Preparation and antibacterial activity of coronarin E derivatives.

Coronarin E is a main diterpene ever isolated from . With the aim to enlarge its potential application, four butenolide derivatives (compounds , , and ) were obtained from coronarin E synthetic method, and their antibacterial effects were also evaluated. It is noteworthy that compounds and exhibited stronger antibacterial activities against most of the tested bacterial strains than ampicillin and kanamycin, two first- and second-line antimicrobials in clinical. For example, minimum inhibitory concentration (MIC) of , , ampicillin and kanamycin against were 2, 1, 8 and 4 μg/mL, respectively, and MIC of the four compounds mentioned above against were 1, 0.5, 16 and 4 μg/mL, respectively. The current studies not only enrich the structural diversity of diterpenes derived from genus, but also provide potent candidates for the development of antibacterial medicines.