Propyl gallate

Description

Propyl gallate is an antioxidant. It protects against oxidation by hydrogen peroxide and oxygen free radicals. It appears as a white to creamy-white crystalline odorless solid.

Propyl gallate (PG) is a white to nearly white odorless crystalline powder that has slightly bitter taste and darkens in the presence of iron salts. It is an irritant that can cause skin dryness, dermatitis, and sensitization. Inhalation may cause chemical pneumonia

Production

Propyl gallate does not occur naturally, and is prepared either from reactions with gallic acid and 1-propanol, or by enzyme catalysis of tannic acid. Syntheses with gallic acid have been the most prominent methods of production, and include Steglich esterification with N,N'-diisopropylcarbodiimide and 4-dimethylaminopyridine, anhydrous addition of thionyl chloride, and Fischer esterification with various catalysts.

Uses

Propyl gallate is used to protect oils and fats in products from oxidation; it is used in foods, cosmetics, hair products, adhesives, biodiesel, and lubricants. It is often used interchangeably with octyl gallate and dodecyl gallate in these applications.

Propyl gallate is an antioxidant that neutralizes free radicals, which are unstable molecules that can damage cells, proteins, and DNA. It is used as a triplet state quencher and an antioxidant in fluorescence microscopy.

Biological effects

A 1993 study in fat rodents found little or no effect on carcinogenesis by propyl gallate.

A 2009 study found that propyl gallate acts as an estrogen antagonist.

Propyl gallate has many biological activities, including:

• Enzyme inhibition
• Antimicrobial activity
• Inhibition of nitrosamine formation
• Anticarcinogenesis
• Antitumorigenesis
• Anesthesia
• Anti-nociceptive
• Inhibition of biosynthetic processes
• Ionizing/ultraviolet (UV) radiation protection

Safety

• Propyl gallate is an irritant to the skin and eyes, and it can be inhaled. Some studies have reported that propyl gallate is toxic, while others have reported therapeutic benefits.
• The FDA recognizes propyl gallate as being generally safe, but in other countries, it's either been used on a very limited basis or completely banned. This is because some preliminary studies have suggested that propyl gallate may cause cancer (in several organs) in rats and be an endocrine disrupter.

References

References

1. (2007). "Final Report on the Amended Safety Assessment of Propyl Gallate". International Journal of Toxicology.
2. (2015-09-01). "Thermal and spectroscopic studies of the antioxidant food additive propyl gallate". Food Chemistry.
3. EFSA Panel on Food additives and Nutrient Sources added to Food (ANS). (2014). "Scientific Opinion on the re-evaluation of propyl gallate (E 310) as a food additive". EFSA Journal.
4. (2012). "Synthesis of propyl gallate from tannic acid catalyzed by tannase from Aspergillus oryzae: Process optimization of transesterification in anhydrous media". Journal of Molecular Catalysis.
5. (2021-04-12). "Propyl Gallate". Molbank.
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8. Hirose, Masao, ''et al.''. "Modification of carcinogenesis by α-tocopherol, t-butylhydro-quinone, propyl gallate and butylated hydroxytoluene in a rat multi-organ carcinogenesis model." ''Carcinogenesis'' 14.11 (1993): 2359-2364.
9. (2009). "Identification of Xenoestrogens in Food Additives by an Integrated in Silico and in Vitro Approach". Chem. Res. Toxicol..
10. "5 Preservatives to Avoid {{!}} MDVIP".