Opisana je izolacija silimarina, smjese dobro definiranih flavonolignana, iz sjemena biljke sikavice (Silybum marianum). Silimarin je ekstrahiran acetonom iz deoleinizirana sjemena bez zagrijavanja. Iskorištenje je iznosilo Y = 4,1 %. Antioksidacijska aktivnost silimarina određena je na sobnoj temperaturi kolorimetrijski 2,2-difenil-1-pikrilhidrazilom (DPPH) pri λ = 515 nm. Aktivnost je određena na temelju smanjenja apsorbancije, kao rezultat promjene boje DPPH iz purpurne u žutu. Dobiveni rezultati pokazuju da je askorbinska kiselina znatno jači antioksidans od ispitivana silimarina, ali je silimarin znatno jači hvatač radikala DPPH od standarda silibinina.Isolation of silymarin, a mixture of well-defined flavonolignans, from the seeds of milk thistle (Silybum marianum) was achieved. Silymarin was extracted from defatted seed with acetone without heating; the yield was Y=4.1 %. The antioxidant activity of silymarin was determined at ambient temperature by means of a 2,2-diphenyl-1-picrylhydrazyl (DPPH) colorimetry with a detection scheme at λ= 515 nm. The activity was evaluated by the decrease in absorbance as the result of a DPPH radical color change from purple to yellow. The results obtained showed that ascorbic acid was a substantially more powerful antioxidant than silymarin, but silymarin was a significantly stronger quencher of DPPH radical than the standard silibinin
