Effects of nitrogen and calcium fertilization on yield, flavonolignans, and anti-teratoma activity of greenhouse grown "Silybum marianum"

Silybum marianum (L.) Gaertn. plants were grown in a bag culture system in a greenhouse on the University of Tennessee campus during the Spring of 2001 and the Fall of 2001. For the Spring 2001 experiment, calcium concentration was altered to produce three nitrogen to calcium ratio treatments. For the Fall 2001 experiment, nitrogen concentration was altered to produce three nitrogen treatments. Plant samples were analyzed for anti-teratoma activity in a modified potato-disc bioassay and for chemical composition using capillary electrophoresis. Ca:N ratio treatments had no effect on seed yield (15 g/ plant) or raw plant extract activity. However, nitrogen treatments had significant effects on both yield and raw plant extract actvity, with plants from the highest N treatment (152 mg/L) producing the greatest biomass (421g of pre-anthesis fresh weight per plant), seed yield (102 g/plant) and seed activity. Ethanolic extracts from roots, stems, and young leaves of pre-anthesis plants inhibited growth of teratomas in the potato disc bioassay. However, only the roots contained the flavonolignan compound silybin, which has been credited for the majority of the bioactivity of seed extracts. Seedlings of S. marianum had high levels of activity in the bioassay, matching that of seed extracts, yet only small concentrations of chemical constituents, which were not identified, were found in the extracts.