Three new 2,5-diketopiperazines from the fish intestinal Streptomyces sp. MNU FJ-36

Area of Science:

• Microbiology and Natural Products Chemistry
• Marine Biotechnology

Background:

• Gut actinobacteria in marine fish are valuable sources of novel natural products.
• Marine-derived microorganisms, particularly Streptomyces species, are prolific producers of bioactive secondary metabolites.

Purpose of the Study:

• To isolate and characterize novel 2,5-diketopiperazines (2,5-DKPs) from the gut actinobacteria of marine fish.
• To evaluate the cytotoxic activity of the isolated compounds against selected cancer cell lines.

Main Methods:

• Isolation of Streptomyces sp. MNU FJ-36 from the gut of Katsuwonus sp.
• Identification of the bacterial isolate using 16S rRNA gene sequencing.
• Structure elucidation of new 2,5-diketopiperazines using spectroscopic data analysis (e.g., NMR, MS).
• Cytotoxicity evaluation using the MTT assay against P388, A-549, and HCT-116 cell lines.

Main Results:

• Three new 2,5-diketopiperazines were discovered and identified: 3-(3-hydroxy-4-methoxybenzyl)-6-isobutyl-2,5-diketopiperazine (1), 3-(1,3-benzodioxol-5-ylmethyl)-6-isobutyl-2,5-diketopiperazine (2), and 3-(1,3-benzodioxol-5-ylmethyl)-6-isopropyl-2,5-diketopiperazine (3).
• The structures of these compounds were confirmed through comprehensive spectroscopic analysis.
• Preliminary evaluation of their inhibitory activity against P388, A-549, and HCT-116 cell lines was performed.

Conclusions:

• The marine fish gut bacterium Streptomyces sp. MNU FJ-36 is a source of novel 2,5-diketopiperazine derivatives.
• These newly identified compounds warrant further investigation for their potential therapeutic applications, particularly in cancer treatment.
• This study highlights the potential of marine actinobacteria as a reservoir for discovering new bioactive natural products.