Phenolic Profile and In Vitro Anti‐Inflammatory Activities of Salvia officinalis 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.