| Summary: | 碩士 === 國立臺灣大學 === 食品科技研究所 === 99 === In recent years, skin aging is a popular issue. Skin aging is a complex biological process that is a consequence of both intrinsic and extrinsic aging. Extrinsic aging is caused by environmental factors such as exposure to ultraviolet rays (UV). Chronic exposure to UV irradiation is the major factor of causing premature skin aging (photo-aging). Today, there are many methods for anti-aging and the most common way is to eat food from nature or to consume functional food. Yam, consumed and regarded as medicinal food in traditional Chinese herbal medicine, is a seasonal food. Yam is perennial trailing rhizome plants of the Dioscorea species and they belong to Dioscoreaceae family. Yam possesses many nutrients and active compounds such us mucilage, choline, allantoin and steroidal saponins. Yam peel is not edible and is treated as waste. However, yam peel contains more diosgenin than yam tuber. Diosgenin extracted from many plants has been a valuable precursor for the synthesis of pharmaceutical steroids. Furthermore, some literatures show that it has similar structure to 17β-estradiol (E2) and speculate it might have the efficacy against skin aging. Media milling can reduce the particle size to 1-100 nm and increase the percentage of nano/submicron particle. Therefore, the objectives of this study are to investigate the diosgenin content through media milling and to investigate the protective efficacy of nano/submicron yam peel on skin photo-aging induced by UV- light. It also can increase the release of some nutrients and active compounds such as soluble dietary fiber and diosgenin. The content of diosgenin from media milled sample is 2.5 folds and 1.75 folds higher than untreated and blended samples. It also reveals that media milled sample possesses more suspensibility than blended sample. Then, in cell experiment, it indicates that yam peel can reduce the expression of MMP-1/TIMP-1 and increases the content of collagen in human skin fibroblasts, and the protective efficacy of media milled sample is better than blended sample. As a result, media milling can reduce the particle size of yam peel and increase the release of diosgenin from yam peel. It also has better protective efficacy of skin photo-aging induced by UVA-light than blended sample.
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