Non-oxidized phosphatidylserine (PS) is known to play a key role in apoptosis but there is considerable research evidence suggesting that oxidized PS also plays a role in this event, leading to the increasing interest in studying PS oxidative modifications. In this work, different PS (1-palmitoyl-2-linoleoyl-sn-glycero-3-phospho-L-serine (PLPS), 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-L-serine (POPS), and 1,2-dipalmitoyl-sn-glycero-3-phospho-L-serine (DPPS) were oxidized in vitro by hydroxyl radical, generated under Fenton reaction conditions, and the reactions were monitored by ESI-MS in negative mode. Oxidation products were then fractionated by thin layer chromatography (TLC) and characterized by tandem mass spectrometry (MS/MS). This approach allowed the identification of hydroxyl, peroxy, and keto derivatives due to oxidation of unsaturated fatty acyl chains. Oxidation products due to oxidation of serine polar head were also identified. These products, with lower molecular weight than the non-modified PS, were identified ashydroxyacetaldehyde plus hydroxy fatty acyl chain). Phosphatidic acid was also formed in these conditions. These findings confirm the oxidation of the serine polar head induced by the hydroxyl radical. The identification of these modifications may be a valuable tool to evaluate phosphatidylserine alteration under physiopathologic conditions and also to help understand the biological role of phosphatidylserine oxidation in the apoptotic process and other biological functions.

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Pyridines substituted with different aromatic groups at C-2, C-4 and C-6 were prepared following a Kröhnke synthetic route. Introducing ortho-anisole at C-2 resulted in deep blue emitters in solution, with quantum yields up to 74 %. On the other hand, when ortho-phenol was introduced, forming a strong hydrogen bond with the pyridine nitrogen, excited-state intramolecular proton transfer was witnessed by the dual emission of the fluorophores, which is sensitive to the dye environment. The phenyl ring at C-4 was used to introduce electron-donating or withdrawing groups, to fine-tune the photophysical properties of the dyes. Crystal structures of the fluorophores, together with theoretical studies using DFT/TD-DFT calculations, were used to rationalize the experimental photophysical properties of the two families of dyes. Unsymmetrical 2,4,6-triarylpyridines are therefore versatile scaffolds for the preparation of deepblue and dual emission fluorophores, and are promising building blocks for luminescent devices and sensors.