Antimicrobial bianthrones from the crinoid Heterometra sp

Area of Science:

• Marine Natural Products Chemistry
• Antimicrobial Drug Discovery
• Echinoderm Biochemistry

Background:

• Antimicrobial resistance (AMR) poses a significant global health challenge.
• Discovering novel chemical scaffolds is crucial for developing new antimicrobial agents.
• Marine organisms, such as crinoids, are a rich source of unique bioactive compounds.

Purpose of the Study:

• To investigate the antibacterial activity of the organic extract from the crinoid, *Heterometra* sp.
• To isolate and characterize novel natural products with potential antimicrobial properties.
• To determine the chemical structures and absolute configurations of isolated compounds.

Main Methods:

• High-throughput screening of crinoid extract fractions.
• Chemical investigation involving isolation and purification techniques.
• Structure elucidation using High-Resolution Electrospray Ionization Mass Spectrometry (HRESIMS) and 1D/2D Nuclear Magnetic Resonance (NMR) spectroscopy.
• Determination of absolute configurations via chemical and chirooptical methods.

Main Results:

• Three natural products were isolated from the *Heterometra* sp. extract: crinemodin bianthrone (1), 1''-dehydrocrinemodin bianthrone (2) (a new structure), and 1''-hydroxycrinemodin bianthrone (3).
• The planar structures and absolute configurations of compounds 1-3 were determined.
• Compound 3 exhibited instability in DMSO and pyridine, with observed variations in proton chemical shifts.
• Compounds 1 and 3 demonstrated selective antimicrobial activity against Gram-positive bacterial strains.

Conclusions:

• The study successfully isolated and characterized three bianthrone derivatives from a crinoid, including a new compound.
• Compounds 1 and 3 possess selective antimicrobial activity, highlighting their potential as leads for new antibacterial agents.
• This research contributes to the search for novel chemical scaffolds to combat antimicrobial resistance.