Antibacterial, antifungal and antioxidant activity of four species from Arnebia genus growing wild in Iran

Antibacterial, antifungal and antioxidant activities of methanolic crude extracts from aerial parts of four Arnebia species namely Arnebia fimbriopetala, Arnebia linearifolia, Arnebia garandiflora, Arnebia tubata were screened. Total phenolic contents were determined by Folin-Ciocalteu procedure and ranged from 2.2 ± 0.13 (A. fimbriopetala) to 1.6 ± 1.0 mg (Arnebia tubata) gallic acid µmol equivalent /g extract. The antioxidant activities were evaluated using 2, 2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assays. All of the four Arnebia polar extracts showed good radical scavenging activity with an averaged IC50 value of 3.3 ± 0.15 µg/ml. DPPH assay results showed good correlations with the total phenolic contents of the plants, measured by the Folin-Ciocalteau assay. The antimicrobial activity was tested by using the disc-diffusion (DD) method and determining the minimal inhibitory concentration (MIC) using the macro dilution broth technique. The tested plants showed a mild antimicrobial activity against all nine tested strains. The best result belonged to the methanol extract of A. linearifolia against Bacillus pumilus with MIC value of 85µg/ml. Ampicillin, gentamicin and ketoconazole were used as references. The results obtained indicate that tested plant species from Arnebia genus may become important in the obtainment of noticeable sources of compounds with health protective potential, antioxidant and antimicrobial activity.