Optimization of Heat-Reflux Extraction of Silymarin from Silybum Marianum Seeds and Evaluation of its DPPH Radical Scavenging Activity, Total Phenolic and Total Flavonoid Content

Having miraculous therapeutic effects on liver disorders, Silymarin has been proved to be effective in treating diabetes mellitus, hyperglycemia and many other fast-growing lifestyle-dependent diseases. This study was purposed to optimize the extraction of silymarin, an economically important natural product, from the seeds of Silybum marianum. To aim this, Response Surface Methodology (RSM) based on Box-behnken design was applied to determine the best extraction condition within the defined range of three process parameters, including extraction temperature (30°C-50°C), extraction time (3-8 hours), and solid to liquid ratio (1:5-1:15). Fifteen runs of designed experiments were performed and the results were fitted to a quadratic polynomial equation, which showed a good fittness (R2>0.90). The highest extraction yield was obtained at extraction temperature of 50°C, extraction time of 6.17 hours, and solid to liquid ratio of 1:15. This extract was further evaluated for its DPPH radical scavenging capacity, Total Phenolic Content (TPC), and Total Flavonoid Content (TFC). IC50 value of DPPH scavenging capacity was found to be 122.22 ± 0.01µg/ml, while TPC value (expressed as GAE) and TFC value (expressed as RE) was determined to be 101.97 ± 7.89 mg/g and 141.79 ± 5.78 mg/g respectively. These findings revealed the extract that was prepared in the optimum condition bears appropriate biological activities and could be considered as a qualified choice of crude pharmaceutics material for use in formulation studies