Ellagic acid: its multiple functions of anti-oxidation and whitening

Ellagic acid, a chemical substance, has attracted much attention in the field of beauty and skin care. Its unique molecular structure and excellent biological activity give it multiple functions from anti-oxidation to whitening. Let us explore the beauty secrets of ellagic acid and uncover the scientific principles behind it.Featured Snippet (Instant Answer)

What is Ellagic Acid used for?
Ellagic acid is a natural polyphenol found in fruits like pomegranate and berries. It is widely used in skincare for its antioxidant, whitening, and anti-inflammatory properties, helping to reduce pigmentation, protect against UV damage, and slow skin aging.

🔬 What is Ellagic Acid?

Ellagic acid (C₁₄H₆O₈) is a natural antioxidant compound formed by the dimerization of gallic acid. It appears as a white to grey-brown powder with a high melting point over 360°C. Although it is poorly soluble in water and ethanol, it dissolves well in alkaline solutions.

Common natural sources include:

• Pomegranate peel
• Blueberries & raspberries
• Gallnuts
• Green tea

In nature, ellagic acid exists either freely or bound in the form of ellagitannins and glycosides.

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1. Multiple functions of ellagic acid

1.1 ► Basic information
Ellagic acid, also known as gallic acid, has a chemical formula of C14H6O8 and a relative molecular mass of 302.20. This chemical substance has shown remarkable effects in the field of beauty and skin care. Its unique molecular structure and excellent biological activity give it multiple functions from anti-oxidation to whitening. Next, we will explore the beauty secrets of ellagic acid in depth and reveal the scientific principles behind it.

Ellagic acid, a white to gray-brown powder, has remarkable chemical properties. Its melting point is as high as 360℃. Although it is slightly soluble in water and ethanol, it can be well dissolved in alkali solution. This polyphenol dilactone component is widely present in a variety of plant tissues such as blueberries, raspberries, gallnuts, green tea and pomegranate peels, and is a dimer derivative of gallic acid. In nature, ellagic acid exists both in free form and more in condensed form, such as ellagitannins and ellagic glycosides, which are present in every corner of our lives.

The unique chemical and physiological activities of ellagic acid make it shine in the field of skin care products. It can not only effectively scavenge reactive oxygen free radicals and inhibit oxidative stress reactions, but also resist lipid peroxidation and reduce DNA damage, thus showing unique effects on skin aging problems caused by various factors, such as wrinkles and pigmentation. Therefore, ellagic acid has a broad application prospect in the field of cosmetics.

In addition, ellagic acid also has a strong antioxidant effect. Its catechol-type hydroxyl structure allows the phenolic hydroxyl group to form an intramolecular hydrogen bond with another phenolic hydroxyl group after dehydrogenation, thereby producing a stable o-benzoquinone resonance structure and enhancing the activity of scavenging free radicals. The study also found that ellagic acid can bind to divalent cations to prevent metal ions from catalyzing lipid compounds to produce free radicals, thereby further enhancing its antioxidant effect. These properties enable ellagic acid to quench lipid free radicals, interrupt the chain reaction of lipid oxidation, and show excellent antioxidant activity. In mammals, ellagic acid and its derivatives have a significant inhibitory effect on the peroxidation of lipid compounds in mitochondria and microsomes. Related studies have shown that its antioxidant activity is as high as 50 times that of vitamin E. This finding has allowed ellagic acid to be used as a food antioxidant in Japan.

1.2 ► Antioxidant effect
During the synthesis of melanin, tyrosinase catalyzes the gradual oxidation of monophenolic hydroxyl groups to o-diphenols, and then to o-quinones. As a catechol compound, ellagic acid has a unique diphenol structure that makes it possible to become a substrate for tyrosinase, thereby inhibiting the production of melanin. In order to further explore the whitening mechanism of ellagic acid, Ortiz-Ruiz et al. studied its kinetic properties.

The research team used UV-visible spectrophotometry to observe the reaction process of tyrosinase to typical substrates and ellagic acid, and used time determination to characterize the kinetic properties of ellagic acid. The results showed that ellagic acid can indeed serve as an alternative substrate for tyrosinase and be oxidized to unstable o-quinone by enzyme catalysis. In addition, ellagic acid also has strong antioxidant capacity. This polyphenol compound can reduce o-quinone or semiquinone generated in the pathway, further inhibiting the production of melanin.

1.3 ► Whitening mechanism
Ellagic acid reduces melanin production by inhibiting the activity of tyrosinase. The study by Yoshimasa et al. showed that the inhibitory effect of ellagic acid on mushroom tyrosinase is non-competitive, and its inhibition constant K is 81.6mmol/L. It is worth noting that the tyrosinase inhibitory ability of ellagic acid will weaken with the decrease of copper ion concentration, and when Cu or Cu is added, the enzyme activity inhibited by ellagic acid can be partially restored.

In order to further verify the whitening effect of ellagic acid, Liu Dong and others used different concentrations of ellagic acid to intervene in human epidermal melanocytes cultured in vitro. The results showed that ellagic acid can significantly downregulate the tyrosinase activity of melanocytes, and this inhibitory effect is concentration-dependent. In addition, ellagic acid also has the effect of blocking the transmission of melanin to keratinocytes, and its inhibitory effect is more obvious as the concentration increases.

In order to simulate the pigmentation phenomenon under human skin conditions, the researchers cut the hair on the back of colored guinea pigs and irradiated ultraviolet light to induce skin pigmentation. Subsequently, ellagic acid preparations were applied to the pigmented areas of the skin. After 4 weeks of observation, it was found that the color of the applied area gradually approached normal skin, and even reached the skin color level before ultraviolet irradiation. This experimental result further confirmed the significant effect of ellagic acid in whitening.

Ellagic acid exhibits absorption ability in the ultraviolet region of 200~400nm, especially in the 220~300nm band, and also has a strong absorption peak at 320~380nm, which proves that ellagic acid has a very strong absorption function for ultraviolet rays. When ellagic acid is added to cosmetics, it can effectively protect the skin from excessive exposure to ultraviolet light, thereby inhibiting the activity of tyrosinase, reducing the production of melanin, and reducing the risk of skin darkening due to sun exposure, thereby achieving a certain whitening effect. In addition, ellagic acid also exhibits anti-inflammatory properties. The results of clinical animal tests show that compared with other whitening ingredients, such as kojic acid, ellagic acid is more effective in skin whitening and also helps prevent the formation of chloasma.