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At least 613 records · Page 34Linked to original sources
PubMed1989

[Ion pair HPLC determination of p-aminobenzoic acid as an impurity in procaine and procainamide hydrochlorides].

A simple, specific and sensitive high-performance liquid chromatographic method for the determination of p-amino benzoic acid (PABA) as impurity in procaine and procainamide hydrochlorides has been developed. The compounds were chromatographed on reversed phase C-18 using water-methanol-acetonitrile solvent system containing sodium lauryl sulphate ion-pair reagent.

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PubMed2006

A novel in vitro percutaneous penetration model: evaluation of barrier properties with p-aminobenzoic acid and two of its derivatives.

PURPOSE: The objective of this study was to evaluate the utility of a stratum corneum substitute (SCS) as a novel in vitro percutaneous penetration model. The SCS consists of synthetic stratum corneum (SC) lipids (cholesterol, free fatty acids, and specific ceramides) applied onto a porous substrate. The composition, organization, and orientation of lipids in the SCS bear high resemblance to that of the intercellular barrier lipids in SC. METHODS: The barrier integrity of the SCS was evaluated by means of passive diffusion studies, using three model compounds with different lipophilicities. The effects of lipid layer thickness, permeant lipophilicity, and altered lipid composition on the barrier properties were investigated, using isolated human SC as a control sample. RESULTS: For all three model compounds, the permeability characteristics of the SCS with a 12-mum-thick lipid layer closely resemble those of human SC. Modification of the lipid composition, generating an SCS that lacks the characteristic long periodicity phase as present in SC, was accompanied by a 2-fold increased permeability. CONCLUSIONS: The SCS offers an attractive tool to predict solute permeation through human skin. Moreover, as its lipid composition can be modified, they may also serve as a suitable screening model for diseased skin.

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PubMed1998

[Study on the biosynthesis of para-aminobenzoic acid by S. sanguis. II. Qualitative and quantitative analysis].

In this study, the method established in paper 1 was used to analyze PABA synthesized by S. sanguis S34. The results showed: 1. S. sanguis S34 did synthesize PABA and the mean concentration of PABA was 1.236 micrograms/ml. 2. the components had good linear relation and average recovery was 80%. The results of this paper will be helpful to studying influencing factors on PABA synthesis of S. sanguis and the roles of PABA in microbial homeostasis of dental plaque.

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PubMed2003

[Scanning electron microscope observation of morphological influence P-aminobenzoic acid (PABA) on Porphyromonas gingivalis].

OBJECTIVE: In order to investigate the effect of PABA produced by Streptococcus sanguis on microecological balance of subgingival plaque, different concentrations of PABA were applied to see if it can influence the form and adherence of P. gingivalis. METHODS: After adding different concentrations of PABA into 1/2 concentration of BHI media, an anaerobic technique was used to culture P. gingivalis. P. gingivalis grew in the medium was observed by a scanning electron microscope. RESULTS: Excessively high or low PABA concentration could influence the form and adherence of P. gingivalis. CONCLUSION: PABA produced by Streptococcus sanguis can affect the form and adherence of P. gingivalis. It indicates that Streptococcus sanguis plays regulative effect on the microecological balance of subgingival plaques.

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PubMed1996

UVA-potentiated damage to calf thymus DNA by Fenton reaction system and protection by para-aminobenzoic acid.

Calf thymus DNA was irradiated with low-intensity UVA (main output at 365 nm, 2 mW cm-2 or 36 kJ m-2 for 30 min), and the role of metal ions, hydrogen peroxide and reactive oxygen species (ROS) was examined. DNA damage was measured as thiobarbituric acid-reactive substances (possibly from degradation of deoxyribose) and as changes in ethidium bromide-DNA fluorescence due to unwinding from strand breaks. Under the present experimental conditions, UVA alone or in the presence of H2O2 had no effect on DNA but slightly enhanced the damage by iron/EDTA. Ultraviolet A strongly enhanced DNA damage (ca four- to five-fold) by the Fenton reaction system (50 microM Fe2+/100 microM EDTA + 0.5 mM H2O2). The results suggest that the Fenton reaction system was "photosensitized" to damage DNA by low-intensity UVA radiation. The enhanced damage by UVA was attributed in part to the reduction of Fe3+ to Fe2+. Ultraviolet A had no effect when iron (ferric or ferrous) ions were replaced by Cu2+, Zn2+, Mn2+ or Cd2+. The ROS involved in the UVA-enhanced damage to DNA by the Fenton reagents were OH and, to a lesser extent, superoxide anions. The UVA-potentiated DNA damage by the Fenton reaction system was then used to examine the protective effect of para-aminobenzoate (PABA), a UVB-absorbing sunscreen that protects against photocarcinogenesis in hairless mice. The results show that PABA and mannitol dose-dependently inhibited the damage with concentrations required for 50% inhibition at 0.1 mM and 3 mM, respectively. The protection by PABA was attributed to its radical-scavenging ability because PABA does not absorb light in the UVA region. These findings may be relevant to the biological damage by UVA and suggest that PABA is useful in protection against photocarcinogenesis by wide-range UV radiation.

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PubMed1995

Preliminary assessment of glycine conjugation of para-aminobenzoic acid as a quantitative test of liver function.

OBJECTIVES: Our hypothesis is that because of its hepatic metabolism paraaminobenzoic acid (PABA) could be a test of liver function. DESIGN AND METHODS: PABA is well absorbed by the gastrointestinal tract and acetylated and conjugated in the liver to glycine before being excreted. Its three major metabolites include para-acetoamidobenzoic acid (PAABA), paraaminohippuric acid (PAHA), and paraacetamidohippuric acid (PAAHA). In this study, we measured the metabolism of lidocaine to monoethylglycinexylidide (MEGX) and PABA to PAHA+PAAHA/PABA+PAABA+PAHA+PAAHA (hippurate ratio) in 14 patients with liver disease and 12 control subjects. RESULTS: Comparison of the total bilirubin with the hippurate ratio (at 30 min) and the conventional MEGX test (at 15 min) was assessed. The 30 min hippurate ratio correlated well with the 15 min MEGX results (r = 0.69). CONCLUSIONS: While these results are preliminary the PABA test appears to be equally sensitive to MEGX and has the distinct advantage over the MEGX test of being administered orally versus the intravenous administration of lidocaine which is often associated with unwanted side-effects such as hypotension, drowsiness and paresthesias.

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PubMedDate not supplied

[The effect of para-aminobenzoic acid on the level of proliferative activity in the regenerating cornea of adult rats (a radioautographic study)].

[3H]-Thymidine radioautography showed that 0.005% p-aminobensoic acid (PABA) solution applied three times per day on penetrating wounds in central part of the adult rat cornea selectively stimulates proliferative activity of corneal stroma keratoblasts. In control rats, a curve showing changes in index of labeled nuclei in corneal stroma had two peaks, on the second and sixth day after injury (about 5 and 3%, respectively), whereas in animals receiving PABA treatment it had a single peak on the second day (about 12%). On days 7-14, indices of labeled nuclei in corneal stroma of both experimental and control rats become similarly low. No difference between experimental and control animals was revealed in indices of labeled nuclei in corneal epithelium: in both groups, corresponding curves had two peaks (about 9%) on the first and fifths days, and proliferation still continued two weeks after injury.

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