ABSTRACT
The presentstudydescribes the biochemical evaluation of Silybum marianum seed. The analysis of essential oil composition of Silybum marianum seed by Gas Chromatography-Mass Spectrometry GC-MS showed the presence of14 volatile components with the predominance of gamma-cadinene [49.8%] and alpha-pinene [24.5%]. Whereas, the analysis of fatty acids composition, showed the predominance of linoleic [50.5%] and oleic [30.2%] acids. Silybum marainum presented also an important polyphenol contents with 29mgGAE/g DW, a good antiradical activity [CI50=39microg/ml] but a lower reducing power ability. Flavonoid and condensed tannin contents were about 3.39mg EC/g DW and 1.8mg EC/gDW, respectively. The main phenolic compounds identified by RP-HPLC, were silybin A [12.2%], silybin B [17.67%], isosilybin A [21.9%], isosilybin B [12.8%], silychristin [7.9%] andsilydianin [7.5%]