Effect of phosphoric acid containing polyvinylpyrrolidone as protective etchant for dentin bonding.

STATEMENT OF PROBLEM: Phosphoric acid is commonly used in dentistry as an etchant but can result in excessive demineralization of dentin, a major contributor to the instability of dentin-bonded restorations. Nevertheless, research on the development of etchants that can reduce acid damage is sparse. PURPOSE: The purpose of this in vitro study was to investigate the effects of polyvinylpyrrolidone-modified phosphoric acid on the dentin bonding of an etch-and-rinse adhesive. MATERIAL AND METHODS: Protective etchants were prepared by adding polyvinylpyrrolidone to 35% phosphoric acid aqueous solutions: the 3 concentrations were 0.5% (P0.5% group), 1% (P1% group), and 2% (P2% group) w/v. The treatment agent of the control group (C) was 35% phosphoric acid gel. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), microhardness, microtensile bonding strength (µTBS), nanoleakage, and in situ zymography were used to evaluate the appearance of the protective etchant on dentin bonding. The results were analyzed with a 1-way ANOVA test (α=.05). RESULTS: SEM showed no obviously exposed collagen fiber in the P1% and P2% groups. FTIR showed less demineralization of the dentin surface, and microhardness was higher after treatment with the protective etchant (P<.05). The µTBS of P1% (70 ±9.2 MPa) was the highest, and group C (44 ±5.8 MPa) was the lowest in all groups (P<.05). Moreover, there was weaker MMP activity in the P1% and P2% groups (P<.05). CONCLUSIONS: This study demonstrated that the protective etchant effectively reduced demineralization, enhanced bond strength, and reduced nanoleakage and enzyme activity within the hybrid layer.

The effect of the use of the deproteinization agent hypochlorous acid and two different pit and fissure sealant self-adhesive flowable composites upon its bonding with the enamel.

This study evaluates the effect of the deproteinization agents hypochlorous acid and sodium hypochlorite upon the bonding of the two different pit and fissure sealant, self-adhesive flowable composites with the enamel. Thirty-six third molars were randomly divided into six different groups. The groups were formed as follows: Group 1: 37% phosphoric acid + VertiseTM Flow; Group 2: 200 ppm hypochlorous acid + 37% phosphoric acid VertiseTM Flow; Group 3: 5.25% sodium hypochlorite + 37% phosphoric acid + VertiseTM Flow; Group 4: 37% phosphoric acid + Constic; Group 5: 200 ppm hypochlorous acid + 37% phosphoric acid + Constic; Group 6: 5.25% sodium hypochlorite + 37% phosphoric acid + Constic. In each group, samples were obtained that were rectangular prisms in shape (n = 12). Groups to which a deproteinization agent was applied (Groups 2, 3 and 5, 6) showed statistically higher microtensile bonding strength than Group 1, Group 4. There was no statistically significant difference in terms of microtensile bonding strength values between the Groups 3 and the Group 6. The study found that the groups to which deproteinization agents were applied had statistically higher microtensile bonding strength values compared with those groups to which acid and fissure sealants were applied. In this study, it was concluded that the use of fissure-sealing self-adhesive flowable composites after acid application to permanent tooth enamel provides an acceptable bond strength given the limitations of in vitro studies. In line with the results obtained, it was observed that in addition to the removal of the inorganic structure with the application of acid, the removal of the organic structure with the use of deproteinization agent increased the bond strength to the enamel.

EFFECTS OF ACID ETCHING ON COLOR CHANGES AND SURFACE MORPHOLOGY OF ENAMEL TO BE BLEACHED WITH DIFFERENT TECHNIQUES.

Aims - to compare the color changes, the surface roughness and morphology of the enamel bleached with two different bleaching solutions (chemical and laser activated), preceded or not with acid etching. Thirty teeth of bovine prepared and haphazardly assigned to 2 groups (n=15) depending on bleaching technique. Each group subdivided to 3 subgroup (n=5) consistent with acid etching by 37% phosphoric acid. Atomic force microscopy and VITA easy shade spectrophotometer were performed twice for all the specimens before and after bleaching. ANOVA, the Paired sample t-test, and the independent sample t-test used for statistical analysis. As for the color changes, the groups that were bleached by the chemical method, the difference among the three subgroups was statistically significant. This also applies to the groups bleached with the laser method. When comparing the results of the chemical bleaching subgroups with the laser bleaching ones, the difference was not significant. Roughness results showed significant differences between certain subgroups and non-significant differences among others. However, the difference was statistically significant between the chemical and laser groups, laser technique resulted in less surface roughness than the chemical one. Acid etching before bleaching produced better colour change in both the chemical and laser assisted bleaching. In chemical bleaching, surface roughness was higher when acid etching was used. This was also true for laser bleaching technique. In general, laser assisted bleaching produced less surface roughness than chemical bleaching.

Formulating an altered dentin substrate to improve dentin bonding.

STATEMENT OF PROBLEM: Secondary caries is a major factor in the failure of dental restorations. However, studies on the fabrication of acid-resistant and antibacterial dentin to improve dentin bonding are sparse. PURPOSE: The purpose of this in vitro study was to compare the effects of 2 types of fluoride-containing etchants on dentin bonding and explore the feasibility of formulating an altered dentin substrate to improve dentin bonding. MATERIAL AND METHODS: NaF-containing and SnF2-containing etchants were developed by adding sodium fluoride and stannous fluoride to a 35% phosphoric acid aqueous solution. Two groups (N1 and N2) containing NaF, 10 and 30 mg/mL respectively, and 2 groups (S1 and S2) containing SnF2, 18.6 and 55.8 mg/mL respectively, were formulated. The etchant of the control group (C) was 35% phosphoric acid gel. Scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), Fourier transform infrared spectroscopy (FTIR), microhardness, antierosion, and antibacterial tests were performed on the treated dentin. Moreover, the microtensile bond strength (µTBS) of each group was tested, and the fracture mode was determined after testing. Statistical analysis was performed with the 2-way ANOVA test (α=.05). RESULTS: The exposed collagen fiber was observed in group C, and minerals were formed on the dentin in the experimental groups. SEM, FTIR, and the microhardness test indicated more remineralization in the SnF2-containing etchant groups. The µTBS of S1 (77.5 ±10.36 MPa) was the highest in all groups, and group C (38.5 ±9.01 MPa) was the lowest. Moreover, the antierosion and antibacterial properties of the S2 group were the best among all groups (P<.05). CONCLUSIONS: Compared with NaF-containing etchant, SnF2-containing etchant could improve the dentin substrate, increase remineralization, improve bonding strength, and enhance antibacterial ability, especially by increasing resistance to acid erosion.

Synthesis and anti-parasitic activity of achiral N-benzylated phosphoramidic acid derivatives.

Synthetic pathways have been developed to access a series of N-benzylated phosphoramidic acid derivatives as novel, achiral analogues of the established Plasmodium falciparum 1-deoxy-d-xylulose-5-phosphate reductase (PfDXR) enzyme inhibitor, FR900098. Bioassays of the targeted compounds and their synthetic precursors have revealed minimal antimalarial activity but encouraging anti-trypanosomal activity - in one case with an IC50 value of 5.4 µM against Trypanosoma brucei, the parasite responsible for Nagana (African cattle sleeping sickness). The results of relevant in silico modelling and docking studies undertaken in the design and evaluation of these compounds are discussed.

Modeling the inactivation of Lactobacillus brevis DSM 6235 and retaining the viability of brewing pitching yeast submitted to acid and chlorine washing.

This study aimed to model the inactivation of Lactobacillus brevis DSM 6235 while retaining the viability of yeasts during washing brewer's yeast with phosphoric acid and chlorine dioxide. The independent variables in the acid washing were pH (1-3) and temperature (1-9 °C), whereas in the washing with chlorine dioxide, concentration (10-90 mg/L) and temperature (5-25 °C) were assessed. The predictive models obtained for the four response variables γLA, γCl (decimal reduction of L. brevis DSM 6235), Vf/V0LA, and Vf/V0Cl (brewer's yeast viability ratio) were found to have R2 > 0.80 and values of Fcalc > Freference. Then, the models were considered predictive and statistically significant (p < 0.10). Our results indicated that phosphoric acid and chlorine dioxide washing resulted in up to 7 and 6.4 (log CFU/mL) decimal reductions of L. brevis DSM 6235, respectively. On the other hand, the viability of the brewer's yeast ranged from 22.3 to 99.4%. L. brevis DSM 6235 inactivation was significantly influenced by parameters pH(Q) and T°C(Q) when phosphoric acid was applied, and by parameters mg/L(L), mg/L(Q), T°C(Q), and mg/L × T°C when ClO2 was applied. The validation of the models resulted in bias (γLA, 0.93/Vf/V0LA, 0.99 - γCl, 1.0/Vf/V0Cl, 0.99) and accuracy values (γLA, 1.12/Vf/V0LA, 1.01 - γCl, 1.08/Vf/V0Cl, 1.03). The results of this study indicate that it might be possible to decontaminate brewer's yeast through acid and chlorine dioxide washing while keeping its viability. This procedure will result in the reduction of costs and the lower generation of brewer's waste.

Phosphonamidates are the first phosphorus-based zinc binding motif to show inhibition of ß-class carbonic anhydrases from bacteria, fungi, and protozoa.

A primary strategy to combat antimicrobial resistance is the identification of novel therapeutic targets and anti-infectives with alternative mechanisms of action. The inhibition of the metalloenzymes carbonic anhydrases (CAs, EC 4.2.1.1) from pathogens (bacteria, fungi, and protozoa) was shown to produce an impairment of the microorganism growth and virulence. As phosphonamidates have been recently validated as human α-CA inhibitors (CAIs) and no phosphorus-based zinc-binding group have been assessed to date against ß-class CAs, herein we report an inhibition study with this class of compounds against ß-CAs from pathogenic bacteria, fungi, and protozoa. Our data suggest that phosphonamidates are among the CAIs with the best selectivity for ß-class over human isozymes, making them interesting leads for the development of new anti-infectives.

Inactivation kinetics of beer spoilage bacteria (Lactobacillus brevis, Lactobacillus casei, and Pediococcus damnosus) during acid washing of brewing yeast.

This work aimed to estimate the inactivation kinetic parameters of four potential beer spoilage bacteria (Lactobacillus brevis DSM 6235, Lactobacillus casei ATCC 334, Pediococcus damnosus DSM 20289 and Pediococcus damnosus ATCC 29358) inoculated in brewing yeast submitted to acid washing with purposes of yeast recycle. The experiments were conducted at 4 °C in solutions with pH 1.5, pH 2, and pH 3 adjusted employing 85% phosphoric acid. The acid washing treatment of brewing yeasts in the most common pH used (pH 2.0) demanded almost 50 min for the first decimal reduction (δ) of L. brevis DSM 6235. Sensible strains to acid washing such as P. damnosus DSM 20289 demanded almost 70 min for 4 log reductions to be achieved. On the other hand, pH reduction of the acid washing from 2.0 to 1.5 allowed 4 log reduction of L. brevis DSM 6235) to be obtained in less than 50 min, without ruining brewer's yeast viability. Acid washing in pH 1.5 is a viable method for the inactivation of bacterial contaminants of brewing yeasts. Recycling of brewing yeasts through this approach may contribute to a more sustainable and environmental-friendly industry.

Designing Efficient Processes for Sustainable Bioethanol and Bio-Hydrogen Production from Grass Lawn Waste.

The effect of thermal, acid and alkali pretreatment methods on biological hydrogen (BHP) and bioethanol production (BP) from grass lawn (GL) waste was investigated, under different process schemes. BHP from the whole pretreatment slurry of GL was performed through mixed microbial cultures in simultaneous saccharification and fermentation (SSF) mode, while BP was carried out through the C5yeast Pichia stipitis, in SSF mode. From these experiments, the best pretreatment conditions were determined and the efficiencies for each process were assessed and compared, when using either the whole pretreatment slurry or the separated fractions (solid and liquid), the separate hydrolysis and fermentation (SHF) or SSF mode, and especially for BP, the use of other yeasts such as Pachysolen tannophilus or Saccharomyces cerevisiae. The experimental results showed that pretreatment with 10 gH2SO4/100 g total solids (TS) was the optimum for both BHP and BP. Separation of solid and liquid pretreated fractions led to the highest BHP (270.1 mL H2/g TS, corresponding to 3.4 MJ/kg TS) and also BP (108.8 mg ethanol/g TS, corresponding to 2.9 MJ/kg TS) yields. The latter was achieved by using P. stipitis for the fermentation of the hydrolysate and S. serevisiae for the solid fraction fermentation, at SSF.

Evaluation of Homeopathic Phosphoric Acid, Silica and Pathogenic Vibrio on Digestive Enzyme Activity of Longfin Yellowtail Fish (Seriola rivoliana).

BACKGROUND: This research aimed to observe the effect of homeopathically prepared Vibrio parahaemolyticus (ViP) and V. alginolyticus (ViA) and the commercial homeopathic compound Similia (Phosphoricum acidum and Silicea terra) on the digestive enzyme activities of Seriola rivoliana juveniles under usual culture conditions. MATERIALS AND METHODS: Biochemical analysis was used to study the effect of highly diluted substances (7C potency) prepared from ViP and ViA (Treatment 1: T1) and the homeopathic compound Phosphoricum acidum and Silicea terra (Treatment 2: T2) on changes in the main digestive enzymes on weaning-state fish (WS; 30 days post-hatching [DPH]) and early juveniles (EJ; 62 DPH) versus a reference control group that received no homeopathic medicines. RESULTS: Treatment T2 significantly increased the activity of trypsin and lipase and decreased the activity of amylase, whereas treatment T1 increased the activity of chymotrypsin and reduced the activity of aminopeptidase-N in WS fish. Except for alkaline phosphatase, which was significantly reduced in the intestine, no significant differences in enzymatic activity were found between treated EJ fish and controls. The fish of the WS group had a higher growth rate with the T2 treatment. CONCLUSIONS: T1 treatment stimulated chymotrypsin in EJ fish and T2 promoted intestinal maturation of WS fish. Higher growth rate with the T2 treatment may be associated with the stimulation of trypsin activity. Thus, T2 may be applied, under hatchery conditions, during larval stages with an aim to enhance digestion and assimilation of inert food.

Synthesis of an Anti-hepatitis B Agent, 2'-Fluoro-6'-methylene-carbocyclic Adenosine (FMCA) and Its Phosphoramidate (FMCAP).

2'-Fluoro-6'-methylene-carbocyclic adenosine (FMCA, 12) and its phosphoramidate prodrug (FMCAP, 14) have been proven as a potential anti-HBV agent against both adefovir-resistant as well as lamivudine-resistant double (rtL180M/rtM204V) mutants. Furthermore, in vitro, these agents have demonstrated significant activity against lamivudine/entecavir triple mutants (L180M + S202G + M204V). These preliminary results encourage us for further biological evaluation of FMCA and FMCAP to develop as a potential clinical candidate as an anti-HBV agent, which may overcome the problem of drug resistance in HBV therapy. To support the preclinical exploration, a scalable synthesis of this molecule was needed. In this communication, a practical and scalable synthesis of FMCA, and its prodrug, is reported via ketone 1. The selective opening of the isopropylidene group of 2 led to compound 3. Protection of the allylic hydroxyl group of 3, followed by fluorination and deprotection, afforded the key intermediate 10, which was condensed with a Boc-protected adenine, followed by deprotection, furnished the target nucleoside FMCA (12) in high yield. Further coupling of phosphorochloridate of L-alanine isopropyl ester (13) with FMCA gave its phosphoramidate prodrug FMCAP (14) in good yield.

2'-Fluoro-6'-methylene carbocyclic adenosine and its phosphoramidate prodrug: A novel anti-HBV agent, active against drug-resistant HBV mutants.

Chronic hepatitis B (CHB) is one of the major causes of morbidity and mortality worldwide. Currently, clinically approved nucleos(t)ide analogs (NAs) are very efficient in reducing the load of hepatitis B virus (HBV) with minimum side effects. However, the long-term administration of antiviral drugs promotes HBV for potential drug resistance. To overcome this problem, combination therapies are administered, but HBV progressively altered mutations remain a threat. Therefore, optimally designed NAs are urgently needed to treat drug-resistant HBV. Herein, 2'-fluoro-6'-methylene carbocyclic adenosine (FMCA) and its phosphoramidate (FMCAP) have been discovered, which may be utilized in combination therapies for curing drug-resistant chronic hepatitis B. In preclinical studies, these carbocyclic NAs demonstrated potential anti-HBV activity against adefovir, as well as lamivudine (LMV/LAM) drug-resistant mutants. In vitro, these molecules have demonstrated significant activity against LMV/entecavir (ETV) triple mutants (L180M + S202G + M204V). Also, preliminary studies of FMCA/FMCAP in chimeric mice and female Non-obese diabetic/severe combined immunodeficiency (NOD/SCID) mouse models having the LMV/ETV triple mutant have shown a high rate of reduction of HBV DNA levels compared to ETV. In this review, we have summarized preclinical studies of FMCA and its phosphoramidate prodrug (FMCAP).

Effects of stannous fluoride on eroded enamel permeability.

This study aimed to evaluate the effect in vitro of a single application of a stannous fluoride- (SnF2-) containing toothpaste on eroded enamel. Forty-eight teeth were subjected to three acid treatments: 15% hydrochloric acid for 120 s (HA group); 1% citric acid (pH=4) for 180 s (CA group); 37% phosphoric acid for 30 s (PA group). They were brushed with an electric toothbrush with pressure control and 1 g of SnF2 (1100 ppm) toothpaste for 2 min. Polyether replicas of buccal enamel surfaces were obtained at baseline, after acid exposure and after brushing, gold sputtered and inspected by SEM for fluid droplets presence. Hydrochloric and citric acid treatments increased enamel permeability while, on the contrary, phosphoric acid reduced enamel fluid release. SnF2 application of ameliorated acid induced permeability in citric and hydrochloric treated samples. Permeability in phosphoric treated enamel was unchanged after topical application of SnF2. Our data show specific acid-dependent effects on enamel permeability and demonstrate that SnF2 application can reverse acid-induced permeability.

Release of TGF-ß1 into root canals with various final irrigants in regenerative endodontics: an in vitro analysis.

AIM: To investigate the release of growth factors into the root canal space after various final irrigants during regenerative endodontic procedures. The residual cytotoxic effect of final irrigants on stem cells from the apical papilla (SCAP) was also examined. METHODOLOGY: To measure the release of TGF-ß1, root segments (8 mm long) were irrigated with 1.5% NaOCl followed by 20 mL of final irrigants; Saline, 17% EDTA, 10% citric acid, 10% or 37% phosphoric acid. Specimens were then immersed into culture medium for 24 h and the supernatants were collected to measure TGF-ß1 by ELISA. For the cytotoxicity of residual final irrigants, dentine chips (5 × 5 × 1 mm) treated with irrigants as above were placed in the upper chamber of transwell system. Stem cells from the apical papilla were incubated indirectly in the lower chamber for 24 h and MTS assay was performed after 24 h. The surfaces of irrigated root canals were examined for smear layer with a scanning electron microscope (SEM). Log transformation was performed for ELISA data to compare different groups (one-way ANOVA, α = 0.05). RESULTS: Ten percent citric acid released the greatest amount of TGF-ß1 amongst all groups, which was significantly different to 17% EDTA (P < 0.01). All dentine chips irrigated with the irrigants showed no significant difference of cytotoxicity on SCAP compared to nonirrigated dentine (P > 0.05). SEM revealed completely open dentinal tubules in 10% citric acid, whereas 17% EDTA was associated with partially open dentinal tubules. CONCLUSIONS: Ten percent citric acid was effective as a final irrigant for releasing TGF-ß1 with good biocompatibility in regenerative endodontics.

Effect of Enamel Deproteinization in Primary Teeth.

OBJECTIVE: To evaluate and compare the topographical features of enamel surface, etched with different materials. STUDY DESIGN: 10 extracted human primary molars were randomly selected and cut and trimmed to 1 mm2. Each group comprised of 10 blocks and the enamel was treated as follows: Group I-35% H3PO4; Group II-5.25% NaOCl + 35% H3PO4 ;Group III-5.25% NaOCl; Group IV no treatment was carried out. All the samples were prepared for Scanning electron microscope analysis. The images were obtained and evaluated for the quality type I-II etching of the enamel surface using Auto-CAD 2011 software. STATISTICAL ANALYSIS USED: Wilcoxon Signed Ranks Test (p<0.001). RESULTS: The mean surface area of type I and II etching pattern values for Group- I was 39608.18 µm2 and Group- II was 45051.34 µm2. CONCLUSION: Deproteinization with 5.25% Sodium hypochlorite prior to acid etching could be used to increase the surface area of adhesion of composite material with the tooth surface.

Effect of deproteinization before and after acid etching on the surface roughness of immature permanent enamel.

OBJECTIVE: The purpose of this in vitro investigation was to assess the effect of deproteinization before and after acid etching on the surface roughness of immature human enamel of permanent teeth compared to acid etching alone using noncontact three-dimensional (3D) optical profilometer. MATERIALS AND METHODS: Forty-eight enamel blocks were randomly distributed into 4 groups (12 each) according to the surface treatment in the form of deproteinized with 2.5% sodium hypochlorite (NaOCl) before and after acid etching with 32% phosphoric acid (H3PO4) compared to application of H3PO4 alone. The surface roughness (Sa) was measured using a 3D optical noncontact surface profiler. Two specimens from each group were selected and prepared for scanning electron microscopic (SEM) analysis. Shapiro-Wilk test, one-way analysis of variance, and Tukey's honest significance difference test were used. All statistical analyses were established with a significance level of P < 0.05. RESULTS: The highest surface roughness (Sa) was recorded for Group 3/NaOCl ± H3PO4 and the lowest Sa was recorded for Group 1 (control). All surface treatments applied showed significantly greater values of surface roughness (Sa) than the enamel surfaces with no surface treatment (control). There was significant difference between control group and Group 2/H3PO4 (P = 0.002), Group 3/NaOCl ± H3PO4 (P = 0.0001), and Group 4/H3PO4 ± NaOCl (P = 0.017). There was no significant difference between Group 2/H3PO4 and Group 4/H3PO4 ± NaOCl. SEM evaluation showed different topographical features of deproteinized enamel surface. CONCLUSIONS: Deproteinizing the enamel of immature permanent teeth with 2.5% NaOCl before and after acid etching with 32% H3PO4 increased surface roughness compared to the application of H3PO4 alone.

Nucleotide Substrate Specificity of Anti-Hepatitis C Virus Nucleoside Analogs for Human Mitochondrial RNA Polymerase.

Nucleoside analog inhibitors (NAIs) are an important class of antiviral agents. Although highly effective, some NAIs with activity against hepatitis C virus (HCV) can cause toxicity, presumably due to off-target inhibition of host mitochondrial RNA polymerase (POLRMT). The in vitro nucleotide substrate specificity of POLRMT was studied in order to explore structure-activity relationships that can facilitate the identification of nontoxic NAIs. These findings have important implications for the development of all anti-RNA virus NAIs.

Surface Properties and MC3T3-E1 Cell Response of Cortical Bone Allografts Modified with Low-Concentration Phosphoric Acid.

BACKGROUND/AIMS: This experimental study aimed to evaluate the effect of low-concentration phosphoric acid on the surface structure of cortical allografts. METHODS: Allogenic cortical bones were obtained from femurs and tibias of New Zealand white rabbits. The bones were modified by treatment with various concentrations of phosphoric acid (10%, 20% or 30%) for 10, 30 or 60 minutes, then evaluated by the following methods: 3-(4,5-Dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) and LIVE/DEAD assay, alkaline phosphatase (ALP) assay, biomechanical properties testing, contact angle detection, quantitative real-time polymerase chain reaction (Q-PCR), western blotting and scanning electron microscopy (SEM). RESULTS: Compared with the other groups, the group modified with 10% H3PO4 for 10 minutes had lower cytotoxicity according to MTT and LIVE/DEAD assays, higher hydrophilicity in the contact angle detection test and greater stability in the biomechanical properties test. Moreover, an up-regulation of osteopontin (OPN) in bones modified with 10% H3PO4 was observed by Q-PCR and western blotting. In addition, ALP assay and SEM showed that surface porosity and osteoinductivity were increased in the group modified with 10% H3PO4. CONCLUSIONS: Low-concentration phosphoric acid may be a potential method for surface modification of cortical allografts. Further animal experiments and animal infection model studies are required to validate the efficacy of surface-modified cortical allografts to repair large segmental bone defects.

Kinase-independent phosphoramidate S1P1 receptor agonist benzyl ether derivatives.

Previously published S1P receptor modulator benzyl ether derivatives have shown potential as being viable therapeutics for the treatment of neurodegenerative diseases, however, two of the most S1P1-selective compounds are reported as being poorly phosphorylated by kinases in vivo. Phosphoramidates of BED compounds (2a, 2b) were synthesised with the aim of producing kinase-independent S1P receptor modulators. Carboxypeptidase, human serum and cell lysate processing experiments were conducted. ProTide BED analogues were found to have an acceptable level of stability in acidic and basic conditions and in vitro metabolic processing experiments showed that they are processed to the desired pharmacologically active monophosphate. The research describes the development of an entirely novel family of therapeutic agents.

Synthesis and anti-HCV activity of a series of ß-d-2'-deoxy-2'-dibromo nucleosides and their corresponding phosphoramidate prodrugs.

Several ß-d-2'-deoxy-2'-substituted nucleoside analogs have displayed potent and selective anti-HCV activities and some of them have reached human clinical trials. In that regard, we report herein the synthesis of a series of 2'-deoxy,2'-dibromo substituted U, C, G and A nucleosides 10a-d and their corresponding phosphoramidate prodrugs 13a-d. The synthesized nucleosides 10a-d and prodrugs 13a-d were evaluated for their inhibitory activity against HCV as well as cellular toxicity. The results showed that the most potent compound was prodrug 13a, which exhibited micromolar inhibitory activity (EC50 = 1.5 ±â€¯0.8 µM) with no observed toxicity. In addition, molecular modeling and free energy perturbation calculations for the 5'-triphosphate formed from 13a and related 2'-modified nucleotides are discussed.