Protonation Equilibria of N-Acetylcysteine

Ahmed E Fazary; Nasser S Awwad; Hala A Ibrahium; Ali A Shati; Mohammad Y Alfaifi; Yi-Hsu Ju

doi:10.1021/acsomega.0c02080

Protonation Equilibria of N-Acetylcysteine

ACS Omega. 2020 Aug 3;5(31):19598-19605. doi: 10.1021/acsomega.0c02080. eCollection 2020 Aug 11.

Authors

Ahmed E Fazary¹, Nasser S Awwad², Hala A Ibrahium^{3

4}, Ali A Shati⁵, Mohammad Y Alfaifi⁵, Yi-Hsu Ju⁶

Affiliations

¹ Applied Research Department, Research and Development Sector, Egyptian Organization for Biological Products and Vaccines (VACSERA Holding Company), 51 Wezaret El-Zeraa St., Agouza, Giza 22311, Egypt.
² Department of Chemistry, Faculty of Science, King Khalid University, P.O. Box 9004, Abha 61413, Saudi Arabia.
³ Biology Department, Faculty of Science, King Khalid University, Abha 9004, Kingdom of Saudi Arabia.
⁴ Department of Semi Pilot Plant, Nuclear Materials Authority, P.O. Box 530, El Maadi, Cairo 11381, Egypt.
⁵ Department of Biology, Faculty of Science, King Khalid University, Abha 9004, Kingdom of Saudi Arabia.
⁶ Graduate Institute of Applied Science and Technology, Department of Chemical Engineering, Taiwan Building Technology Center, National Taiwan University of Science and Technology, 43 Section 4, Keelung Road, Taipei 10607, Taiwan.

Abstract

The acid base protonation equilibria of N-acetylcysteine (Nac) and its equilibrium constants in water solutions were determined by the Hyperquad 2008 software assessment from the pH potentiometry data, which provides a diversity of statistics presentations. The effect of a number of organic solvents on the acid base protonation processes was also examined. The solution equilibria of N-acetylcysteine (Nac) were studied at T = 298.15 K in water (w ₁) + organic liquid mixtures [100 w ₂ = 0, 20, 40, 60, and 80%] with an ionic strength of I = 0.16 mol·dm^-3 NaNO₃. Also, the organic solvent's influence was studied based on the Kamlet-Taft linear solvation energy relationship. The experimental results were compared with theoretical ones obtained via the Gaussian 09 calculation computer program. The protonation equilibria of Nac were found to be important in the progress of separation systems in aqueous and non-aqueous ionic solutions. Nac showed a likely good metal dibasic chelating bioligand as the DFT calculations proved two binding sites. Spectrophotometry evaluation was also done for N-acetylcysteine bioligands at various pH values in water solutions then its absorbance ratio was measured.