured in an outdoor raceway pond was investigated for 28 days by detecting the psb31 gene in vessels, settled at variable distances (between 5 and 60 m) from the pond. The diatom was detected only in one vessel placed 5 m apart. To estimate the influence on the environment, WT and GM strains were inoculated into freshwater, seawater and soil. The influence on the microbiome in those samples was assessed by 16S rRNA gene amplicon sequencing, in addition to the analysis of the survivability of those strains in the freshwater and the seawater. The results indicated that the effect to the microbiome and the survivability were comparable between WT and GM strains. All results showed that the introduction of the ptxD gene into the diatom had a low risk on biodiversity.

An uncommon example of stable mixed-ligand zinc phosphite with genuine pores has been synthesized by using zinc metal, inorganic phosphite acid, thio-functionalized O-donor (2,5-thiophenedicarboxylate, TPDC), and tetradentate N-donor [1,2,4,5-tetrakis(imidazol-1-ylmethyl)benzene, TIMB] units assembled into one crystalline structure according to a hydro(solvo)thermal method. This is a very rare case of a metal phosphite incorporating both N- and O-donor ligands. The tetradentate TIMB linker bound to zinc atoms of the isolated zincophosphite hexamers to form a 3D open-framework structure by crosslinking structural components of 1D chains and 2D layers. Here, the TPDC ligand acts as a monodentate binding model to functionalize its porous structure with the uncoordinated S atom and COO

This article contains a synthetic protocol for solvent-assisted mechanochemical synthesis of a nucleotide dimer. First, a dinucleoside phosphite is prepared by solvent-assisted mechanochemistry via the phosphoramidite method. Second, the dinucleoside phosphite is oxidized to form the dinucleotide under mechanochemical conditions. Finally, the dinucleotide is purified by column chromatography. Support protocols are also provided for preparing the acidic salts that can be utilized for phosphoramidite couplings and for demonstrating that the reaction occurs under mechanochemical conditions rather than as a result of solvent added for analysis. Mechanochemistry as applied to synthesis of dinucleotides is a recent development and it is anticipated that the principles in this protocol will be widely applicable to a range of nucleoside and ribonucleoside monomers. The advantages of mechanochemistry over traditional solution-phase chemistry are the simplicity of the procedure, improved hydrolytic stability, and elimination of the need to solubilize poorly soluble compounds. © 2022 Wiley Periodicals LLC. Basic Protocol: Solvent-assisted mechanochemical synthesis of a nucleotide dimer Supplementary Protocol 1: Synthesis of N-methylimidazolium triflate Supplementary Protocol 2: Synthesis of pyridinium trifluoroacetate Supplementary Protocol 3: Confirmation of the efficacy of mechanochemical conditions.

Reduction of fungicide consumption in agriculture is globally recognized as a priority. Government authorities are fostering research to achieve a reduction of risks associated with conventional pesticides and promoting the development of sustainable alternatives. To address these issues, in the present study, alternative protocols for the control of downy mildew infection in grapevine were compared to the standard protocol. In the first protocol, only resistance inducers were used, comprising a single formulation with Acibenzolar S-methyl, laminarin and disodium-phosphonate. The second and third protocols followed the standard protocol but substituted phosphonates with phosphorus pentoxide and Ecklonia maxima extract.The results showed that at veraison downy mildew incidence and severity in all tested protocols were significantly reduced compared to nontreated controls on both canopy and bunches. Expression analysis of key genes involved in plant stress response, indicated that the two protocols for phosphites substitution induced a remodulation of salicylic acid (SA) and jasmonic acid (JA), with positive impact on yields. Analysis of the first protocol revealed that the primed state induced a short delay in bunch ripening, with a shift of carbohydrate metabolism to boost the plant defences, involving an upregulation of defence related-gene, SAR response and a decreased ROS detoxification. Additionally, analysis on the arthropods populations, in parallel with the positive results achieved using alternatives to conventional fungicides, were enriched by those showing the potential of naturally occurring predators of spider mites.This study provides practical solutions to reduce the environmental impact of treatments for the control downy mildew in viticulture. © 2022 Society of Chemical Industry.

Enzymes with dedicated cofactor preference are essential for advanced biocatalysis and biomanufacturing, especially when employing nonnatural nicotinamide cofactors in redox reactions. However, directed evolution of an enzyme to switch its cofactor preference is often hindered by the lack of efficient and affordable method for screening as the cofactor per se or the substrate can be prohibitively expensive. Here, we developed a growth-based selection platform to identify nonnatural cofactor-dependent oxidoreductase mutants. The growth of bacteria depended on the nicotinamide cytosine dinucleotide (NCD) mediated conversion of non-metabolizable phosphite into phosphate. The strain BW14329 lacking the ability to oxidize phosphite was suitable as host, and NCD-dependent phosphite dehydrogenase (Pdh*) is essential to the selection platform. Previously confirmed NCD synthetase with NCD synthesis capacity and NCD-dependent malic enzyme were successfully identified by using the platform. The feasibility of this strategy was successfully demonstrated using derived NCD-active malic enzyme as well as for the directed evolution of NCD synthetase in Escherichia coli. A phosphite-based screening platform was built for identification of enzymes favoring nonnatural cofactor NCD. In the future, once Pdh variants favoring other biomimetic or nonnatural cofactors are available this selection platform may be readily redesigned to attain new enzyme variants with anticipated cofactor preference, providing opportunities to further expand the chemical space of redox cofactors in chemical biology and synthetic biology.

Renewed interest in phosphite, an analog of phosphate, has increased due to its widespread distribution and increasing abundance in many waterbodies. However, up until recently very little is known about their ecological effects on aquatic organisms. Herein we studied the effects of phosphite via root and foliar exposure on the growth responses of the dominant pioneer macrophyte V. natans. Overall, both exposures of phosphite to V. natans resulted in significant reductions in the leaf length, root length, relative growth rate (RGR) and photosynthetic pigments, suggesting phosphite had an inhibitory effect on the plant growth. Our results further confirmed phosphite could induce the oxidative stresses in the V. natans cells, as indicated by the significantly increased intracellular enzyme activities i.e. superoxide dismutase activity (SOD) and malondialdehyde (MDA). Microscopic evidence also showed phosphite penetrated the cell membrane and destroyed membrane integrity under high phosphite stress. Besides, V. natans leaves exhibited intuitive deterioration symptoms, which seemed to be more sensitive to phosphite toxicity than roots. It is concluded that the increased abundance of phosphite in waterbodies cannot be utilized as a bioavailable P source but impose adverse physiological and metabolic limitations to plant growth, which should be receive more attention in the ecological risk assessment. Our result is necessary to build a comprehensive understanding of phosphite biogeochemical behaviors in aquatic ecosystems.

The role of a global, substrate-driven, enzyme conformational change in enabling the extraordinarily large rate acceleration for orotidine 5’-monophosphate decarboxylase (OMPDC)-catalyzed decarboxylation of orotidine 5’-monophosphate (OMP) is examined in experiments that focus on the interactions between OMPDC and the ribosyl hydroxyl groups of OMP. The D37 and T100’ side chains of OMPDC interact, respectively, with the C-3’ and C-2’ hydroxyl groups of enzyme-bound OMP. D37G and T100’A substitutions result in 1.4 kcal/mol increases in the activation barrier ΔG(‡) for catalysis of decarboxylation of the phosphodianion truncated substrate 1-(β-D-erythrofuranosyl)orotic acid (EO), but in larger 2.1–2.9 kcal/mole increases in ΔG(‡) for decarboxylation of OMP, and for phosphite dianion-activated decarboxylation of EO. This shows that these substitutions reduce transition state stabilization by the Q215, Y217 and R235 side chain at the dianion binding site. The D37G and T100’A substitutions result in

Treatment of alkynes with diethyl phosphite and

A highly regio- and diastereoselective approach for the synthesis of phosphate substituted dihydrocoumarins via Brønsted base catalyzed [1,2]-phospha-Brook rearrangement is reported. The two-step, one-pot Michael addition of α-phosphonyloxy enolates proceeds by coupling of dialkyl phosphite and α-ketoesters to

Substituted cyclohexylamines are becoming increasingly important in drug discovery. Asymmetric Heck insertion/amination of nonconjugated cyclodienes proceeds to give 5-aryl cyclohexenylamines with good enantioselectivity and exclusive trans configurations. Primary and secondary anilines, indoline, and benzylamines are suitable amines. The weakly donating diphosphite Kelliphite forms a deep unsymmetrical pocket, which is essential for stereoselective anti attack of amines. Agency for Science, Technology and Research (A*STAR) Economic Development Board (EDB) Accepted version We acknowledge financial support from Peking UniversityShenzhen Graduate School, Shenzhen Bay Laboratory(21230011-Scripps), Nanyang Technological University,GSK-EDB Trust Fund (2017 GSK-EDB Green and Sustain-able Manufacturing Award) and A*STAR Science andEngineering Research Council (AME IRG A1783c0010).

The projected decline of available phosphorus necessitates alternative methods to derive usable phosphate for fertilizer and other applications. Phosphite dehydrogenase oxidizes phosphite to phosphate with the cofactor NAD+ serving as the hydride acceptor. In addition to producing phosphate, this enzyme plays an important role in NADH cofactor regeneration processes. Mixed quantum mechanical/molecular mechanical free energy simulations were performed to elucidate the mechanism of this enzyme and to identify the protonation states of the substrate and product. Specifically, the finite temperature string method with umbrella sampling was used to generate the free energy surfaces and determine the minimum free energy paths for six different initial conditions that varied in the protonation state of the substrate and the position of the nucleophilic water molecule. In contrast to previous studies, the mechanism predicted by all six independent strings is a concerted but asynchronous dissociative mechanism in which hydride transfer from the phosphite substrate to NAD+ occurs prior to attack by the nucleophilic water molecule. His292 is identified as the most likely general base that deprotonates the attacking water molecule. However, Arg237 could also serve as this base if it were deprotonated and His292 were protonated prior to the main chemical transformation, although this scenario is less probable. The simulations indicate that the phosphite substrate is monoanionic in its active form and that the most likely product is dihydrogen phosphate. These mechanistic insights may be helpful for designing mutant enzymes or artificial constructs that convert phosphite to phosphate and NAD+ to NADH more effectively.

Two crystalline open-framework indium phosphites (denoted SCU-31 and SCU-32) were prepared using amino acids as structure-directing agents. They have isoreticular pillared-layered structures built up from 6 × 1 and 4 = 1 clusters. Notably, the two compounds show excellent water stability and exhibit blue fluorescence under UV light irradiation at room temperature. The proton-conducting behaviour of SCU-31 was also investigated.

Edible microalgae have potential as low-cost cell factories for the production and oral delivery of recombinant proteins such as vaccines, anti-bacterials and gut-active enzymes that are beneficial to farmed animals including livestock, poultry and fish. However, a major economic and technical problem associated with large-scale cultivation of microalgae, even in closed photobioreactors, is invasion by contaminating microorganisms. Avoiding this requires costly media sterilisation, aseptic techniques during set-up and implementation of ‘crop-protection’ strategies during cultivation. Here, we report a strain improvement approach in which the chloroplast of Chlamydomonas reinhardtii is engineered to allow oxidation of phosphite to its bio-available form: phosphate. We have designed a synthetic version of the bacterial gene (ptxD)-encoding phosphite oxidoreductase such that it is highly expressed in the chloroplast but has a Trp→Opal codon reassignment for bio-containment of the transgene. Under mixotrophic conditions, the growth rate of the engineered alga is unaffected when phosphate is replaced with phosphite in the medium. Furthermore, under non-sterile conditions, growth of contaminating microorganisms is severely impeded in phosphite medium. This, therefore, offers the possibility of producing algal biomass under non-sterile conditions. The ptxD gene can also serve as a dominant marker for genetic engineering of any C. reinhardtii strain, thereby avoiding the use of antibiotic resistance genes as markers and allowing the ‘retro-fitting’ of existing engineered strains. As a proof of concept, we demonstrate the application of our ptxD technology to a strain expressing a subunit vaccine targeting a major viral pathogen of farmed fish.

The activity of diethyl phosphite and diphenyl phosphate in propargylation reactions with N-nucleophiles of varying basicity is presented. A careful choice of the reaction conditions minimized undesired rearrangements and arylation processes, typical side reactions with Brønsted acid catalysis. These systems are compatible with technical solvents and presence of air, and they are also applicable to C-, O-, and S-nucleophiles.

Elimination of phosphite from water is more difficult than elimination of phosphate owing to its higher solubility and resistance to biotransformation. Herein, we report an efficient, facile, electrochemical method integrating electrooxdiation (EO) and electrocoagulation (EC) to treat phosphite-laden wastewater. The mechanistic studies demonstrate that in-situ-generated Fe2+ at an Fe anode can react with in-situ-generated O2 at a mixed metal oxide (MMO) anode, leading to formation of •O2-, a reactive species predominantly responsible for oxidation of phosphite to phosphate. The phosphate is immediately coagulated by Fe hydroxides that are formed due to the production of OH- at a stainless-steel cathode. The integrated EO/EC system enables a phosphite removal efficiency of 74.25% (MMO anode, 100 mA; Fe anode, 100 mA; reaction time, 60 min), a significantly higher efficiency rate than the rate obtained in the control experiments in the absence of an MMO anode (

Hybrid organic–inorganic compounds crystallizing in a three-dimensional (3D) perovskite-type architecture have attracted considerable attention due to their multifunctional properties. One of the most intriguing groups is perovskites with hypophosphite linkers. Herein, the optical properties of six hybrid hypophosphite perovskites containing manganese ions are presented. The band gaps of these compounds, as well as the luminescence properties of the octahedrally coordinated Mn2+ ions associated with the 4T1g(G) → 6A1g(S) transition are shown to be dependent on the organic cation type and Goldschmidt tolerance factor. Thus, a correlation between essential structural features of Mn-based hybrid hypophosphites and their optical properties was observed. Additionally, the broad infrared luminescence of the studied compounds was examined for potential application in an indoor lighting system for plant growth.

Bacterial wilt caused by

A novel approach to 2-substituted-2-(dimethoxyphosphoryl)-pyrrolidines

In rice farming, the blast disease caused by Magnaporthe oryzae (T.T. Hebert) M.E. Barr. is one of the primary production constraints worldwide. The current blast management options such as blast-resistant varieties and spraying fungicides are neither durable nor commercially and environmentally compatible. In the present study, we investigated the antifungal and defense elicitor activity of potassium phosphite (Phi) against M. oryzae on elite rice cultivar BPT5204 (popularly known as Samba Mahsuri in India) and its transgenic rice variant (ptxD-OE) over-expressing a phosphite dehydrogenase enzyme. The Phi was evaluated both preventively and curatively on rice genotypes where the preventive spray of Phi outperformed the Phi curative application with significant reductions in both rice blast severity (35.67-60.49%) and incidence (22.27-53.25%). Moreover, the application of Phi increased the levels of photosynthetic pigments (Chlorophyll and Carotenoids) coupled with increased activity of defense enzymes (PAL, SOD, and APx). Besides, Phi application also induced the expression of defense-associated genes (OsCEBiP and OsPDF2.2) in the rice leaf. Furthermore, the Phi application reduced the reactive Malondialdehyde (lipid peroxidation) to minimize the cellular damage incited by Magnaporthe in rice. Overall, the present study showed the potential of Phi for blast suppression on rice as an alternative to the current excessive use of toxic fungicides.

Nowadays, the ubiquitous distribution and increasing abundance of P

Selective markers are generally indispensable in plant genetic transformation, of which the frequently used are of antibiotic or herbicide resistance. However, the increasing concerns on transgenic biosafety have encouraged many new and safe selective markers emerging, with an eminent representative as phosphite (Phi) in combination to its dehydrogenase (PTDH, e.g. PtxD). As bacterial alkaline phosphatase (BAP) can resemble PtxD to oxidatively convert toxic Phi into metabolizable phosphate (Pi), herein we harnessed it as the substitute of PtxD to develop an alternative Phi-based selection system. We first validated the Escherichia coli BAP (EcBAP) did own an extra enzymatic activity of oxidizing Phi to Pi. We further revealed EcBAP could be used as a dominant selective marker for Agrobacterium-mediated tobacco transformation. Although the involved Phi selection for transformed tobacco cells surprisingly required the presence of Pi, it showed a considerable transformation efficiency and dramatically accelerated transformation procedure, as compared to the routine kanamycin selection and the well-known PtxD/Phi system. Moreover, the EcBAP transgenic tobaccos could metabolize toxic Phi as a phosphorus (P) fertilizer thus underlying Phi-resistance, and competitively possess a dominant growth over wild-type tobacco and weeds under Phi stress. Therefore, this novel BAP/Phi-coupled system, integrating multiple advantages covering biosafe dominant selective marker, plant P utilization and weed management, can provide a PTDH-bypass technological choice to engineer transgenic plant species, especially those of great importance for sustainable agriculture.

Phytophthora root rot, caused by

Diethyl phosphite-initiated coupling of isatins with

Kanosamine is an antibiotic and antifungal compound synthesized from glucose 6-phosphate (G6P) in Bacillus subtilis by the action of three enzymes: NtdC, which catalyzes NAD-dependent oxidation of the C3-hydroxyl; NtdA, a PLP-dependent aminotransferase; and NtdB, a phosphatase. We previously demonstrated that NtdC can also oxidize substrates such as glucose and xylose, though at much lower rates, suggesting that the phosphoryloxymethylene moiety of the substrate is critical for effective catalysis. To probe this, we synthesized two phosphonate analogues of G6P in which the bridging oxygen is replaced by methylene and difluoromethylene groups. These analogues are substrates for NtdC, with second-order rate constants an order of magnitude lower than those for G6P. NtdA converts the resulting 3-keto products to the corresponding kanosamine 6-phosphonate analogues. We compared the rates to the rate of NtdC oxidation of glucose and xylose and showed that the low reactivity of xylose could be rescued 4-fold by the presence of phosphite, mimicking G6P in two pieces. These results allow the evaluation of the individual energetic contributions to catalysis of the bridging oxygen, the bridging C6 methylene, the phosphodianion, and the entropic gain of one substrate versus two substrate pieces. Phosphite also rescued the reversible formation 3-amino-3-deoxy-d-xylose by NtdA, demonstrating that truncated and nonhydrolyzable analogues of kanosamine 6-phosphate can be generated enzymatically.

The chemical reactivity of 3-[(E)-3-(dimethylamino)-2-propenoyl]-4-hydroxy-1-methy-2(1H)-quinolinone (1) towards some phosphorus reagents was studied. The enaminone 1 was cyclized into pyranoquinolinylphosphonate 2 via treatment with diethyl phosphite in basic medium. However, its reaction with triethoxy phosphonoacetate gave the substituted oxopyranylphosphonate 3. Using the same reaction conditions, both thioxopyridinylphosphonate 4 and oxopyranylphosphonate 5 were produced via a reaction of enaminone 1 with both diethyl 2-amino-2-thioxoethylphosphonate and diethyl vinylphosphonate, respectively, in low yields. In addition, the two novel oxopyridinylphosphonates 6 and 7 were obtained by treatment of enaminone 1 with a diethyl cyanomethylphosphonate reagent. Two oaxathiaphosphininyl derivatives, 8 and 9, were obtained by treatment of the enaminone 1 with O, O-diethyl dithiophosphoric acid under different reaction conditions. Diazaphosphininyl 11 and oxazaphosphininyl 12 derivatives were obtained in excellent yields using a P-phenylphosphonic diamide reagent under different reaction conditions. The treatment of the enaminone 1 with phosphorus pentasulfide produced the non-phosphorylated product thioxothiopyranoquinolinone 13. Finally, the enaminone was turned into oxathiaphosphininyl 14 using Lawesson’s reagent. The possible reaction mechanisms of the formation of these products were discussed. The structures of newly isolated products were established by elemental analysis and spectral tools. The compounds were evaluated for their antioxidant activities.

BACKGROUND Proper management of Phytophthora capsici in pepper cultivation is extremely important, since Phytophthora blight is the main disease of this crop worldwide. In the past, the main strategy adopted had been the use of fungicides, causing, in some cases, the development of P. capsici resistant strains. In this work three different treatments selected from previous studies (potassium phosphite, calcium oxide and a water suspension from Trichoderma sp. TW2 enriched compost) were tested to prove their ability to activate the systemic acquired resistance (SAR) in pepper against P. capsici; acibenzolar‐s‐methyl was used as positive control. Two independent growth chamber pot experiments were performed, spatially dividing the site of treatments application (as radical drench) and the site of inoculation (as agar plug on the third leaf). RESULTS Leaf lesions were measured, showing a significant reduction on all treated plants compared to the untreated control. To further confirm this hypothesis, the expression levels of three SAR key genes (CaPBR1, CaPO1 and CaDEF1) were evaluated though RT‐Real Time PCR at the three end‐point times: T0, T6 and T24. A significant increase of target genes expression at least in one end‐point time in each treated plant was observed. Eventually, statistical overaccumulation of salicylic acid was observed in the upper leaves at the same end‐point times, through HPLC‐MS/MS analysis. CONCLUSION This work confirmed the hypothesis that the three treatments tested have the ability to prime the plant immune system, leading pepper to an alert status able to confer a better defence against P. capsici. © 2021 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry., Three treatments (Calcium oxide, potassium phosphite and a Trichoderma enriched compost water suspension) were demonstrated to activate the systemic acquired resistance on Capsicum annuum plants against Phytophthora capsici attacks through the study of genes (CaPBR1, CADEF1 and CAPO1) expression and salicylic acid accumulation. ​ © 2021 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Phosphite is the most energetically favorable chemotrophic electron donor known, with a half-cell potential (E(o)′) of −650 mV for the PO(4)(3−)/PO(3)(3−) couple. Since the discovery of microbial dissimilatory phosphite oxidation (DPO) in 2000, the environmental distribution, evolution, and diversity of DPO microorganisms (DPOMs) have remained enigmatic, as only two species have been identified. Here, metagenomic sequencing of phosphite-enriched microbial communities enabled the genome reconstruction and metabolic characterization of 21 additional DPOMs. These DPOMs spanned six classes of bacteria, including the Negativicutes, Desulfotomaculia, Synergistia, Syntrophia, Desulfobacteria, and Desulfomonilia_A. Comparing the DPO genes from the genomes of enriched organisms with over 17,000 publicly available metagenomes revealed the global existence of this metabolism in diverse anoxic environments, including wastewaters, sediments, and subsurface aquifers. Despite their newfound environmental and taxonomic diversity, metagenomic analyses suggested that the typical DPOM is a chemolithoautotroph that occupies low-oxygen environments and specializes in phosphite oxidation coupled to CO(2) reduction. Phylogenetic analyses indicated that the DPO genes form a highly conserved cluster that likely has ancient origins predating the split of monoderm and diderm bacteria. By coupling microbial cultivation strategies with metagenomics, these studies highlighted the unsampled metabolic versatility latent in microbial communities. We have uncovered the unexpected prevalence, diversity, biochemical specialization, and ancient origins of a unique metabolism central to the redox cycling of phosphorus, a primary nutrient on Earth.

The combination of MicroScale Thermophoresis (MST) and near-native site-specific His-tag labeling enables simple, robust, and reliable determination of the binding affinity between proteins and ligands. To demonstrate its applicability for periplasmic proteins, we provide a detailed protocol for determination of the binding affinity of phosphite to three ABC transporter periplasmic-binding proteins from environmental microorganisms. ABC transporters are central to many important biomedical phenomena, including resistance of cancers and pathogenic microbes to drugs. The protocol described here can be used to quantify protein-ligand and protein-protein interactions for other soluble, membrane-associated and integral membrane proteins.

Chiral bridged [2,2,1] bicyclic lactones are privileged structural units in pharmaceutics and bioactive nature products. However, the synthetic methods for these compounds are rare. Here we report an efficient method for enantioselective construction of bridged [2,2,1] bicyclic lactones bearing a quaternary stereocenter via Rh-catalyzed asymmetric hydroformylation/intramolecular cyclization/pyridium chlorochromate (PCC) oxidation. By employing a hybrid phosphine-phosphite chiral ligand, a series of cyclopent-3-en-1-ols are transformed into corresponding γ-hydroxyl aldehydes with specific syn-selectivity. Then, hemiacetals form in situ and oxidation with PCC in one-pot affords bridged [2,2,1] bicyclic lactones in high yields and excellent enantiomeric excess. Replacing the hydroxyl group by an ester group, cyclopentanecarbaldehydes with a chiral all-carbon quaternary stereocenter in the γ-position can be generated efficiently., Enantiomeric bridged [2,2,1] bicyclic lactone skeletons and their ring-opening products are important scaffolds widely occurring in both pharmaceutics and biology active compounds. Here the authors show an efficient method for enantioselective construction of these compounds bearing a quaternary stereocenter via Rh-catalyzed asymmetric hydroformylation/intramolecular cyclization/ pyridinium chlorochromate oxidation.

Phosphite is the most energetically favorable chemotrophic electron donor known, with a half-cell potential (E°’) of −650 mV for the PO43-/PO33- couple. Since the discovery of microbial dissimilatory phosphite oxidation (DPO) in 2000, the environmental distribution, evolution, and diversity of DPO microorganisms (DPOM) has remained enigmatic and only two species have been identified. Here metagenomic sequencing of phosphite enriched microbial communities enabled the reconstruction and metabolic characterization of 21 novel DPOM. These DPOM spanned six classes of bacteria, including the Negativicutes, Desulfotomaculia, Synergistia, Syntrophia, Desulfobacteria and Desulfomonilia_A. Comparing the DPO genes from the genomes of enriched organisms to over 17,000 publicly available metagenomes revealed the global existence of this metabolism in diverse anoxic environments, including wastewaters, sediments, and subsurface aquifers. Despite their newfound environmental and taxonomic diversity, metagenomic analyses suggested that the typical DPOM is a chemolithoautotroph that occupies low-oxygen environments and specializes in phosphite oxidation coupled to CO2 reduction. Phylogenetic analyses indicated that the DPO genes form a highly conserved cluster that likely has ancient origins predating the split of monoderm and diderm bacteria. By coupling microbial cultivation strategies with metagenomics, these studies highlighted the unsampled metabolic versatility latent in microbial communities. We have uncovered the unexpected prevalence, diversity, biochemical specialization, and ancient origins of a unique metabolism central to the redox cycling of phosphorus, a primary nutrient on earth.Significance StatementGeochemical models of the phosphorus (P) cycle uniquely ignore microbial redox transformations. Yet phosphite is a reduced P source that has been detected in several environments at concentrations that suggest a contemporary P redox cycle. Microbial dissimilatory phosphite oxidation (DPO) converts soluble phosphite into phosphate, and a false notion of rarity has limited our understanding of its diversity and environmental distribution. Here we demonstrate that DPO is an ancient energy metabolism hosted by taxonomically diverse, autotrophic bacteria that exist globally throughout anoxic environments. DPO microorganisms are therefore likely to have provided bioavailable phosphate and fixed carbon to anoxic ecosystems throughout Earth’s history and continue to do so in contemporary environments.

Although phosphite (Phi)-based fertilizers are used in large quantities in agriculture, the use of Phi-based fungicides against soybean root rot caused by Phytophthora sojae are limited. While, their low toxicity are of high ecological and economic focus. Limited attention has been paid to Phi translocation efficiency in soybeans and the efficacy of Phi as a fungicide against P. sojae. In this study, we evaluated the efficiency of Phi translocation in the Williams soybean cultivar by determining the Phi concentrations in roots, stems, and leaves using high-performance ion chromatography after the application of Phi to the roots. Phi was translocated from roots to leaves within 1 h and its concentration increased significantly in leaves within 36 h after Phi application. Results of an in vitro growth inhibition assay and an in vivo infection assay showed that Phi inhibited P. sojae. Additionally, we examined the activation of the salicylic acid (SA) and ethylene (ET) defense pathways by Phi. The expression of SA and ET pathway-related genes was upregulated in most soybean tissues after Phi application. Our results provide evidence that Phi translocation suppresses root rot caused by P. sojae in soybean.

In this study, phosphite (HPO32−) was used as a novel activator to activate peroxymonosulfate (PMS) for acid orange 7 (AO7) removal. Under the optimized conditions, the decolorization efficiency of AO7 was 82.1% within 60 min with rate constant values (kobs) of 0.0301 min−1. Besides, effects of the solution pH and the co-existing inorganic anions including Cl−, HCO3−, HPO42− and SO42− on AO7 removal were also investigated. Except for SO42−, other examined co-existing inorganic anions displayed favorable effects on the removal of AO7. Furthermore, the mechanism for PMS activation by the HPO32− was deeply elucidated by radical scavenger including ethanol (EtOH), tert-butanol (TBA), l -histidine and tiron, and electron spin resonance (ESR) studies. It was proposed that singlet oxygen (1O2) would be the dominant reactive oxygen species (ROS) in the HPO32−/PMS system for contamination degradation at neutral pH condition. The findings of this study provided useful information for the application of the substances in industrial wastewaters to activate PMS for organic contaminants degradation and in particular for HPO32--rich electroplating wastewater treatment.

A simple and efficient microwave (MW)-assisted method was elaborated for the catalyst-free synthesis of isoindolin-1-one-3-phosphonates by the three-component condensation of 2-formylbenzoic acid, aliphatic primary amines and various dialkyl phosphites. The batch and the continuous flow reactions were optimized in respect of the temperature, the reaction time and the molar ratio of the starting materials. To evaluate the potential of MW irradiation, comparative thermal experiments were also carried out. In order to obtain “real time” information about the condensation, the special Kabachnik–Fields reaction of 2-formylbenzoic acid, butylamine and diethyl phosphite was monitored by in situ FT-IR spectroscopy. The novel title compounds could be prepared in high yields at low temperature under a short reaction time. A suitable method could also be developed for the preparation of the isoindolin-1-one-3-phosphonates at a “few g” scale by using a continuous flow MW reactor.