P-aminobenzoic acid

4-Aminobenzoic acid

Names
Preferred IUPAC name 4-Aminobenzoic acid
Other names para-Aminobenzoic acid p-Aminobenzoic acid PABA Vitamin B10 Vitamin Bx Bacterial vitamin H1
Identifiers
CAS Number	150-13-0 Y
3D model (Jmol)	Interactive image
ChEBI	CHEBI:30753 Y
ChEMBL	ChEMBL542 Y
ChemSpider	953 Y
DrugBank	DB02362 Y
ECHA InfoCard	100.005.231
KEGG	D02456 Y
PubChem	978
UNII	TL2TJE8QTX Y
InChI InChI=1S/C7H7NO2/c8-6-3-1-5(2-4-6)7(9)10/h1-4H,8H2,(H,9,10) Y Key: ALYNCZNDIQEVRV-UHFFFAOYSA-N Y InChI=1/C7H7NO2/c8-6-3-1-5(2-4-6)7(9)10/h1-4H,8H2,(H,9,10) Key: ALYNCZNDIQEVRV-UHFFFAOYAH
SMILES O=C(O)c1ccc(N)cc1
Properties
Chemical formula	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)
Solubility in water	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).
Y  (what is YN ?)
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 B_x", 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.