Antioxidant, antiradical, and anticholinergic properties of cynarin purified from the Illyrian thistle (Onopordum illyricum L.)

Figures & data

Figure 1. Total antioxidant activities of cynarin and standard antioxidant compounds like trolox, α-tocopherol, BHT, and BHA at the same concentration (30 µg/mL) assayed by the ferric thiocyanate method. The control value reached a maximum 50 h (BHA, butylated hydroxyanisole; BHT, butylated hydroxytoluene).

Figure 2. Reducing power of cynarin. (A) Fe³⁺→ Fe²⁺ reductive potential of different concentrations (10–30 µg/mL) of cynarin (r²: 0.983) and reference antioxidants. (B) Cu²⁺ reducing ability of different concentrations (10–30 µg/mL) of cynarin (r²: 0.840) and reference antioxidants (BHA, butylated hydroxyanisole; BHT, butylated hydroxytoluene).

Figure 3. Comparison of Fe²⁺ chelating activity of cynarin (r²: 0.898) and standard antioxidant compounds like trolox, α-tocopherol, BHT, and BHA at the concentrations of 10–20 µg/mL (BHA, butylated hydroxyanisole; BHT, butylated hydroxytoluene).

Figure 4. Comparison of superoxide anion radical () scavenging activities of cynarin and standard antioxidant compounds like trolox, α-tocopherol, BHT, and BHA at the concentration of 30 µg/mL (BHA, butylated hydroxyanisole; BHT, butylated hydroxytoluene).

Figure 5. Radical-scavenging activities of cynarin. (A) DPPH free radical scavenging activity of different concentrations (10–30 µg/mL) of cynarin (r²: 0.950) and reference antioxidants. (B) ABTS radical scavenging activity of different concentrations (10–20 µg/mL) of cynarin (r²: 0.956) and reference antioxidants. (C) DMPD radical scavenging activity of different concentrations (10–30 µg/mL) of cynarin (r²: 0.982) and reference antioxidants (BHA, butylated hydroxyanisole; BHT, butylated hydroxytoluene; DPPH•, 1,1-diphenyl-2-picryl-hydrazyl free radical; ABTS^•+, 2,2′-Azino-bis(3-ethylbenzthiazoline-6-sulfonic acid; DMPD^•+, N,N-dimethyl-p-phenylenediamine radical).

Figure 6. (A) The reaction scheme between DPPH free radicals and cynarin. (B) The proposed reaction for chelating of ferrous ions by cynarin.

Figure 7. Stabilization of radicals by the phenol group of cynarin.

Figure 8. Determination of IC₅₀ (A) and K_i (B) values of cynarin for acetylcholinesterase enzyme by the Lineweaver–Burk graph.