Propyl gallate explained

Propyl gallate, or propyl 3,4,5-trihydroxybenzoate, is an ester formed by the condensation of gallic acid and propanol. Since 1948, this antioxidant has been added to foods containing oils and fats to prevent oxidation.^[1] As a food additive, it is used under the E number E310.

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.^{[2] [3]}

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.^[4] 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.^[5]

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.^[6] It is often used interchangeably with octyl gallate and dodecyl gallate in these applications.

It is used as a triplet state quencher and an antioxidant in fluorescence microscopy.^[7]

Biological effects

A 1993 study in fat rodents found little or no effect on carcinogenesis by propyl gallate.^[8]

A 2009 study found that propyl gallate acts as an estrogen antagonist.^[9]

References

1. 2007 . Final Report on the Amended Safety Assessment of Propyl Gallate . International Journal of Toxicology . 26 . suppl. 3 . 89–118 . 10.1080/10915810701663176 . 18080874 . 39562131 . 1091-5818 .
2. Gálico . D. A. . Nova . C. V. . Guerra . R. B. . Bannach . G. . 2015-09-01 . Thermal and spectroscopic studies of the antioxidant food additive propyl gallate . Food Chemistry . 182 . 89–94 . 10.1016/j.foodchem.2015.02.129 . 0308-8146.
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 . 12 . 4 . 10.2903/j.efsa.2014.3642.
4. Nie . Guangjun . Liu . Hui . Chen . Zhen . Wang . Peng . Zhao . Genhai . Zheng . Zhiming . 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 . 82 . 102–108 . 10.1016/j.molcatb.2012.06.003 . 1381-1177.
5. Nguyen . Van Hai . Le . Minh Ngoc . Nguyen . Hoa Binh . Ha . Kieu Oanh . Pham . Thai Ha Van . Nguyen . Thi Hong . Dao . Nguyet Suong Huyen . Nguyen . Van Giang . Nguyen . Dinh Luyen . Trinh . Nguyen Trieu . 2021-04-12 . Propyl Gallate . Molbank . en . 2021 . 2 . M1201 . 10.3390/M1201 . 1422-8599 . free .
6. Hosseinzadeh-Bandbafha . Homa . Kumar . Dipesh . Singh . Bhaskar . Shahbeig . Hossein . Lam . Su Shiung . Aghbashlo . Mortaza . Tabatabaei . Meisam . 2022-07-01 . Biodiesel antioxidants and their impact on the behavior of diesel engines: A comprehensive review . Fuel Processing Technology . 232 . 107264 . 10.1016/j.fuproc.2022.107264 . 0378-3820.
7. Jerker Widengren . Andriy Chmyrov . Christian Eggeling . Per-Åke Löfdahl . Claus A. M. Seidel . amp . 2007 . Strategies to Improve Photostabilities in Ultrasensitive Fluorescence Spectroscopy . The Journal of Physical Chemistry A . 111 . 3 . 429–440 . 10.1021/jp0646325 . 17228891 . 2007JPCA..111..429W .
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. Identification of Xenoestrogens in Food Additives by an Integrated in Silico and in Vitro Approach . Alessio Amadasi . Andrea Mozzarelli . Clara Meda . Adriana Maggi . Pietro Cozzini . Chem. Res. Toxicol. . 2009 . 22 . 19063592 . 1 . 52–63 . 2758355 . 10.1021/tx800048m.