Antioxidant and inhibitory effect of selected ghanaian vegetables on nitric oxide expression in lipopolysaccharide-induced macrophage cells

Objective: Nitric oxide (NO) is a signaling molecule that plays a key role in the pathogenesis of inflammation. Inhibitors of NO may be useful candidates for the treatment of inflammatory diseases. The study aimed to determine the antioxidant and inhibitory effect of commonly used Ghanaian vegetables, namely Corchorus olitorius (CO), Solanum melongena (SM), Solanum torvum (ST), Xanthosoma sagittifolia (XS) and Abelmoschus esculentus (AE) on NO expression in a Lipopolysaccharide (LPS)-induced RAW 264.7 macrophage cell line. Methods: The cytotoxic effects of the vegetables on the cell line were determined using a tetrazolium-based colorimetric assay. The inflammatory activity was determined by measuring the inhibition of NO production in LPS-induced RAW 264.7 macrophage cells. Total antioxidant activity, total phenolic, flavonoid, and reduced glutathione contents were evaluated using 2, 2-diphenyl-1-picrylhydrazyl (DPPH) assay, Folin-Ciocalteu, aluminium chloride, and O-Phthalaldehyde methods, respectively. Results: Our results showed that CO and ST significantly inhibited NO production in a concentration-dependent manner with good cell viability. Solanum torvum also exhibited strong antioxidant activity (IC50= 0.466±0.23 mg/ml) with total phenolic content of 230.73±1.84 mg/g GAE, while CO showed high flavonoid content (291.45±2.14 mg/g QUE). Abelmoschus esculentus recorded the highest glutathione content (58.6 µg/g GSH. Saponins, alkaloids, tannins, terpenoids, and cardiac glycosides were present in all the samples except SM and AE, which lacked terpenoids. Conclusion: These findings suggest that CO and ST possess anti-inflammatory and antioxidant activities that could be explored as potential therapeutic remedies for inflammatory disorders.