Lemon Pepper Fruit Extract (Zanthoxylum acanthopodium DC.) Suppresses the Expression of Inflammatory Mediators in Lipopolysaccharide-Induced Macrophages In Vitro

Problem statement: Lemon pepper fruits (Zanthoxylum acanthopodium DC.; Rutaceae) have been used as a traditional source against stomach ache by Batak people in North Sumatera province, Indonesia. However, its scientific evidence for treatment of inflammatory disorders particularly gastritis has not been reported. Approach: Here, we investigated the inhibitory effects of Lemon Pepper Fruit Extract (LPFE) against inflammatory biomarkers by conducting cell culture experiments in vitro. The fruits of lemon pepper were dried and extracted twice in 70% ethanol, followed by evaporation and freeze-drying. The concentrated extract was further tested for its potential inhibition on the protein and gene expression of several inflammatory biomarkers, i.e., Tumor Necrosis Factor (TNF)-α, Interleukin (IL)-6, inducible Nitric Oxyde Synthase (iNOS), Cyclooxygenase (COX)-2 and Matrix Metalloproteinase (MMP)-9, in lipopolysaccharide (LPS)-induced macrophages by performing Western blot, gelatin zymography and Reverse Transcription-Polymerase Chain Reaction (RT-PCR). Results: LPFE (1-10 μg mL^-1) and LPS (2 μg mL^-1) had no cytotoxicity effects on macrophages. LPFE dose dependently decreased the expression of TNF-α and COX-2 proteins and MMP-9 activity in macrophages treated with LPS. At the gene level, LPFE were effectively found to block the mRNA expression of TNF-α, IL-6, iNOS, COX-2 and MMP-9. Conclusion: Our results suggest that LPFE significantly inhibits selected inflammatory biomarkers at the protein and gene levels in LPS-induced macrophages. Further in vivo study using animal models is needed to determine the exact anti-inflammatory potential of LPFE.