Endemic Plant <i>Rumex balcanicus</i>: Phenolic Composition, Antioxidant Activity, Enzyme Inhibitory Potential and Molecular Docking Analysis

Although the nutritional and health benefits of Rumex species are well known, little is known about the chemical composition and pharmacological activities of Rumex balcanicus Rech. fil. (Polygonaceae), an endemic plant of the Balkan Peninsula. To the best of our knowledge, this paper represents the first attempt to comparatively analyse phenolic composition, as well as in vitro pharmacological activites of dry hydromethanol extracts of R. balcanicus fruit (RBF), leaf (RBL) and root (RBR), collected in Serbia. The maximum total phenolic content was found in RBF (386.6 mg GAE/g). The RBF was characterized by high amounts of miquelianin (28.8 mg/g) and procyanidin B₁ (28.1 mg/g). The RBL was the richest in quercitrin (18.4 mg/g) and miquelianin (15.0 mg/g), while nepodin (54.1 mg/g) and procyanidin B₂ (40.6 mg/g) were the major compounds in RBR. The RBF exhibited significant antioxidant activity, evaluated by DPPH (IC₅₀=4.9 μg/mL), ABTS (IC₅₀=0.8 μg/mL) and FRAP (5.9 mmol Fe²⁺/g) assays. Moreover, RBF showed strong α-glucosidase inhibitory activity (IC₅₀=1.8 μg/mL), in addition to notable anti-α-amylase, anti-acetylcholinesterase and anti-tyrosinase activities. Molecular docking analysis predicted miquelianin and procyanidin B₂ as the greatest inhibitors of these enzymes. Overall, R. balcanicus fruits stood out as the most promising plant material worth further research.