Phenolic Profile and In Vitro Anti‐Inflammatory Activities of <i>Salvia officinalis</i> L. Hydrodistillation Wastewater

Salvia officinalis L. essential oil production process generates an exhausted residue of vegetable biomass, returned by hydrodistillation, along with a variable amount of wastewater enriched in water-soluble compounds of high added value and biological activity. The aim of this study was to investigate the in vitro anti-inflammatory effects of S. officinalis L. hydrodistillation wastewater using murine macrophage Raw 264.7 cells stimulated with Escherichia coli lipopolysaccharide (LPS) and human intestinal epithelial Caco-2 cells exposed to E. coli. Polyphenolic compounds in wastewater were identified by high-performance liquid chromatography-mass spectrometry analysis, confirming the presence of organic acids (particularly hydroxycinnamic acids), flavones, and flavonols. This phytocomplex protected Raw 264.7 from E. coli LPS-induced inflammation by reducing nuclear factor kappa B nuclear translocation and its transcriptional activity (interleukin [IL]-6, IL-8, and tumor necrosis factor-alpha messenger RNA levels). Additionally, the wastewater reduced cyclooxygenase-2 protein expression in Caco-2 cells challenged with E. coli. Interestingly, E. coli exposure resulted in a significant decrease in trans-epithelial electrical resistance values in Caco-2 cells, reflecting impaired barrier integrity, which was reverted by S. officinalis L. wastewater, and this effect was associated with claudin-1 and occludin restoration, essential for maintaining intestinal barrier function. Present data confirms the protective effect of S. officinalis L. hydrodistillation wastewater in E. coli-induced inflammation, suggesting its potential application in the prevention and/or treatment of intestinal inflammation.