## 4 Discussion
Out of the numerous acyl-CoA dehydrogenases engaged in the mitochondrial \(\beta\)-oxidation, we chose ACAD9 because it plays a dual function, being not only responsible for providing long-chain fatty acyl-CoA for the breakdown, but it is also necessary for the proper assembly of subunits to form the functional respiratory complex I; therefore, its level reflects the cellular respiratory capacity [51; 52; 53; 54]. ACAD9 is produced in a precursor form with a higher molecular mass (Figures 3d and 4c) and resides mainly in the cytoplasm or nucleus (c/n form). However, after processing with mitochondrial peptidases a 37-amino acid leader peptide is cleaved and a lower molecular mass, approximately 65 kDa, form is finally found in the mitochondria [55]. In HepG2 lysates from the cells treated with the extracts, we noticed a decreased abundance of lower MW mitochondrial forms (Figure 3d) but increased levels of the higher MW forms, which might suggest increased production of premature forms not yet transported to the mitochondria. Decreased FAS protein levels and concomitantly higher ATP-CL amounts in the HepG2 cells treated with RL and RO extracts indicate a possible accumulation of malonyl-CoA (produced by ATP-CL), which is a direct substrate for FAS. Downregulation of FAS suggests that malonyl-CoA cannot be readily utilised, therefore it may act as a carnitine palmitoyltransferase CPT1 inhibitor that blocks fatty acyl-CoA entry to the mitochondria and their subsequent \(\beta\)-oxidation. Such a situation would not be beneficial for efficient lipid catabolism, which is necessary to reduce intracellular lipid storage. On the other hand, malonyl-CoA can be also transformed into acetyl-CoA by malonyl-CoA decarboxylase (MCD). Acetyl-CoA fuels the Krebs cycle to produce reducing equivalents NADH and FADH\({}_{2}\) for oxidative phosphorylation, as well as numerous other important metabolites, so this is the other catabolic route for acetyl-CoA. Although we did not detect any significant differences in the oxLDL phagocytosis by the monocytes treated with the extracts and the control ones, we noticed a strong impact of the treatment on the intensity of the oxidative burst. The RL, RO and DL extracts in the concentration of 50 \(\mu\)g/mL blocked ROS production by monocytes, whereas 10 \(\mu\)g/mL of DL and 50 \(\mu\)g/mL of DO enhanced this response as compared to the control (Figure 5a-d). Large quantities of superoxide anion released during the oxidative burst can react with NO secreted by monocytes and macrophages to form a highly microbicidal and cytotoxic peroxynritrite (ONOO\({}^{-}\)). In our experimental setting, the higher dose of RL extract significantly decreased the amount of NO metabolites in the cell culture supernatants from LPS-stimulated monocytes in comparison to the control. Other extracts showed a modest effect, not reaching statistical significance (Figure 5e). The experiments with J774.A1 monocytes treated with methanolic extracts from the _Cresentia alata_ medicinal plant revealed the inhibition of NO release from the LPS-stimulated cells, as well as decreased iNOS protein levels [56]. The extracts contained rutin, kaempferol glycoside and kaempferol aglycone, but the authors identified kaempferol as the most effective inhibitor of NO production, whereas rutin and kaempferol glycoside were inactive. In our case,the RO extract was the richest source of kaempfer, but it did not significantly affect NO secretion (Figure 5e). Uncontrolled production of reactive oxygen and nitrogen species contributes to intestinal mucosa damage seen in chronic inflammatory conditions such as IBD [57]. The loss of barrier function in the damaged epithelium increases bacterial endotoxin leakage from the lumen, which leads to increased vascular permeability in the jejunum and colon and further aggravates inflammation [58]. RL, RO and DL extracts are particularly rich in rutin and cinnamic acid (RL), myricetin and resveratrol (RO) and phenolic acids and quercetin (DL).