## 3 Results and Discussion
### High-Resolution Mass Spectrometry Analysis
As previously reported [47], the molecular formulas and the abundance of lipids, extracted from mass list gained by ESI(\(-\)) MS analysis, have been summed up here in two main clusters: saturated medium-long chain fatty acids (SFA, 18:0-20:0) and C18 series (18:0-18:4) (Figure 3A,B). Figure 3A displays that the most abundant SFA are palmitic acid (C16:0) and stearic acid (C18:0), reaching 56% and 26%, respectively, followed by arachidonic (12%) and myristic (6%) acids. Notably, considering the unsaturation degree within the C18 series, the percentage of oleic acid (C18:1) appears relatively higher (>60%), followed by stearic and linoleic (C18:2) acids that both achieve ca. 15%. Linolenic (C18:3) and stearic acid (C18:4) turned out to be the least abundant fatty acids, with values less than 1% and 5%, respectively. Thereby, FT-ICR MS analysis has confirmed a composition rich in saturated and unsaturated fatty acids, particularly palmitic (C16:0) and oleic (C18:1) acids. These molecules, along with capric (C10:0), linoleic (C18:2) and hydroxylinoleic acids, all identified in the analyzed sample, are well recognized for their antimicrobial properties, in particular their activity against _S. aureus_ and _S. epidermidis_[48]. Indeed, as reported in the literature [49], long-chain unsaturated fatty acids, including some of the fatty acids identified herein, exhibit their antimicrobial property by inhibiting bacterial enoyl-acyl carrier protein reductase (FabI), consequently stopping the bacterial fatty acids' biosynthesis. In addition, palmitoleic acid (C16:1), found in ESI(\(-\)) MS at \(m/z\) 253.21685 as a deprotonated ion, is endowed with selective antibacterial activity against _S. aureus_[50]. Figure 2: Donut chart regarding the elemental composition of LO sample. The chart shows the relative frequency of the CHO, CHNO, CHNOS, CHNOP, CHOS, CHN, CHOP, CHNOPS population. Numerous phenolic compounds, such as organic acids, terpenes and flavonoids, have been also revealed. Due to the presence of hydroxyl groups, phenolic compounds show high antimicrobial activity by disrupting cellular membrane integrity [51]. Among the organic acids, to name a few, chlorogenic acid (5-caffeoylquinic acid), vanillin acid, a hydroxybenzoic acid, hydroxycinnamics acids, like p-coumaric, caffeic, feruloylquinic and dihydroferulic acids, and an intermediate in the metabolism of ferulic acid, were found. These metabolites refer to the general families of chlorogenic acids known for their antioxidant, anti-inflammatory and anticancer properties [52]. In particular, chlorogenic acid acts as an antimicrobial agent by irreversibly permeating the bacterial cell membrane, leading to an alteration of intracellular potential and consequent cell death [53]. ESI FT-ICR MS revealed the presence of a rich variety of terpenes and terpenoids, endowed with antioxidant and antimicrobial activities [54], like monoterenes as myrcene [C\({}_{10}\)H\({}_{16}\) + H]\({}^{+}\) discovered at \(m/z\) 137.13247 and also confirmed by GC-MS, monoterpenoids, such as geraniol [C\({}_{10}\)H\({}_{18}\)O\({}_{4}\) + H]\({}^{+}\) revealed at \(m/z\) 203.12755, citronellic acid, limonea aldehyde, and thymol/carvacrol (C\({}_{10}\)H\({}_{14}\)H) isomers identified at \(m/z\) 149.09815 as deprotonated ion,  
Figure 3: Histograms of the relative abundance distribution within specific classes of FA: saturated (**A**); C18 series (**B**) obtained by ESI(\(-\)) FT-ICR MS analyses of LO sample. and at \(m/z\) 189.06837 as potassiated adduct. As reported in recent works [55], the latter complex is known for the antimicrobial activity alongside the potential reduction in biofilm formation against _S. aureus_. MS analysis also evidenced the presence of sesquiterpenes, including gingerol and cadalene, revealed as protonated species. Furthermore, geranyl-diphosphate, an intermediate in the biosynthesis pathway of terpen, with a toxic effect in vitro on _E. coli_[56], has been identified at \(m/z\) 315.07614 ([M + H]+).