Paraaminobenzoic acid

Author: Prof. Dr. med. Peter Altmeyer

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Last updated on: 29.10.2020

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4-aminobenzoic acid; acidum para-aminobenzoicum; CAS number: 150-13-0; PAB; PABA; PABA (INCI); p-Aminobenzoic acid; para-Aminobenzoic acid; p-Carboxyaniline; vitamin B10; vitamin B 10

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Paraaminobenzoic acid, PABA for short, is an aromatic hydrocarbon compound with the molecular formula C7H7NO2. It is easily soluble in water, ether and ethanol. The melting point is 186-190 °C.

Paraaminobenzoic acid was formerly also called vitamin H (see biotin below). Paraaminobenzoic acid is a weak organic acid which is present at room temperature as an odourless, slightly yellowish solid which turns brown under the influence of light.

General information
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The p-aminobenzoic acid serves as a food supplement under the name PABA. It is the starting substance for e.g. local anaesthetics (benzocaine, cycloform, procaine).

In cosmetics p-aminobenzoic acid serves as UVB absorber (see below UV filter).

In technical areas the substance is the starting product for azo dyes.

The absorption via the skin is low. Orally absorbed PABA is metabolized by the organism to paraaminohippuric acid.

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PABA is slightly toxic, but not carcinogenic.

PABA is an essential growth agent for bacteria in the synthesis of folic acid. Since this process can be inhibited by sulfonamides (structural analogy to PABA), this leads to an inhibition of bacterial growth.

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  1. Von Bruchhausen et al (1991) Hager's Handbook of Pharmaceutical Practice. Springer Publishing House Berlin Heidelberg New York p.184

Outgoing links (2)

Biotin; Light stabilizers;


Last updated on: 29.10.2020