Design, synthesis and antimycobacterial activity evaluation of natural oridonin derivatives.

In an effort to develop novel potent antitubercular drugs, thirty-one oridonin derivatives were designed and prepared. All the compounds obtained were screened for their in vitro activities against Mycobacterium phlei, Mycobacterium smegmatis and Mycobacterium marinum. Among them, thirteen compounds showed significant inhibitory activity against M. phlei with MICs less than 2 μg/mL. Compounds 2k, 8d, 10c, 10d containing trans-cinnamic acid moiety were the most potent (MIC=0.5 μg/mL), comparable to the well-known antitubercular drug streptomycin. The preliminary structure-activity relationships (SARs) were also analyzed.