Anti-Inflammatory and Anti-Fibrotic Effects of a Mixture of Polyphenols Extracted from “Navelina” Orange in Human Hepa-RG and LX-2 Cells Mediated by Cannabinoid Receptor 2

Navelina oranges (<i>Citrus sinensis</i>) are rich in phytonutrients and bioactive compounds, especially flavonoids like hesperidin. This study investigates the anti-inflammatory and anti-fibrotic properties of hesperidin (HE) and a polyphenol mixture from Navelina oranges (OE) in human hepatocytes (Hepa-RG) and hepatic stellate cells (LX-2), in order to elucidate the underlying molecular mechanisms. In Hepa-RG cells, HE treatment increased expression of cannabinoid receptor 2 (CB2R), which was associated with down-regulation of p38 mitogen-activated protein kinases (p38 MAPK) but had minimal impact on cyclooxygenase-2 (COX-2) and transforming growth factor-β (TGF-β) levels. Conversely, OE treatment not only enhanced CB2R levels and reduced p38 MAPK, but also promoted a significant reduction in both COX-2 and TGF-β levels, suggesting that OE might be more effective in mitigating inflammatory and fibrotic processes than HE. In LX-2 cells, HE treatment caused a notable decrease in both COX-2 and TGF-β levels, reflecting its efficacy in targeting fibrosis-associated inflammation. OE treatment, on the other hand, reduced Nuclear Factor-Kappa B p65 (NF-κB) expression, a critical transcription factor involved in inflammatory responses, though it did not significantly affect COX-2. LX-2 cells induced to fibrosis with TGF-β and treated with HE and OE showed a reduction in the expression levels of several fibrosis markers. In addition, HE and OE showed antioxidant effects by increasing protein levels of Cu, Zn superoxide dismutase (SOD1), Mn superoxide dismutase (SOD2) and catalase (CAT) and influencing the state of lipid peroxidation. Further research is needed to explore the effects of the treatments in activated hepatic stellate cells and in vivo liver disease models.