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. 2024 Feb 9;17(2):233.
doi: 10.3390/ph17020233.

Determining the Oxidation Mechanism through Radical Intermediates in Polysorbates 80 and 20 by Electron Paramagnetic Resonance Spectroscopy

Adam T Sutton  1 , Richard R Rustandi  1
Affiliations

Determining the Oxidation Mechanism through Radical Intermediates in Polysorbates 80 and 20 by Electron Paramagnetic Resonance Spectroscopy

Adam T Sutton et al. Pharmaceuticals (Basel). .

Abstract

Polysorbates 20 and 80 (PS20 and PS80) are added to many commercial biologic and vaccine pharmaceuticals. It is commonly known that these polysorbates undergo a radical oxidation mechanism; however, the identity of these radical intermediates has not been clearly determined. Furthermore, PS20 and PS80 differ by the presence of a lauric acid instead of an oleic acid, respectively. The oxidation of PS80 is thought to be centered around the double bond of the oleic acid even though PS20 also undergoes oxidation, making the mechanism of oxidation unclear for PS20. Using commercial stocks of PS20 and PS80 alkyl (R•), alkoxyl (C-O•) and peroxyl (C-OO•) radicals were detected by electron paramagnetic resonance spectroscopy likely originating from radical-initiating species already present in the material. When dissolved in water, the peroxyl radicals (C-OO•) originally in the stocks were not detected but poly(ethylene oxide) radicals were. An oxidative pathway for polysorbates was suggested based on the radical species identified in the polysorbate stock material and solutions.

Keywords: electron paramagnetic resonance spectroscopy; oxidation; polysorbates; radical intermediates; reaction mechanism.

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Conflict of interest statement

Authors Adam T. Sutton and Richard R. Rustandi were employed by the company Merck & Co., Inc. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Figures

Figure 1
Figure 1
Target chemical structure of (a) polysorbate 20 and (b) polysorbate 80. The polyethylene oxide (PEO) chains are shown in blue; the fatty acid is shown in red, and the sorbitol group is shown in black.
Figure 2
Figure 2
EPR spectra of neat PS20 and PS80 stocks with DMPO, as well as simulations of spectra from DMPO radical adducts of R•, R-OO•, R-O• and DMPO-X.
Figure 3
Figure 3
EPR spectra of 10% aqueous PS20 and PS80 with DMPO, as well as simulations of spectra from DMPO radical adducts of •OH, R•, R-O• and DMPO-X.
Figure 4
Figure 4
Proposed oxidation pathway for PSs. Full-line boxes indicate intermediate radical species were detected. R1 is the saturated and unsaturated alkyl chains of the fatty acids in the PS. R2 is the sorbitol and PEO groups of the PS (see Figure 1). The black dots show the position of the radical.
See this image and copyright information in PMC

References

    1. Ionova Y., Wilson L. Biologic excipients: Importance of clinical awareness of inactive ingredients. PLoS ONE. 2020;15:e0235076. doi: 10.1371/journal.pone.0235076. - DOI - PMC - PubMed
    1. Tekewe A., Connors N.K., Sainsbury F., Wibowo N., Lua L.H.L., Middelberg A.P.J. A rapid and simple screening method to identify conditions for enhanced stability of modular vaccine candidates. Biochem. Eng. J. 2015;100:50–58. doi: 10.1016/j.bej.2015.04.004. - DOI
    1. Benkert C., Freyburger A., Huber V., Touraud D., Kunz W. Development of a fully water-dilutable mint concentrate based on a food-approved microemulsion. Food Chem. 2022;372:131230. doi: 10.1016/j.foodchem.2021.131230. - DOI - PubMed
    1. Agarkhed M., O’Dell C., Hsieh M.C., Zhang J., Goldstein J., Srivastava A. Effect of Surfactants on Mechanical, Thermal, and Photostability of a Monoclonal Antibody. AAPS PharmSciTech. 2018;19:79–92. doi: 10.1208/s12249-017-0845-7. - DOI - PubMed
    1. Cottrell T., Peij J.V. Emulsifiers in Food Technology. 2nd ed. John Wiley & Sons; Hoboken, NJ, USA: 2015. Sorbitan Esters and Polysorbates; pp. 271–296.

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