P-Amino-benzoic acid

One of the classic examples in this series is the solubilization of p-amino-benzoic acid (PABA) by caffeine [51], for which the essential data are summarized in Fig. 9. The solubility of PABA in the absence of caffeine was reported to be 6.2 mg/ml, which could be increased to 7.7 mg/ml by the addition of at least 2 mg/ml of caffeine. The linear increase in PABA concentration as a function of caffeine concentration is consistent with the formation of a 1 1 stoichiometric complex. From the data obtained in the linear concentration region, a value of 48 L/mol was calculated for K. Further increases in the caffeine concentration up to 6 mg/ml had no effect on the PABA solubility. However, larger concentrations of caffeine led to a reduction in the dissolved... 

Figure 8.6 Competitive inhibition. Sulphonamide drugs compete with p-amino-benzoic acid, which is an essential growth factor for many bacteria.

In acute and chronic urinary tract infection, the combination of trimethoprim and sulfamethoxazole (Bactrim, Septra) exerts a truly synergistic effect on bacteria. The sulfonamide inhibits the utilization of p-amino-benzoic acid in the synthesis of folic acid (Figure 2.3), whereas trimethoprim, by inhibiting dihydrofolic acid reductase, blocks the conversion of dihydrofolic acid to tetrahydrofolic acid, which is essential to bacteria in the denovo synthesis of purines, pyrimidines, and certain amino acids. Because mammalian organisms do not synthesize folic acid and therefore need it as a vitamin in their daily diets, trimethoprim-sulfamethoxazole does not interfere with the metabolism of mammalian cells. 

In a similar manner the copper salt of p-amino-benzoic acid gives benzidine —... 

Alva K, Marx KA, Kumar J et al (1996) Biochemical synthesis of water soluble polyanilines poly(p-Amino Benzoic Acid). Macromol Rapid Commun 17 859-863... 

Amino acids (p-amino benzoic acid) Undeconoic acid Organic liquid membranes R Uegla and Zanoaga (1989)... 

C17H27N02 amyidimethyl-p-amino benzoic acid 58817-05-3 598.15 53.390 2 30365 C17H36S ethyl pentadecyl sulfide 64919-20-6 611.00 65.548 2... 

A closer look at these events reveals that bacteria synthesize folic acid using several enzymes, including one called dihydropteroate synthetase, which catalyzes the attachment of p-aminobenzoic acid to a pteridine ring system. When sulfanilamide is present it competes with the p-amino-benzoic acid (note the structural similarity) for the active site on the enzyme. This activity makes it a competitive inhibitor. Once this site is occupied on the enzyme, folic acid synthesis stops and bacterial growth stops. Folic acid can also be synthesized in the laboratory. ... 

Various preparations of antisera to atropine have been reported. A racemic hemisuccinate ester was prepared and conjugated to bovine serum albumin by the carbodiimide technique. Antisera formed to the original immunogen selectively bound the R isomer (34), but a later antiserum prepared by this approach was reported to bind both R and S forms with "equal efficiency" (35). R, S-atropine was treated with diazotized p-amino-benzoic acid, and the resulting compound (which was not further characterized) was used for conjugation to bovine serum albumin by means of a carbodiimide-mediated reaction. Antisera resulting from use of this material were quite selective for the R isomer, with a cross-reaction of only about 2% for the S isomer (36). Virtanen et al. followed this procedure with S-atropine. Their antiserum bound equally to S- and R,S-atropine, as measured by displacement of tritium-labeled R,S-atropine (37). In another study (31), both racemic atropine and the S isomer were coupled to human serum albumin by the technique of Wurtzburger et al. (36), Antisera were obtained that were selective for both the R and S isomers (33). 

Alternately, specific stabilizers can also be added into the formulations. The protection against aldehydes, whether present initially in the formulation or released in situ, can be provided by the addition of aldehyde scavengers like, lysine, phenylamine, glutamine, hydroxylamine hydrochloride, p-amino benzoic acid, glycine, etc. " The in situ release of aldehydes as a consequence to degradation of the contents can... 

The antibacterial activity—and toxicity—of a sulfanilamide stems from a rather simple fact enzymes in the bacteria (and in the patients) confuse it for p-amino-benzoic acid, which is an essential metabolite. In what is known as metabolite antagonism the sulfanilamide competes with p-aminobenzoic acid for reactive... 

When DHA was allowed to react with p-amino-benzoic acid and hydrochloric acid, 6-carboxy-2-hydroxy-4-hydroxymethyIquinoline (283) was obtained (64AK121). 

Keywords /p-hydroxybenzaldehyde, p-amino benzoic acid, condensation, large scale, ball-mill, waste-free, solid-solid reaction, azomethine... 

Extension of the isomeric trimellitimide of p-amino benzoic acid with a hydroxy alkyl thiophenol (p-HO-Ph-S-(CH2)n-OH) does yield nematic PEIs (5) [19]. 

Kricheldorf has reported the synthesis of lyotropic poly(amide-imide)s and poly(benzoxazole-amide)s. These were prepared by the polycondensation of N,N-bis(trimethylsilyl)-p-phenylenediamine or N,AT -bis(trimethylsilyl)-3,3 -dim-ethylbenzidine with the diacyl chloride of trimellitimide of p-aminobenzoic acid, or the imide formed from p-amino benzoic acid and terephthalic acid. Lyotropic behaviour was observed in cone, sulphuric acid solution [38]. A series of thermotropic poly(imide-amide)s was prepared based on trimellitimides formed from trimellitic anhydride and an a, -bis(4-aminophenoxy) alkane with carbon chain lengths 9-12. Melting points were in the range 250-300 °C. They formed smectic A phases and tended to degrade around the isotropisation temperatures (around 350 °C). Pendant methyl groups or occupied meta- groups tended to prevent mesophase formation [39]. Novel LC poly(imide-amides) have also been synthesised from new diamine spacers derived from linear diaminoalkanes and 4-nitrophthalic anhydride. A smectic and nematic phase were observed when 4,4 -biphenyl dicarboxylic acid was used as co-monomer [40]. 

Benzophenones camphor derivatives p-amino benzoic acid vanillin... 

Kicska, G. A., Ting, L. M., Schramm, V. L., and Kim, K. (2003). Effect of dietary p-amino-benzoic acid on murine Plasmodium yoelii infection. J. Infect. Dis. 188,1776-1781. 

PEI with 5-95 wt% LCP and p-amino benzoic acid or pyromellitic anhydride compatibilized moldable blends, useful as matrix for composites. Roemer Schleicher, 1993... 

The procaine base is obtained by the dehydration of molecule of p-amino benzoic acid and 2-hydroxy triethyl amine, which on treatment with hydrochloric acid yields the official compound. Method-Ill From Ethylene Chlorohydrin ... 

---