| Description | Propyl gallate (also known as propyl 3, 4, 5-trihydroxybenoate) is a kind of ester formed through the condensation of gallic acid and propanol. It appears as a fine white to creamy-white crystalline powder. It has long been used as a kind of antioxidants to be supplied to foods especially animal fats and vegetable oil, being especially effective with polyunsaturated fats. Propyl gallate, as an anti-oxidant, can protect the food and oils from the attack of hydrogen peroxide and oxygen free radicals, having an effect similar to the superoxide dismutase. It can also be applied to ethers, emulsion, waxes, and transformer oil as the antioxidants.
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| References | https://pubchem.ncbi.nlm.nih.gov/compound/propyl_gallate#section=Top
https://en.wikipedia.org/wiki/Propyl_gallate
http://www.hmdb.ca/metabolites/HMDB33835
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| Description | Propyl gallate is an antioxidant with antimicrobial activity. It is hepatoprotective in vitro and in vivo, preventing CCl4 induced lipoperoxidation and reduction in polysomes in rat liver. Propyl gallate (100 mg/kg, i.p.) increases expression of HIF-1α, EPO, and VEGF mRNA levels and the number of normal neurons in rat brains after 8 minutes of forebrain ischemia. Propyl gallate in combination with potassium sorbate is bactericidal and bacteriostatic against S. aureus strains known to produce enterotoxins in food. Propyl gallate is commonly added to foods to prevent autoxidation and microbial growth. |
| Description | It caused
contact dermatitis in a baker and in a female confectioner
who fried doughnuts, primarily sensitized by
her night cream; the margarine probably contained
gallates. |
| Chemical Properties | Propyl gallate is an odorless powder having a slightly bitter taste. It functions particularly well in stabilizing animal
fats and vegetable oils. With a melting point of 148°C, propyl gallate loses its effectiveness during heat processing and is therefore
not suitable in frying applications that involve temperatures exceeding 190°C. Propyl gallate chelates iron ions and forms an unappealing,
blue–black complex. Hence, it is always used with chelators such as citric acid to eliminate the pro-oxidative iron and copper
catalysts. Good synergism is obtained with BHA and BHT; however, application with TBHQ is not permitted. For additional details,
refer to Burdock (1997). |
| Chemical Properties | white to light beige crystalline powder |
| Chemical Properties | 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. |
| Uses | Propyl Gallate is a known inhibitor of Tyrosinase, a polyphenol oxidase, which is an important enzyme in pigment biosynthesis in various organisms. It has also recently been seen to boost biodiesel li
pid biosynthesis in cultures. |
| Uses | Antioxidant for cosmetics, foods, fats, oils, ethers, emulsions, waxes, transformer oils. |
| Uses | Propyl Gallate is an antioxidant that is the n-propylester of 3,4,5-tri-
hydroxybenzoic acid. natural occurrence of propyl gallate has not
been reported. it is commercially prepared by esterification of gallic
acid with propyl alcohol followed by distillation to remove excess
alcohol. |
| Uses | propyl gallate is an anti-oxidant with preservative properties. |
| Preparation | Produced commercially by the esterification of gallic acid with propyl alcohol followed by distillation to remove the
excess alcohol. |
| Production Methods | Propyl gallate is prepared by the esterification of 3,4,5-trihydroxybenzoic
acid (gallic acid) with n-propanol. Other alkyl gallates are
prepared similarly using an appropriate alcohol of the desired alkyl
chain length. |
| Definition | ChEBI: N-propyl gallate is a trihydroxybenzoic acid. |
| General Description | Fine white to creamy-white crystalline powder. Odorless or with a faint odor. Melting point 150°C. Insoluble in water. Slightly bitter taste. |
| Air & Water Reactions | Insoluble in water. |
| Reactivity Profile | Propyl gallate can react with oxidizing agents. Incompatible with strong acids, strong bases and strong reducing agents. Darkens in the presence of iron and iron salts. Contact with metals should be avoided . |
| Hazard | Use in foods restricted to 0.02% of fat con-
tent.
|
| Fire Hazard | Propyl gallate is combustible. |
| Flammability and Explosibility | Notclassified |
| Pharmaceutical Applications | 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. |
| Contact allergens | This gallate ester (E 311) is an antioxidant frequently
used in the food, cosmetic, and pharmaceutical industries
to prevent the oxidation of unsaturated fatty acids
into rancid-smelling compounds. It causes cosmetic
dermatitis mainly from lipsticks and induced contact
dermatitis in a baker, and in a female confectioner, primarily
sensitized by her night cream, who fried doughnuts
the margarine probably containing gallates. |
| Biochem/physiol Actions | An antioxidant that exhibits antimicrobial activity. Propyl gallate has been reported to be an effective antioxidant-based hepatoprotector, both in vitro and in vivo. It has also been shown to prevent neuronal apoptosis and block the death of neurons exposed to FeSO4/GA as well as partially protect endothelial cells against TNF-induced apoptosis. |
| Safety Profile | Poison by ingestion and
intraperitoneal routes. Experimental
teratogenic and reproductive effects.
Questionable carcinogen with experimental
tumorigenic data. Mutation data reported.
Combustible when exposed to heat or
flame; can react with oxidizing materials.
When heated to decomposition it emits
acrid smoke and irritating fumes. |
| Toxicology | Propyl gallate (n-propyl-3,4,5-trihydroxybenzoate) is used in vegetable oils and butter. When 1.2 or 2.3% propyl gallate was added to feed for rats, loss of weight was observed. This may be due to the rats reluctance to eat food that was contaminated with the bitter taste of propyl gallate. When it was given for 10 to 16 months at the 2 to 3% level, 40% of the rats died within the first month and the remainder showed severe growth inhibition. Autopsies of rats indicated kidney damage resulting from the ingestion of propyl gallate. However, no other animal studies show serious problems and further studies indicated that propyl gallate does not cause serious chronic toxicities. |
| Safety | 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.
The WHO has set an estimated acceptable daily intake for
propyl gallate at up to 1.4 mg/kg body-weight.
(cat, oral): 0.4 g/kg
(mouse, oral): 1.7 g/kg
(rat, oral): 2.1 g/kg
(rat, IP): 0.38 g/kg |
| storage | 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. |
| Purification Methods | Crystallise the ester from aqueous EtOH or *C6H6 (m 146-146.5o). [Beilstein 10 III 2078, 10 IV 2003.] |
| 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. |
| Regulatory Status | GRAS listed. Accepted for use as a food additive in Europe.
Included in the FDA Inactive Ingredients Database (IM injections;
oral, and topical preparations). Included in nonparenteral medicines
licensed in the UK. Included in the Canadian List of
Acceptable Non-medicinal Ingredients. |
