| Summary: | 碩士 === 國立中興大學 === 生物科技學研究所 === 92 === Sesame （Sesamun indicum L.） belongs to the Pedaliaceae family and is an annual, self-pollinated oilseed crop. Sesame oil, comprising 45% ~ 60% of the seed dry weight, has been preferentially consumed in oriental food because of its distinctive flavor and the stabilizing antioxidant properties of sesame lignans. Sesamin, the major lignan antioxidant in sesame oil, has been demonstrated as a healthy ingredient in animal tests, and considered as a potential target for new drug design. However, the biosynthetic pathway of sesamin has not been fully resolved as well as enzymes involved in this pathway since they are mostly insoluble and present as minor constituents in maturing seeds. It is assumed that sesamin is derived from phenylanaline via several enzymatic reactions known as lignin and lignan biosynthetic pathway. Phenylanaline is metabolized into coniferyl alcohol, one kind of lignan monomers, and two coniferyl alcohols are coupled to form pinoresinol mediated by dirigent protein. It is likely that the massive accumulation of sesamin in sesame seed is resulted from metabolizing pinoresinol into sesamin via two enzymatic reactions conducted by one or two key enzymes. My work is focused on cloning of the corresponding genes of key enzymes in sesamin synthesis. It is supposed that cytochrome P450s play catalytic roles in this pathway according to the structure of enzymatic products. At present, a stage specific cDNA library from maturing sesame seeds is constructed, and is used as template to clone all the candidate genes. Moreover, I had successfully cloned the sesame dirigent protein complete DNA sequences. The research results will be helpful for further studies to elucidate our hypothesis in the future.
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