Sesterterpenoids isolated from a northeastern Pacific Phorbas sp.

Area of Science:

• Marine Natural Products Chemistry
• Organic Chemistry
• Biochemistry

Background:

• Marine sponges are a rich source of structurally diverse secondary metabolites.
• Sesterterpenoids are a class of 17-carbon terpenoids with various biological activities.
• The genus Phorbas is known to produce unique chemical compounds.

Purpose of the Study:

• To isolate and characterize new sesterterpenoids from the sponge Phorbas sp.
• To investigate the chemical structures and potential biological activities of the isolated compounds.
• To explore novel chemical skeletons within marine natural products.

Main Methods:

• Specimens of Phorbas sp. were collected from British Columbia.
• Chemical isolation was performed using chromatographic techniques.
• Structural elucidation was achieved through spectroscopic methods (e.g., NMR, MS).
• Biological activity was assessed using cell-based assays (HEK cells).

Main Results:

• Four new sesterterpenoids were identified: ansellone B (4), phorbadione (5), secoepoxyansellone A (6), and alotaketal C (7).
• Ansellone B (4) exhibits a novel heterocyclic skeleton with an oxocane ring.
• Secoepoxyansellone A (6) represents the first reported instance of a degraded "secoansellane" sesterterpenoid skeleton.
• Alotaketal C (7) demonstrated activity as an activator of cAMP signaling in HEK cells.

Conclusions:

• The Phorbas sponge from British Columbia yielded novel sesterterpenoids with unique structural features.
• The discovery of ansellone B and secoepoxyansellone A expands the known structural diversity of sesterterpenoids.
• Alotaketal C's ability to activate cAMP signaling suggests potential therapeutic applications.