title: New Synthetic Pyrazine Carboxamide Derivatives as Potential Elicitors in Production of Secondary Metabolite in In vitro Cultures.
abstract: BACKGROUND
  Silymarin, an active polyphenolic fraction of Silybum marianum, and high flavonoid content of Fagopyrum possess various interesting biological activities. The substituted pyrazine-2-carboxamides were previously used as effective elicitors of studied secondary metabolites.
  
  
  OBJECTIVE
  To study the effect of new synthetic pyrazine carboxamide derivatives, N-(4-chlorobenzyl)-5-tert-butylpyrazine-2-carboxamide (1) and 3-(3-((trifluoromethyl) benzyl) amino) pyrazine-2-carboxamide (2), on flavonolignan and flavonoid production in S. marianum and Fagopyrumes culentum in vitro cultures.
  
  
  METHODS
  Callus and suspension cultures were cultured on MS medium containing α-naphtaleneacetic acid or 2,4-D. Three elicitor concentrations for different exposure times were tested. Dried and powdered samples of callus and suspension cultures were extracted with methanol and analyzed by DAD-HPLC.
  
  
  RESULTS
  Compound 1 showed as a good elicitor of taxifolin production. The effect on silymarin complex was less visible with a maximum between 24 and 48 h after 3.292 ×10(-4) mol/L concentration. The detailed analysis showed that silychristin was the most abundant. Compound 2 was effective in rutin production only in callus culture with maximum 24 h and 168 h after application of 3.3756 ×10(-3) mol/L concentration and 48 and 72 h after 3.3756 ×10(-4) mol/L concentration.
  
  
  CONCLUSIONS
  From the results of the performed experiments, it can be concluded that compound 1 shows to be suitable elicitor for enhanced production of taxifolin and silychristin in S. marianum, mainly when 3.292 ×10(-4) mol/L concentration was used, and compound 2 is suitable for increase rutin production in callus cultures and less appropriate for suspension cultures of F. esculentum.
  
  
  CONCLUSIONS
  The influence of two new synthetic pyrazine-2-carboxamidesderivatives on secondary metabolite content of Silybum marianum and Fagopyrum esculentum in vitro cultures was tested.In S. marianum, the derivate N-(4-chlorobenzyl)-5-tert-butylpyrazine-2-carboxamide showed as a good elicitor of taxifolin production and less effective for silymarin complex production with silychristin as the most abundant.The derivate 3-(3-((trifluoromethyl) benzyl) amino) pyrazine-2-carboxamide is suitable for increase rutin production in callus cultures and less appropriate for suspension cultures of F. esculentum.
authors.affiliation: Department of Pharmacognosy, Faculty of Pharmacy in Hradec Kralove, Charles University in Prague, Heyrovskeho 1203, 500 05 Hradec Kralove, Czech Republic.
authors.forename: Lenka
authors.initials: L
authors.lastname: Tůmová
authors.affiliation: Department of Biology, Faculty of Science, University of Hradec Kralove, Rokitanskeho 62, 500 03 Hradec Kralove, Czech Republic.
authors.forename: Jiří
authors.initials: J
authors.lastname: Tůma
authors.affiliation: Department of Pharmaceutical Chemistry and Pharmaceutical Analysis, Faculty of Pharmacy in Hradec Kralove, Charles University in Prague, Heyrovskeho 1203, 500 05 Hradec Kralove, Czech Republic.
authors.forename: Martin
authors.initials: M
authors.lastname: Doležal
authors.affiliation: Department of Pharmacognosy, Faculty of Pharmacy in Hradec Kralove, Charles University in Prague, Heyrovskeho 1203, 500 05 Hradec Kralove, Czech Republic.
authors.forename: Zuzana
authors.initials: Z
authors.lastname: Dučaiová
authors.affiliation: Department of Pharmacognosy, Faculty of Pharmacy in Hradec Kralove, Charles University in Prague, Heyrovskeho 1203, 500 05 Hradec Kralove, Czech Republic.
authors.forename: Jan
authors.initials: J
authors.lastname: Kubeš
keywords: Fagopyrum; Silybum; flavonoids; flavonolignans; pyrazine carboxamide