title: NMR investigation of magnesium chelation and cation-induced signal shift effect of testosterone.
abstract: We have previously reported that testosterone (Tes) is able to interact with magnesium chloride dissolved in methanol. In this study, we have applied1H and13C NMR spectroscopies to a series of Tes solutions containing Mg2+at various concentrations. High-resolution13C NMR spectra of Tes/Mg2+revealed well-resolved13C signals, and the intensities of those arising from C3, C5, C16, and C17 decreased linearly with increasing Mg2+concentration. The magnitude of the chelation affinity could be deduced from the slopes of the13C intensity variations; typically, the greater the slope the higher the chelation affinity. The results revealed Tes/Mg2+chelation to be mediated by the oxygen atom attached to C3 in ring A, and the hydroxyl group attached to C17 in ring D. With regard to the chelation specificity, we showed that Tes chelates Mg2+, but not Ca2+or Zn2+. We also explored the cation-induced signal shift effects of Tes in the presence of Mg2+, Ca2+, or Zn2+. We demonstrate that high-resolution13C NMR spectroscopy provides a better probe than1H NMR for the detection of cation chelation and cation-induced signal shift effects for steroid compounds such as Tes.
authors.affiliation: Institute of Chemistry, Academia Sinica, Nankang, Taipei 11529, Taiwan, Republic of China.
authors.forename: Jen-Yu
authors.initials: JY
authors.lastname: Chang
authors.affiliation: Institute of Chemistry, Academia Sinica, Nankang, Taipei 11529, Taiwan, Republic of China.
authors.forename: Kathleen D
authors.initials: KD
authors.lastname: Carollo
authors.affiliation: Institute of Chemistry, Academia Sinica, Nankang, Taipei 11529, Taiwan, Republic of China.
authors.forename: Su-Ching
authors.initials: SC
authors.lastname: Lin
authors.affiliation: Material and Chemical Research Laboratories, Industrial Technology Research Institute, Hsinchu 31040, Taiwan, Republic of China.
authors.forename: Ying-Yann
authors.initials: YY
authors.lastname: Wu
authors.affiliation: Institute of Chemistry, Academia Sinica, Nankang, Taipei 11529, Taiwan, Republic of China. Electronic address: tzougate@gate.sinica.edu.tw.
authors.forename: Der-Lii M
authors.initials: DM
authors.lastname: Tzou
mesh_terms: D002247:Carbon Isotopes / Q000737:chemistry; D008274:Magnesium / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D010100:Oxygen / Q000737:chemistry; D013739:Testosterone / Q000737:chemistry*
chemical_list: D002247:Carbon Isotopes; D013739:Testosterone; D008274:Magnesium; D010100:Oxygen
keywords: Cations; Magnesium chloride; Shielding effect; Steroidal ring conformation; Testosterone