PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “AMINOBENZOIC ACID”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 199 records · Page 11Linked to original sources
PubMed1988

N-benzoyl-L-tyrosyl-p-aminobenzoic acid hydrolase: a metalloendopeptidase of the human intestinal microvillus membrane which degrades biologically active peptides.

Particulate fractions of human small intestinal mucosa contain an enzyme capable of hydrolyzing N-benzoyl-L-tyrosyl-p-aminobenzoic acid (PABA-peptide), a substrate used for clinical purposes to assess exocrine function of the pancreas (PABA test, pancreas function test). In this paper we describe the purification of PABA-peptide hydrolase (PPH) by immunoaffinity chromatography using a monoclonal antibody (Mab), HBB 3/716/36, bound to protein A-Sepharose, and the characterization of the purified enzyme. The final preparation of the enzyme was in the immobilized form, i.e., bound to Mab-protein A-Sepharose, and showed a 765-fold enrichment over the mucosal homogenate. The enrichment factor in purified microvillus membranes was comparable to that of sucrase-isomaltase, a microvillar marker enzyme. This, together with immunoelectron microscopy using protein A-gold, indicated that PPH is located in the apical membrane of intestinal epithelial cells. The enzyme was found to be present throughout the small intestine with the activity in distal ileum being 4.5-fold higher than that in the proximal duodenum. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the immunoaffinity-purified PPH under reducing conditions revealed a polypeptide band with a relative molecular weight (Mr) of 100,000; under nonreducing conditions a major band with Mr 200,000 was observed. This indicates that PPH consists of two subunits with Mr 100,000 each, which are held together by one or more disulfide bonds. Two-dimensional polyacrylamide gel electrophoresis of the enzyme showed marked microheterogeneity, with pI's ranging from 6.0 to 6.85, probably due to glycosylation. The Km for PABA-peptide was 16.7 mM, and the pH optimum was 7.5-8.0 PPH activity was not inhibited by phenylmethylsulfonyl fluoride; pepstatin, leupeptin, amastatin, bestatin, puromycin, iodoacetate, or phosphoramidon. Activity was affected by captopril and Zinkov inhibitor, and in particular by thiol and chelating reagents. Chelator-inhibited PPH could be reactivated by bivalent metal ions, Zn2+ being the most effective. The enzyme catalyzed the hydrolysis of peptides including insulin B-chain, angiotensins I and II, bradykinin and bradykinin derivatives, oxytocin, and substance P, in each case yielding reproducible peptide fragments. On the basis of amino acid analysis of the products it could be concluded that peptides are hydrolyzed preferentially after an aromatic residue.

4-Aminobenzoic Acid↗
PubMed1986

Reduced acetylation of procainamide by para-aminobenzoic acid.

Acetylation is the major route of metabolism of many drugs including the antiarrhythmic agent procainamide. Coadministration of para-aminobenzoic acid was observed to decrease the biotransformation of procainamide to N-acetylprocainamide in a patient with rapid acetylation kinetics. In view of the distinct antiarrhythmic and toxic properties of procainamide and N-acetylprocainamide, the observed drug interference may have great clinical relevance in long-term oral antiarrhythmic therapy and in instances where other drugs converge for acetylation.

4-Aminobenzoic Acid↗
PubMed1995

Rapid reaction of singlet molecular oxygen (1O2) with p-aminobenzoic acid (PABA) in aqueous solution.

The reaction of singlet molecular oxygen (1O2) with p-aminobenzoic acid (PABA) is quite rapid. The rate constant for reaction of 1O2 with PABA was measured in buffered aqueous solution by the method of competition kinetics and found to be 8.9 x 10(8) M-1 sec-1. The results of a Stern-Volmer analysis indicate that additional loss of 1O2 does not occur through physical quenching by PABA. Although illuminated PABA solutions are known to form 1O2, it appears that PABA is also a very efficient sink for 1O2.

4-Aminobenzoic Acid↗
PubMed2001

[Effect of para-aminobenzoic acid on the adhesion of Streptococcus mutans].

OBJECTIVE: To investigate the effects of Para-aminobenzoic acid (PABA) on the adhesion of Streptococcus mutans to saliva-coated hydroxyapatite (S-HA). METHODS: The adhesion model in vitro established by Gibbons was adopted in this study to quantify adsorptive cells through [3H] thymidine labelling. RESULTS: PABA solution over a range of concentration from 10(-9) to 10(-3) g/L could inhibit the attachment of S. mutans to S-HA effectively, and the inhibition declined when the concentration of PABA solution was 10(-3) g/L. CONCLUSION: PABA can inhibit the adherence of Streptococcus mutans to S-HA effectively.

4-Aminobenzoic Acid↗
PubMed2002

A sequential-injection system for spectrophotometric determination of p-aminobenzoic acid in sunscreens.

A sequential injection method is proposed for spectrophotometric determination of p-aminobenzoic acid (PABA) in cosmetic formulations. The method is based on diazotization of the analyte, coupling with 8-hydroxyquinoline, and the subsequent formation of a colored product. The experimental conditions used (coupling reagent, sandwich arrangement, volumes aspirated, propulsion flow rate, reaction coil length) were studied. Response of the sequential injection method were linearly dependent on concentrations up to 25 micro g mL(-1) and the detection limit was 2 micro g mL(-1). Throughput was 51 measurements per hour and a complete cycle, including three measurement per sample and a washing step, resulted in a sample throughput of 13.8 h(-1). Sunscreen formulations containing PABA were analyzed by the proposed method and validated by use of an HPLC procedure. The two methods gave comparable results. Yields ranged between 97-103% and good precision (RSD between 2 and 6%) was obtained. The accuracy, speed, and selectivity of the method make it suitable for safe application for quality-control of final products.

4-Aminobenzoic Acid↗
PubMed2002

The effect of para-aminobenzoic acid on growth and metabolism of Porphyromonas gingivalis.

OBJECTIVE: To study the effect of para-aminobenzoic acid (PABA) on the growth and metabolism of Porphyromonas gingivalis (P.g). METHODS: After adding different concentrations of PABA into the medium, anaerobic technique was applied to culture P.g. The products' A value and action of TLP was assayed, and P.g grew in the medium was observed by a scanning electron microscope. RESULTS: PABA promoted the growth of P.g and action of TLP, which would reach the highest level when PABA was 1 mg/L, and would decrease with the increasing of concentration of PABA. When the concentration arrived at 100 mg/L, PABA had no effect on them. In the mean time, PABA had effect on the form and adherence of P.g. When the concentration was 1 mg/L and 100 mg/L, this effect was strong, but as the concentration was 10 mg/L, the effect disappeared. CONCLUSIONS: PABA influences the growth and metabolism of P.g, which indicate that Streptococcus sanguis has regulative effect on the microecology of subgingival plaque.

4-Aminobenzoic Acid↗
PubMed2005

Promotion of thyroid carcinogenesis by para-aminobenzoic acid in rats initiated with N-bis(2-hydroxypropyl)nitrosamine.

Sulfonamide analogues of para-aminobenzoic acid (PABA), a precursor of folate synthesis, have beneficial effects as antifolate, but thyroid peroxidase inhibition has been reported as a side effect that results in promotion of rat thyroid carcinogenesis. In the present study, effects of PABA itself on F344 rat thyroid carcinogenesis after initiation with N-bis(2-hydroxypropyl)nitrosamine (DHPN) were evaluated. In experiment 1, rats in groups 1-4 received a single subcutaneous injection of DHPN at 2800 mg/kg, and groups 5 and 6 received vehicle saline alone. From 1 week after DHPN initiation, rats in groups 2, 3, 4, and 6 were fed basal diet containing 0.25%, 0.5%, 1.0%, and 1.0% PABA, respectively, for 40 weeks. Rats in groups 1 and 5 received basal diet alone throughout the experiment. The final incidence of thyroid follicular cell adenomas and adenocarcinomas was significantly (p < 0.05 or 0.01) increased in groups 3 and 4 as compared to group 1. No thyroid tumors were found in groups 5 and 6. In experiment 2, animals in group 1 were fed basal diet alone, while groups 2 and 3 were given 0.5% and 1.0% PABA in the diet, respectively, for 2 weeks. Thyroid weights in group 3, and serum thyroid stimulating hormone level and proliferative activity of follicular cells in groups 2 and 3 were significantly (p < 0.05 or 0.01) elevated. In addition, the serum thyroxine level in group 3 was significantly (p < 0.05) depressed. These results clearly indicate that PABA exerts promotion/progression effects on rat thyroid carcinogenesis as a result of hypothyroidism followed by negative-feedback via the thyroid-pituitary axis.

4-Aminobenzoic Acid↗
PubMedDate not supplied

Effect of para-aminobenzoic acid on the pharmacokinetics and urinary excretion of cis-diamminedichloroplatinum(II) in rats.

Para-aminobenzoic acid (PABA) has been previously reported as being an inhibitor of DDP toxicity, and its use did not result in any observable loss in antitumor activity of DDP. The following studies investigated the effect of PABA on the pharmacokinetics and urinary excretion of cis-diamminedichloroplatinum(II) (DDP) in male Sprague-Dawley rats. DDP was injected i.p. at the dose of 7.5 mg/kg in normal saline alone and with a concurrent i.p. injection of PABA (100 mg/kg). The combined treatment with PABA produced a significant increase in the plasma concentrations of total platinum, without affecting the levels of platinum species in the plasma ultrafiltrate. Similar results were also obtained in additional studies in rats receiving the same dose of DDP plus PABA through different routes of administration (i.e. DDP i.v. and PABA i.p.). Both the area under the total platinum plasma concentration-time curve (AUC) up to 60 min and AUC0-120 min were increased by PABA by an average of 113% and 66% respectively. The administration of PABA in rats was followed by a substantial reduction in total urinary excretion of platinum (P < 0.05) and by a significant (P < 0.01) lower concentration of DDP derived platinum in the urine collected during the first 4 h after treatment. The renal clearance of filterable platinum was reduced by PABA by an average of 67.5% from 1.11 to 0.36 ml/min/100 g body wt. Total 24-h urinary excretion of platinum was also decreased, although not significantly, by PABA. Urine volumes from rats treated with DDP+PABA were similar to those from animals receiving DDP alone. HPLC studies indicate that PABA reacts readily with the species generated from DDP in vitro, while the agent is essentially unreactive toward the parent DDP and does not influence its decomposition rate. The overall data of this study suggest that the protective effect exerted by PABA on DDP toxicity may be at least partially due to its ability to interact with aquated DDP as well as to alter the renal excretion of platinum.

4-Aminobenzoic Acid↗
PubMed1982

The sensitization of near-ultraviolet radiation killing of mammalian cells by the sunscreen agent para-aminobenzoic acid.

The wavelengths of sunlight considered to be responsible for erythema and skin cancer formation are in the range 290-340 nm. Formulated sunscreens usually contain an agent that absorbs in this wavelength region, and one of the most widely used is para-aminobenzoic acid (PABA). Previous work has demonstrated the sensitization by PABA of the lethal and mutagenic effects of near-ultraviolet (UV) radiation in a model bacterial system. Experiments with the mouse lymphoma L5178Y cell line have now demonstrated sensitization by PABA of the lethal effect of near-UV radiation, the extent of which, after correction for absorption of UV radiation by PABA, bears a direct relationship to PABA concentration. The limitations of these results in predicting the response of human skin to the presence of PABA during exposure to UV radiation is emphasized.

4-Aminobenzoic Acid↗
PubMed1983

Comparative study of the estimation of exocrine pancreatic function using p-(N-acetyl-L-tyrosyl)- and p-(N-benzoyl-L-tyrosyl)aminobenzoic acid.

A comparative study using the oral test with chymotrypsin substrates p-(N-acetyl-L-tyrosyl)- and p-(N-benzoyl-L-tyrosyl) aminobenzoic acid (Ac-Tyr-PAB and Bz-Tyr-PAB) was carried out in 43 adults divided into four groups comprising controls (n = 18), chronic pancreatitis (n = 13), after acute pancreatitis (n = 7), and celiac sprue (n = 4), after separate administration of both derivatives and determination of PABA urinary output in 6 and 8 hours. Both derivatives were diagnostically comparable. The specificity of both derivatives in the investigated group in 6 and 8 hours was 100%, and test sensitivity in patients with chronic pancreatitis, was in 6 hours 90.9% for Ac-Tyr-PAB and 72.7% for Bz-Tyr-PAB, and 8 hours 81.8% for both compounds. Differentiation between the controls and the chronic pancreatitis group was better in Ac-Tyr-PAB, as adjudged by the sensitivity and significance of the Student t-test criterion.

4-Aminobenzoic Acid↗
PubMed1996

Effects of aminobenzoic acid derivatives with 4-AET/HEMA in self-etching primer on bonding to ground dentin.

The effect of the inclusion of aminobenzoic acid derivatives (ABAD) in a self-etching primer comprising 4-acryloxyethyltrimellitic acid (4-AET), HEMA and water on shear bond strength to ground dentin was investigated. The mean bond strengths to dentin were significantly increased by the inclusion of 0.307 mol% ABAD in the 4-AET/HEMA primer, when compared with the control (0 wt% ABAD) (p < 0.01). A particularly high value (38.0 MPa) of shear bond strength was obtained in the use of the primer containing p-nitroanthranilic acid (p-NAA). It seemed to assume that the effect of p-NAA could be caused by the strong electron-withdrawing group of -NO2. From SEM observation, it was found that bonding resin appeared to adhere strongly to the ground dentin without formation of any resin-tags in the dentinal tubules. It was thought that the ABAD with 4-AET/HEMA could perform facilitating photo-polymerization at the bonding interface, and resulted in increased bond strength to ground dentin, and that the bond strength could be affected by the electronegativities of substitutional groups of ABAD.

4-Aminobenzoic Acid↗
PubMed1985

Antagonism of sulfadoxine and pyrimethamine antimalarial activity in vitro by p-aminobenzoic acid, p-aminobenzoylglutamic acid and folic acid.

The activity of pyrimethamine and sulfadoxine against two strains of Plasmodium falciparum has been studied in vitro by a radioisotopic technique. Low level antagonism of pyrimethamine resulted from the inclusion of p-aminobenzoic acid, p-aminobenzoylglutamic acid or folic acid in the test medium. Sulfadoxine activity was antagonised slightly by p-aminobenzoic but not by p-aminobenzoylglutamic acid, and antagonised markedly by folic acid at concentrations above 4 X 10(-8) M. At 10(-7) M folic acid, a concentration lower than that of normal RPMI medium 1640, sulfadoxine activity was reduced 7000 to 9000-fold in comparison with controls. These results are of importance in terms of the utilisation of folates by P. falciparum, the susceptibility of the parasite to antifolate drugs and the in vitro determination of parasite susceptibility.

4-Aminobenzoic Acid↗
PubMed1999

p-Aminobenzoic acid and its metabolite p-acetamidobenzoic acid inhibit agonist-induced aggregation and arachidonic acid-induced [Ca2+]i transients in human platelets.

We have previously found that the naturally occurring amine p-aminobenzoic acid (PABA) inhibits the thrombin-induced thromboxane B2 production in human platelets. In this report we show that PABA and its acetylated metabolite p-acetamidobenzoic acid (PACBA) inhibit platelet aggregation induced by agonists such as adenosine diphosphate (ADP) and arachidonic acid (AA). Both substances were equipotent to acetylsalicylic acid regarding inhibition of ADP-induced aggregation and approximately 50% as potent as acetylsalicylic acid regarding arachidonic acid-induced aggregation. Although not significantly inhibiting collagen aggregation, PABA and PACBA reduced the concomitant adenosine triphosphate (ATP) secretion by approximately 30 and 20%, respectively. The antiaggregatory effect does not seem to be mediated through cyclic adenosine monophosphate (cAMP) increase because in our experiments PABA and PACBA did not significantly affect cAMP levels. However, we have found that PABA and PACBA inhibit the intracellular aequorin indicated Ca2+ transient upon arachidonic acid stimulation. Our results describe a hitherto unknown effect of PABA and PACBA on platelet aggregation.

4-Aminobenzoic Acid↗
PubMed1983

[Vitamin para-aminobenzoic acid inhibits development of SOS function in tif-1 mutants of Escherichia coli at nonpermissive temperatures].

The development of "SOS" inducible functions in lysogenic and non-lysogenic strains of Escherichia coli tif-1 sfiA11 (lambda) at nonpermissive temperature of 42 degrees C was strongly suppressed by para-aminobenzoic acid (PABA). The rate of prophage lambda induction decreased 400 times, as compared to the control level; the efficiency of W-reactivation of UV-irradiated phage lambda decreased 37.5 to 16%. PABA also inhibited to some extent (1.5 times) the process of inducible recombination on the RecF pathway. The processes of spontaneous lambda induction and W-reactivation, as well as spontaneous recombination on RecBC and RecF pathways, were not influenced by PABA. The above data are in accordance with previous studies of PABA action when the manifestation of "SOS" functions was induced by chemical mutagens. The action of PABA has been tentatively interpreted on the basis of negative control of "SOS" repair pathway.

4-Aminobenzoic Acid↗