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Para-aminobenzoic acid

4-Aminobenzoic acid
Skeletal formula of PABA
Ball-and-stick model of the PABA molecule
Names
Preferred IUPAC name
4-Aminobenzoic acid
Other names
para-Aminobenzoic acid
p-Aminobenzoic acid
PABA
Vitamin B10
Vitamin Bx
Bacterial vitamin H1
Identifiers
3D model (Jmol)
ChEBI
ChemSpider
DrugBank
ECHA InfoCard 100.005.231
KEGG
PubChem CID
UNII
Properties
C7H7NO2
Molar mass 137.14 g·mol−1
Appearance White-grey crystals
Density 1.374 g/mL
Melting point 187 to 189 °C (369 to 372 °F; 460 to 462 K)
Boiling point 340 °C (644 °F; 613 K)
1 g/170 mL (25 °C)
1 g/90 mL (90 °C)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
YesY  (what is YesYN ?)
Infobox references

4-Aminobenzoic acid (also known as para-aminobenzoic acid or PABA because the number 4 carbon in the benzene ring is also known as the para position) is an organic compound with the formula H2NC6H4CO2H. PABA is a white solid, although commercial samples can appear gray. It is slightly soluble in water. It consists of a benzene ring substituted with amino and a carboxyl groups. The compound occurs naturally.

In industry, PABA is prepared mainly by two routes:

Food sources of PABA include liver, brewer's yeast (and unfiltered beer), kidney, molasses, mushrooms, and whole grains.

PABA is an intermediate in the synthesis of folate by bacteria, plants, and fungi. Many bacteria, including those found in the human intestinal tract such as E. coli, generate PABA from chorismate by the combined action of the enzymes 4-amino-4-deoxychorismate synthase and 4-amino-4-deoxychorismate lyase. Plants produce PABA in their chloroplasts, and store it as a glucose ester (pABA-Glc) in their tissues. Humans lack the enzymes to convert PABA to folate, so require folate from dietary sources such as green leafy vegetables. In humans, PABA is considered nonessential and, although it has been referred to historically as "vitamin Bx", is no longer recognized as a vitamin, because most people have colon bacteria that generate PABA.

Sulfonamide drugs are structurally similar to PABA, and their antibacterial activity is due to their ability to interfere with the conversion of PABA to folate by the enzyme dihydropteroate synthetase. Thus, bacterial growth is limited through folate deficiency.

The potassium salt is used as a drug against fibrotic skin disorders, such as Peyronie's disease, under the trade name Potaba. PABA is also occasionally used in pill form by sufferers of irritable bowel syndrome to treat its associated gastrointestinal symptoms, and in nutritional epidemiological studies to assess the completeness of 24-hour urine collection for the determination of urinary sodium, potassium, or nitrogen levels.


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Wikipedia

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