Four New Polyhydroxysteroids From the South China Sea Cryptomonad Rhodomonas sp

Area of Science:

• Marine Natural Products Chemistry
• Organic Chemistry
• Pharmacology

Background:

• Cryptomonad metabolites from the South China Sea remain largely uninvestigated.
• Marine microorganisms are a rich source of novel bioactive compounds.

Purpose of the Study:

• To explore the chemical diversity of cryptomonads from the South China Sea.
• To isolate and characterize new bioactive metabolites.

Main Methods:

• Isolation and purification of compounds using chromatographic techniques.
• Structure elucidation using high-resolution electrospray ionization mass spectrometry (HRESIMS).
• Nuclear magnetic resonance (NMR) spectroscopy and single-crystal X-ray diffraction (SCXRD) for structural and stereochemical determination.

Main Results:

• Four new highly-oxidized steroids, rhodomonasterols A-D (1-4), were identified.
• Compounds 1, 2, and 4 feature a long-conjugated carbon chain.
• Rhodomonasterols A (1) and D (4) exhibited significant inhibition of nitric oxide (NO) production in lipopolysaccharide-induced BV2 cells at 10.0 µM.
• Inhibition of inducible NO synthase (iNOS) expression was observed, indicating anti-inflammatory properties.

Conclusions:

• The study expands the known chemical diversity of marine cryptomonads.
• Rhodomonasterols A and D possess anti-inflammatory potential through the inhibition of NO production.
• Further investigation into the mechanism of action and therapeutic potential of these steroids is warranted.