DFT Cancer Energy Barrier and Spectral Studies of Aspirin, Paracetamol and Some Analogues

Abstract

Comparative DFT computations were studied between Paracetamol (PA) and its analogues such as p-nitroacetanilide (PA-NO 2 ), p-bromoacetanilide (PA-Br) and N-acetylanthranilic acid (NAA) which can be considered also as analogue of Aspirin (ASP). As well, Thio-Aspirin, Acetyl-Thio-Salicylic acid, (TASP) is another analogue of ASP. From DFT studies, it has been concluded that PA and its analogues have the predominant trans-conformers with respect to directions of the carbonyl group in the acetyl moiety and the amino-hydrogen atom but the predominant conformer of NAA molecule is the cis-form. Phenacetin (PH) molecule which has ethoxy group in the Para-position instead of the hydroxyl group in the Para-position in PA molecule is another analogue of PA. The electron transfer energy between the drugs and the nucleic acid bases can be illustrated as cancer energy barrier. The cancer energy barriers were calculated from the DFT parameters for all the studied molecules showing the carcinogenic effect. The metabolized product N-acetylimidoquinone, m-PA, is produced in the liver from PA and PH. m-PA has higher electron affinity more than those of the nucleic acid bases indicating to the strong electronic withdrawing power from the nucleus in the human being liver cell, hence m-PA is responsible for the carcinogenic behavior of the liver cell since it has low energy barrier with guanine, 0.3 eV. Therefore the electron transfer between m-PA and guanine takes place spontaneously in the liver. From CI calculations it has been concluded that the singlet transition energies for the trans and cis conformers of PA are the same. The comparative spectral studies have been scanned for some analogues in the visible and UV regions using solvents of different polarities. The complex between PA and Zn 2+ was studied by DFT method.

DFT-Comparison of Anti-Cancer Effect of Ibuprofen Drug Anions and Breast Cancer Treatment by Ethanolic Solution of Nitrobenzaldehyde in Two Hours

“…Minimum energy structure was achieved using semiempirical AM1 method. DFT/6-31**G calculations were performed on the minimum energy structures using the closed shell Hartree-Fock, Becke's three parameters density functional theory, DFT, [13] [14] in combination with the Lee, Yang and Parr correlation functional B3LYP. The differentiation between the conformers' R and S of the ibuprofen drug has been based on the total energy difference which can be calculated via SCF using RHF for these types of molecules and UHF for the molecular anions.…”

“…The electron transfer energy (E CT ) in the CT-complex between the donor and the acceptor (cation and anion) was calculated according to the following equation [13].…”

“…C + is the columbic potential energy of the donor as a cation, and C − is the columbic potential energy of the acceptor as an anion. The columbic potential energy can be calculated, according to the following equation [13].…”

“…change the orientation of the polarized light. DFT calculations have been performed according to El-Shahawy, [13] [14] using the basis set 6-31**G ( Figure 1, Table 1). To give more information about cancer, it is mutual electron transfer between the nucleic acid bases and electron acceptor, i.e.…”

“…free radicals, drugs even some food like grills and fries. Losing an electron from the nucleic acid bases inside the nucleus produces carcinogenic cell in which the nucleus acts as electron donor to any electron acceptor such as in case of Paracetamol metabolite in the liver, NABQI, Figure 2, which has high electron affinity being sufficient to withdraw an electron from guanine of the lowest Ip energy among all the other nucleic acid bases, Table 2, in the liver cell nucleus in absence of glutathione [13]. Therefore the nucleus lacks an electron to produce cationic nucleus as a free radical producing cancerous cell.…”