Safety Assessment of Phosphoric Acid and Its Salts as Used in Cosmetics.

The Expert Panel for Cosmetic Ingredient Safety (Panel) assessed the safety of Phosphoric Acid and its salts (31 ingredients), which are reported to function as buffering agents, corrosion inhibitors, chelating agents, and pH adjusters in cosmetic products. The Panel reviewed data relating to the safety of these ingredients and concluded that Phosphoric Acid and its salts are safe in the present practices of use and concentration in cosmetics when formulated to be nonirritating.

[An unusual bodily injury]. / Eine ungewöhnliche Körperverletzung.

In most cases, bodily harm results from the use of sharp objects or blunt force. This paper deals with a 42-year-old pharmacist who was known to the police and the courts because of several previous convictions for bodily injury. The man had visited a pub just before it closed and was therefore not served any drinks. He got angry about this and returned to his pharmacy (within walking distance) to fetch three disposable syringes which he filled with phosphoric acid (85%). Through the open pub window, he splattered the acid from the syringes on two guests and the host, who were hit on the upper part of their bodies and the arms. All the victims developed dermal alterations such as focal erythema and small blisters (pemphigus-like efflorescences, as already described by Weyrich). At first, the pharmacist denied the use of phosphoric acid and claimed to have used a mixture of urine and water. Examinations of spots on the still unwashed clothes revealed very low pH-values (ca. 2.0; pH-Indicator-Stripes, Merck; Medi-Test, Machery & Nagel). Tests for substances typical of urine produced completely negative results. However, very high phosphate concentrations were found on the spots in question. Thus, the probability that the pharmacist had used phosphoric acid to commit the offence was very high. The pharmacist was sentenced to one year and two months' imprisonment for dangerous bodily harm according to Section 224 German Criminal Code. In accordance with the law, phosphoric acid was classified as "poison", for which application on the skin is sufficient.

Evaluation of New Fluorescent Lipophosphoramidates for Gene Transfer and Biodistribution Studies after Systemic Administration.

The objective of lung gene therapy is to reach the respiratory epithelial cells in order to deliver a functional nucleic acid sequence. To improve the synthetic carrier's efficacy, knowledge of their biodistribution and elimination pathways, as well as cellular barriers faced, depending on the administration route, is necessary. Indeed, the in vivo fate guides the adaptation of their chemical structure and formulation to increase their transfection capacity while maintaining their tolerance. With this goal, lipidic fluorescent probes were synthesized and formulated with cationic lipophosphoramidate KLN47 (KLN: Karine Le Ny). We found that such formulations present constant compaction properties and similar transfection results without inducing additional cytotoxicity. Next, biodistribution profiles of pegylated and unpegylated lipoplexes were compared after systemic injection in mice. Pegylation of complexes led to a prolonged circulation in the bloodstream, whereas their in vivo bioluminescent expression profiles were similar. Moreover, systemic administration of pegylated lipoplexes resulted in a transient liver toxicity. These results indicate that these new fluorescent compounds could be added into lipoplexes in small amounts without perturbing the transfection capacities of the formulations. Such additional properties allow exploration of the in vivo biodistribution profiles of synthetic carriers as well as the expression intensity of the reporter gene.

DNA damage in human lymphocytes exposed to four food additives in vitro.

In vitro genotoxic effects of antioxidant additives, such as citric acid (CA) and phosphoric acid (PA) and their combination, as well as antimicrobial additives, such as benzoic acid (BA) and calcium propionate (CP), on human lymphocytes were determined using alkaline single-cell gel electrophoresis. There was a significant increase in the DNA damage in human lymphocytes after 1 h of in vitro exposure to CA, PA, BA and CP (200, 25-200, 50-500, 50-1000 µg/mL, respectively). The combination of CA and PA significantly increased the mean tail intensity at all the concentrations used (25-200 µg/mL) and significantly increased the mean tail length mainly after higher concentrations (100 and 200 µg/mL). Data in this study showed that the concentrations of food additives used induce DNA damage and PA was the most genotoxic and CA was less genotoxic additives among them.

Radionuclide concentrations in raw and purified phosphoric acids from Brazil and their processing wastes: implications for radiation exposures.

Radionuclides from the U and Th natural series are present in alkaline rocks, which are used as feedstock in Brazil for the production of raw phosphoric acid, which can be considered as a NORM (naturally occurring radioactive material). As a result of the purification of raw phosphoric acid to food-grade phosphoric acid, two by-products are generated, i.e., solid and liquid wastes. Taking this into account, the main aim of this study was to evaluate the fluxes of natural radionuclide in the production of food-grade phosphoric acids in Brazil, to determine the radiological impact caused by ingestion of food-grade phosphoric acid, and to evaluate the solid waste environmental hazards caused by its application in crop soils. Radiological characterization of raw phosphoric acid, food-grade phosphoric acid, solid waste, and liquid waste was performed by alpha and gamma spectrometry. The (238)U, (234)U, (226)Ra, and (232)Th activity concentrations varied depending on the source of raw phosphoric acid. Decreasing radionuclides activity concentrations in raw phosphoric acids used by the producer of the purified phosphoric acid were observed as follows: Tapira (raw phosphoric acid D) > Catalão (raw phosphoric acids B and C) > Cajati (raw phosphoric acid A). The industrial purification process produces a reduction in radionuclide activity concentrations in food-grade phosphoric acid in relation to raw phosphoric acid produced in plant D and single raw phosphoric acid used in recent years. The most common use of food-grade phosphoric acid is in cola soft drinks, with an average consumption in Brazil of 72 l per person per year. Each liter of cola soft drink contains 0.5 ml of food-grade phosphoric acid, which gives an annual average intake of 36 ml of food-grade phosphoric acid per person. Under these conditions, radionuclide intake through consumption of food-grade phosphoric acid per year per person via cola soft drinks is not hazardous to human health in Brazil. Considering these annual additions of (238)U, (226)Ra, (232)Th and (40)K, and since these radionuclide should be homogeneously distributed in the upper 10 cm of soils with an assumed apparent density of 1.5 g/cm(3), a maximum increase of 0.19 ± 0.03 Bq kg(-1) of soil is expected for (238)U and (234)U. Thus, the addition of solid waste as phosphate fertilizers to Brazilian agricultural soils does not represent a hazard to the ecosystem or to human health.

A novel way to facilely degrade organic pollutants with the tail-gas derived from PHP (phosphoric acid plus hydrogen peroxide) pretreatment of lignocellulose.

The abundantly released tail-gas from lignocellulose pretreatment with phosphoric acid plus hydrogen peroxide (PHP) was found to accelerate the aging of latex/silicone textural accessories of the pretreatment device. Inspired by this, tail-gas was utilized to control organic pollutants. Methylene blue (MB), as a model pollutant, was rapidly decolorized by the tail-gas, and oxidative degradation was substantially proven by full-wavelength scanning with a UV-visible spectrometer. The tail-gas from six typical lignocellulosic feedstocks produced 68.0-98.3% MB degradation, suggesting its wide feedstock compatibility. Three other dyes, including rhodamine B, methyl orange and malachite green, obtained 97.5-99.5% degradation; moreover, tetracycline, resorcinol and hexachlorobenzene achieved 73.8-93.7% degradation, suggesting a superior pollutant compatibility. In a cytotoxicity assessment, the survival rate of the degraded MB was 103.5% compared with 80.4% for the untreated MB, implying almost no cytotoxicity after MB degradation. Mechanism investigations indicated that the self-exothermic reaction in PHP pretreatment drove the self-generated peroxy acids into tail-gas. Moreover, it heated the pollutant solution and thermally activated peroxy acids as free radicals for efficient pollutant degradation. Here, a brand-new technique for degrading organic pollutants with a "Win-Win-Win" concept was purposed for lignocellulose valorization, pollutant control by waste tail-gas, and biofuel production.

Insect infection model for Campylobacter jejuni reveals that O-methyl phosphoramidate has insecticidal activity.

Galleria mellonella (wax moth) larvae have elsewhere been shown to be susceptible to pathogens such as Francisella tularensis, Burkholderia mallei, and Pseudomonas aeruginosa. We report that the larvae are rapidly killed by Campylobacter jejuni at 37C. Three strains of C. jejuni tested, 11168H (human diarrheal isolate), G1 (human Guillain-Barré syndrome isolate), and 81-176 (human diarrheal isolate), were equally effective at killing G. mellonella larvae. A panel of defined mutants of C. jejuni 11168H, in known or putative virulence genes, showed different degrees of attenuation in G. mellonella larvae. A mutant lacking the O-methyl phosphoramidate (MeOPN) capsule side group was attenuated, clearly demonstrating that MeOPN has a role in virulence. This new model of C. jejuni infection should facilitate the identification of novel virulence genes.

Environmental benefits of using magnesium carbonate minerals as new wildfire retardants instead of commercially available, phosphate-based compounds.

A serial batch leaching experiment has been carried out to evaluate the release of elements from the ash of Pinus halepensis needles burned under two test conditions-with and without treatment of the forest species with the carbonate minerals (huntite and hydromagnesite) in aqueous solution (pH 6). The ash (before and after leaching) and leachates were analyzed using atomic absorption spectroscopy and X-ray diffraction. Compared with data from samples treated with the commercially available, phosphate-based fire retardant diammonium phosphate (DAP), we found that use of huntite or hydromagnesite was much more successful in obstructing the release of the toxic elements present in the ash, probably because of the alkaline conditions resulting from decomposition of the minerals during burning. In contrast, DAP tended to be more able to facilitate the extraction of some toxic metals (e.g., Zn, Cu, Mn), probably because of the acidic conditions resulting from its decomposition to phosphoric acid. Data from this study thus lend strong support to the use of magnesium carbonate minerals as new wildfire retardants, because they were shown to be more friendly to the environment (e.g., soil, ground, and underground water streams) than those currently in use (e.g., phosphate or sulfate salt type).

Self-assembled nanostructures of phosphomolybdate, nucleobase and metal ions synthesis and their in vitro cytotoxicity studies on cancer cell lines.

The ability of the multidentate nucleobases, adenine and thymine, to coordinate polyoxometalate and metal ions leading to the formation of self-assembled nanostructures and their strong cytotoxicity toward cancer cell lines have been demonstrated. A unique synthetic approach is developed to make a series of functional nanoscale hybrid materials consisting of nucleobases (adenine and thymine) and phosphomolybdic acid (PMA) through solid state chemical reaction and self-assembly process. Adenine was protonated through its ring nitrogen, while the ketone group in thymine was protonated during the addition of PMA to these nucleobases. The self-assembled nanostructures formed as a result of the electrostatic interaction between the protonated nucleobases and polyanionic PMA. To promote the base pairing between the nucleobases, chloroaurate ions and silver ions were added to each PMA/adenine and PMA/thymine nanostructures. The complexation between the nucleobases and the added metal ions was found to drive the formation of subsequent self-assembled nanostructures. All the materials were screened for their anticancer activity against breast (MDAMB-231) and prostate (PC-3) cancer cells, and non-cancerous keratinocyte cells HaCaT. PMA/adenine/[AuCl4]- and PMA/thymine/Ag+ nanostructures were found to have strong anti-cancer activity, while PMA/adenine/Ag+, PMA/thymine/[AuCl4]-, and PMA/pdenine, PMA/thymine nanostructures did not exhibit such activity. The unique redox properties of these materials and the self-assembly of the PMA and metal ions were the major factors responsible for the cytotoxicity. This unique approach of making functional nanomaterials incorporate the nucleobase, PMA and metal ions using solid state self-assembly and their anti-cancer applications are considered to be an effective approach for the development of inorganic nucleoside analogue bio-pharmaceutical agents.

Near-Surface Studies of the Changes to the Structure and Mechanical Properties of Human Enamel under the Action of Fluoride Varnish Containing CPP-ACP Compound.

Changes to the features of the enamel surface submitted to induced demineralisation and subsequent remineralisation were studied. The in vitro examination was conducted on polished slices of human molar teeth, divided in four groups: the untreated control (n = 20), challenged by a demineralisation with orthophosphoric acid (H3PO4) (n = 20), and challenged by a demineralisation following remineralisation with fluoride (F) varnish containing casein phosphopeptides (CPP) and amorphous calcium phosphate (ACP) compounds (n = 20). The specimens' enamel surfaces were subjected to analysis of structure, molecular arrangement, mechanical features, chemical composition, and crystalline organization of apatite crystals. Specimens treated with acid showed a significant decrease in crystallinity, calcium, and phosphorus levels as well as mechanical parameters, with an increase in enamel surface roughness and degree of carbonates when compared to the control group. Treatment with fluoride CPP-ACP varnish provided great improvements in enamel arrangement, as the destroyed hydroxyapatite structure was largely rebuilt and the resulting enamel surface was characterised by greater regularity, higher molecular and structural organisation, and a smoother surface compared to the demineralised one. In conclusion, this in vitro study showed that fluoride CPP-ACP varnish, by improving enamel hardness and initiating the deposition of a new crystal layer, can be an effective remineralising agent for the treatment of damaged enamel.

The application of the phosphoramidate ProTide approach confers micromolar potency against hepatitis C virus on inactive agent 4'-azidoinosine: kinase bypass on a dual base/sugar modified nucleoside.

Novel phosphoramidate ProTides derived from 4'-azidoinosine have been prepared and evaluated in the replicon assay against hepatitis C Virus (HCV). The parent nucleoside analogue is inactive in this assay, while the ProTides are active at low microM levels in some cases. This is a rare example of an inosine nucleoside analogue with potent antiviral activity and further supports the notion of ProTides as a drug discovery motif.

Chemical stabilization of medical waste fly ash using chelating agent and phosphates: Heavy metals and ecotoxicity evaluation.

Chemical stabilization of heavy metals in medical waste fly ash has been carried out using the following compounds: a chelating agent (Ashnite S803), a commercial acidic phosphoric acid solution (Ashnite R303) as well as basic one (Ashnite R201). In order to predict the leachability of heavy metals, Japanese Leaching Test (JLT-13) procedure was applied to the stabilized fly ash products. An ecotoxicity assessment of the stabilized fly ash products leachate and the unstabilized fly ash leachate was conducted using a battery of bioassays based on lettuce root elongation inhibition, Daphnia magna mortality and Vibrio fischeri photoinhibition. The results showed that the three stabilizing agents were able to significantly decrease (ANOVA, P < 0.05) the concentration of heavy metals in the leachates. Although the leachate from both stabilized and unstabilized fly ash were very toxic to lettuce and daphnids, the incorporation of these stabilizing agents diminished significantly (ANOVA, P < 0.05) the toxicity of the leachates towards the three tested organisms. Pearson correlation analysis was used to analyze the strength of the relationship between chemical elements concentration in the leachate and bioassays results. Most of the heavy metals in the leachate were significantly correlated (ANOVA, P < 0.05) with the toxicity values of the bioassays. However, the correlation was not found between the concentration of dissolved organic carbon (DOC) and the toxicity effect of the leachate to the tested organisms.

Analytical Capabilities of the Community Bureau of Reference Protocol to Estimate the Mobility of Nutrients and Toxic Elements from Mineral Fertilizer.

The sequential extraction procedure of the Community Bureau of Reference (BCR) was applied to investigate the mobility of potentially toxic elements (As, Cd, Cr, and Pb) and nutrients (P, Ca, Mg, Cu, Fe, Mn, and Zn) in a multinutrient mineral fertilizer based on phosphate rocks supplemented with 10% (w w-1) micronutrient mixture (raw material used as a micronutrient source). For both samples, As and Cd were more mobile, whereas Cr remained in the solid residue. A higher mobility of Pb was observed in the micronutrient mixture; however, the high concentration of P (8.3% w w-1) in the fertilizer could have decreased Pb mobility as a result of Pb3(PO4)2 formation. The nutrients had great mobility, except Fe, which remained almost totally in the residual fraction in both samples. X-ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy analyses of solid residues showed that the ways in which elements were distributed in the sample particles could affect their mobility.

L929 fibroblast bioassay on the in vitro toxicity of SnCl2, H3PO4, Clearfil SE primer and combinations thereof.

Stannous chloride (SnCl(2), 35%) can increase microtensile bond strength between a self-etching adhesive and dental hard tissue either alone or in combination with phosphoric acid (H(3)PO(4), 35%). Whereas cell toxicity of H(3)PO(4) has been sufficiently investigated, little is known about the toxicity of concentrated SnCl(2). The present study determined the in vitro toxicity of SnCl(2), H(3)PO(4), the primer of a self-etching adhesive (Clearfil SE) and combinations thereof at three concentrations (0.01%–0.3%) in a L929 fibroblast bioassay. Cell viability was determined by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, the integrity of cell membranes was visualised by trypan blue staining (cell necrosis assay). Cell viability was impaired at concentrations between 0.09% and 0.13% for SnCl(2), between 0.06% and 0.09% for H(3)PO(4), and between 0.19% and 0.29% for Clearfil SE primer. Combinations of agents showed additive toxic effects. SnCl(2) showed a slightly lower but comparable in vitro toxicity to H(3)PO(4), which gives a perspective for further in vitro, in situ and clinical studies on this issue, and for the intraoral use of SnCl(2) to increase bond strength between an adhesive system and both enamel and dentine.

Biocompatibility evaluation of orthodontic composite by real-time cell analysis.

INTRODUCTION: The aim of this study was to evaluate the cytotoxic effects of three different light-cured orthodontic composites. MATERIAL AND METHODS: Light Bond (Reliance orthodontic products), Grengloo (Ormco corporation), and Kurasper F (Kuraray Europe GmbH) were selected for the experiment. Specimens were prepared according to the manufacturers' instructions, measuring 5 mm in diameter and 2 mm in thickness. Fibroblast cells were obtained from healthy gingival connective tissues. The composite cylinders were incubated in Dulbecco's modified Eagle's culture medium for 72 h according to ISO 10993-5 standards. The xCELLigence method was used to evaluate fibroblast cell vitality. After seeding 200 mL of the cell suspensions into the wells (20,000 cells/well) of the E-plate 96, gingival fibroblasts were treated with bioactive components released by the orthodontic composite materials and monitored every 15 min for 121 h. RESULTS: There were no significant differences between the human gingival fibroblast (HGF) cell indexes of the control and all testing groups (p > 0.05) at 24 and 48 h. Light Bond demonstrated statistically significant decrease in HGF index (p < 0.05) at 72 h, but there was no significant difference among the Kurasper F, Grengloo, and untreated control groups (p > 0.05). Light Bond (p < 0.001) and Grengloo (p < 0.05) groups had lower HGF cell index values when compared to untreated control group, but Kurasper F demonstrated no significant differences between the control groups at 96 h (p > 0.05). CONCLUSION: Orthodontic composite materials include biologically active components and may change oral tissue. So, biocompatible orthodontic bonding composites should be used.

Quantitative studies of the effect of antagonists on the acute toxicity of organophosphates in rats.

1. The subcutaneous acute toxicities of the vinyl phosphate pesticides monocrotophos, dicrotophos, chlorfenvinphos, crotoxyphos, dichlorvos, mevinphos, and of the experimental compounds SD 4455 (cis-2-carboxy-1-methylvinyl dimethylphosphate) and SD 7779 (cis-2-(1-phenylethoxy) carbonyl-1-methylvinyl diethylphosphate) have been determined in female rats.2. The effects on the log dose-probit mortality curves to the vinylphosphates of the therapeutic subcutaneous administration of methylatropine, atropine, N-methylpyridinium-2-aldoxime methanesulphonate and obidoxime have been studied.3. Elevation of the LD50 values by the therapeutic regimens was shown to be an unsatisfactory measure of therapeutic efficiency, while reduction of the effect of a maximally lethal dose (LD90) to less than that of a minimally lethal dose (LD10) provided a better quantitative measure of therapeutic efficiency.4. The combination of atropine sulphate (50 mumol base/kg) with obidoxime (250 mumol/kg) was found to be generally the most effective of the antidotal regimens.

Acetylcholine content in the brain of rats treated with paraoxon and obidoxime.

1. The effect of obidoxime on the rise in brain acetylcholine caused by the anticholinesterase paraoxon was studied in the rat.2. In animals poisoned with a sublethal dose of paraoxon and thereafter treated with obidoxime the levels of both "free" and total brain acetylcholine were practically the same as those in rats injected with paraoxon only.3. After poisoning with doses of paraoxon which are lethal unless an oxime is also given, the total acetylcholine in the brain of obidoxime-protected rats continued to accumulate, reaching a peak 2 h after injection of paraoxon. At this time no signs of central effects such as convulsions or tremor were seen.4. Atropine, given 30 min before paraoxon, markedly reduced the rise in total brain acetylcholine seen when the anticholinesterase is given alone.5. In rats pretreated with atropine and obidoxime excessive doses of paraoxon which are lethal in the absence of the antidotes produced a rise in total brain acetylcholine which was directly proportional to the dose of paraoxon administered.

Evidence that acidosis alters the high-affinity dopamine uptake in rat striatal slices and synaptosomes by different mechanisms partially related to oxidative damage.

Several experimental studies have shown that acidosis impairs neurotransmitter uptake processes. The purpose of this study was to determine the mechanism underlying acidosis-induced alterations of the high-affinity dopamine (DA) uptake in rat striatal synaptosomes and slices. Acidosis (pH 5.5) performed either by lactic acid or phosphoric acid induced a decrease in the high-affinity DA uptake in the two striatal models, slices being lesser affected than synaptosomes. Addition of the acid prior to uptake measurement led to a strong reduction of the DA uptake velocity. This early inhibitory effect was completely reversed when acid was removed from the medium by washings. Conversely, when slices and synaptosomes were pre-incubated for different times with each acid, DA uptake remained inhibited in spite of washings. This later inhibition was accompanied by the production of thiobarbituric acid reactive substances, a marker of lipid peroxidation, and was partially prevented by the antioxidant Trolox. Taken together, these results suggest that acidosis, in a degree encountered during ischemia, alters the high-affinity DA uptake by at least two ways: an early and direct effect of H(+) ions on the DA transporters, and subsequently an inhibition partially mediated by free radical damage.

A new screening test for toxicity testing of dental materials.

OBJECTIVES: The development of a micro plate assay for cytotoxicity testing of dental materials based on a bioassay using brine shrimp larvae (artemia salina) as sensitive organisms. METHODS: Brine shrimp larvae are commonly used for cytotoxicity assays in pharmacology. These larvae are sensitive to toxic substances. The ratio between dead larvae (no motility) and living larvae (high motility) in comparison to a control without any toxic substances is used to estimate the toxicity of the test solutions. The test materials (Arabesk((R)), Solitaire((R)), Pertac((R)) II, Tetric((R)), Herculite((R)) and the compomer materials Dyract((R)), Hytac((R)), Compoglass((R))) were polymerized and consecutively milled. After incubation of 1g in 4ml distilled water at 37 degrees C for 48h, the solid materials were separated by centrifugation. The solutions were equibrilated with NaCl to a salt content of 25g/l. Aliquots of 200microl were distributed in eight micro wells and 50microl of a artemia salina containing (n=8-14) solution were added to each well. As controls eight wells with 250microl salt solution containing a comparable number of brine shrimp were used. At baseline, after 2, 5, 24 and 48h, the dead shrimp were counted using a stereo microscope. Finally all shrimps were sacrificed using Na-acid (5%) and counted to get the number of shrimps per well. RESULTS: All compomers and Solitaire caused 100% brine shrimp lethality after 24h and showed significantly (p<0.01, signed rank test) higher toxicities than the remaining composites. With the exception of Pertac II, all composites showed significantly higher toxic values than the control. Pertac II did not show any differences from the controls used. CONCLUSIONS: This new technique has some advantages for toxicity testing of restorative materials, because it can quickly be carried out at low costs. The disadvantage is the high quantity of material used and the low sensitivity.

Activated transformations of organophosphorus insecticides in the case of non-AChE inhibitory oxons.

Many organophosphorus (OP) compounds are of the thiono form and in insects or animals are converted by microsomal mixed function oxidases (MFO) into the oxon forms which inhibit acetylcholinesterase (AChE) and give toxic activity. However, certain S-alkyl phosphorothiolates (RS-P(O) <) such as methamidophos, profenophos and prothiophos oxon are strongly insecticidal, but very poor inhibitors of AChE in vitro. Their oxons are converted further to the S-oxides, which either inhibit AChE or decompose, depending on the alkyl substituents on the sulfur atom. It is also inferred in the case of prothiophos oxon that its S-oxide not only inhibits AChE but also conjugates with glutathione (GSH) by the action of glutathione S-transferase (GST), and the conjugate inhibits AChE. Certain phosphoramidates (R2N-P(O) <) such as isofenphos oxon, schradan and propetamphos oxon are weak AChE inhibitors, but strongly insecticidal. It is well known that isofenphos oxon is converted into the stable N-desalkyl form (H2N-P(O) <) by oxidative dealkylation to inhibit AChE. The authors have studied activation of phosphoramidates using 2,4-dichlorophenyl methyl N-alkylphosphoramidates as model compounds using various approaches including computational chemistry, and these studies indicated that the O-aminophosphate structure (R2N-O-P(O) <) is an activated form.