This study applies Density Functional Theory (DFT), using the B3LYP functional, and via ab initio Restrict Hartree-Fock (RHF) methods [1-13] to study the infrared spectrum of the steroid 17-Iodo-androst-16-ene-derived [14].

The spectrum was obtained via computational methods ab initio RHF and DFT. [1-13] Optimization of molecular structure via UFF (Universal Force Field), followed by PM3 (Parametric Method 3) [1-13], with geometric optimization, obtaining the spectrum of other basis sets of the steroid 17-Iodo-androst-16-ene [1] derived [14]. [1] The steroid [15] 17-Iodo-androst-16-ene is derived from testosterone. Testosterone is the primary male sex hormone and anabolic steroid in males [16].

A steroid (named after the steroid cholesterol) is a biologically active organic compound with four fused rings arranged in a specific molecular configuration. Steroids have two principal biological functions: as important components of cell membranes that alter membrane fluidity, and as signaling molecules. Hundreds of steroids are found in plants, animals, and fungi. All steroids are manufactured in cells from the sterols lanosterol (opisthokonts) or cycloartenol (plants). Lanosterol and cycloartenol are derived from the cyclization of the triterpene squalene [15].

The steroid nucleus (core structure) is called gonane (cyclopentanoperhydrophenanthrene). It is typically composed of seventeen carbon atoms, bonded in four fused rings: three six-member cyclohexane rings (rings A, B and C in the first illustration) and one five-member cyclopentane ring (the D ring). Examples include anabolic steroids, the lipid cholesterol, the sex hormones estradiol and testosterone, and the anti-inflammatory corticosteroid drug dexamethasone [15].

Some aromatase enzyme inhibitor drugs have been used to treat cancer; however, their interaction with aromatase is not clear. Evaluated the interaction of steroid 17-Iodo-androst-16-ene derivatives with aromatase enzyme surface using 3 eqm protein. The results showed differences in the amino acid residues involved in the interaction of steroid derivatives with the 3 eqm protein surface. Arg115; Phe134; Trp224; Ala306; Thr310; Val370; Met374; Leu477. The steroid derivatives could act as aromatase enzyme inhibitors, and this phenomenon could be translated into good compounds to treat breast cancer [17].

The ab initio and  DFT [12-18] calculations have been performed to study the equilibrium configuration and calculation of its infrared spectrum (IR), entropy (S), heat capacity (CV), chemical and molecular structure of the steroid derived via GAMESS [1].

[1] The computational chemistry software program stands for General Atomic and Molecular Electronic Structure System (GAMESS) [21,22].

The molecular Hartree-Fock [1-4,7-12] wave function is written as an antisymmetrized product (Slater determinant) of spin-orbitals, each spin-orbital being a product of a spatial orbital  and a spin function (either α or β).

The expression for the Hartree-Fock molecular electronic energy  is given by the variation theorem as

 where D is the Slater-determinant Hartree-Fock wave function and  are given by

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