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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. 

Abstract Photodeoxygenation of dibenzothiopheneS‐oxide (DBTO) is believed to produce ground‐state atomic oxygen [O(³P)] in solution. Compared with other reactive oxygen species (ROS), O(³P) is a unique oxidant as it is potent and selective. Derivatives of DBTO have been used as O(³P)‐precursors to oxidize variety of molecules, including plasmid DNA, proteins, lipids, thiols, and other small organic molecules. Unfortunately, the photodeoxygenation of DBTO requires ultraviolet irradiation, which is not an ideal wavelength range for biological systems, and has a low quantum yield of approximately 0.003. In this work, benzo[b]naphtho[1,2‐d]selenopheneSe‐oxide, benzo[b]naphtho[2,1‐d]selenopheneSe‐oxide, dinaphtho[2,3‐b:2’,3’‐d]selenopheneSe‐oxide, and perylo[1,12‐b,c,d]selenopheneSe‐oxide were synthesized, and their ability to utilize visible light for generating O(³P) was interrogated. Benzo[b]naphtho[1,2‐d]selenopheneSe‐oxide produces O(³P) upon irradiation centered at 420 nm. Additionally, benzo[b]naphtho[1,2‐d]selenopheneSe‐oxide, benzo[b]naphtho[2,1‐d]selenopheneSe‐oxide, and dinaphtho[2,3‐b:2’,3’‐d]selenopheneSe‐oxide produce O(³P) when irradiated with UVA light and have quantum yields of photodeoxygenation ranging from 0.009 to 0.33. This work increases the utility of photodeoxygenation by extending the range of wavelengths that can be used to generate O(³P) in solution.