EUROPEAN JOURNAL OF MEDICINAL CHEMISTRY, vol.69, pp.348-355, 2013 (SCI-Expanded)
New 1-alkyl-4-(1-alkyl-4-oxo-1,4-dihydroquinolin-2-yl)pyridinium bromides (3aek) were synthesized
from 1,40-diazaflavone [2-pyridin-4-ylquinolin-4(1H)-one] and evaluated for antibacterial and antioxidant
activities. A rapid one-pot preparation of 1,40-diazaflavone (2) was done from 20-amino substituted
chalcone (1) by intramolecular Michael addition using solvent-free microwave heating. New N,N0-dialkyl
substituted (C5eC15) 1,40-diazaflavonium bromides were synthesized from compound 2 with corresponding
alkyl halides. Compounds 3aek were active against six bacteria (MIC: 7.8e500.0 mg/mL). They
also showed good antioxidant activities in DPPH scavenging (SC50: 45e133 mg/mL) and ferric reducing/
antioxidant power (14e141 mM TEAC) tests. The biological activities decreased as alkyl chain length
increased. The reason behind the obvious negative effect of alkyl chain elongation is unclear and requires
investigations about the intermolecular interactions of these pyridinium salts with bioassay
components.