Triterpenoids with bioactivities from Oenothera biennis

Area of Science:

• Natural Product Chemistry
• Pharmacology
• Organic Chemistry

Background:

• Oenothera biennis (common evening primrose) is a plant source of diverse phytochemicals.
• Triterpenoids are a class of natural compounds with a wide range of biological activities.
• Novel chemical structures and their bioactivities contribute to drug discovery.

Purpose of the Study:

• To conduct a phytochemical investigation of Oenothera biennis whole plants.
• To isolate, identify, and characterize new triterpenoids.
• To evaluate the bioactivity of isolated compounds, specifically their inhibitory effects on alpha-glucosidase and indoleamine 2,3-dioxygenase 1 (IDO1).

Main Methods:

• Whole plants of Oenothera biennis were subjected to phytochemical analysis.
• Isolation and identification of triterpenoids using spectroscopic methods, including Nuclear Magnetic Resonance (NMR).
• Bioactivity assays were performed to assess inhibitory effects against alpha-glucosidase and IDO1 enzymes.

Main Results:

• Twenty-eight triterpenoids were isolated and identified.
• Seven new compounds, named oenothebienoids A-G, were discovered.
• Oenothebienoids A-D possess a rare 20-epi-ursane triterpenoid framework.
• A method for differentiating C-20 configurations using NMR data was established.
• Compounds 13 and 14 showed moderate inhibition of alpha-glucosidase (IC50 values 5.16–4.24 μM).
• Compounds 14 and 26 exhibited significant inhibition of IDO1 (IC50 values 8.47–8.83 μM).

Conclusions:

• The study successfully identified novel triterpenoids from Oenothera biennis, expanding the known chemical diversity of this plant.
• The discovery of the 20-epi-ursane framework contributes valuable structural information to triterpenoid chemistry.
• The identified compounds show promising inhibitory activities against alpha-glucosidase and IDO1, indicating potential for developing new therapeutic agents.