Silybum marianum L. is a therapeutic plant belonging to the family Asteraceae, which has exhibited silymarin, a principal component used to cure various physiochemical disorders. The study appraised the phytochemical analysis, antioxidant activity and chemical analysis of an extract from the seed, stem and leaves. Qualitative and quantitative phytochemical analysis was evaluated by the Folin-Ciocalteu reagent method and aluminum chloride colorimetric method, respectively. While the antioxidant activity was determined by using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and acetate buffer in ferric chloride (FRAP) assay, respectively, the chemical profile was evaluated by Gas Chromatography-Mass Spectrometry (GC-MS) assay. The study outcomes identified that alkaloids, glycosides, flavonoids, terpenoids, steroids and catcholic tannins were present in seed, stem and leaves extracts except for saponins and Gallic tannins. Whereas, phenols were absent only in seed extract. Quantitative analysis revealed the presence of phenols and flavonoids in appreciable amounts of 21.79 (GAE/g), 129.66 (QE/g) and 17.29 (GAE/g), 114.29 (QE/g) from the leaves and stem extract, respectively. Similarly, all extracts expressed reasonable DPPH inhibition (IC50) and FRAP reducing power such as 75.98, 72.39 and 63.21% and 46.60, 51.40 and 41.30 mmol/g from the seeds, stem and leaves extract, respectively. Additionally, chemical analysis revealed the existence of 6, 8 and 9 chemical compounds from the seeds, stem and leaves extract, respectively, corresponding to 99.95, 99.96 and 98.89% of the whole extract. The chemical compound, Dibutyl phthalate was reported from all extracts while, Hexadecanoic acid, methyl ester and Silane, (1,1-dimethylethyl), dimethyl (phenylmethoxy) were reported only from the seed and leaves extract. Moreover, Methyl stearate was also a major compound reported from all extracts except for seed extract. It is demonstrable that extracts from different parts of S. marianum possess significant antioxidant activity, as well as valuable chemical compounds accountable for therapeutic effects that might be incorporated as an alternative to synthetic chemical agents.
Keywords: GC-MS; Milk thistle; antioxidant activity; phytochemicals; silymarin.