Silymarin has antioxidant potential and changes the activity of Na+/K+-ATPase and monoamine oxidase in vitro

• Silymarin has antioxidant effects in different models in vitro.
• Silymarin increases Na+ /K+-ATPase activity in vitro.
• Silymarin inhibits MAO activity with a noncompetitive profile in vitro.

Silymarin is an extract of the milk thistle seeds Silybum marianum (L.) Gaerth used to treat liver disorders and recently reported as a putative neuroprotective agent against neurologic diseases including Parkinson’s disease. However, its action mechanism is not completely investigated. In the present study, we investigated in vitro the antioxidant effects of silymarin as well as on Na+/K+-ATPase and monoamine oxidase (MAO) activity in rat brain homogenate. HPLC fingerprinting of silymarin extract revealed the main component present is silibinin. Furthermore, silymarin showed a total antioxidant capacity and ability to scavenging the DPPH radical dependent of the concentration used. Silymarin decreased lipid peroxidation induced by both pro-oxidants tested, sodium nitroprusside (SNP) and iron (Fe2+), respectively. Silymarin also avoided the loss in activity of catalase and protein and non-protein thiol oxidation pre-incubated with SNP or Fe2+. With regard to MAO and Na+/K+-ATPase activity, silymarin inhibited MAO in a noncompetitive way with a higher potency to MAO-B and could activate Na+/K+-ATPase. Taken together, our in vitro data suggest that neuroprotective effects of silymarin may involve antioxidant and modulatory effects on MAO and Na+/K+-ATPase activity.