Milkthistle (Silybum marianum L.) has been used in medicine since ancient times but has been cultivated as a medicinal plant only in recent decades. In the modern pharmaceutical industry different types of medicines such as legalonR, DurasilymarinR, HegrimarinR and MariendistelR are derived from it. Flavonoids accumulated in the fruit wall of the milkthistle up to amount of 2-5 percent. The main flavonoides are silybin, silydianin and silychristin known as silymarin. In this investigation three different kinds of seeds; Hungarian (Budakalaszi CV.), German origin, and seeds collected from wild plants in Challus (North of Iran) have been used. After extracting and analysis of their silymarin and silybin, the seeds were sown in the same climatic conditions in Zardband region (north of Tehran) with randomised complete blocks design with three replications per treatment. We have measured plant hight, No. of capitule and capitul diameter in full flowering stage. After ripening the fruits, we have collected the seeds and measured thier active substances (Silymarin and silybin) and compared to each treatment. According to data milkthistle varieties have expressive effect on their silymarin and silybin content. The highest amount of silymarin and silybin, extracted from seeds of Hungarian origin (Budakalaszi CV.) milkthistle and the lowest one from wild grown (Challus) and German origin types.
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