## 3 Results
### Structural Elucidation of PLs by LC-MS Analysis  
LC-MS (Liquid Chromatography-Mass Spectrometry) was used for the identification of the bioactive polar lipids contained in apple-derived TAC extracts from juice and its by-products. The results showed a variety of polar lipids as presented in Table 9. Moreover, the analysis focused on Glycerophospholipids (GP) and Glyceroglycolipids (GL), specifically in Phosphatidylethanolamines (PE), phosphatidylcholines (PC), Glycerophosphoinositi (PI), Digalactosyl diglyceride (DGDG), monogalactosyl di-glyceride (MGDG) and Sulfoquinovosyldiacylglycerols (SQDG), as other studies on apples presented that the vast majority of the polar lipids in such extracts consist mainly of these subclasses [29; 30]. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & \multicolumn{4}{c}{**TAC Extracts from Apple Juice**} & \multicolumn{4}{c}{**TAC Extracts from Apple By-Products**} \\ \hline
**Main** & **Elution** & **Time** & **Representative** & **Proposed** & **Elution** & **Time** & **Mr** & **Representative** & **Proposed** \\
**Classes of** & **Time** & **(min)** & **Mr** & **Species** & **(min)** & **Mr** & **Species** & **Structures** \\ \hline  & 5.4–5.7 & 718.9 & PC 32:0 & (i.e., PC 16:0/16:0 or PC 18:0/14:0) & 6.3–6.4 & 786.9 & PC 0-3  
Similarly to what was observed by the quantification of the fatty acid composition of apple PL, most of these bioactives were found to contain esterified in their structures mainly the SFA SA (Stearic acid) (18:0) and PA (Palmitic acid) (16:0) followed by the PUFA LA (18:2 n-6), ALA (18:3 n-3) and MUFA OA (Oleic acid) (18:1), with the SFA tending to be present in the \(sn1\) position of the glycerol backbone of their structures, while the UFA (either MUFA or PUFA) being commonly present at the \(sn2\) position of these PL. This positional specificity strongly affects the biochemical properties and functions of the compounds, including membrane fluidity and enzyme interactions. The majority of these bioactives were found to contain esterified in their structures, primarily the SFA SA (stearic acid) (18:0) and PA (palmitic acid) (16:0), followed by the PUFA LA (18:2 n-6), ALA (18:3 n-3), and MUFA OA (oleic acid) (18:1). Similar to what was observed by the quantification of the fatty acid composition of apple PL, the SFA tended to be present in the sn1 position of the glycerol backbone of these PL, while the UFA (either MUFA or PUFA) was frequently present at the sn2 position. The chemicals' biological characteristics and functions, such as membrane fluidity and enzyme interactions [31], like the previously described one with PLA2, which provides anti-inflammatory intracellular signaling, are significantly impacted by this positional specificity [24]. More specifically, in the primary classes of interest within apple PL, namely PC and PE, both alkyl-acyl and/or di-acyl variants were identified. Notably, these molecules contain MUFA or PUFA in the SN2 position of their glycerol backbones. Such phospholipids have shown significant anti-PAF anti-inflammatory actions, by functioning as a potent PAF antagonist or, in some cases, less active agonist. They achieve this by inhibiting the binding of PAF to its specific receptor (PAF-r), thereby preventing PAF-induced activation of various cells including platelets and disrupting the thrombo-inflammatory cascades associated with the PAF/PAF-R pathway [3,24]. In platelets, the antagonistic or agonistic inhibition of PAF activity by these bioactive phospholipids diminishes PAF-induced platelet activation and aggregation. This results in protective and therapeutic benefits, contributing to the prevention of cardiovascular diseases and tumor metastasis [24]. Also, following digestion, some parts of these dietary PL bioactives have the ability to incorporate into the lipoproteins and cell membranes of various cells, which can positively