Identification of a novel class of small compounds with anti-tuberculosis activity by in silico structure-based drug screening.

The enzymes responsible for biotin biosynthesis in mycobacteria have been considered as potential drug targets owing to the important role in infection and cell survival that the biotin synthetic pathway plays in Mycobacterium tuberculosis. Among the enzymes that comprise mycobacterium biotin biosynthesis systems, 7,8-diaminopelargonic acid synthase (DAPAS) plays an essential role during the stationary phase in bacterial growth. In this study, compounds that inhibit mycobacterial DAPAS were screened in the virtual chemical library using an in silico structure-based drug screening (SBDS) technique, and the antimycobacterial activity of the selected compounds was validated experimentally. The DOCK-GOLD programs utilized by in silico SBDS facilitated the identification of a compound, referred to as KMD6, with potent inhibitory effects on the growth of model mycobacteria (M. smegmatis). The subsequent compound search, which was based on the structural features of KMD6, resulted in identification of three additional active compounds, designated as KMDs3, KMDs9 and KMDs10. The inhibitory effect of these compounds was comparable to that of isoniazid, which is a first-line antituberculosis drug. The high antimycobacterial activity of KMD6, KMDs9 and KMDs10 was maintained on the experiment with M. tuberculosis. Of the active compounds identified, KMDs9 would be a promising pharmacophore, owing to its long-term antimycobacterial effect and lack of cytotoxicity.

In silico structure-based drug screening of novel antimycobacterial pharmacophores by DOCK-GOLD tandem screening.

BACKGROUND: Enzymes responsible for cell wall development in Mycobacterium tuberculosis are considered as potential targets of anti-tuberculosis (TB) agents. Mycobacterial cyclopropane mycolic acid synthase 1 (CmaA1) is essential for mycobacterial survival because of its critical role in synthesizing mycolic acids. MATERIALS AND METHODS: We screened compounds that were capable of interacting with the mycobacterial CmaA1 active site using a virtual compound library with an in silico structure-based drug screening (SBDS). Following the selection of such compounds, their antimycobacterial activity was examined. RESULTS: With the in silico SBDS, for which we also used DOCK-GOLD programs and screening methods that utilized the structural similarity between the selected active compounds, we identified two compounds with potent inhibitory effects on mycobacterial growth. The antimycobacterial effect of the compounds was comparable to that of isoniazid, which is used as a first-line anti-TB drug. CONCLUSION: The compounds identified through SBDS were expected to be a novel class of anti-TB pharmacophores.