Microwave-assisted synthesis of 4'-azaflavones and their N-alkyl derivatives with biological activities.
4'-Azaflavone (=2-(pyridin-4-yl)-4H-1-benzopyran-4-one; 4) and 3-[(pyridin-4-yl)methyl]-4'-azaflavone (5) were synthesized by a simple environmentally friendly microwave-assisted one-pot method through the cyclization of 3-hydroxy-1-(2-hydroxyphenyl)-3-(pyridin-4-yl)propan-1-one (1), (E)-2'-hydroxy-4-azachalcone (2; chalcone=1,3-diphenylprop-2-en-1-one), and 2'-hydroxy-2-[(hydroxy)(pyridin-4-yl)methyl]-4''-azachalcone (3) under solventless conditions using silica-supported NaHSO(4), followed by treatment with base. In addition, N-alkyl-substituted 4'-azaflavonium bromides 6 and 7 were prepared from compounds 4 and 5, respectively. The antimicrobial and antioxidant activities of compounds 1-7 were tested. The N-alkyl-substituted 4'-azaflavonium bromides 6 and 7 showed high antimicrobial activity against the Gram-positive bacteria and the fungus tested, with MIC values close to those of reference antimicrobials ampicilline and fluconazole. The alkylated compounds 6 and 7 also showed a good antioxidant character in the two antioxidant methods, DPPH (=1,1-diphenyl-2-picrylhydrazyl) radical-scavenging and ferric reducing/antioxidant power (FRAP) tests.
Yaşar
Ahmet
A
Department of Chemistry, Faculty of Arts and Sciences, Karadeniz Technical University, TR-61080 Trabzon, Turkey.
Akpinar
Kurtuluş
K
Burnaz
Nesibe Arslan
NA
Küçük
Murat
M
Karaoğlu
Sengül Alpay
SA
Doğan
Neşe
N
Yayli
Nurettin
N
D000478:Alkylation; D000900:Anti-Bacterial Agents / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D000975:Antioxidants / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D001372:Aza Compounds / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D047309:Flavones / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D050296:Microbial Viability / Q000187:drug effects; D008872:Microwaves; D015394:Molecular Structure
D000900:Anti-Bacterial Agents; D000975:Antioxidants; D001372:Aza Compounds; D047309:Flavones