Anti-inflammatory labdane diterpenoids from Leonurus japonicus Houtt

Area of Science:

• Natural Product Chemistry
• Pharmacology
• Organic Chemistry

Background:

• Leonurus japonicus Houtt. is a traditional medicinal plant.
• Labdane diterpenoids are a class of natural products with diverse biological activities.
• Identifying novel compounds with anti-inflammatory properties is crucial for drug discovery.

Purpose of the Study:

• To isolate and characterize new labdane diterpenoids from Leonurus japonicus.
• To investigate the anti-inflammatory potential of the isolated compounds.

Main Methods:

• Isolation and purification of compounds using chromatographic techniques.
• Structure elucidation using High-Resolution Electrospray Ionization Mass Spectrometry (HRESIMS), 1D and 2D Nuclear Magnetic Resonance (NMR) spectroscopy, and Electronic Circular Dichroism (ECD).
• In vitro anti-inflammatory assay by measuring prostaglandin E2 (PGE2) inhibition in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages.

Main Results:

• Seven undescribed labdane diterpenoids, named japonicones A-G, were successfully isolated.
• Japonicones C-G possess a rare structural feature of two keto carbonyl groups at C-3 and C-7.
• Japonicones A-D and G exhibited significant inhibition of PGE2 production, with IC50 values ranging from 8.62 to 30.71 μM.

Conclusions:

• The study successfully identified novel labdane diterpenoids from Leonurus japonicus.
• Japonicones A-D and G show promising anti-inflammatory activity, warranting further investigation for therapeutic potential.
• The rare structural motif in japonicones C-G may contribute to their biological activity.