Tuberculosis (TB) caused by Mycobacterium tuberculosis (Mtb) has become a frequently deadly infection due to increasing antimicrobial resistance. This serious issue has driven efforts worldwide to discover new drugs effective against Mtb. One research area is the synthesis and evaluation of pyrazinamide derivatives as potential anti-TB drugs. In this paper we report the synthesis and biological evaluations of a series of ureidopyrazines. Compounds were synthesized by reacting alkyl/aryl isocyanates with aminopyrazine or with propyl 5-aminopyrazine-2-carboxylate. Reactions were performed in pressurized vials using a CEM Discover microwave reactor with a focused field. Purity and chemical structures of products were assessed, and the final compounds were tested in vitro for their antimycobacterial, antibacterial, and antifungal activities. Propyl 5-(3-phenylureido)pyrazine-2-carboxylate (compound 4, MICMtb = 1.56 μg/mL, 5.19 μM) and propyl 5-(3-(4-methoxyphenyl)ureido)pyrazine-2-carboxylate (compound 6, MICMtb = 6.25 μg/mL, 18.91 μM) had high antimycobacterial activity against Mtb H37Rv with no in vitro cytotoxicity on HepG2 cell line. Therefore 4 and 6 are suitable for further structural modifications that might improve their biological activity and physicochemical properties. Based on the structural similarity to 1-(2-chloropyridin-4-yl)-3-phenylurea, a known plant growth regulator, two selected compounds were evaluated for similar activity as abiotic elicitors.

• Keywords
• Mycobacterium tuberculosis, abiotic elicitors, anti-infectives, callus culture, ester, pyrazinoic acid, ureidopyrazine,
• MeSH
• Antitubercular Agents chemical synthesis   chemistry   pharmacology   MeSH
• Hep G2 Cells MeSH
• Fagopyrum chemistry   MeSH
• Stress, Physiological drug effects   MeSH
• Humans MeSH
• Microbial Sensitivity Tests MeSH
• Molecular Structure MeSH
• Mycobacterium tuberculosis drug effects   MeSH
• Cell Proliferation drug effects   MeSH
• Pyrazinamide chemistry   pharmacology   MeSH
• Pyrazines chemical synthesis   chemistry   pharmacology   MeSH
• Plant Growth Regulators chemical synthesis   chemistry   pharmacology   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Antitubercular Agents MeSH
• propyl 5-(3-(4-methoxyphenyl)ureido)pyrazine-2-carboxylate MeSH Browser
• propyl 5-(3-phenylureido)pyrazine-2-carboxylate MeSH Browser
• Pyrazinamide MeSH
• Pyrazines MeSH
• Plant Growth Regulators MeSH

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. MATERIALS AND 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. CONCLUSION: 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. SUMMARY: 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.

• Keywords
• Fagopyrum, Silybum, flavonoids, flavonolignans, pyrazine carboxamide,
• Publication type
• Journal Article MeSH