Antioxidant and antimicrobial activities of ethanol and aqueous extracts from Urtica urens

Context: Urtica urens L. (Urticaceae) is an important and commonly used plant for its medicinal and pharmacological properties. Objective: We analyzed the antioxidant and antimicrobial activities of the leaves of Urtica urens in ethanol (EtOH) and water (WA) solvents, employing standard analytical methods. Materials and methods: Polyphenol, flavonoid and tannin content of Urtica urens leaves were determined, after their extraction, using EtOH (70%) and WA extracts as well as the antioxidant (DPPH, ABTS, β-carotene and FRAP) and the antibacterial (via the method of dilution tests) activities of EtOH and WA extracts. Results: The 70% EtOH of Urtica urens showed the highest values of total phenolic (31.41 mg GAE/g DW), flavonoids (6.81 mg quercetin/g DW), tannin (8.29 mg GAE/g DW) and TEAC (560 mmol Trolox/g DW), compared to the WA. The results of DPPH for EtOH (95.56%) were higher than that of WA (64.56%) at a concentration of 40 mg/L. The extracts displayed a FRAP 106.23 for EtOH and 30.55 μmol Fe(II)/g DW for WA. The results clearly indicated that EtOH was the strongest radical scavenger (IC50 = 245.65 ± 10.2 μg/mL). Ethanol was the most effective with minimum inhibitory concentration (MIC) < 250 μg/mL. WA has no antibacterial activity. Discussion and conclusion: The results indicate that leaves of Urtica urens could be used as natural antioxidant and antimicrobial agents