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Abstract Lipid oxidation by reactive oxygen species (ROS) provide several different oxidation products that have been implicated in inflammatory responses. Ground state atomic oxygen [O(³P)] is produced by the photodeoxygenation of certain heterocyclic oxides and has a reactivity that is unique from other ROS. Due to the reactive nature of O(³P), the site of O(³P)‐generation is expected to influence the products in heterogenous solutions or environments. In this work, the oxidation of low‐density lipoprotein (LDL) by lipids with covalently bound O(³P)‐photoprecursors was compared to more hydrophilic O(³P)‐photoprecursors. Lipid oxidation products were quantified after Bligh‐Dyer extraction and pentafluorobenzyl bromide (PFB) derivatization by GC–MS. Unlike the more hydrophilic O(³P)‐photoprecursors, the oxidation of LDL during the irradiation of lipid‐(O³P)‐photoprecursor conjugates showed little quenching by the addition of the O(³P)‐scavenging sodium allyl sulfonate. This indicated that lipophilic O(³P)‐photoprecursors are expected to generate lipid oxidation products where other more hydrophilic O(³P)‐photoprecursors could be quenched by other reactive groups present in solution or the environment. 

A beneficial property of photogenerated reactive oxygen species (ROS) is the capability of oxidant generation within a specific location or organelle inside a cell. Dibenzothiophene S -oxide ( DBTO ), which is known to undergo a photodeoxygenation reaction to generate ground state atomic oxygen [O( 3 P)] upon irradiation, was functionalized to afford localization within the plasma membrane of cells. The photochemistry, as it relates to oxidant generation, was studied and demonstrated that the functionalized DBTO derivatives generated O( 3 P). Irradiation of these lipophilic O( 3 P)-precursors in the presence of LDL and within RAW 264.7 cells afforded several oxidized lipid products (oxLP) in the form of aldehydes. The generation of a 2-hexadecenal ( 2-HDEA ) was markedly increased in irradiations where O( 3 P) was putatively produced. The substantial generation of 2-HDEA is not known to accompany the production of other ROS. These cellular irradiation experiments demonstrate the potential of inducing oxidation with O( 3 P) in cells.