SKIN AGING AND TEA

Author

Assoc. Prof. Gulsah Gedik

Lecturer - Trakya University, Faculty of Pharmacy, Department of Pharmaceutical Technology

"Drink tea, stay healthy!"

What is aging?

Aging is a complex process that includes changes observed in the human organism throughout life. Although there is no definitive information about the cause of aging and the factors that determine the rate of aging, there are different theories:

a) Genetic theory (Intrinsic aging)

b) Environmental factors theory (Extrinsic aging).

How does aging occur theoretically?

According to genetic theory, aging, like many of our other characteristics, is a programmed feature and is sensitively engraved in our genes in a way that is different for each of us. It is thought that it may be due to a biological program processed into individual cells or a center such as the brain where the whole system is managed. It has been reported that there are differences in genetic aging according to race. In the extrinsic aging theory, UV, smoking, excessive alcohol, poor nutrition, constant wear, free radicals, accumulation of waste, etc. It is thought that the damage caused by these events on our genes and proteins is effective. When we look at the current theories of aging, we see that both origins are effective and the assumptions are connected to each other with complex cause-effect relationships. Most likely, many mechanisms act together to initiate and sustain aging by causing deterioration and damage first at the molecular, then at the cellular, and then at the organ level. Aging theories: 1-Cell cycle theory 2- Oxidation-reduction theory 3-Mutation theory 4-Free radical theory

What causes skin aging and what happens in aged skin?

Skin is a tissue that is more prone to aging, especially due to contact with external factors. External factors include ultraviolet rays, cigarette smoke, automobile exhaust and industrial waste. Cellular DNA is constantly damaged internally and externally. This damage applies not only to genomic DNA but also to mitochondrial DNA. Since most of the free oxygen radicals in the cell are produced in the mitochondria, mitochondrial mutations are more common with aging. Therefore, it can be assumed that mitochondrial damage may occur earlier in tissues with faster metabolism. Accumulated damage to genomic and mitochondrial DNA plays an important role in premature aging of cells. Following exposure to gamma and ultraviolet rays, there is an increase in spontaneous DNA damage and a decrease in DNA repair in cells. Besides DNA damage, the aging process also involves protein damage. The conversion of D-amino acids into L-amino acids in protein greatly affects protein function. With the aging process, sugar aldehydes combine with amino acids in proteins, causing brown color transformation and loss of function. This process affects extracellular matrix proteins, especially dermal collagen. The first aging-related changes seen in skin exposed to sunlight are dryness, coarsening, laxity and the appearance of benign neoplasias.

Does smoking affect skin aging?

Smoking accelerates skin aging, especially in women. Wrinkles are evident on the skin of smokers. Additionally, a grayish color formation is also noticeable. There is a correlation between differences in skin and the accumulated total of cigarettes smoked. Smoking also increases the frequency of skin cancer.

What is effective in protecting against skin aging?

The most important preparations in protecting against skin aging are those with sunscreen and antioxidant properties. The catechins found in tea, our national drink that we enjoy, have both properties and are good substances that can be used for skin aging.

Which substances in the structure of tea protect against aging?

Anti-inflammatory, anti-aging and wound healing properties of catechins have also been discovered. Evidence obtained from studies shows that catechins are not only a group of reactive oxygen species (ROS) scavengers that act as antioxidants in the epidermis, but also act as modulators of different gene groups and signaling pathways. When applied topically, green tea polyphenols reduced inflammation, ornithine decarboxylase activity, hyperplasia, and hydrogen peroxidase production, suggesting that these substances serve as regulators of both antioxidant and enzymatic activities.

How does green tea help to delay aging?

Green tea polyphenols can interact with ROS and be rapidly metabolized, thus forming the first line of defense against ROS in vivo. They also inhibit pro-oxidant enzymes such as nitric oxide synthase, lipoxygenase, cyclooxygenase and xanthine oxidase, which form the second line of defense against free radicals, especially hydrogen peroxidase. Compared to animal studies, there are very few studies evaluating the effects of green tea polyphenols on human skin. Epigallocatechin gallate (EGCG), a tea polyphenol, effectively crosses the dermal barrier in mice but not in humans.

A study on the protective effects of catechins has brought to the fore that they may be responsible for their antioxidant effects and anticarcinogenic potential against free radicals. EGCG was later found to have very potent anticarcinogenic activity in a chemically induced skin cancer model. EGCG significantly inhibited the binding of 3H-labeled polycyclic aromatic hydrocarbons to epidermal DNA. Pretreatment of mice topically with EGCG resulted in significant reductions in tumor size and number per mouse in a DMBA tumor induction model. Two years later, the first UVB light-induced photocarcinogenesis study using catechins as protective agents was published by Mukhtar et al. Female SKH–1 hairless mice were fed 0.1% green tea polyphenols or catechins topically and then exposed to UVB light. Both applications provided photoprotection against UVB.

In a human biopsy study, green tea extracts and polyphenols were applied topically for 30 minutes before a 2-minute exposure to UV light, and skin samples were examined immunohistochemically. Topical application of these agents dose-dependently suppressed the UV light-induced erythema response. Green tea extracts reduced sunburn cells and DNA damage.

When EGCG was administered at a dose of 3 mg/2.5 cm² before UVB exposure, UVB-induced erythema and leukocyte infiltration were reduced. Therefore, catechins can be used to prevent the effects of sun exposure in humans.

In a study using multiple in vitro and in vivo models, including humans, it was found that erythema induced by psoralen and UVA application (PUVA) was almost completely suppressed by topical application of 0.2 mg/cm² green tea extract for 30 minutes; the same extract also suppressed PUVA-induced DNA damage; These findings suggested that green tea polyphenols protect epidermal keratinocytes from PUVA treatment-induced carcinogenesis.

The protective effects of green tea extracts prepared at 10%, 5%, 2.5% and 0.5% were applied to the skin before UVB and UVA radiation on volunteers and their protective effects were investigated. This effect was evaluated clinically by erythema and histologically by sunburn cell count and Langerhans cell count. Green tea extracts applied just before UV exposure provided the most significant protection. Even green tea extracts applied 4 hours before UV exposure have been shown to have protective properties. It has been shown that the functions of Langerhans cells damaged by UV radiation improve by 58%.

In an article published in 2011, they reported that 60 female volunteers drank 1402 mg of green tea catechins every day for 12 weeks, and that, in addition to the protective effects of UV radiation applied with a solar simulator, the blood circulation in the skin increased and the surface properties of the appearance became better.

Can we say that black tea is effective in protecting against aging?

Apart from green tea, black tea used orally and topically has also been found to play an important role in sun protection. A study found that black tea extracts reduced the erythema and skinfold thickness associated with UVB-induced cancer formation in keratinocyte cultures in humans and animal models.

In our study at Marmara University, the protection of black gel against erythema caused by artificial UV source was demonstrated with gel formulations. In the studies carried out, the UV protection activities of gels obtained from black and green tea were demonstrated through in vivo and in vitro tests, and stability studies and in vitro toxicological tests were carried out. The fact that both tea gels have similar UV protection potential suggests that this is due to EGCG, which is found more in green tea, and theaflavin, which is only found in black tea. It has been shown that caffeine alone, which is known to have UV protective properties, is not sufficient for this protection, and polyphenols are effective in UV protection.

Cosmetic and nutraceutical products prepared from black and green teas also have antioxidant, anti-carcinogenic, anti-inflammatory and wound healing potential in skin aging.

Abstract

According to genetic theory, aging, like many of our other characteristics, is a programmed feature and is sensitively engraved in our genes in a way that is different for each of us. It is thought that it may be due to a biological program processed into individual cells or a center such as the brain where the whole system is managed. It has been reported that there are differences in genetic aging according to race. In the extrinsic aging theory, UV, smoking, excessive alcohol, poor nutrition, constant wear, free radicals, accumulation of waste, etc. It is thought that the damage caused by events on our genes and proteins is effective. Catechins, found in both green and black tea, have also been discovered to have anti-inflammatory, anti-aging, and wound-healing properties. Evidence obtained from studies shows that catechins are not only a group of reactive oxygen species (ROS) scavengers that act as antioxidants in the epidermis, but also act as modulators of different gene groups and signaling pathways. When applied topically, green tea polyphenols reduced inflammation, ornithine decarboxylase activity, hyperplasia, and hydrogen peroxidase production, suggesting that these substances serve as regulators of both antioxidant and enzymatic activities. Cosmetic and nutraceutical products prepared from black and green teas also have antioxidant, anti-carcinogenic, anti-inflammatory and wound healing potential in skin aging.

1. Afaq F, Ahmad N, and Mukhtar H, Suppression of UVB-induced phosphorylation of mitogen-activated protein kinases and nuclear factor kappa B by green tea polyphenol in SKH-1 hairless mice. (2003).

2. Afaq F, Katiyar SK, Polyphenols: skin photoprotection and inhibition of photocarcinogenesis. (2011).

3. Agarwal R, et al., Inhibition of skin tumor promoter-caused induction of epidermal ornithine decarboxylase in SENCAR mice by polyphenolic fraction isolated from green tea and its individual epicatechin derivatives. (1992).