International Numbering System (INS) for Food Additives: 310
Food additives Europe numbers: E310
Functional Category
Antioxidant.
Applications in Pharmaceutical Formulation
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.(1,2) It is primarily used, in concentrations up to 0.1% w/v, to prevent the rancidity of oils and fats;(3) 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 P Propyl Gallate 587 hydroxytoluene have been reported. Propyl gallate is also said to possess some antimicrobial properties; see Section 10. Studies have shown that, when added to powder blends containing ketorolac, propyl gallate significantly increases the drug stability in the preparation.(4) Other alkyl gallates are also used as antioxidants and have approximately equivalent antioxidant properties when used in equimolar concentration; however, solubilities vary; see Section 17. Propyl gallate has also been investigated for its therapeutic properties, mainly in animal studies
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.
Stability and Storage Conditions
Propyl gallate is unstable at high temperatures and is rapidly destroyed in oils that are used for frying purposes. The bulk material should be stored in a well-closed, nonmetallic container, protected from light, in a cool, dry place.
Incompatibilities
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.
Safety
It has been reported, following animal studies, that propyl gallate has a strong contact sensitization potential.(7) Propyl gallate has also produced cytogenic effects in CHO-K1 cells.(8) However, despite this, there have been few reports of adverse reactions to propyl gallate.(9) Those that have been described include contact dermatitis, allergic contact dermatitis,(9–13) and methemoglobinemia in neonates.(14) Wavelength/nm 1100 1300 1500 1700 1900 2100 2300 2500 2303 2268 2143 2014 2081 1955 1653 1463 1999 2033 2289 −2.2 1.5 0.0 1000 × [2nd deriv. log(1/R)] –0.2 0.6 log(1/R) Figure 1: Near-infrared spectrum of propyl gallate measured by reflectance. P 588 Propyl Gallate The WHO has set an estimated acceptable daily intake for propyl gallate at up to 1.4 mg/kg body-weight.(15) LD50 (cat, oral): 0.4 g/kg(16) LD50 (mouse, oral): 1.7 g/kg LD50 (rat, oral): 2.1 g/kg LD50 (rat, IP): 0.38 g/kg