Antioxidant Potential and Antibacterial Activities of Caucasian Endemic Plants Sempervivum transcaucasicum and Paeonia daurica subsp. mlokosewitschii Extracts and Molecular In Silico Mechanism Insights

Antioxidants derived from plant extracts have attracted considerable attention due to their potential in mitigating oxidative damage through free radical scavenging mechanisms. Although 700 species have been used for centuries in Georgian traditional medicine, the chemical composition and antioxidant and antibacterial properties of Caucasian endemic medicinal plants remain largely unknown. In this study, the antioxidant and antibacterial activities of leaf and root extracts of Caucasian endemic medicinal plants Sempervivum transcaucasicum Muirhead and Paeonia daurica subsp. mlokosewitschii (Lomakin) D. Y. Hong were investigated. The highest antioxidant activity and phenolic and flavonoid content were revealed in Paeonia daurica leaf extract. The analysis of the content of water-soluble antioxidants revealed the highest content of reduced glutathione and ascorbate in Paeonia daurica leaves. Moreover, the antibacterial activity of leaf and root extracts against Escherichia coli ATCC 25922 strain was investigated, and minimal inhibitory concentration (MIC) values were determined. While the antibacterial activity against E. coli ATCC 25922 was not revealed for the Sempervivum transcaucasicum leaf extract, antibacterial properties were detected for the root extract (MIC 5 mg/mL). Collectively, the highest antibacterial activity was revealed for Paeonia daurica leaf and root extracts (MIC 2 mg/mL and 3 mg/mL, respectively). From a molecular perspective, molecular docking simulations were performed using HDOCK software, with reduced glutathione and ascorbic acid as ligands, in order to analyse their potential binding affinity to the OmpX protein. Inhibiting this protein would likely disrupt bacterial function and produce an antibacterial effect. Our results provide a possible mechanism for the antibacterial activity of Paeonia daurica subsp. mlokosewitschii. Overall, the results of the study demonstrate the potential of Caucasian endemic medicinal plants as natural antioxidants and antimicrobial agents.