Protective effects of corn silk extracts on UV-induced skin damage

[옥수수수염 추출물의 UV 피부손상의 보호효과 연구]

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As life expectancy increases in developed countries, the impact of aging on the function and appearance of skin is receiving growing interest. Skin aging is influenced by several factors, including genetics, environmental exposure, hormonal changes, and metabolic processes. The influence of the environment, especially solar UV irradiation, is of considerable importance for skin aging. Also exposure to ultraviolet(UV) radiation, the major cause for skin disorders such as sunburn, photodamage, and skin cancer, is an issue concerning the entire life span (2).

Skin is continuously exposed to ultraviolet (UV) radiation. UV irradiation acts as a broad activator of cell surface growth factor and cytokine receptors. This ligand-independent receptor activation induces multiple downstream signaling pathways that regulate expression of multiple genes. These signaling pathways converge to simulate transcription factor AP-1. Among genes whose expression is regulated by AP-1 are several matrix-metalloproteinase(MMP) family members and type Ⅰ procollagen. UV-enhanced matrix degradation is accompanied with decreased collagen production mediated not only by activation of AP-1, but also by inhibition of transforming growth factor(TGF)-β signaling (3).

Multiple lines of evidence suggest that natural compounds can prevent skin aging induced by ultraviolet light. Corn Silk is a traditional herbal herb drug in China. It is rich in phenolic compounds known to significantly affect human health, such as anthocyanins, quercetin, and ferulic acid (4). Especially it has been found to be an excellent source of bioactive compound. Two novel flavone glycosides of corn silk were identified by means of spectral analyses as 2″-O-a-L-rhamnosyl-6-C-3″-deoxyglucosyl-3′-methoxyluteolin and 6,4′-dihydroxy- 3′-methoxyflavone -7-O-glucoside (5).

Luteolin has been reported to exhibit antioxidant, anti-cancer, anti-inflammatory and anti-allergenic effects. Moreover, recent studies have shown inhibitory effects of luteolin on UVA-induced MMP activation in human dermal fibroblasts and on DMBA/TPA-induced skin tumorigenesis in a murine model. However, the molecular mechanisms and targets of luteolin in the prevention of photoaging remain poorly understood (6).

Our present study is aimed to assess the effects of Corn Silk extracts on UVB irradiation induced skin aging in female SKH-1 hairless mice. Inhibitory effects of corn silk extract on UVB irradiation-induced skin aging in hairless mice were determined by the measurement of wrinkle, MMP expression and immunohistology. This study is shown that corn silk extracts may be functional food candidate for skin photoaging.

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Molecules 2008;13:2628-51.

2. Sies H, Stahl W. Nutritional protection against skin damage from sunlight. Annu Rev Nutr 2004;24:173-200.

3. Rittié L, Fisher GJ. UV-light-induced signal cascades and skin aging. Ageing research reviews 2002;1:705-20.

4. Liu J, Wang C, Wang Z, Zhang C, Lu S, Liu J. The antioxidant and free-radical scavenging activities of extract and fractions

from corn silk (Zea mays L.) and related flavone glycosides. Food Chemistry 2011;126:261-9.

5. Kim S-L, Kim M-J, Lee Y-Y, et al. Isolation and Identification of Flavonoids from Corn Silk. Korean Journal of Crop Science

2014;59:435-44.

6. Lim SH, Jung SK, Byun S, et al. Luteolin suppresses UVB‐induced photoageing by targeting JNK1 and p90RSK2. Journal of

cellular and molecular medicine 2013;17:672-80.

Laboratory of

Molecular and Cellular Nutrition

Protective effects of corn silk extracts on UV-induced skin damage