Abstract

In our research, 8 kinds of solvents extracts from roots of Onosma dichroanthum Boiss. were used to examine the effects of extraction solvent on total phenolics (TP), total flavonoids (TF) , total anthocyanin (TA) content and antioxidant activity by 1,1-diphenyl-2-picryl hydrazyl radical scavenging (DPPH), total antioxidant capacity (TAC), reducing power (RP) and antioxidant activity (AA) were determined spectrophotometrically. Results showed that extraction solvent had significant effects on TP, TF, TA content and antioxidant activity of acetone extract. The highest content of TP, TF and TA were found in acetone extracts. The TP varied from 4.5 ± 0.7 to 125.6 ± 3.01 mgGAE g ^-1 dry weight, TF contents were between 9.8 ± 3 to 41 ± 2.3 mgQUE g^-1and TA  were 11.5± 3.4 to 47.8± 6.8 mgECGgr^-1. Effective concentration (EC₅₀) (antioxidant activity) in TAC, RP and 2,2- diphenyl-1-picrylhydrazyl (DPPH) methods were measured at 0.495, 0.844 mg/ml and 4.21 mg dw, respectively and the amount of antioxidant activity (AA%) reported was 38.02%. The greater amount of phenolic compounds which leads to more potent radical scavenging effect was shown by acetone extract. Additionally, amount of phenolic compounds and antioxidant activities increased in acetone extract. Thus, a positive correlation existed between antioxidant activity and their total phenolic content. Acetone solvent showed the greatest capability in extracting antioxidants and inhibiting the free radicals produced.

Key words: Solvents, total phenol, flavonoid, anthocyanin, 1,1-diphenyl-2-picryl hydrazyl radical scavenging (DPPH), Onosma dichroanthum Boiss.