Comparative study of the antioxidant properties of silymarin and milk thistle extracts

Purpose: Milk thistle (Silybum marianum (L.) Gaertn) has been used for centuries as a natural remedy for liver and gall bladder / biliary tract diseases. Silymarin is the purified and standardized extract from milk thistle seeds. The purpose of the present study is to present a comparative analysis of the total phenolic substances content and the antioxidant effect of silymarin and three different types of Silybum marianum extracts (i.e. ethanol extract, water extract and lyophilized extract). Methods: Total phenolic and flavonoid content of extracts was analysed and the antioxidant activity was assessed by determining their free radical scavenging ability by DPPH method. Results: Total phenolic content is the highest in silymarin– 134.12±3.22 mg GAE/g, followed by lyophilized water extract – 51.74±2.10 mg GAE/g. Silymarin has also been found to have the highest antioxidant activity among all extract samples (338.03 VCEAC µmol /g), followed by S.marianum lyophilised extract (123.05 VCEAC µmol/g). Conclusions: A strong correlation between total phenolic and flavonoid content in the extracts and their antioxidant activity has been found.