Antibacterial and antioxidant activities of root extract of Onosma dichroanthum Boiss. in north of Iran

Onosma dichroanthum Boiss. (Boraginaceae) is locally known as "Hava Chobeh" in north of Iran, which has been used by the rural people as anti-inflammation and antiseptic to treat skin burns and wound healing. In this context, the antimicrobial potential of acetone, chloroform, methanol, ethanol and n-hexane-dichloromethane extracts from root plant against Gram positive and negative bacteria were studied by "agar dilution" and "well diffusion" methods, and the antioxidant properties were obtained by various methods including reducing power (RP), total antioxidant capacity (TAC) and 2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity. Results showed that Gram positive bacteria were more sensitive than Gram negative bacteria, especially to acetone extract in the well diffusion method. Bacillus cereus with minimum inhibitory concentration (0.078 mg/ml) was the most sensitive bacterium but no significant difference has been seen in antibacterial activity of various solvents. The antioxidant activity with IC50 was measured by TAC and RP methods 1 and 0.72 mg/ml respectively. Therefore, reducing power assay had more antioxidant activity than TAC method. IC50 in DPPH method was 4.08 mg dry weight. These results indicated that the use of O. dichroanthum root can be a confirmation for using this plant in traditional medicine, as antiseptic and antioxidant effect.