Reactive oxygen species (ROS) in colloidal systems: Are “PEG-free” surfactants the answer?

[Display omitted] •Reactive oxygen species (ROS) and autoxidative markers were formed in polyethylene glycol and polyglycerol (PG) surfactants.•Based on the polyether structure and the autoxidative marker PG-surfactant degradation by radical chain reaction is assumed.•Superior stability to heat- and photo-induced autoxidation and reduced ROS formation was shown for PG- over PEG-surfactants.•This higher autoxidative stability improved colloidal stability of PG-surfactant-based systems under stress conditions.•The oxidation of ß-carotene in colloidal systems based on PG-surfactants was 40-fold lower than with PEG-surfactants.•PG-surfactants represent a promising "PEG-free" alternative to tackle oxidation processes in colloidal systems. Evaluation and comparison of polyglycerol- (PG-) and saccharide- (SA-) surfactants as “PEG-free”-alternative for polyethylene glycol- (PEG-) surfactants to tackle autoxidation, reactive oxygen species (ROS) formation and degradation of oxidation-prone active ingredients in colloidal systems. 30 different surfactants were screened for hydroperoxides (HPO), aldehydes, and acid formation serving as autoxidative markers. In a comparative set-up, selected surfactants of each head group type were investigated for temperature- and photo-induced ROS formation. Oxidation markers, as well as the degradation of ß-carotene as model active ingredient in colloidal systems were monitored. The screening revealed elevated HPO and aldehyde levels for both PG and PEG surfactants, unlike SA surfactants, suggesting similar autooxidation processes due to their polyether substructure. However, in a comparative set-up, PEG-surfactants showed irrespective of the stress conditions or the colloidal systems at least 4-fold higher HPO and aldehyde concentrations, as well as more pronounced pH drops compared to PG- and SA-surfactants. ß-Carotene oxidation was 40- to 50-fold lower in colloidal systems based on PG- or SA-surfactants, confirming reduced ROS formation by “PEG-free”-surfactants. Moreover, superior autoxidation and degradation stability under oxidative conditions resulted in improved colloidal stability of PG- and SA-surfactant based systems. Hence, “PEG–free”– surfactants represent a causal approach to mitigate autoxidation processes in oxidation-prone pharmaceutical and cosmetic products.