Novel Aspects of Intrinsic and Extrinsic Aging of Human Skin: Beneficial Effects of Soy Extract^¶

Abstract

Biochemical and structural changes of dermal connective tissue substantially contribute to the phenotype of aging skin. To study connective tissue metabolism with respect to ultraviolet (UV) exposure, we performed an in vitro (human dermal fibroblasts) and an in vivo complementary DNA array study in combination with protein analysis in young and old volunteers. Several genes of the collagen metabolism such as Collagen I, III and VI as well as heat shock protein 47 and matrix metalloproteinase‐1 are expressed differentially, indicating UV‐mediated effects on collagen expression, processing and degradation. In particular, Collagen I is time and age dependently reduced after a single UV exposure in human skin in vivo. Moreover, older subjects display a lower baseline level and a shorter UV‐mediated increase in hyaluronan (HA) levels. To counteract these age‐dependent changes, cultured fibroblasts were treated with a specific soy extract. This treatment resulted in increased collagen and HA synthesis. In a placebo‐controlled in vivo study, topical application of an isoflavone‐containing emulsion significantly enhanced the number of dermal papillae per area after 2 weeks. Because the flattening of the dermal‐epidermal junction is the most reproducible structural change in aged skin, this soy extract appears to rejuvenate the structure of mature skin.

Daidzein stimulates collagen synthesis by activating the TGF‐β/smad signal pathway

“…In in vitro testing, genistein isoflavone is shown to stimulate collagen synthesis and downregulate matrix metalloproteinases (MMP) . Another study has reported that the use of soy extracts results in increased collagen synthesis in skin fibroblasts and the flattening of the dermal‐epidermal junction . Isoflavones have also been demonstrated to produce an anti‐aging effect on a UV‐damaged hairless mice model, which is partly due to its inhibitory effects on UV‐induced MMP‐1 expression and the subsequent collagen degradation .…”

Analysis on Age Invariance Face Recognition Study and Effects of Intrinsic and Extrinsic Factors on Skin Ageing

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