Bio: Dr. Yasumitsu Ogra is a Professor at the Laboratory of Toxicology and Environmental Health, Graduate School of Pharmaceutical Sciences, Chiba University. After receiving his Ph.D. at Chiba University, he worked as a post-doctoral fellow at the National Institute of Industrial Health. In 1997, he worked at Chiba University as a Research Associate. In 2002, he worked as a visiting scientist in a research unit of the French National Centre for Scientific Research. He was promoted to an Associate Professor at the Graduate School of Pharmaceutical Sciences, Chiba University, in 2004. He moved to Showa Pharmaceutical University as a Professor in 2009, and then he returned to the Graduate School of Pharmaceutical Sciences, Chiba University, as a Professor in 2015. In April 2024, he became Dean of the Faculty of Pharmaceutical Sciences and Research Director of the Graduate School of Pharmaceutical Sciences, Chiba University. His research interests are metal toxicology based on analytical chemistry. In addition, he is also interested in developing novel techniques for bio-trace elements using inductively coupled plasma mass spectrometry (ICP-MS) and electrospray ionization mass spectrometry (ESI-MS). He has been a Fellow of the Royal Society of Chemistry since 2013 and a Vice President (President-elect) of the Asian Society of Toxicology since 2023.

Abstract: Chalcogen (the group 16) elements have unique physicochemical and biological properties. Sulfur and selenium are essential elements of animals, but tellurium is non-essential. Selenium is excreted into urine as a selenosugar and trimethylselenonium ion (TMSe). Contrary, tellurium is excreted into urine as an only trimethyltelluronium ion (TMTe), and no tellurosugars have not been detected in urine. Sulfur is not a trace element, and is multiply metabolized and utilized in a body. However, no thiosugar have not been also identified in urine. We intended to clarify the molecular mechanisms underlying the metabolisms of selenium, tellurium and sulfur. First, we evaluated the methylation of the chalcogen elements by inorganic (ICP) and organic (ESI) mass spectrometry. A chemiluminescence-based enzyme assay was also used to evaluate the methylation. We observed that two methyltransferases, i.e., thiopurine S-methyltransferase (TPMT) and indolethylamine N-methyltransferase (INMT) cooperatively acted to produce the methylated metabolites of selenium, tellurium and sulfur. Namely, TPMT drove the first methylation, and INMT drove the second and third methylation. Supersulfides were also methylated with TPMT. According to the results, we concluded that surplus amounts of essential chalcogen and even a trace amount of non-essential chalcogen were metabolized by the common methylation pathway. In addition, other metabolic pathways of chalcogens will be discussed.