**4. Conclusions**

In conclusion, we have isolated 10 angucycline glycosides from the culture broth of *Streptomyces ardesiacus* 156VN-095 and three of them were new compounds (**1**, **2**, and **9**). The structures of the new metabolites were elucidated by spectroscopic analysis and comparison of their experimental data with those reported in the literature. The new compounds showed selective anti-bacterial effects against three Gram-positive bacterial strains and significant cytotoxicity against a panel of cancer cell lines with a different potency. Among them, **1** showed the strongest activities against all the tested cell lines with GI50 values of 0.019–0.104 μM. These results expanded biochemical diversities of naturally occurring angucycline glycosides.

**Supplementary Materials:** The following supporting information can be downloaded at: https: //www.mdpi.com/article/10.3390/ijms232213779/s1.

**Author Contributions:** Conceptualization, H.J.S.; investigation, C.V.A. and J.-H.K.; resources, H.- S.L. and C.-S.H.; writing—original draft preparation, C.V.A.; writing—review and editing, H.J.S.; visualization, J.S.K.; project administration, H.J.S.; funding acquisition, H.J.S. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was supported by the project titled "Development of potential antibiotic compounds using polar organism resources (No. 20200610, KIOST Grant PM62930)" and PM58482, funded by the Ministry of Oceans and Fisheries, Korea.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** The data presented in the article are available in the Supplementary Materials.

**Acknowledgments:** The authors express gratitude to Jung Hoon Choi, Korea Basic Science Institute, Ochang, Korea, for providing mass data. Authors would like to thank the Vietnam Government for allowing us to do marine microbial research.

**Conflicts of Interest:** The authors declare no conflict of interest.

#### **References**

