p-aminobenzoic acid Research Papers - Academia.edu (original) (raw)

In this work, the cocrystallization approach was applied to itraconazole (ITR), a very slightly soluble triazole antifungal drug, which led to the formation of two new solid forms of ITR with 4-aminobenzoic acid (4AmBA) and... more

In this work, the cocrystallization approach was applied to itraconazole (ITR), a very slightly soluble triazole antifungal drug, which led to the formation of two new solid forms of ITR with 4-aminobenzoic acid (4AmBA) and 4-hydroxybenzamide (4OHBZA). A thermodynamic analysis of the solid-liquid binary phase diagrams for the (ITR + 4AmBA) and (ITR + 4OHBZA) systems provided conclusive evidence of the cocrystal stoichiometry: 1:1 for the cocrystal with 4-aminobenzoic acid, and 1:2 for the cocrystal with 4-hydroxybenzamide. Powder X-Ray diffraction analysis confirmed the formation of two different polymorphic forms of the [ITR + 4OHBZA] (1:2) cocrystal obtained either through solution or melt crystallization. Cocrystal formation and polymorphic transition processes were investigated in detail by the DSC and HSM methods. The thermodynamic functions of cocrystal formation were estimated from the solubility of the cocrystals and the corresponding solubility of the pure compounds at different temperatures. The combination of ITR and 4OHBZA was found to be more favorable than the reaction between ITR and 4AmBA in terms of both Gibbs energy and enthalpy. The pH-solubility behavior of the cocrystals was investigated at different pH values using eutectic concentrations of the components and the cocrystal solubility advantage was estimated. It was found that the cocrystallization of itraconazole with 4OHBZA and 4AmBA can potentially increase the drug solubility at pH1.2 and 37 • C by 225 and 64 times, respectively. The cocrystal dissolution behavior in biorelevant media was analyzed in terms of C max , σ max parameters (the maximum ITR concentration and supersaturation), and AUC (the concentration area under the curve during the dissolution-supersaturation-precipitation process). The cocrystals had similar σ max values during the dissolution and sustained supersaturation for up to 6 h, which gave them an advantage in the AUC values (13-37 times higher) over the drug. The differences in the dissolution profiles of the cocrystals were rationalized in terms of their dissolution rate values.

The photocatalytic degradation of p-aminobenzoic acid was studied using C-doped ZnO nanorods as the catalyst synthesized through a low cost and simple precipitation method. The as-synthesized nanorods were fully characterized by SEM, TEM,... more

The photocatalytic degradation of p-aminobenzoic acid was studied using C-doped ZnO nanorods as the catalyst synthesized through a low cost and simple precipitation method. The as-synthesized nanorods were fully characterized by SEM, TEM, XRD, BET and XPS. The photocatalytic degradation of p-aminobenzoic acid was carried out under sunlight irradiation. Optimal experimental conditions were determined for C-doped ZnO nanorods with a catalyst dosage of 0.5 g/L in a p-aminobenzoic acid solution, and 97% degradation was obtained. The results showed that the C-doped ZnO nanorods can be reusable and retain good photodegradation efficiency. A pseudo first order reaction was found to provide the best correlations, with a constant rate of 0.028 min −1 .

A non-radioactive in situ hybridization (ISH) protocol for localization of mRNAs encoding peroxisomal proteins in hepatoma cell lines from humans (HepG2) and rats (MH1C1) is presented. In comparison to a similar procedure reported for... more

A non-radioactive in situ hybridization (ISH) protocol for localization of mRNAs encoding peroxisomal proteins in hepatoma cell lines from humans (HepG2) and rats (MH1C1) is presented. In comparison to a similar procedure reported for tissue sections, the cell culture preparations require only brief fixation in 4% paraformaldehyde and their permeabilization is achieved by a very low concentration (1 microg/ml) of proteinase K. The exclusive localization of transcripts in the cytoplasm of hepatoma cells with the absence of nuclear staining and the completely negative sense controls confirm the specificity of the method. The marked differences in signal intensity between the results of albumin and beta-actin mRNAs which are of high abundance in contrast to moderate to low abundance of peroxisomal mRNAs show the high sensitivity and the wide range of applicability of our protocol. This is also confirmed by divergent results of treatment of hepatoma cell lines with clofibrate and cetabe...

The synthetic substrate cholyl-PABA, developed by conjugating cholic acid with paraaminobenzoic acid, is hydrolyzed by the bacterial enzyme cholyl hydrolase to release free PABA. This study aimed to evaluate whether quantitating urinary... more

The synthetic substrate cholyl-PABA, developed by conjugating cholic acid with paraaminobenzoic acid, is hydrolyzed by the bacterial enzyme cholyl hydrolase to release free PABA. This study aimed to evaluate whether quantitating urinary excretion of PABA after oral administration of cholyl-PABA can detect small intestinal bacterial overgrowth. In the first phase, investigations were performed on 10 healthy volunteers to study the dynamics of urinary excretion of PABA and any adverse reactions after oral administration of 1.2 g of cholyl-PABA. Another 10 healthy volunteers and 25 adult patients with various gastrointestinal disorders participated in the second phase, where the urinary cholyl-PABA test was compared to the [14C]xylose breath test (XBT). The upper limit of normal levels of urinary PABA excretion at the end of 4 h was 1.1% of the administered dose of cholyl-PABA. The urinary PABA excretion after 4 hr [median (range), in percentage] in the XBT-positive group was 1.6 (0.6-...

Background Organic nanomaterials having specific biological properties play important roles in in vivo delivery and clearance from the live cells. To develop orally deliverable nanomaterials for different biological applications, we have... more

Background Organic nanomaterials having specific biological properties play important roles in in vivo delivery and clearance from the live cells. To develop orally deliverable nanomaterials for different biological applications, we have synthesized several fluorescently labelled, self-assembled PABA nanoparticles using possible acid side chain combinations and tested against insect and human cell lines and in vivo animal model. Flurophores attached to nanostructures

The use of vitamins including vitamin B1, B2 and K3 for the induction of systemic acquired resistance (SAR) to protect crops against plant pathogens has been evaluated previously. The use of vitamins is beneficial because it is cost... more

The use of vitamins including vitamin B1, B2 and K3 for the induction of systemic acquired resistance (SAR) to protect crops against plant pathogens has been evaluated previously. The use of vitamins is beneficial because it is cost effective and safe for the environment. The use of folate precursors, including ortho-aminobenzoic acid, to induce SAR against a soft-rot pathogen in tobacco has been reported previously. In the present study, para-aminobenzoic acid (PABA, also referred to as vitamin Bx) was selected owing to its effect on the induction of SAR against Xanthomonas axonopodis pv. vesicatoria in pepper plants through greenhouse screening. Dipping of pepper seedlings in a 1 mm PABA solution in field trials induced SAR against artificially infiltrated X. axonopodis pv. vesicatoria and naturally occurring cucumber mosaic virus. Expression of the Capsicum annuum pathogenesis-related 4 gene was primed in response to pathogen infection as assessed by quantitative real-time PCR. T...

One hundred and twenty two 24-h urine collections were obtained from a representative sample of men and women in the general population aged 25–44 years. The collections were verified for their completeness by urine recovery of oral doses... more

One hundred and twenty two 24-h urine collections were obtained from a representative sample of men and women in the general population aged 25–44 years. The collections were verified for their completeness by urine recovery of oral doses of para-amino benzoic acid. Means (with 0·95 reference intervals) for both sexes for 24-h urinary output were determined for nitrogen, urea, creatinine, urate, ammonia, sodium, potassium, volume, and pH. Within person variation in nitrogen, urea, creatinine, ammonia, sodium and potassium was estimated for a consecutive 28-day series of 24-h urine collections for eight individuals. Within person variation was greatest for sodium and least for creatinine. These differences when compared with the between person variation in the analytes studied have implications for the precision with which a result from a single specimen can be used to place an individual within a distribution of values for epidemiological purposes. In clinical biochemistry, the popu...

A new analytical method, using gas chromatography-mass spectrometry (GC/MS) and liquid chromatography-mass spectrometry (LC/MS) techniques, was developed for the determination in packaged food beverages of five ink photoinitiator... more

A new analytical method, using gas chromatography-mass spectrometry (GC/MS) and liquid chromatography-mass spectrometry (LC/MS) techniques, was developed for the determination in packaged food beverages of five ink photoinitiator residues: 2-isopropylthioxanthone (ITX), benzophenone, 2-ethylhexyl-4-dimethylaminobenzoate (EHDAB), 1-hydroxycyclohexyl-1-phenyl ketone (IRGACURE 184) and ethyl-4-dimethylaminobenzoate (EDAB). Samples were extracted from selected beverages (milk, fruit juices and wine) and relative packagings, using n-hexane and dichloromethane, respectively, purified on solid-phase extraction (SPE) silica gel cartridges, and then analyzed in GC/MS and LC/MS. The recovery percentages, obtained spiking the beverage samples at concentrations of 4 and 10 microgl(-1) with a standard mixture of photoinitiators, were in the range 42-108% (milk), 50-84% (wine), and 48-109% (fruit juices). The repeatability of the method was assessed in all cases by the % of correlation value, tha...

The oral (PABA) pancreatic function test (PFT), the secretin-pancreozymin test and endoscopic retrograde pancreatography (ERCP) have been carried out in 32 patients with suspected chronic alcohol induced pancreatitis (CAIP) in order to... more

The oral (PABA) pancreatic function test (PFT), the secretin-pancreozymin test and endoscopic retrograde pancreatography (ERCP) have been carried out in 32 patients with suspected chronic alcohol induced pancreatitis (CAIP) in order to evaluate which, if any, test was most likely to confirm the provisional diagnosis. Thirty one patients had changes of minimal (n = 6) moderate (n = 7) or advanced (n = 18) chronic pancreatitis on pancreatography, whilst one patient had a pancreas divisum. Eight hour urinary PABA excretion was significantly reduced in patients with moderate and advanced structural changes (p less than 0.001) and correlated significantly with all parameters of the PFT, although eight patients with an abnormal pancreatogram and pancreatic function test had a normal PABA value. The PFT was abnormal in 23 patients, but normal in five patients with an abnormal pancreatogram and low PABA value. Most patients with minimal change pancreatitis had a normal PABA test and PFT. We...

We characterize here an arachidonic acid (AA)-derived metabolite previously found to have an adjuvant effect in phytohemagglutinin-induced mitogenesis of lymphocytes from mothers of newborn babies and from immunodeficient infants. We... more

We characterize here an arachidonic acid (AA)-derived metabolite previously found to have an adjuvant effect in phytohemagglutinin-induced mitogenesis of lymphocytes from mothers of newborn babies and from immunodeficient infants. We named the metabolite 'compound 4' due to its position in a thin-layer chromatography system developed for isolation of eicosanoids. The compound was originally found to be produced by peripheral blood mononuclear leukocytes and the T cell leukemia line Jurcat after long-term (18-24 h) incubation with [1-14C]AA. Compound 4 is also produced by lymphocytes, monocytes, platelets, thrombocytes, cultured fibroblasts and various types of malignant cell lines. We purified this metabolite by means of high pressure liquid chromatography with synchronous detection of radioactivity and measurement of ultraviolet-light absorption at 278 nm. Proton nuclear magnetic resonance spectroscopy and mass spectrometry with electron impact techniques demonstrated that ...

To evaluate the efficiency of the photopolymerization of dental resins it is necessary to know to what extent the light emitted by the light curing units is absorbed by the photoinitiators. On the other hand, the efficiency of the... more

To evaluate the efficiency of the photopolymerization of dental resins it is necessary to know to what extent the light emitted by the light curing units is absorbed by the photoinitiators. On the other hand, the efficiency of the absorbed photons to produce species that launch the polymerization process is also of paramount importance. Therefore, the previously determined PAE (photon absorption efficiency) is used in conjunction with the polymerization quantum yields for the photoinitiators, in order to be able to compare the total process on an equivalent basis. This parameter can be used to identify the best performance for the photochemical process with specific photoinitiators. The efficiency of LED (Ultrablue IS) and QTH (Optilux 401) lamps were tested comparing their performances with the photoinitiators camphorquinone (CQ); phenylpropanedione (PPD); monoacylphosphine oxide (Lucirin TPO); and bisacylphosphine oxide (Irgacure 819). The extent of photopolymerization per absorbed photon was determined from the polymerization quantum yields obtained by using the photoinitiators to polymerize methyl methacrylate, and afterwards combined with the previously determined PAEs. Although CQ presents a rather low polymerization quantum yield, its photopolymerization efficiency is practically the highest when irradiated with the Ultrablue LED. On the other hand, Lucirin is much more efficient than the other photoinitiators when irradiated with a QTH lamp, due to its high quantum yield and the overlap between its absorption spectrum and the output of the visible lamp light. Difference in photopolymerization efficiencies arise when combinations of photoinitiators are used, and when LED sources are used in preference to QTH. Mechanistic understanding is essential to optimal initiator formulation.

Human HepG2 and rat MH1C1 hepatoma cell lines were examined for their response to cetaben, an exceptional type of peroxisome proliferator. Shape change and proliferation of peroxisomes as well as induction of selected peroxisomal enzymes... more

Human HepG2 and rat MH1C1 hepatoma cell lines were examined for their response to cetaben, an exceptional type of peroxisome proliferator. Shape change and proliferation of peroxisomes as well as induction of selected peroxisomal enzymes catalase, acyl-CoA oxidase, and peroxisomal bifunctional enzyme, were assessed in response to cetaben. In MH1C1 cells, peroxisomes were seen in clusters displaying typical features of microperoxisomes. Cetaben caused little but reversible proliferation and morphological heterogeneity with the occurrence of dumbbell-shaped and cup-shaped peroxisomal profiles. Peroxisomes in HepG2 cells showed marked variation in size and shape. Cetaben treatment of HepG2 cells caused disintegration of Golgi regions and augmented mitochondrial matrix. Interestingly, MH1C1 cells showed different subunit composition of acyl-CoA oxidase in immunoblot analysis: only subunit A at 72 kDa was detected but not the cleavage products. In situ hybridization underlined the marked...

Two noninvasive tests for assessing pancreatic exocrine function, the cholesteryl-[14C]octanoate breath test and the HPLCN-benzoyl-tyrosyl-p-aminobenzoic acid/p-aminosalicylic acid (NBT-PABA/PAS) test, were simultaneously performed in... more

Two noninvasive tests for assessing pancreatic exocrine function, the cholesteryl-[14C]octanoate breath test and the HPLCN-benzoyl-tyrosyl-p-aminobenzoic acid/p-aminosalicylic acid (NBT-PABA/PAS) test, were simultaneously performed in nine patients with pancreatic exocrine insufficiency due to chronic pancreatitis and in nine healthy volunteers. 14CO2 output in breath and plasma PABA concentration rose slowly in patients but increased rapidly in healthy subjects. The measurement time giving the best discrimination between both groups was 120 min for the cholesteryl-[14C]octanoate breath test and 90 min for the plasma PABA test. At these points, both single-sample tests had essentially identical diagnostic sensitivity. The diagnostic sensitivities of the two single-sample tests were equal to that of the cumulative 6-h urinary PABA recovery and the cumulative 6-h urinary PABA/PAS ratio. We conclude that, for both the cholesteryl-[14C]octanoate breath test and the plasma PABA test, a s...