Streptothiazolidine B, a new cytotoxic alkaloid produced by Streptomyces violaceoruber

Abstract

A new cytotoxic alkaloid, named streptothiazolidine B (1), together with three known compounds (2-4), were isolated from Streptomyces violaceoruber. The structure of the undescribed compound was established using 1D and 2D NMR, and HRESIMS. Streptothiazolidine B was isolated and identified as an amide alkaloid with a unique thiazolidine side chain and its absolute configuration was determined by a combination of NOESY experiment and ECD analysis. Streptothiazolidine B exhibited significant cytotoxic activities against two human tumor cell lines, Li-7 and A2780, with IC₅₀ values of 7.8, and 9.1 μM. Meanwhile, compound 4 showed obvious cytotoxic activities against four human tumor cell lines, THP-1, HT29, Li-7 and A2780, with IC₅₀ values ranging from 3.1 to 10.2 μM.

Keywords:

• Streptomyces violaceoruber
• cytotoxic
• alkaloids
• streptothiazolidine B

Acknowledgments

This research was financially supported by the National Natural Science Foundation of China under Grant (numbers 32160019); Spring City Project (C201914001); Yunnan Applied Basic Research Program University Joint General Fund Project (2018FH001-003,202001BA070001-028,043).

Disclosure statement

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Additional information

Funding

This work was supported by National Natural Science Foundation of China under Grant number [32160019]; Spring City Project (C201914001).