Synthesis and structure–activity relationship of rhodomyrtone derivatives as antibacterial agent

To study structure–activity relationship of rhodomyrtone against Gram-positive bacteria, structural modification of rhodomyrtone was carried out to afford its 10 analogues. All compounds were assayed for their antibacterial potency using broth microdilution method. The results indicated that rhodomyrtone exhibited higher antibacterial activity against all Gram-positive bacteria than its analogues, with the exception of rhodomyrtone 6,8-diacetate (3) and oxime analogues 6 and 7 which demonstrated similar activity as the parent compound against Bacillus subtilis and Staphylococcus epidermidis with minimum inhibitory concentration and minimum bactericidal concentration ranged from 1 to 4 μg/mL and 2 to 4 μg/mL, respectively. In contrast, all analogues displayed no activity against Acinetobacter baumannii. Hydroxyl and ketone groups of rhodomyrtone were elucidated to be essential for the antibacterial property.