Terahertz time-domain spectroscopy of testosterone, estradiol and estriol

The chosen steroid hormones are the human sexual hormones. Estradiol and estriol are femail hormones (estrogens), testosterone is male hormone (androgen). The greatest difference in structure of these molecules is observed in the A-ring which in an estrogen molecule is aromatic and planar while in an androgen molecule the A-ring has a distorted 1α-sofa conformation (Fig. 1). The estrogen molecule also is characterized by absence of angular methyl group in C10-position. DFT calculations are shown that these molecules contain vibration modes in terahertz range connected by deformations of all steroid rings and by the COH and methyl-group twisting [5]. The analysis of vibration spectra indicates that there are some interesting correlations between molecular structure and spectral properties. The THz absorption spectrum of testosterone has intensive absorption maxima at 48(v₂) and 81(v₅) cm^-1 (Fig.1). Raman spectrum of testosterone has several absorption maxima at 28, 37(v₁), 44(v₂) and 58(₃) cm^-1. Vibration modes v₁, v₂, v₃ and v₅ are determined by deformation of all steroid rings and also are visible in estrogen spectra (Fig. 2). The structures of testosterone and estradiol differ only the A-ring conformation and vibration mode v₂ is more intensive in testosterone.