Oligomeric acylphloroglucinols from myrtle (Myrtus communis).

The dimeric nonprenylated acylphloroglucinol semimyrtucommulone (6) was obtained from the leaves of myrtle (Myrtus communis) as a 2:1 mixture of two rotamers. The known trimeric phloroglucinol myrtucommulone A (1) was also isolated and characterized spectroscopically as a silylated cyclized derivative (5). Myrtucommulone A showed significant antibacterial activity against multidrug-resistant (MDR) clinically relevant bacteria, while semimyrtucommulone was less active.