Phytochemical Characterization of Euphorbia peplis Extracts and Their Antioxidant, Enzyme Inhibitory, and Cytotoxic Activities: An Integrated Experimental and In Silico Study

Euphorbia members (Euphorbiaceae) are valuable sources of lead compounds for potential drug discovery. This study was conducted to evaluate, for the first time, the phytoconstituents, antioxidant capacity, enzyme inhibitory, and cytotoxic properties of E. peplis. Extracts were prepared from the aerial parts using ethyl acetate (EtOAc), ethanol (EtOH), 70% EtOH, and water. Results showed that the 70% EtOH and EtOH extracts contained the highest levels of total phenolics (68.12 mg GAE/g) and flavonoids (45.49 mg RE/g). UPLC-ESI-MSn analysis revealed a variety of phytochemicals, including flavonoids, cinnamic acid derivatives, tannins, triterpenoids, and saponins, with 24 metabolites tentatively identified. PCA grouped these metabolites into three clusters, and their distribution was visualized with a heatmap. Polar extracts demonstrated strong antioxidant activity, with the 70% EtOH extract showing the highest values in most assays (DPPH = 385.50 mg TE/g; ABTS = 466.31 mg TE/g; CUPRAC = 439.95 mg TE/g; FRAP = 305.07 mg TE/g; PBD = 2.45 mmol TE/g). The EtOH and EtOAc extracts exhibited the strongest anti-acetylcholinesterase (2.83 mg GALAE/mg) and anti-butyrylcholinesterase (2.18 mg GALAE/mg) activities, respectively. Both the 70% EtOH and EtOH extracts showed the best anti-tyrosinase effects (54.40 and 53.39 mg KAE/g; p ≥ 0.05). The EtOAc extract was more toxic toward SHSY5Y cells, with a viability of 4.31%, compared to 8.18% in normal KEK293 cells. Network pharmacology identified 11 common targets for E. peplis metabolites, with AKT1, EGFR, GSK3B, ESR1/ESR2, and CCND1 serving as key hubs. Pathway enrichment analysis highlighted PI3K-Akt, EGFR, and hormone-related pathways. Docking and molecular dynamics simulations confirmed stable multi-target binding. These findings suggest that E. peplis could be a promising source of antioxidants and compounds with potential anticancer and enzyme-inhibitory activities relevant to human diseases.