Seconeolitsine, an antibiotic , and is an inhibitor of targeting topoisomerase I (TopA) . Seconeolitsine also is a new antimicrobial agent that can inhibit S. pneumoniae growth. Seconeolitsine can inhibit TopA relaxation activity with an IC 50 value of 17 μM. Seconeolitsine can be used for the research of S. pneumoniae infections resistant to other antibiotics In Vitro Seconeolitsine (compounds 17) inhibits TopA relaxation activity in a concentration-dependent manner, with an IC 50 value of 17 μM and the inhibition of TopA is enhanced by preincubation of the enzyme with the alkaloid. Seconeolitsine shows great inhibition of S.pneumoniae growth with MIC 50 values of 16 μM for R6, ATCC6303, CipS8, CipS9, CipR20, CipR16, CipR8, CipR45 and CipR5. And shows great inhibition of S. pneumoniae growth with MIC 50 values of 8 μM for CipR42, CipR68 and CipR15. Seconeolitsine has activation at low concentrations and partial inhibition at 50 μM, a concentration at which the pneumococcal TopA showed full inhibition, but not inhibits Human TOPO1. Seconeolitsine (0.25×-1×MIC) affects cell growth and division in a concentration-dependent manner. Seconeolitsine (30 and 100 μM), is not affected neutrophil apoptosis and human cell viability. MCE has not independently confirmed the accuracy of these methods. They are for reference only. In Vivo Seconeolitsine (compounds 17) increases supercoiling and TopA is target in vivo . MCE has not independently confirmed the accuracy of these methods. They are for reference only. Form:Solid IC50& Target:Topoisomerase I 17 μM (IC 50 )