In this study, we successfully isolated two compounds, 17T223A (1, C22 H22 O10 ) and 17T223B (2, C22 H20 O9 ), from a culture of Streptomyces sp. 17T223. Spectroscopic analyses revealed that these two compounds belong to the spiroximicin family. The chemical structure of 2 was consistent with that of the established antibiotic spiroximicin, whereas 1 was previously unknown. Furthermore, 1 exhibited moderate radical -scavenging activity, with an ED 50 of 1000 μM, whereas 2 showed no radical -scavenging activity, even at an ED50 of 2000 μM. Significant antimicrobial activity was exhibited by 2 whereas 1 exhibited no antimicrobial activity, suggesting that the epoxide portion of 2 influences its antimicrobial activity.
Keywords: 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenger; Streptomyces sp.; antimicrobial activity; nuclear magnetic resonance (NMR); spiroximicin.