Structural and Vibrational Study On the Acid, Hexa-Hydrated and Anhydrous Trisodic Salts of Antiviral Drug Foscarnet

Abstract

The structural and vibrational properties of acid species, hexa-hydrated and anhydrous trisodic salts of antiviral drug foscarnet in gas phase and in aqueous solution have been studied in this work by using the hybrid B3LYP method with the 6-31G* and 6-311++G** basis sets. The properties in solution were carried out with the self consistent reaction force (SCRF) method by using the integral equation formalism variant polarised continuum (IEFPCM) and SD models while the complete vibrational assignments for those three species were performed in both media by using the experimental available infrared spectrum of hexa-hydrated trisodic salt and the scaled quantum mechanical force field (SQMFF) methodology. The natural bond orbital (NBO) studies suggest that the hexa-hydrated salt in solution is most stable than the anhydrous one in the same medium but in gas phases the anhydrous salt shows a higher stability in solution. The atoms in molecules (AIM) analyses have revealed the ionic characteristics of the O--- Na bonds in both salts supporting the higher stability of the hexa-hydrated salt in solution. The evaluation of the frontier orbitals show that the anhydrous salt is the most reactive species in solution, as supported by its higher solvation energy and volume variation. Apparently, the presences of phosphate group in foscarnet probably increase its activity when it is used as drug. The experimental infrared bands observed in the hexa-hydrated species at 1059 and 983 cm-1 are clearly attributed to the stretching modes of phosphate group while the strong bands at 1445 and 1333 cm-1 are associated to the stretching modes of carboxylate group. In addition, the force constants for the carboxylate and phosphate groups are reported. Foscarnet is an antiviral agent used in the treatment of human immunodeficiency virus (HIV) infections and of herpes viruses (HSV-1, HSV-2, VZV, CMV, etc.), as was reported from long time ago [1-4]. However, the continuous use of this drug in numerous patients can generate pathological micro calcifications in various tissues and, as a consequence different kinds of diseases can be found, being among others, cancer and cardiovascular abnormalities including in patient’s transplanted kidney produces nephro toxicity [5-13]. This later disease can be diagnosed analyzing carefully from a biopsy the crystal solid deposited in the sample by using different spectroscopic techniques, as reported in the literature [5-13]. Hence, the preparations of other derivatives of foscarnet are useful and important to design new drugs with the same biological activities but with fewer side effects [14-18]. Temperini et al. [19] have found that foscarnet also can acts as an activator/inhibitor of the metallo enzyme carbonic anhydrase and they have resolved the structure of this adduct by using X-ray diffraction, including the structure of foscarnet. Structurally, this drug is the trisodium phosphonoformate salt and, despite their very simple structure the conformers in gas phase only for the acid form of foscarnet were recently studied by Khalili et al. [20] from a theoretical point of view [20]. Thus, these authors have studied conformers, gas phase acidity and metal ion affinity with selected cations and alkaline earths by using DFT calculations but the trisodium phosphonoformate and their hexahydrated salts were not studied in that work. On the other hand, the Micro-Fourier Transform Infrared (μFTIR) and Raman spectres copies are very useful techniques to identify and analyze samples in different aggregation state in easy and quick form, such as biopsies and, in particular the presence of phosphate group in foscarnet [9-13]. Hence, the experimental infrared spectrum and imaging from Raman spectroscopy were reported by those authors but the structural properties and vibrational spectra of the trisodium phosphonoformate and their hexa-hydrated salts of foscarnet were no assigned so far.

Authors and Affiliations

Maximiliano A Iramain, Silvia A Brandán

Keywords

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  • EP ID EP585987
  • DOI 10.32474/DDIPIJ.2018.01.000114
  • Views 222
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How To Cite

Maximiliano A Iramain, Silvia A Brandán (2018). Structural and Vibrational Study On the Acid, Hexa-Hydrated and Anhydrous Trisodic Salts of Antiviral Drug Foscarnet. Drug Designing & Intellectual Properties International Journal, 1(3), 90-106. https://europub.co.uk./articles/-A-585987