ANALYSIS OF PHENOLIC AND FLAVONOID COMPOUNDS IN INDIGENOUS Silybum marianum SEED EXTRACT FROM EGYPT BY GC-MASS

Silybum marianum is an indigenous plant which grows naturally in the neglected areas in the road sides and irrigation canals in Egypt. The objective of the present study was to determine the total phenolic and total flavonoid contents and to evaluate the antioxidant potential of seed extract of Silybum marianum, a traditional medicinal plant of Egypt. The plant seeds were extracted by using 70% methanol and BUCH Rotatory evaporator at very deep vacuum. The extracted components were lyophilized by using lyophilized system. The Silybum marianum seed extract (SMSE) was subjected to phytochemicals screening to detect the presence of bioactive compounds. The study revealed the presence of phenols, flavonoids and evaluated the free radical scavenging activity and antioxidant properties of SMSE. Total phenol content of SMSE was 0.454±0.017 mg Gallic acid equivalent per mg dry material. The amount of flavonoid content in SMSE was 40.0±0.09 mg quercetin equivalent per mg dry material. The IC50 value of SMSE on DPPH radical scavenging assay was found to be 0.83 mg/ml compared with 1.64 mg/ml those of BHT. A lowered IC50 value indicated an increase in the scavenging capacity. Results revealed that Egyptian species of Silybum marianum seeds can be considered as a valuable source of natural antioxidants due to the presence of silymarin which can protect biological system against the oxidative stress. Also, GC-MS showed that the SMSE has more peaks and that means it has extra components which needs further study for its identification.