| Summary: | 碩士 === 國立嘉義大學 === 生物科技研究所 === 94 === Soybean is rich in not only nutritional composition such as edible oil and protein, but also various kinds of functional components. Soybean isoflavones were considered as having potential protective effect against some cancers and diseases and have received increasing attention of the public in recent years. The soybean isoflavone contents varied as affected by both cultivar and growth environment. In this study, various fall and spring crops of soybean were collected as raw materials, and the four main isoflavones including daidzein, genistein, daidzin and genistin, were analyzed by HPLC. As shown by the results, daidzin and genistin were the main isoflavones of all tested cultivars. For each cultivar, daidzin and genistin contents of the fall crops were higher than their spring crops. Among the tested cultivars, Shih-Shih and Tailientou exhibited great potency source of isoflavones based on their yearly repetition of bearing considerably high isoflavone contents in both crops. As subjected to combined statistic variance and interaction analyses for six crops in three years, daidzin, genistin, daidzein, genistein and their total (sum) contents were significantly different as affected by cultivar, crop-season, year, year × crop-season, cultivar × year, cultivar × crop-season, and cultivar × year × crop-season. In the epidemiologic aspects, urinary excretion of equol, the metabolite of the daidzein was observed in association with reduced risk of breast and prostate cancer incidence. Soybean food is popular in Taiwan, and literature about investigating the urinary equol content of Taiwan residents is limited. In this study, 182 volunteers of urinary equol execretion after consumption of soymilk were analyzed. As urine samples were consecutively collected from equol producing individuals and analyzed, the urinary equol content reached the highest level between 8-15 hr after soymilk consumption. Accordingly, urine samples of the 182 volunteers with various genders and ages were collected after 8-12 hr of soymilk consumption for equol analysis. Of the group over 40 years of age, equol has been detected in the urine samples of 53.3% males and 61.3% females. As for the group under 40 years of age, the ratio were 64.6% males and 65.8% females, correspondingly. After continuous soymilk consumption for 16 wk, there were 9 from 20 testing individuals who changed from equol non-producers at the initial stage to equol-producers. This result suggested that induced equol production of equol non-producers could be achieved after continuous consumption of isoflavone-containing foods for a prolonged period. This finding is of merit and significance from the viewpoint that appropriate diets are closely related to health care and enhancement. As closely related, HPLC analysis of urinary equol was investigated. When urine samples containing various contents of equol were subjected to GC-MS as a reference and HPLC run under an achieved optimized condition, the equol concentrations obtained by HPLC were closely correlated with those obtained by GC-MS （r=0.9788）. It reveals that the developed HPLC quantification of urinary equol is practical.
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