A New Analogue of Echinomycin and a New Cyclic Dipeptide from a Marine-Derived Streptomyces sp. LS298

• Main Authors: Xin Zhen, Ting Gong, Fu Liu, Pei-Cheng Zhang, Wan-Qi Zhou, Yan Li, Ping Zhu
• Format: Article
• Language: English
• Published: MDPI AG 2015-11-01
• Series: Marine Drugs
• Subjects: marine-derived Streptomyces; secondary metabolites; antibacterial activity; anti-tumor activity
• Online Access: http://www.mdpi.com/1660-3397/13/11/6947

Quinomycin G (1), a new analogue of echinomycin, together with a new cyclic dipeptide, cyclo-(l-Pro-4-OH-l-Leu) (2), as well as three known antibiotic compounds tirandamycin A (3), tirandamycin B (4) and staurosporine (5), were isolated from Streptomyces sp. LS298 obtained from a marine sponge Gelliodes carnosa. The planar and absolute configurations of compounds 1 and 2 were established by MS, NMR spectral data analysis and Marfey’s method. Furthermore, the differences in NMR data of keto-enol tautomers in tirandamycins were discussed for the first time. Antibacterial and anti-tumor activities of compound 1 were measured against 15 drug-sensitive/resistant strains and 12 tumor cell lines. Compound 1 exhibited moderate antibacterial activities against Staphylococcuse pidermidis, S. aureus, Enterococcus faecium, and E. faecalis with the minimum inhibitory concentration (MIC) values ranged from 16 to 64 μg/mL. Moreover, it displayed remarkable anti-tumor activities; the highest activity was observed against the Jurkat cell line (human T-cell leukemia) with an IC50 value of 0.414 μM.