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PubMed2002

Complete development of mosquito phases of the malaria parasite in vitro.

Methods for reproducible in vitro development of the mosquito stages of malaria parasites to produce infective sporozoites have been elusive for over 40 years. We have cultured gametocytes of Plasmodium berghei through to infectious sporozoites with efficiencies similar to those recorded in vivo and without the need for salivary gland invasion. Oocysts developed extracellularly in a system whose essential elements include co-cultured Drosophila S2 cells, basement membrane matrix, and insect tissue culture medium. Sporozoite production required the presence of para-aminobenzoic acid. The entire life cycle of P. berghei, a useful model malaria parasite, can now be achieved in vitro.

4-Aminobenzoic Acid↗
PubMed2000

Inhibition by vitamin C of DNA adduct formation and arylamine N-acetyltransferase activity in human bladder tumor cells.

Previous studies have already demonstrated the protective role of vitamin C (ascorbic acid) in certain types of cancer. This study reports on the effects of vitamin C on arylamine N-acetyltransferase (NAT) activity and DNA adduct formation in a human bladder tumor cell (T24) line. The activity of NAT was measured using high-performance liquid chromatography (HPLC), by assaying for the amounts of acetylated 2-aminofluorene (AF) and p-aminobenzoic acid (PABA) and the remaining amounts of AF and PABA. T24 cells were used for examining NAT activity and carcinogen DNA adduct formation. The results demonstrated that NAT activity and 2-aminofluorene DNA adduct formation in T24 cells were inhibited and decreased by vitamin C in a dose-dependent manner. The apparent kinetic parameters (apparent values of Km and Vmax) from T24 cells were also determined with and without vitamin C cotreatment. The data also indicated that vitamin C decreased the apparent values of Km and Vmax from T24 cells.

4-Aminobenzoic Acid↗
PubMed2006

G-CSF receptor-binding cyclic peptides designed with artificial amino-acid linkers.

Designing small molecules that mimic the receptor-binding local surface structure of large proteins such as cytokines or growth factors is fascinating and challenging. In this study, we designed cyclic peptides that reproduce the receptor-binding loop structures of G-CSF. We found it is important to select a suitable linker to join two or more discontinuous sequences and both termini of the peptide corresponding to the receptor-binding loop. Structural simulations based on the crystallographic structure of KW-2228, a stable and potent analog of human G-CSF, led us to choose 4-aminobenzoic acid (Abz) as a part of the linker. A combination of 4-Abz with beta-alanine or glycine, and disulfide bridges between cysteins or homocysteins, gave a structure suitable for receptor binding. In this structure, the side-chains of several amino acids important for the interactions with the receptor are protruding from one side of the peptide ring. This artificial peptide showed G-CSF antagonistic activity in a cell proliferation assay.

4-Aminobenzoic Acid↗
PubMed1986

Effects of solvent polarity on the acid dissociation constants of benzoic acids.

The pKa values of benzoic acid, p-methylbenzoic, and p-aminobenzoic acid (PABA) were determined by potentiometric titration in mixtures of 0-0.5 volume fractions of various cosolvents and water. The differences between the aqueous and semiaqueous pKa values were similar for the three solutes at a particular cosolvent-water mixture for most of the cosolvents studied. The largest differences occurred in the dimethyl sulfoxide (Me2SO)-water system, where the pKa changes were larger for PABA than the other two solutes. The data are analyzed by a consideration of both electrostatic and nonelectrostatic medium effects. The electrostatic medium effect was calculated from the Born Equation while any residual pKa change was attributed to nonelectrostatic medium effects. The residual effects were found to correlate well with indexes of solvent hydrogen bond acceptor ability such as HBA and beta-values. These results provide a rationale for the use of two solvent polarity indexes for more accurate estimates of pKa values of weak electrolytes in semiaqueous solvent systems. Analysis of solubility data of the salt and acid forms of PABA and benzoic acid in ethanol-water and Me2SO-water mixtures suggests that the higher activity of the anionic form of PABA in Me2SO-water mixtures is primarily responsible for the large pKa changes observed for that solute.

Benzoates↗
PubMed1987

Central receptor binding and cardiovascular effects of GABA analogues in the cat.

Several structural analogues of GABA were shown to be inhibitors of GABAA receptor binding in membranes from cat cerebral cortex. These compounds were 3-aminopropanesulfonic acid (APS; IC50 = 0.04 microM), imidazoleacetic acid (IMA; IC50 = 0.4 microM), morpholinopropanesulfonic acid (MOPS; IC50 = 1.6 microM), 5-phenylpyrrolepropionic acid (PPP; IC50 = 15 microM), aminoethanethiosulfonic acid (AETS; IC50 = 22 microM), 3-amino-3-phenylpropionic acid (APP; IC50 = 35 microM), meta-aminobenzoic acid (MABA; IC50 = 58 microM) and urocanic acid (UCA; IC50 = 354 microM). The IC50 value for GABA was 0.03 microM. GABA, PPP, AETS, MABA and UCA were previously shown to reduce arterial pressure in the cat after intracerebroventricular infusion. In the present study MOPS (ED50 = 0.26 nmol/kg), APS (ED50 = 4.7 nmol/kg), APP (ED50 = 49 nmol/kg), and IMA (ED50 = 350 nmol/kg) were also found to be able to decrease blood pressure when infused into the fourth ventricle. All nine compounds reduced blood pressure to the same extent, but in some cases their relative potencies (ED50 values) exhibited significant differences. When the IC50 values for receptor binding were plotted against the ED50 values for the cardiovascular effects, no significant correlation emerged. This lack of a correlation does not necessarily imply that the reductions in blood pressure elicited by the drugs are not related to an activation of central GABAA receptors. Instead, it highlights the difficulties that are sometimes encountered in attempting to obtain quantitative measurements after intracerebroventricular infusion.

Animals↗
PubMed2001

The historical aspects of sunscreens.

While there is little literature on the way in which people protected themselves against the sun, evidence from paintings suggest that clothing covering the body, veils and large brim hats were used by ancient Greeks, and that umbrellas existed in ancient Egypt, Mesopotamia, China and India. Veiel in 1887 (Vierteljahresschr. Derm. Syph. 14, 113-116) was able to protect a patient with eczema solare by the use of a tightly woven red veil. In 1889, Widmark (Uber den Einfluss des Lichtes auf die Haut. Hygiea, Festband #3, Samson and Wallin, Stockholm) used acidified quinine sulfate to absorb UVB, apparently because, since quinine fluoresces when irradiated with UVR, he rightly assumed that it would absorb the short wavelengths. In 1891, Hammer (Uber den Enfluss des Lichtes auf die Haut, Ferdinand Enke, Stuttgart) repeated Widmark's experiments and used quinine prepared in lotion or ointment as the first human sunscreen. Various plant extracts had been used at the turn of the century in folk medicine. One of the most effective was a chestnut extract from which aesculin was derived. Unna (Med. Klinik. 1911;7:454-456) developed several glycosides of aesculin,which were introduced as Zeozon and Ultrazeozon. In 1922, Eder and Freund (Wiener. Klin. Wchnschr. 35, 681-684) introduced 2-naphthol-6,8-disulfonic acid salts (Antilux) which were quite effective in both the UVB and UVA region. Over the next 40 years a number of different chemicals were introduced for sunscreen purposes: tannic acid (1925), benzyl salicylate (1931), para-aminobenzoic acid derivatives and 2-phenylimidazole derivatives (1942), anthranilic acid (1950), various cinnamates (1954), chloroquine (1962), benzophenones (1965) and many more since then. The list of chemical useful for sunscreen formulation is now extensive, the US Food and Drug Administration and the European Community have published compendia of approved chemicals and inorganic filters.

Drug Design↗
PubMed2000

Helical-chain copper(II) complexes and a cyclic tetranuclear copper(II) complex with single syn-anti carboxylate bridges and ferromagnetic exchange interactions.

Tridentate Schiff-base carboxylate-containing ligands, derived from the condensation of 2-imidazolecarboxaldehyde with the amino acids beta-alanine (H2L1) and 2-aminobenzoic acid (H2L5) and the condensation of 2-pyridinecarboxaldehyde with beta-alanine (HL2), D,L-3-aminobutyric acid (HL3), and 4-aminobutyric acid (HL4), react with copper(II) perchlorate to give rise to the helical-chain complexes [[Cu(mu-HL1)(H2O)](ClO4)]n (1), [[Cu(mu-L2)(H2O)](ClO4).2H2O]n (2), and [[Cu(mu-L3)(H2O)](ClO4).2H2O]n (3), the tetranuclear complex [[Cu(mu-L4)(H2O)](ClO4)]4 (4), and the mononuclear complex [Cu(HL5)(H2O)](ClO4).1/2H2O (5). The reaction of copper(II) chloride with H2L1 leads not to a syn-anti carboxylate-bridged compound but to the chloride-bridged dinuclear complex [Cu(HL1)(mu-Cl)]2 (6). The structures of these complexes have been solved by X-ray crystallography. In complexes 1-4, roughly square-pyramidal copper(II) ions are sequentially bridged by syn-anti carboxylate groups. Copper(II) ions exhibit CuN2O3 coordination environments with the three donor atoms of the ligand and one oxygen atom belonging to the carboxylate group of an adjacent molecule occupying the basal positions and an oxygen atom (from a water molecule in the case of compounds 1-3 and from a perchlorate anion in 4) coordinated in the apical position. Therefore, carboxylate groups are mutually cis oriented and each syn-anti carboxylate group bridges two copper(II) ions in basal-basal positions with Cu...Cu distances ranging from 4.541 A for 4 to 5.186 A for 2. In complex 5, the water molecule occupies an equatorial position in the distorted octahedral environment of the copper(II) ion and the Cu-O carboxylate distances in axial positions are very large (>2.78 A). Therefore, this complex can be considered as mononuclear. Complex 6 exhibits a dinuclear parallel planar structure with Ci symmetry. Copper(II) ions display a square-pyramidal coordination geometry (tau = 0.06) for the N2OCl2 donor set, where the basal coordination sites are occupied by one of the bridging chlorine atoms and the three donor atoms of the tridentate ligand and the apical site is occupied by the remaining bridging chlorine atom. Magnetic susceptibility measurements indicate that complexes 1-4 exhibit weak ferromagnetic interactions whereas a weak antiferromagnetic coupling has been established for 6. The magnetic behavior can be satisfactorily explained on the basis of the structural data for these and related complexes.

Journal Article↗
PubMed1983

Bactericidal photoproducts in medium containing riboflavin plus aromatic compounds and MnCl2.

Exposure to visible light of growth medium containing riboflavin and indole at low concentrations created photoproducts highly toxic to Salmonella typhimurium and other bacteria. No toxicity was detected in the dark or when either of these two components was present singly. Other aromatic compounds (serotonin, indole-3-acetic acid, indole-3-propionic acid, tryptophan, tyrosine, phenylalanine, and p-aminobenzoic acid) tested in place of indole produced various degrees of toxicity. The presence of MnCl2 significantly enhanced the toxicity. Addition of catalase eliminated the toxicity, indicating an important role for hydrogen peroxide.

Bacteria↗
PubMed1992

[Transport of drugs through human erythrocyte membrane. Structure-activity relationship of benzoic acid and its derivatives between membrane transport and partition coefficient].

The transport properties of benzoic acid and its eighteen derivatives such as o-, m- or p-hydroxybenzoic acid (o-, m- or p-HBA), aminobenzoic acid (o-, m- or p-ABA), toluic acid (o-, m- or p-TA), fluorobenzoic acid (o-, m- or p-FBA), chlorobenzoic acid (o-, m- or p-CBA) and bromobenzoic acid (o-, m- or p-BBA) through human erythrocyte membranes were examined. The drugs having a hydrophilic ortho-substituent and those having a hydrophobic meta- or para-substituent showed higher transport. The ratio of free drugs in erythrocytes, fuR, did not relate to the partition coefficient (P). However, fuM (the ratio of free drugs in the plasma) and Kp (the ratio of partition between erythrocytes and plasma) related to the P: fuM = -0.3128 x log P + 0.9727 (R2 = 0.8722***), Kp = -0.2558 x log P + 0.8642 (R2 = 0.8413***). In p-nitrophenol-glycosides, the fuM and the Kp that were predicted from these equations were compatible with the experimental results. It was suggested from these results that the fuM and the Kp may be predictable from the P.

Benzoates↗
PubMed1982

Vitamin and nitrogen base requirements for Listeria monocytogenes and haemolysin production.

A complete chemically defined medium is described for the growth of different serovars of Listeria monocytogenes. The medium supported rapid, luxuriant and transferable growth. At the same time haemolysin production was induced to the same extent as in tryptose phosphate broth. Riboflavin and calcium-pantothenate were essential for the growth of all six strains tested. Biotin, pyridoxal-hydrochloride and p-aminobenzoic acid were either essential or stimulatory to all strains. Most strains did not require folic acid, thiamin, nicotinic acid and inositol, but they were stimulatory for some strains. Adenine was essential for two strains (NCTC 7973, 5214 m) while cytosine exhibited an inhibitory effect on the growth of all the strains.

4-Aminobenzoic Acid↗
PubMed1987

Two indirect tests of exocrine pancreatic function evaluated.

We describe and evaluate two frequently used indirect methods for assessing exocrine pancreatic function: the N-benzoyl-L-tyrosyl-p-aminobenzoic acid test (NBT-PABA) and the pancreolauryl test. In both procedures, the patient is orally administered a substrate that is metabolized into two or more products by pancreatic enzymes. At least one of the reaction products is absorbed from the gut, conjugated, and excreted in urine, where it can be measured. Both tests can be used in the diagnosis and monitoring of cystic fibrosis, chronic pancreatitis, and pancreatic carcinoma, and in monitoring pancreatic enzyme replacement therapy to determine the appropriate dose. In comparison with the NBT-PABA procedure, the pancreolauryl test seems to have better specificity and sensitivity, undergoes almost no interference from other drugs or serum compounds, requires no complex hydrolytic conditions, and is independent of renal function.

4-Aminobenzoic Acid↗
PubMed2003

Promoter strength of folic acid synthesis genes affects sulfa drug resistance in Saccharomyces cerevisiae.

The enzyme dihydropteroate synthase (DHPS) is an important target for sulfa drugs in both prokaryotic and eukaryotic microbes. However, the understanding of DHPS function and the action of antifolates in eukaryotes has been limited due to technical difficulties and the complexity of DHPS being a part of a bifunctional or trifunctional protein that comprises the upstream enzymes involved in folic acid synthesis (FAS). Here, yeast strains have been constructed to study the effects of FOL1 expression on growth and sulfa drug resistance. A DHPS knockout yeast strain was complemented by yeast vectors expressing the FOL1 gene under the control of promoters of different strengths. An inverse relationship was observed between the growth rate of the strains and FOL1 expression levels. The use of stronger promoters to drive FOL1 expression led to increased sulfamethoxazole resistance when para-aminobenzoic acid (pABA) levels were elevated. However, high FOL1 expression levels resulted in increased susceptibility to sulfamethoxazole in pABA free media. These data suggest that up-regulation of FOL1 expression can lead to sulfa drug resistance in Saccharomyces cerevisiae.

4-Aminobenzoic Acid↗
PubMed1998

Chronic pancreatitis: functional testing.

This article reviews the evolution of functional testing of the pancreas in Japan for the diagnosis and treatment of chronic pancreatitis (CP), contrasting the pre- with the postsecretin test (S test) era. In the pre-S test era, the diagnosis was based on symptoms, clinical findings, fasting serum diastase levels, and the vagostigmin- and ether-stimulation test unless morphologic evidence was available. The S test and CCK-pancreozymin (PZ) test (PS test) were introduced into Japan around 1963 and have been used as the gold standard of the exocrine pancreatic-function test. Through a series of attempts at standardization in 1971, 1985, and 1987, the method was standardized to collect duodenal juice for 60 min through a double- or triple-lumen tube after a bolus or during a continuous i.v. injection of secretin (100 U). The S test, however, is an invasive and cumbersome procedure. As a result, N-benzoyl-L-tyrosal-p-aminobenzoic acid (BT-PABA) testing and fecal chymotrypsin testing were introduced into Japan in the middle and late 1970s, respectively. Although simple and noninvasive, these two methods were found have lower sensitivity and specificity than the conventional S test. These two methods, therefore, are presently used more often for monitoring the course of disease and therapeutic effects. Additionally, the glucose tolerance test can be performed to detect endocrine pancreatic insufficiency.

4-Aminobenzoic Acid↗
PubMed1985

In vitro susceptibility of Plasmodium falciparum collected from pyrimethamine-sulfadoxine sensitive and resistant areas in Thailand.

Seventy Plasmodium falciparum isolates, collected from two geographically separate areas of Thailand, were tested for their in vitro responses to pyrimethamine, sulfadoxine, and a combination of these two drugs. The effects of pyrimethamine and pyrimethamine-sulfadoxine combinations against P. falciparum isolates were found to be significantly greater in a northern area where the combined drug was an effective therapeutic agent than in a south-eastern area, near the Thai-Kampuchean border, where the combined drug was no longer effective. However, the actions of sulfadoxine against parasites obtained from the two areas were not significantly different. There was no significant difference between the mean values of plasma 4-aminobenzoic acid (PABA) in falciparum malaria patients and in healthy controls. The test for PABA determinations used in this study gave positive readings with both PABA and sulfadoxine.

4-Aminobenzoic Acid↗
PubMed1990

Sunscreening agent intolerance: contact and photocontact sensitization and contact urticaria.

Reports in the literature of sensitization associated with many commonly used sunscreening agents including p-aminobenzoic acid (PABA), PABA derivatives, anthranilates, salicylates, cinnamates, benzophenones, and dibenzoylmethane derivatives are reviewed. Several of these case reports involved subjects with various photodermatoses, implicating enhanced sensitivity of the patient's skin to both light and chemicals. Despite the widespread use of sunscreens, the small number of published reports of contact and photocontact sensitization to these agents suggests that either such sensitization is less than commonly perceived or is underreported. Establishment of a registry for reporting adverse effects associated with sunscreening agents would help to characterize the incidence of sensitization.

4-Aminobenzoic Acid↗
PubMed1999

Assessment of exocrine pancreatic dysfunction in chronic pancreatitis.

The clinical diagnosis of chronic pancreatitis is usually based on imaging studies, pancreatic function tests, and the presence of characteristic clinical features. In Japan, diagnostic criteria for chronic pancreatitis were established in 1995. The secretin test (a duodenal intubation test) and the combination of noninvasive tests, N-benzoyl-L-tyrosyl-p-aminobenzoic acid (BT-PABA) and fecal chymotrypsin (FCT), have been recommended for evaluating exocrine pancreatic function in patients with chronic pancreatitis. In the present study, the diagnostic value of these two noninvasive tests was compared to the secretin test. Although noninvasive tests are less sensitive and specific for determining exocrine pancreatic dysfunction than the secretin test, greater reliability for diagnosing chronic pancreatitis can be obtained by performing the BT-PABA and FCT simultaneously. Assessment of exocrine pancreatic function is important not only to diagnose chronic pancreatitis but also to decide a treatment method with pancreatic enzyme preparation.

4-Aminobenzoic Acid↗
PubMed1987

The cholesteryl octanoate breath test: a new procedure for detection of pancreatic insufficiency in the rat.

A breath test for the detection of pancreatic insufficiency was developed and tested in rats. The test features the hydrophobic molecule cholesteryl-1-14C-octanoate, which liberates 14C-octanoic acid when hydrolyzed by carboxyl ester lipase (cholesterol esterase). The 14C-octanoate is absorbed passively and rapidly metabolized to 14CO2, which is excreted in expired air. The compound was administered as an emulsion of cholesteryl octanoate, triglyceride, and lecithin to rats with mild pancreatic insufficiency induced by injecting the pancreatic duct with zein. The animals had exocrine pancreatic hypofunction based on the enzyme content of pancreas at autopsy. Amylase was reduced by 97.1 +/- 1.4%, whereas chymotrypsin was reduced by 73 +/- 14%. The p-aminobenzoic acid test was abnormal at 1 wk (21.68 +/- 8.4%), but become normal at 3 months (72.08 +/- 5.8%) after zein injection. Despite this, the animals gained weight and absorbed fat normally. The 14CO2 excretion rate in the 110-min interval after feeding was significantly reduced to 60% of sham-operated animals. Peak 14CO2 collections 20 min after feeding were reduced by 75 +/- 11%. 14CO2 output was completely normalized by administration of pancreatin prior to the test meal. The results suggest that a sensitive, noninvasive method for detecting deficiency of pancreatic carboxyl ester lipase (cholesterol esterase) secretion in the rat has been developed.

4-Aminobenzoic Acid↗
PubMed1989

Phosphanilic acid inhibits dihydropteroate synthase.

Intact cells of Pseudomonas aeruginosa were more susceptible to phosphanilic acid (PA) than cells of Escherichia coli. In cell extracts, the dihydropteroate synthases of P. aeruginosa and E. coli were about equally susceptible to inhibition by PA. These results suggest that cells of P. aeruginosa are more permeable to PA than cells of E. coli. Although a weak inhibitor, PA acted on dihydropteroate synthase in the same manner as the sulfonamides with which PA is structurally related. Inhibition of E. coli by PA in a basal salts-glucose medium was prevented by p-aminobenzoic acid (pABA). However, pABA did not protect P. aeruginosa from PA under these conditions, possibly because pABA itself exhibited an inhibitory effect. PA also appeared to have a second mode of action. The mechanism was not elucidated.

4-Aminobenzoic Acid↗