Integrated profiling of essential metals, phenolic compounds, anti-inflammatory and hydroxyl radical scavenging activities for five medicinal plants

Abstract

Medicinal plants are valuable sources of bioactive compounds. In this study, we analyzed the levels of essential metals (Fe, Cu, Zn, Mn) in the leaves of Punica granatum, Teucrium montanum, Chaerophyllum coloratum, Petteria ramentacea, and Menyanthes trifoliata using atomic absorption spectrophotometry. Ethanolic leaf extracts were assessed for anti-inflammatory activity via bovine serum albumin BSA and egg albumin (EgA) denaturation assays and for antioxidant potential by hydroxyl radical scavenging using EPR (Electron Paramagnetic Resonance) spectroscopy. Metal concentrations varied across species: Fe (33-93 mg/kg), Cu (4.29-11.61 mg/kg), Zn (12.39-105 mg/kg), and Mn (1.38-1005 mg/kg), with T. montanum showing the highest Fe and M. trifoliata with highest Cu, Zn and Mn levels. Total phenolic content (TPC) ranged from 32 to 117 mg/gDW, with the highest in P. granatum, which also demonstrated the strongest hydroxyl radical scavenging. The highest BSA inhibition (~ 80%) was observed in Ch. coloratum, P. granatum, and T. montanum at 0.01 µg/mL TPC. Egg albumin inhibition ranged from 28-50%, with Ch. coloratum being the most active. Significant correlations were found between Cu, Mn, and anti-inflammatory activity, and between Zn, TPC, and both antioxidant and anti-inflammatory effects. These findings suggest a synergistic role of phenolics and trace elements and support the potential use of these plants as dietary supplements against inflammation and oxidative stress.