Differential Metabolic Stability of 4α,25- and 4β,25-Dihydroxyvitamin D<sub>3</sub> and Identification of Their Metabolites
Yuka Mizumoto,
Ryota Sakamoto,
Kazuto Iijima,
Naoto Nakaya,
Minami Odagi,
Masayuki Tera,
Takatsugu Hirokawa,
Toshiyuki Sakaki,
Kaori Yasuda,
Kazuo Nagasawa
Affiliations
Yuka Mizumoto
Department of Biotechnology and Life Science, Faculty of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei 184-8588, Japan
Ryota Sakamoto
Department of Biotechnology and Life Science, Faculty of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei 184-8588, Japan
Kazuto Iijima
Department of Biotechnology and Life Science, Faculty of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei 184-8588, Japan
Naoto Nakaya
Faculty of Engineering, Toyama Prefectural University, 5180 Kurokawa, Imizu 939-0398, Japan
Minami Odagi
Department of Biotechnology and Life Science, Faculty of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei 184-8588, Japan
Masayuki Tera
Department of Biotechnology and Life Science, Faculty of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei 184-8588, Japan
Takatsugu Hirokawa
Transborder Medical Research Center, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8575, Japan
Toshiyuki Sakaki
Faculty of Engineering, Toyama Prefectural University, 5180 Kurokawa, Imizu 939-0398, Japan
Kaori Yasuda
Faculty of Engineering, Toyama Prefectural University, 5180 Kurokawa, Imizu 939-0398, Japan
Kazuo Nagasawa
Department of Biotechnology and Life Science, Faculty of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei 184-8588, Japan
Vitamin D3 (1) is metabolized by various cytochrome P450 (CYP) enzymes, resulting in the formation of diverse metabolites. Among them, 4α,25-dihydroxyvitamin D3 (6a) and 4β,25-dihydroxyvitamin D3 (6b) are both produced from 25-hydroxyvitamin D3 (2) by CYP3A4. However, 6b is detectable in serum, whereas 6a is not. We hypothesized that the reason for this is a difference in the susceptibility of 6a and 6b to CYP24A1-mediated metabolism. Here, we synthesized 6a and 6b, and confirmed that 6b has greater metabolic stability than 6a. We also identified 4α,24R,25- and 4β,24R,25-trihydroxyvitamin D3 (16a and 16b) as metabolites of 6a and 6b, respectively, by HPLC comparison with synthesized authentic samples. Docking studies suggest that the β-hydroxy group at C4 contributes to the greater metabolic stability of 6b by blocking a crucial hydrogen-bonding interaction between the C25 hydroxy group and Leu325 of CYP24A1.
