COMPARATIVE FEATURES OF STRUCTURE AND PROPERTIES OF BIOMARKERS OF NAPHTHALAN PETROLEUM

Abstract

The results of studies of the structural features of the biomarkers of Naphthalan petroleum (in particular, R, S-cholestanes and hopanes with C28-C31) by the hybrid density functional in the approximation 6-311G+(d,p) are presented. It was shown that the studied substances have a quad-cyclopentanoperhydrophenanthrene system, which is inherent in resins and asphaltenes of heavy oils, and is also characterized by a three-dimensional spatial configuration. Compounds containing such a ring system are of great importance both for the body, including when exposed to antimicrobial reagents. The structure and position of the side groups and atoms adjacent to the main cycle, the position of double bonds in the molecule, and the spatial configuration have a definite effect on the biological activity of the biomarkers of Naphthalan petroleum. The calculated geometric parameters of the studied compounds show that the molecules are stable, and the stability is determined by the conformation of the rings (cyclohexane rings have the chair conformation, and cyclopentane rings have half-chairs), the nature of the connection between each other and the spatial arrangement of hydrogen atoms, radicals and functional groups. From the calculated values of the torsion angles of cholestanes and hopanes, it was shown that the junction of the A/B, B/C and C/D cycles is in the trans configuration (118.37° - 129.94°). The studied molecules possess a trans-articulation of the rings at the 5,10-, 8,9-, and 13,14-positions (in the case of 5-10 hopanes, also at the 17,18-position). The bonds in the molecules that form the rings are slightly distorted, and the rings themselves are not flat. A relationship was found between the biological activity of triterpenes and their values of ionization potentials and electron affinity. The studied biomarkers are similar in geometry and energy parameters to betulin derivatives and can exhibit biological activity.