It is widely known that ultraviolet (UV) light causes significant damage to the skin, which can lead to premature aging (Choi et al., 2015). Exposure to UV light from sunlight causes premature aging that shows symptoms such as wrinkle formation, increased skin thickness, skin pigmentation, or loss in elasticity. Exposure to UV light from the sun also causes excess generation of reactive oxygen species, which are oxygen molecules containing one or more unpaired electrons. These reactive molecules interact with cell components and can cause cell damage (Choi et al., 2015). Many treatments are being studied to prevent sun-induced aging. One treatment, in particular, focuses on a common ingredient, coffee grounds, that can be orally administered to help slow the sun-induced aging process (Choi et al., 2015).
Oral Administration of Caffeine
In one study, scientists dissolved coffee grounds (0.1 to 0.5%) in distilled water for use in oral administration to hairless mice. The mice in the experimental group were orally administered caffeine in their drinking water every day. The mice were then subject to UV exposure 3 times a week for 12 weeks. Data analysis showed that caffeine reduced wrinkle formation in mice by 30% compared to the control group which was not treated with caffeine. This suggests that caffeine inhibited wrinkle formation in the skin (Choi et al., 2015).
To further this study, scientists also tested the effects of caffeine on human keratinocyte HaCaT cells (the most common type of cell in our skin). The keratinocyte cells were treated with caffeine samples for 1 hour and then exposed to UV exposure using a UV lamp. After analyzing the results, it was determined that caffeine inhibited the reactive oxygen species by over 30% (Choi et al., 2015). Another sign of sun-induced aging is skin barrier damage, which can be caused by transepidermal water loss due to a lack of collagen. Further analysis on the caffeine-treated mice in this experiment showed that caffeine significantly reduced transepidermal water loss caused by exposure to UV.
This indicated a possible role that caffeine plays in collagen synthesis. Some collagenases, which degrade collagen in tissues, showed high gene expression of matrix metalloproteinase 2 following UV treatment. Matrix metalloproteinase 2 is a common collagenase in our skin, and its gene expression was found to be reduced by over 60% in caffeine-treated mice (Choi et al., 2015). This suggests that caffeine could play a role in inhibiting collagen degradation in the skin, which is an important factor in preventing sun-induced aging.
In Vitro Enzyme Inhibition Analysis by Caffeine
In addition to an increase of collagenase enzymes found in UV-exposed skin, sun-induced aging is also accompanied by an increase of the activation of elastase and tyrosinase enzymes (Eun Lee et al., 2019). Elastase breaks down elastin in the skin which causes loss of skin elasticity, another symptom of sun-induced aging. Tyrosinase is responsible for the production of melanin in the skin. When the skin is exposed to UV light, high amounts of melanin are produced, which can cause symptoms of sun-induced aging such as freckles (Eun Lee et al., 2019). To test the inhibitory potential of caffeine in elastase and tyrosinase, this study performed molecular docking analysis to predict the caffeine inhibitory impact on these enzymes. Additionally, an in vitro enzyme inhibition assay was performed to determine caffeine inhibitory potential. Analysis of the data obtained by this study showed that caffeine significantly inhibited elastase and tyrosinase by 3.42% and 13.72%, respectively.
Caffeine Applied Topically
Caffeine applied topically is also shown to protect the skin against UV light from the sun. Studies show that topical products of at least 1% caffeine can increase the protection of the skin from sun induced damage and slow the process of sun induced aging (Koo et al., 2007). Additionally, when there is an excessive amount of sun-induced damage to the skin, this can lead to skin cancer. Studies show that caffeine applied topically can kill sun-induced cancer cells on the skin (Herman et al., 2012). Therefore, caffeine applied topically can decrease the sun-induced damage to the skin and slow the process of sun-induced aging.
Conclusion
Prevention of UV damage to the skin and the process of sun-induced aging is an ongoing and evolving research topic that requires more studies to fully understand. However, little changes in the routine of our everyday lives can contribute to the prevention of skin damage and early aging. These changes include using sunscreen every day, wearing clothes and hats to prevent sun exposure, and limiting sun exposure throughout the day. Lastly, studies suggest that caffeine consumption could provide slightly more protection from UV light, which is an important part of slowing the sun-induced aging process.
Written by Christina Vyvoda and edited by Aldrin V. Gomes, PhD
References
Choi HS, Park ED, Park Y, Suh HJ. Spent coffee ground extract suppresses ultraviolet B-induced photoaging in hairless mice. J Photochem Photobiol B. 2015 Dec;153:164-72. doi: 10.1016/j.jphotobiol.2015.09.017. PMID: 26410040. https://www.sciencedirect.com/science/article/pii/S1011134415003085
Eun Lee K, Bharadwaj S, Yadava U, Gu Kang S. Evaluation of caffeine as inhibitor against collagenase, elastase and tyrosinase using in silico and in vitro approach. J Enzyme Inhib Med Chem. 2019 Dec;34(1):927-936. doi: 10.1080/14756366.2019.1596904. PMID: 31039625; https://www.tandfonline.com/doi/full/10.1080/14756366.2019.1596904
Herman A, Herman AP. Caffeine's mechanisms of action and its cosmetic use. Skin Pharmacol Physiol. 2013;26(1):8-14. doi: 10.1159/000343174. PMID: 23075568. https://pubmed.ncbi.nlm.nih.gov/23075568/
S‐W. Koo, S. Hirakawa, S. Fujii, M. Kawasumi, P. Nghiem, Protection from photodamage by topical application of caffeine after ultraviolet irradiation, British Journal of Dermatology, Volume 156, Issue 5, 1 May 2007, Pages 957–964, https://doi.org/10.1111/j.1365-2133.2007.07812.x
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