Substituted Pyrazinecarboxamides as Abiotic Elicitors of Flavolignan Production in Silybum marianum (L.) Gaertn Cultures in Vitro

Substituted pyrazinecarboxamides markedly influenced production of flavonolignans in Silybum marianum callus and suspension cultures. In this study the effect of two compounds, N-(3-iodo-4-methylphenyl)pyrazine-2-carboxamide (1) and N-(3-iodo-4-methylphenyl)-5-tert-butyl-pyrazine-2-carboxamide (2), as abiotic elicitors on flavonolignan production in callus culture of S. marianum was investigated. Silymarin complex compounds have hepatoprotective, anticancer and also hypocholesterolemic activity. In vitro flavonolignan concentration in cells is very low and the elicitation is one of the methods to increase production. Elicitors were tested at three concentrations and at different culture times. In the case of elicitation with 1, the greatest increase of flavonolignan and taxifoline production was observed at concentration c(1a) after 6-hours of elicitation and after 24 and 72-hours at concentration c(1b). However, increased production of silychristin, one of the compounds in the silymarin complex, was achieved after only 6-hours elicitation with c(1a) (2.95 x 10(-4) mol/L). The content of silychristin was 2-times higher compared to the control sample. An increased production of silychristin was reached with compound 2 at the concentration c(2) (2.53 x 10(-3) mol/L) after 72 h of elicitation. The production of silychristin in this case was increased 12-times compared to control.