| Summary: | 碩士 === 長庚大學 === 中醫學系天然藥物 === 99 === Steroid compounds have many important physiological activities in higher organisms. Testosterone and the related steroids are important environmental contaminants that disrupt endocrine systems of animals and aquatic species. The degradation of steroids is challenging in term of its complex chemical structure, especially under anoxic conditions. A denitrifying γ-proteobacterium, Steroidobacter denitrificans, able to grow anaerobically on testosterone as the sole carbon and energy source was adopted as the model organism to study the anoxic degradation of testosterone. [4-14C]Testosterone was used in this study as the tracer to confirm the mineralization of testosterone in the absence of oxygen. So far, eight initial intermediates involved in anoxic testosterone degradation pathway of Steroidobacter denitrificans were purified and identified from in vitro assays. Moreover, we also added [2,3,4-13C3]testosterone and [4-14C]testosterone as the tracer in an in vivo assay to explore the anoxic pathway. Steroid products purified from the in vivo assay were then identified using NMR spectroscopy and UPLC-Mass spectrometry. Surprisingly, a 13C-labeled testosterone-derived compound was identified, and its A-ring might have been cleaved. Thus, it is rational to expect that the cleavage of central ring system of testosterone may begin from the A-ring of testosterone. According to our current data, a novel testosterone catabolic pathway is proposed.
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