Eugenol-based meroterpenoids with neural differentiation activity from Eugenia caryophyllata

Area of Science:

• Natural Product Chemistry
• Organic Chemistry
• Medicinal Chemistry

Background:

• Eugenia caryophyllata (clove) is a source of bioactive compounds.
• Meroterpenoids are complex natural products with diverse biological activities.

Purpose of the Study:

• To conduct a phytochemical investigation of Eugenia caryophyllata buds.
• To discover and characterize novel eugenol-based meroterpenoids.

Main Methods:

• Isolation and structural elucidation of compounds using comprehensive spectroscopic techniques (NMR, MS).
• Single-crystal X-ray diffraction for definitive structure determination.
• Quantum-chemical calculations to support structural assignments.

Main Results:

• Discovery of nine new eugenol-based meroterpenoids, named eugenianols A-I (1-9).
• Compound 1 features an unprecedented tricyclo[9.4.0.04,7]pentadecane core skeleton.
• Compounds 2-5 display unique C-C linkage patterns, with compound 4 showing a rare chiral axis.
• Compounds 6-9 are novel ether-bridged meroterpenoids.
• Proposed a plausible biosynthetic pathway for the discovered compounds.
• Compound 7 demonstrated significant neural differentiation-promoting activity.

Conclusions:

• The study expands the structural diversity of eugenol-based meroterpenoids.
• Compound 7 shows potential for neuroprotection and further investigation.
• The findings contribute to understanding the biosynthesis of these complex natural products.