mgr inż. Justyna Kiewlicz
Promotorzy:
dr hab. Henryk Szymusiak, prof. nadzw. UEP
dr inż. Paulina Malinowska
SUMMARY
LONG-CHAIN ALKYL ESTERS OF PHENOLIC ACIDS AS MULTIFUNCTIONAL
COMPONENTS DETERMINING THE QUALITY OF COSMETIC PRODUCTS
The unsaturated fatty acids are very important components of food and cosmetic
products. These compounds play significant role in accurate function of human organism and
prevent against lots of diseases. They are the basic components of the stratum corneum and
could protect skin from dehydration which leads to a reduction in its elasticity, increased
roughness, desquamation and susceptibility to irritation.
Unfortunately, unsaturated fatty acids are particularly liable to oxidation process
which could induce deterioration of product quality. These undesirable changes would result
in the deterioration of the sensor quality and cause the loss of the care and nutritional value.
Toxic products of lipid oxidation may also contribute to the development of many diseases.
Therefore, several techniques are used to prevent lipid oxidation process. One of them is the
addition of antioxidants. The most popular antioxidants are: BHT, BHA, tocopherols and
ascorbyl palmitate. The synthetic antioxidants such as BHA and BHT are very effective in
small amounts but they may participate in the formation of irritation and various dysfunctions.
BHT reveals hepatic toxicity in rats when administered orally, act as a tumor promoter in
animals treated with tumor initiator, and might have ability to affect allergic disease in human
such as rhinitis and asthma.
The long – chain alkyl esters of phenolic acids exhibit strong antioxidant activity
which consists in free radicals scavenging, singlet oxygen quenching and metal chelation.
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Their activity also depends on length of the lipophilic alkyl side chain. They are highly
soluble in oils so may protect unsaturated fatty acids against oxidation process in hydrophobic
phase.
These compounds demonstrate, moreover, additional properties which affect the
stability, the functional properties and the overall quality of cosmetics. They may be used as
sunscreens, anti-foaming agents, o/w emulsifiers and moisturizing agents.
The aim of this study is to synthesize new long-chain alkyl esters of phenolic acids
and evaluation of their properties as multifunctional components of cosmetic products.
The theoretical part of the paper contains information about:

phenolic acids and their derivatives,

fats and oils as components of cosmetic products,

lipid oxidation process,

antioxidants using in cosmetic industry,

advantages and disadvantages of the use of the synthetic antioxidants,

quality requirements for cosmetic products.
In this study nine long-chain alkyl esters of phenolic acids were synthesized. There
was obtained:

tetradecyl ferulate,

hexadecyl ferulate,

octadecyl ferulate,

tetradecyl gallate,

hexadecyl gallate,

octadecyl gallate,

tetradecyl 3,5-dihydroxybenzoate,

hexaecyl 3,5-dihydroxybenzoate,

octadecyl 3,5-dihydroxybenzoate.
The structure of the obtained compounds was confirmed according to spectroscopic
methods and elemental analysis.
Physical and chemical properties of obtained esters and their thermal stability were
also investigated. The long-chain alkyl esters of phenolic acids exhibit high thermal stability.
The most thermally stable compounds was tetradecyl ferulate. Initial mass loss of this ester
was above 265ºC.
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Then antioxidant activity of long-chain alkyl esters of phenolic acids were studied.
The protection factor of grape seeds oil samples was evaluated. The achieved results have
shown that long – chain alkyl esters of gallic acid exhibit similar to BHT antioxidant
properties and could replace this kind of antioxidants in food and cosmetic formulation.
The o/w emulsions containing long-chain alkyl esters were also prepared. Their
characteristics include: sensory analysis, antiradical properties evaluation, physical stability
evaluation and corneometric estimate of epidermis moisturizing after single application on
skin. The studies have shown that each emulsion was characterized by a very high sensor
quality and the appropriate physical stability. It was also found that tetradecyl ferulate and
tetradecyl 3,5-dihydroxybenzoate demonstrate good moisturizing properties.
On the basis on the obtained results it might be concluded that synthesized long-chain
alkyl esters of phenolic acids exhibit antioxidant properties which can protect unsaturated
fatty acids contained in cosmetics against oxidation process. They are also thermally resistant
compounds and it can be presumed that obtained esters might exhibit carry-through
properties. These compounds demonstrate also the additional properties which could
determinate the stability and functional characteristics of cosmetic emulsions and improve
their quality. Finally, the achieved results suggest that long – chain alkyl esters of phenolic
acids could be used as antioxidants in food and cosmetic formulation.
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