Image for Para-aminobenzoic acid (PABA)
Para-aminobenzoic acid (PABA)

Synonyms/Common Names/Related Substances:

  • 4-aminobenzoic acid, 4-aminobenzoic acid hydrazide, ABAH, Aktipol®, aminobenzoate potassium, BAB, BT-PABA, butyl aminobenzoate, cyclic amino acid, disulphate ester of ursodeoxycholyl-p-aminobenzoic acid, ester oxybenzone, ethyl p-aminobenzoate, ethyl-4-N,N-dimethylaminobenzoate, ethyl dihydroxypropylaminobenzoate, glyceryl paraaminobenzoate, isobutyl p-aminobenzoate, KPAB, K-para-aminobenzoate, monoglyceryl para-aminobenzoate, n-benzyol-l-tyrosyl-p-aminobenzoic acid, NBT-PABA, n-butyl-p-aminobenzoate, n-diethyl-methyl-ammonium ethyl bromide-p-[2(n-octyloxy)-benzoyl-]aminobenzoate, N,N-dimethyl-2-ethylhexyl para-aminobenzoate, octyl dimethyl PABA, Pabafil®, PABA-UDCA, padimate O, PAMBA, p-acetamidobenzoic acid, p-acetamidohippuric acid, p-aminobenzoic acid, p-aminohippuric acid, para-aminobenzoate, para-aminobenzoate potassium, para aminobenzoic acid, paraaminobenzoic acid, para-aminobenzoic acid, para-aminomethylbenzoic acid, PEG-25 PABAs, Peptide-PABA, Photoplex, POTABA®, potassium para-aminobenzoate, synthetic peptide Bz-Ty PABA, 2,3,5,6-tetrafluorophenyl n-(s-benzoylthioacetyl)glycylglycyl-p-aminobenzoate, UDCA-PABA, ursodeoxycholic acid-p-aminobenzoic acid, vitamin Bx, vitamin H.
  • Combination product examples: Cetacaine®, PrimorineTM, RelamineTM, Total Eclipse AB®, Zycose™

Clinical Bottom Line/Effectiveness

Brief Background:

  • Para-aminobenzoic acid (PABA) is a naturally occurring non-protein amino acid. It was previously thought to be a B vitamin, but it is now known that it is neither a vitamin, nor an essential nutrient in humans. Structurally, PABA consists of a benzene ring substituted with an amino and a carboxyl group. Although dietary deficiency in humans is not an issue, PABA is found in foods such as liver, kidney, wheat germ, bran, and yogurt.
  • PABA is most well-known for its topical use as a component of some sunscreen products, since it has the ability to absorb light in the ultraviolet B spectrum, specifically 280-320nm (1;2). Through substitution of its amino and carboxyl groups, PABA has also functioned as a structural moiety for many drugs with a wide range of functions, including antiarrhythmic, antibacterial, anticonvulsant, antiemetic, antineoplastic, antipsychotic, gastrokinetic, local anesthetic, migraine prophylactic, and neuroleptic (3).
  • PABA functions as an intermediate in folic acid synthesis in bacteria. Sulfonamide antibiotics inhibit the conversion of PABA to folic acid, interfering with nucleic acid synthesis in sensitive micro-organisms. Since humans acquire folic acid from the diet and do not have the capability of synthesizing folic acid from PABA, sulfonamides do not affect human cells.
  • PABA has also been used as a urinary excretion marker for non-invasive evaluation of pancreatic exocrine function in the "PABA test" (4;5;6;7;8;9;10;11;12;13;14;15;16;17;18;19;20;21;22;23;24;25;26;27;28;29;30;31;32;33;34;35;36;37;38;39;40). In this test, N-benzoyl-L-tyrosyl-PABA is administered orally, and this peptide is cleaved in the small intestine by chymotrypsin. PABA is then passively absorbed, and renal excretion of PABA is measured as a reflection of trypsin activity. Although the "PABA test" is not adequately sensitive to identify patients with mild pancreatic insufficiency (41), its reproducibility may make it useful in evaluating the efficacy and compliance of replacement therapy in patients with known pancreatic insufficiency (42). The use of PABA as a urinary excretion marker has also been helpful in validating completeness of 24-hour urine samples (7;43;44), as a biomarker of isoflavone exposure over time (45), and in the "PABA-UDCA test" for bacterial overgrowth (46). Measurement of conjugated serum metabolites of PABA, particularly paraacetamidohippuric acid (PAAHA) and paraaminohippuric acid (PAHA), following an oral loading dose, can be useful in assessing liver function, as well as prognosis of patients with acute liver failure (47;48;49). PABA has also been used as a substrate for mononuclear lukocytes from cystic fibrosis patients (50), as a marker for pancreatic insufficiency (51)
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Dosing/Toxicology

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Precautions/Contraindications

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Interactions

Most herbs and supplements have not been thoroughly tested for interactions with other herbs, supplements, drugs, or foods. The interactions listed below are based on reports in scientific publications, laboratory experiments, or traditional use. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy.

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Mechanism of Action

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History

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Evidence Table

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Evidence Discussion

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Products Studied

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References

Natural Standard developed the above evidence-based information based on a thorough systematic review of the available scientific articles. For comprehensive information about alternative and complementary therapies on the professional level, go to www.naturalstandard.com. Selected references are listed below.

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The information in this monograph is intended for informational purposes only, and is meant to help users better understand health concerns. Information is based on review of scientific research data, historical practice patterns, and clinical experience. This information should not be interpreted as specific medical advice. Users should consult with a qualified healthcare provider for specific questions regarding therapies, diagnosis and/or health conditions, prior to making therapeutic decisions.