Proline-containing cyclopeptides from the marine sponge Phakellia fusca

Area of Science:

• Marine Natural Products Chemistry
• Organic Chemistry
• Biochemistry

Background:

• Marine sponges are a rich source of structurally diverse bioactive compounds.
• The genus Phakellia is known to produce various cyclopeptides with potential biological activities.
• Previous research on Phakellia species has identified several cyclopeptide natural products.

Purpose of the Study:

• To isolate and characterize new cyclopeptides from the South China Sea sponge Phakellia fusca.
• To elucidate the structures and absolute configurations of isolated compounds.
• To contribute to the understanding of chemical diversity in marine organisms.

Main Methods:

• Isolation of compounds using chromatographic techniques.
• Structure elucidation via High-Resolution Electrospray Ionization Mass Spectrometry (HR-ESIMS) and Nuclear Magnetic Resonance (NMR) spectroscopy.
• Amino acid sequencing using Matrix-Assisted Laser Desorption/Ionization-Time of Flight/Time of Flight (MALDI-TOF/TOF) analysis.
• Determination of absolute configurations using enantioselective High-Performance Liquid Chromatography (HPLC).

Main Results:

• Four new cyclopeptides, designated phakellistatins 15-18 (compounds 2-5), were isolated.
• Five known cyclopeptides, phakellistatin 13 (1), hymenistatin 1, and hymenamides G, H, and J, were also identified.
• The structures of all isolated compounds were fully elucidated.
• The absolute configurations of the amino acid residues in the new cyclopeptides (2-5) were determined as L-configuration.

Conclusions:

• The study successfully identified novel cyclopeptide structures from Phakellia fusca.
• The findings expand the known repertoire of cyclopeptides from marine sources.
• This research highlights the potential of marine sponges as a source for discovering new chemical entities.