Background: Nitric oxide (NO) is a biological messenger molecule that plays a significant role in the pathogenesis of inflammation. It has anti-inflammatory effects under physiological conditions but can act as a pro-inflammatory mediator when produced excessively under abnormal conditions. NO is involved in the pathogenesis of inflammatory diseases affecting the joints, intestines, and lungs. Therefore, compounds that inhibit NO production are considered important for the treatment of inflammatory diseases and are used clinically. The RAW 264.7 mouse macrophage-like cell line is a widely used model for inflammation studies. Lipopolysaccharide (LPS), a component of the outer membrane of Gram-negative bacteria, is used to activate RAW 264.7 cells and create an inflammation model. Glycyrrhiza uralensis, also known as licorice, is a perennial herbaceous plant in the Fabaceae family. It has been widely used in traditional medicine due to its anti-inflammatory, antiviral, and hepatoprotective properties. Recent studies have shown that licorice contains bioactive compounds such as glycyrrhizin, liquiritigenin, and isoliquiritigenin, which play an important role in inhibiting the synthesis of pro-inflammatory cytokines in macrophages induced by LPS. Inula helenium L., also known as elecampane, is a perennial herbaceous plant used as an expectorant, anti-infective, anti-inflammatory, and anti-helminthic agent in various respiratory diseases. Licorice and Inula helenium are included in Mongolian traditional medicine prescriptions, but their anti-inflammatory effects have not been fully determined, which forms the basis for this research. Aim: To study the effect of Glycyrrhiza uralensis and Inula helenium extracts on the production of NO, the end product of inflammation, in RAW 264.7 macrophage cell lines stimulated with lipopolysaccharide. Materials and Methods: The non-toxic dose of the plant extracts was determined in RAW 264.7 mouse macrophage-like cell line cultures using the MTT assay. Nitric oxide production in RAW 264.7 cell line cultures stimulated with lipopolysaccharide was assessed using the Griess method. Statistical analysis of the results was performed using SPSS 25.0 software, with the p-value calculated by one-way ANOVA, and the differences between groups were evaluated. Results: In RAW 264.7 cell cultures, Glycyrrhiza uralensis and Inula helenium extracts were non-toxic and promoted cell growth at doses ranging from 1 to 25 μg/ml, while a dose of 50 μg/ml was toxic and inhibited cell growth (p<0.01). When the combined plant extracts were applied to cells at doses ranging from 1 to 100 μg/ml, they were also non-toxic and enhanced cell growth, while a dose of 500 μg/ml was toxic and inhibited growth (p<0.001). In terms of nitric oxide production, Glycyrrhiza uralensis extract increased NO production in a dose- and time-dependent manner compared to the control or PBS-treated group. However, Inula helenium extract did not show a dose- or time-dependent effect on NO production. In the lipopolysaccharide-induced inflammation model, licorice extract inhibited NO production at a dose of 30 μg/ml after 12 hours, and further reduced NO production in a dose- and time-dependent manner after 48 hours. Conversely, no significant changes were observed in the Inula helenium extract group at a dose of 25 μg/ml after 48 hours, but a reduction in LPS-induced NO production was observed at a dose of 25 μg/ml after 48 hours. Conclusion Glycyrrhiza uralensis extract alone increased NO production in a dose- and time-dependent manner. It also reduced LPS-induced NO production in a dose- and time-dependent manner. In contrast, Inula helenium extract inhibited LPS-induced NO production at a dose of 25 μg/ml after 48 hours.

: The increasing prevalence of noncommunicable diseases (NCDs), driven by factors such as population growth, urbanization, and economic development, presents significant individuals, families, challenges and to healthcare systems. These diseases are often linked to lifestyle choices, poor diet, and physical inactivity. As a result, there is growing interest in finding alternatives to synthetic drugs, particularly those derived from medicinal plants. Medicinal plants are known to contain bioactive compounds that offer therapeutic properties with fewer side effects compared to conventional pharmaceuticals. This study explores the cytoprotective effects of Glycyrrhiza uralensis (licorice) and Inula helenium (elecampane) extracts against oxidative stress induced by hydrogen peroxide (H₂O₂) in RAW 264.7 macrophage-like cells.
The study found that both plant extracts were non-toxic at doses ranging from 1 to 25 µg/mL and promoted cell growth (p<0.01). The results suggest that these extracts support cell survival and exhibit biological activity.
To assess the antioxidant effects, various concentrations of H₂O₂ (10–400 µM) were tested, and 200 µM was found to significantly reduce cell viability. Licorice and elecampane extracts (10 µg/mL and 25 µg/ mL, respectively) enhanced cell viability and reduced oxidative damage. Both extracts significantly reduced cell death compared to the H₂O₂-only group (p<0.01), highlighting their potent antioxidant properties. Conclusion Glycyrrhiza uralensis and Inula helenium extracts demonstrated strong cytoprotective and antioxidant effects, supporting their potential as natural therapeutics for oxidative stress-related conditions.