Investigation of the Formation of Squalene Oligomers Exposed to Ultraviolet Light and Changes in the Exposed Squalene as a Potential Skin Model

Abstract

UV-induced oligomerisation of squalene was undertaken to indicate the potential for squalene-containing biological systems to exhibit rheology changes. DOSY NMR enabled the determination of the molecular weight (MW) range using Stokes–Einstein Gierer–Wirtz Estimation (SEGWE Calculator, University of Manchester). This approach was validated by Atmospheric Solids Analysis Probe Time of Flight Mass Spectrometry (ASAP TOF MS). To demonstrate the principle, both benzoyl peroxide and AIBN were used, separately, to initiate rapid, radical oligomerisation. Subsequent experiments in the absence of initiators compared the influence of UV wavelength and time on the resulting oligomer formation. To further model a relevant biological implication of this potentially chaotic UV oligomerisation, both saturated and unsaturated free fatty acids were added to squalene and exposed to UV at 285 nm and 300 nm to determine if cross oligomerisation could be observed. This representation of sebum evidenced the formation of a distribution of higher MW oligomers. Internal viscosity was normalised using the DMSO solvent, but to confirm that changes in rheology did not affect diffusion, a final experiment where fresh squalene was added to our oligomer mixture, representative of sebum, showed that unchanged squalene possessed the anticipated monomeric diffusion coefficient and hence MW. This work suggests, at least qualitatively, that UV-induced squalene oligomerisation can occur over time and that this may have a role in the behaviour of squalene on the skin.

Kinetics of Squalene Quenching Singlet Oxygen and the Thermal Degradation Products Identification

“…The 14 components can be classified as 2 ketones, 5 aldehydes, 2 epoxides, and 5 alcohols, among which 1–6 were volatile products, with their retention indices shown in Supporting Information, Table S2, while 7–14 were nonvolatile products. Based on the qualitative analysis of products, the formation of thermal decomposition products of squalene and high molecular weight products may have been due to the free radical-catalyzed polymerization of squalene . Previous literature utilized squalene thermal degradation to identify a total of 8 products but characterizing only the higher molecular weight ones.…”

“…Based on the qualitative analysis of products, the formation of thermal decomposition products of squalene and high molecular weight products may have been due to the free radical-catalyzed polymerization of squalene. 42 Previous literature 15 utilized squalene thermal degradation to identify a total of 8 products but characterizing only the higher molecular weight ones.…”

Squalene Peroxidation and Biophysical Parameters in Acne-Prone Skin: A Pilot “In Vivo” Study

“…The main porphyrin identified in patients with acne is coproporphyrin III, which is present in large amounts in acne lesions, and it is responsible for the inflammatory process [14]. In addition, solar radiation exposure can aggravate skin condition [15]. Squalene peroxide can induce an inflammatory response of keratinocytes through the activation of LOX, a lipoxygenase enzyme capable of producing conjugated hydroperoxides through the oxidation of polyunsaturated fatty acids.…”