Ten undescribed cadinane-type sesquiterpenoids from Eupatorium chinense

Area of Science:

• Natural Product Chemistry
• Organic Chemistry
• Phytochemistry

Background:

• Eupatorium chinense is a plant species known for its diverse secondary metabolites.
• Sesquiterpenes, a class of terpenes, exhibit a wide range of biological activities.
• Cadinane-type sesquiterpenes are characterized by a specific carbon skeleton.

Purpose of the Study:

• To isolate and characterize novel cadinane-type sesquiterpenes from Eupatorium chinense.
• To elucidate the planar structures and absolute configurations of the isolated compounds.
• To propose a biosynthetic pathway for the newly identified sesquiterpenes.

Main Methods:

• Isolation of compounds using chromatographic techniques.
• Structure elucidation via extensive spectroscopic data analysis (NMR, MS).
• Determination of absolute configurations using Density Functional Theory (DFT) calculations (NMR, ECD) and single-crystal X-ray diffraction.

Main Results:

• Ten previously undescribed cadinane-type sesquiterpenes, designated compounds 1-10, were successfully isolated.
• Planar structures were determined through comprehensive spectroscopic analysis and DFT NMR calculations.
• Absolute configurations were established using TDDFT ECD calculations and X-ray diffraction, revealing specific epimeric relationships (C-10, C-1) and isomerizations.

Conclusions:

• The study successfully identified and characterized ten new cadinane-type sesquiterpenes from Eupatorium chinense.
• Advanced computational and crystallographic methods were crucial for structural and stereochemical determination.
• A potential biosynthetic pathway for these novel sesquiterpenes was proposed, contributing to the understanding of plant secondary metabolism.