Cyclizidine-Type Alkaloids from Streptomyces sp. HNA39

Area of Science:

• Marine Natural Products Chemistry
• Medicinal Chemistry
• Biotechnology

Background:

• Marine-derived actinomycetes are a rich source of novel bioactive compounds.
• Cyclizidine alkaloids represent a class of natural products with diverse biological activities.
• Streptomyces species are known producers of complex secondary metabolites.

Purpose of the Study:

• To isolate and characterize new cyclizidine-type alkaloids from a marine-derived Streptomyces sp.
• To evaluate the cytotoxic and enzyme inhibitory activities of the isolated compounds.

Main Methods:

• Chemical investigation of Streptomyces sp. HNA39 using spectroscopic methods (NMR, HRESIMS).
• Determination of absolute configurations via Electronic Circular Dichroism (ECD) calculations.
• In vitro cytotoxicity assays against PC3 and HCT116 cancer cell lines.
• Enzyme inhibition assays against ROCK2 protein kinase.

Main Results:

• Eight new cyclizidine-type alkaloids (1-8) and one known alkaloid (+)-ent-cyclizidine (9) were identified.
• Compounds 3, 7, and 8 were chlorinated cyclizidine alkaloids.
• Compound 2 displayed significant cytotoxicity against PC3 (IC50 = 0.52 μM) and HCT116 (IC50 = 8.3 μM) cell lines.
• Compounds 2, 5, 7, and 8 showed moderate inhibition of ROCK2 protein kinase (IC50 = 7.0–42 μM).

Conclusions:

• The marine-derived Streptomyces sp. HNA39 is a prolific source of cyclizidine alkaloids.
• Compound 2 is a promising candidate for further anticancer drug development.
• The identified alkaloids possess potential as ROCK2 inhibitors, suggesting therapeutic applications.