Cell experiment:

The cytotoxicity of cynarin treatment of T-cells is measured by MTT colorimetric assay. 100 μL Jurkat cells are incubated with cynarin (0-1000 μg/mL) for 24 h at 37℃. The cell solution is then centrifuged and the supernatant removed. 200 μL of MTT is added and the cell solution is incubated again for 4 h at 37℃. 200 μL of DMSO lysis buffer is added into the cell medium and the concentration of dissolved MTT crystals is measured by plate reader at 560 nm[2].

Cynarin is an antichoke agent with a variety of biological activities including antioxidant, antihistamic and antiviral activities.

Cynarin inhibits taste receptors, making water to be sweet. It has been shown to have some pharmacological properties including hypocholesterolemic, hepatoprotective, antiviral, antibacterial, and antihistamic effects. Cynarin has marked antioxidant, anticholinergic, reducing ability, radical-scavenging, and metal-binding activities. Cynarin demonstrates 87.72% inhibition of linoleic acid lipid peroxidation at 30 mg/mL concentration. Cynarin exhibits effective DMPD+, ABTS+, O2-, DPPH1, and H2O2 scavenging effects, reducing capabilities and Fe2+ chelating effects. IC50 and Ki of cynarin for acetylcholinesterase enzyme inhibition are 243.67nM and 39.34±13.88 nM, respectively[1]. Cynarin is a potential immunosuppressant that blocks the interaction between the CD28 of T-cell receptor and CD80 of antigen presenting cells. Cynarin blocks about 87% of the CD28-dependent "signal 2" pathway of T-cell activation under the condition of one to one ratio of T-cell and B-cell. Cynarin binds to the "G-pocket" of CD28 and thus interrupts the site of interaction between CD28 and CD80[2].

References:
[1]. Topal M, et al. Antioxidant, antiradical, and anticholinergic properties of cynarin purified from the Illyrian thistle (Onopordum illyricum L.). J Enzyme Inhib Med Chem. 2016;31(2):266-75.
[2]. Dong GC, et al. Blocking effect of an immuno-suppressive agent, cynarin, on CD28 of T-cell receptor. Pharm Res. 2009 Feb;26(2):375-81.