Pharmacological and toxicological evaluation of Urtica dioica

Medicinal plants are a largely unexplored source of drug repository. Urtica dioica L. (Urticaceae) is used in traditional medicine to treat diverse conditions.

The present study describes the antidiabetic, antiinflammatory, antibacterial activity, and toxicological studies of Urtica dioica.

U. dioica leaves were subjected to solvent extraction with hexane, chloroform, ethyl acetate, methanol, and aqueous, respectively, and screened for antidiabetic (300 mg/kg bw by glucose tolerance test; GTT), antiinflammatory (200 mg/kg bw by rat paw edema assay) and antibacterial activities [by disc-diffusion and minimum inhibitory concentration (MIC) assays]. Toxicological studies were carried on Artemia salina and Wistar rats; phytochemical analyses were carried out, using chromatographic and spectroscopic techniques.

The aqueous extract of U. dioica (AEUD) significantly (p < 0.001; 67.92%) reduced the blood glucose level during GTT in Wistar rats with an effective dose of 300 mg/kg bw in dose-dependent studies. High-performance liquid chromatography with photodiode-array detection (HPLC-DAD) analysis showed the presence of hydroxycinnamic acid derivatives and flavonoids in AEUD. Hexane Fraction-2 (HF2) exhibited both antiinflammatory activity (48.83% after 3 h), comparable to that of indomethacin (53.48%), and potent antibacterial activity with MIC values ranging from 31.25-250 µg/mL against all the tested strains. Gas chromatography-mass spectrometry (GC-MS) analysis showed fatty acid esters and terpenes as the major constituents of HF2. Toxicity tests showed higher safety margin of all the solvent extracts with LC(50) > 1000 μg/mL each on A. salina.

Our results showed that the U. dioica leaves are an interesting source of bioactive compounds, justifying their use in folk medicine, to treat various diseases.