[Study on natural products for drug development].

Area of Science:

• Biochemistry
• Molecular Biology
• Drug Discovery

Background:

• The ubiquitin-proteasome system (UPS) is crucial for protein degradation and cellular regulation.
• Bortezomib's success highlights the proteasome as a viable anticancer target.
• Targeting ubiquitin-dependent protein degradation offers a promising strategy for new drug candidates.

Purpose of the Study:

• To identify drug candidates targeting ubiquitin-dependent protein degradation.
• To find inhibitors of ubiquitin-activating enzyme (E1), ubiquitin-conjugating enzyme (E2), and ubiquitin-protein ligase (E3).
• To explore novel compounds from marine-derived fungi for therapeutic potential.

Main Methods:

• Screening for inhibitors of E1 enzyme activity.
• Assessing inhibition of Ubc13 (E2)-Uev1A interaction.
• Evaluating inhibition of p53-HDM2 (E3) interaction.
• Isolation and structural elucidation of new alkaloids, notoamides, from Aspergillus sp.

Main Results:

• Successfully isolated compounds with inhibitory activity against E1, E2-Uev1A, and p53-HDM2 interactions.
• Identified novel alkaloids, notoamides, including notoamide B and stephacidin A.
• Proposed an intramolecular Diels-Alder (IMDA) reaction mechanism for notoamide biosynthesis.
• Reported isolation of antipodal notoamides from terrestrial Aspergillus, suggesting enantioselective IMDA.

Conclusions:

• Novel compounds targeting key enzymes in the ubiquitin-proteasome system were discovered.
• Marine-derived Aspergillus sp. yielded potential drug candidates with unique chemical structures.
• The study provides insights into the biosynthesis of complex alkaloids via IMDA reactions.
• Enantioselective IMDA reactions may explain the generation of notoamide enantiomers.