Propyl Gallate

Synonyms: E310; gallic acid propyl ester; n-propyl gallate; Progallin P; propyl 3,4,5-trihydroxybenzoate; propylis gallas; Tenox PG.

Description: Propyl gallate is a white, odorless or almost odorless crystalline powder, with a bitter astringent taste that is not normally noticeable at the concentrations employed as an antioxidant.

Chemical Name: 3,4,5-Trihydroxybenzoic acid propyl ester

Antioxidant

• Propyl gallate has become widely used as an antioxidant in cosmetics, perfumes, foods, and pharmaceuticals since its use in preventing autoxidation of oils was first described in 1943.

• It is primarily used, in concentrations up to 0.1% w/v, to prevent the rancidity of oils and fats; it may also be used at concentrations of 0.002% w/v to prevent peroxide formation in ether, and at 0.01% w/v to prevent the oxidation of paraldehyde.

• Synergistic effects with other antioxidants such as butylated hydroxyanisole and butylated hydroxytoluene have been reported.

• Propyl gallate is also said to possess some antimicrobial properties.

• Studies have shown that, when added to powder blends containing ketorolac, propyl gallate significantly increases the drug stability in the preparation.

• Other alkyl gallates are also used as antioxidants and have approximately equivalent antioxidant properties when used in equimolar concentration; however, solubilities vary.

• Propyl gallate has also been investigated for its therapeutic properties, mainly in animal studies.

The alkyl gallates are incompatible with metals, e.g. sodium, potassium, and iron, forming intensely colored complexes. Complex formation may be prevented, under some circumstances, by the addition of a sequestering agent, typically citric acid. Propyl gallate may also react with oxidizing materials.

It has been reported, following animal studies, that propyl gallate has a strong contact sensitization potential. Propyl gallate has also produced cytogenic effects in CHO-K1 cells. However, despite this, there have been few reports of adverse reactions to propyl gallate. Those that have been described include contact dermatitis, allergic contact dermatitis, and methemoglobinemia in neonates.

Observe normal precautions appropriate to the circumstances and quantity of material handled. Eye protection and gloves are recommended. When heated to decomposition, propyl gallate may emit toxic fumes and smoke.

Dodecyl gallate; ethyl gallate; octyl gallate.