Synthesis and biological evaluation of novel luteolin derivatives as antibacterial agents.

A series of luteolin derivatives 2-20 were prepared, 3-20 of which were first reported. The chemical structures of these compounds were confirmed by means of 1H NMR, ESI-MS and elemental analyses. The compounds were assayed for antibacterial (Bacillus subtilis, Staphylococcus aureus, Pseudomonas fluorescens and Escherichia coli) activities by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl trtrazolium bromide) method. Among the compounds tested, most of them displayed significant activity against the tested strains, and 2-(2,3-dihydrobenzo[b][1,4]dioxin-6-yl)-5-hydroxy-7-(2-(3-morpholinopropylamino)ethoxy)-4H-chromen-4-one (17) showed the most favorable antibacterial activity in vitro with MICs of 1.562, 3.125, 3.125, and 6.25 microg/mL against B. subtilis, S. aureus, P. fluorescens and E. coli, respectively. Structure-activity relationships (SAR) were also discussed based on the obtained experimental data.