Surfactin isoforms isolated from a mushroom derived Bacillus halotolerans DMG-7-2

Abstract

A new iso-C₁₄ [Val², Val⁷] surfactin isoform (1) together with eight known ones (2–9), was isolated from the culture of a mushroom derived bacterium, Bacillus halotolerans DMG-7-2. The structures of them were mainly elucidated by NMR and MS data, and the NMR data of 5 also was reported for the first time. The absolute configuration of 1 was determined by Marfey’s analysis (for amino acid residues) and the ¹³C NMR calculation of the two plausible epimers of 1 (for fatty acid). Compounds 1–9 showed moderate cytotoxicity against two human cancer cell lines (A549, MCF-7) and mice microglial BV2 cells, the IC₅₀ values ranged from 8.91 to 33.00 µM, and the IC₅₀ values of the positive control 5-FU were 99.94, 71.49 and 0.12 µM, respectively.

Keywords:

• Surfactin isoform
• mushroom
• Cortinarius lucorum
• Bacillus halotolerans
• cytotoxicity

Acknowledgment

The mushroom DMG-7 and the bacterial strain DMG-7-2 were identified by Prof. Caihong Dong from the Institute of Microbiology of the Chinese Academy of Sciences. Thanks to Prof. Jinwei Ren and Erwei Li from the Institute of Microbiology of the Chinese Academy to perform the NMR, [α] _D, UV, IR and ECD detection. Antibacterial test was performed by Dr. Xiaoyong Huang and was directed by Prof. Kui Zhu from China Agricultural University, Beijing, China. The cancer cell lines were kindly provided by Prof. Zhiyong Xiao and Yuan Luo from Institute of Pharmacology and Toxicology.

Disclosure statement

No potential conflict of interest was reported by the authors.