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Title: A pilot study of the photoprotective effect of almond phytochemicals in a 3D human skin equivalent

Author
item EVANS-JOHNSON, JULIE - Jean Mayer Human Nutrition Research Center On Aging At Tufts University
item GARLICK, JONATHAN - Jean Mayer Human Nutrition Research Center On Aging At Tufts University
item JOHNSON, ELIZABETH - Jean Mayer Human Nutrition Research Center On Aging At Tufts University
item WANG, XIANG-DONG - Jean Mayer Human Nutrition Research Center On Aging At Tufts University
item CHEN, C-Y OLIVER - Jean Mayer Human Nutrition Research Center On Aging At Tufts University

Submitted to: Photochemistry and Photobiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/2/2013
Publication Date: 9/5/2013
Citation: Evans-Johnson, J.A., Garlick, J.A., Johnson, E.J., Wang, X., Chen, C. 2013. A pilot study of the photoprotective effect of almond phytochemicals in a 3D human skin equivalent. Photochemistry and Photobiology. B: Biology. 126:17-25. http://dx.doi.org/10.1016/j.jphotobiol.2013.07.006.

Interpretive Summary: Skin is the largest organ in the human body and is exposed to an array of environmental insults. Among them, Ultraviolet light (UV) is thought to be the most harmful because cumulative UV exposure can cause oxidative stress, inflammation, redness of the skin, wrinkling, and non-melanoma and melanoma skin cancer. Almonds are among the richest dietary sources of vitamin E and contain an array of antioxidant polyphenols. These almond nutrients may serve to increase the skin’s defenses against UV (photoprotection). The objectives of this study were to assess whether vitamin E and polyphenols could protect artificial human skin from UV-induced damages. After the artificial human skin was treated with vitamin E or polyphenols, the skin was irradiated with UV for a certain period. We found that UV decreased skin cell growth, increased death, and caused disorganization of skin structure. However, these UV-induced harmful changes were alleviated by vitamin E or polyphenols. In conclusion, we found that vitamin E and polyphenols present in almonds might provide some degree of photoprotection against UVA in human skins.

Technical Abstract: UV exposure causes oxidative stress, inflammation, erythema, and skin cancer. Alpha-Tocopherol (AT) and polyphenols (AP) present in almonds may serve as photoprotectants. Our objectives were to assess the feasibility of using a 3D human skin equivalent (HSE) in photoprotectant research and to determine photoprotection of AT and AP against UVA radiation. AT or AP was applied to medium (25 and 5 micromoles/L, respectively) or topically (1 mg/cm**2 and 14 microgram/cm**2), followed by UVA. Photodamage assessed 96 h post UVA included HSE morphology, keratinocyte proliferation, apoptosis, and differentiation. UVA induced disorganization of basal layer, alteration of epidermal development, and fibroblast loss which were alleviated by all nutrient pretreatments. UVA significantly decreased keratinocyte proliferation compared to controls, and all pretreatments tended to negate the reduction though only the medium AT effect was statistically significant (p is less than or equal to 0.05). UVA led to a significant 16-fold increase in apoptosis of fibroblasts compared to the control which was alleviated by topical AP pretreatment and completely negated by topical AT (p is less than or equal to 0.05). In conclusion, we validated the feasibility of using HSE in evaluation of photoprotectants and found that AT and AP, applied to medium or topically, provided some degree of photoprotection against UVA.