cis,cis-Germacranolides and melampolides from Mikania thapsoides

Area of Science:

• Phytochemistry
• Organic Chemistry
• Natural Products Chemistry

Background:

• Mikania thapsoides is a plant species known for its diverse chemical constituents.
• Sesquiterpene lactones are a significant class of natural products with various biological activities.
• Previous research on Mikania species has identified numerous bioactive compounds.

Purpose of the Study:

• To isolate and characterize new sesquiterpene lactones from the aerial parts of Mikania thapsoides.
• To elucidate the structures of these novel compounds, including their stereochemistry.
• To investigate the chemical diversity within the Mikania genus.

Main Methods:

• Extraction and isolation of compounds from Mikania thapsoides aerial parts.
• Structure elucidation using comprehensive 1D and 2D Nuclear Magnetic Resonance (NMR) spectroscopy.
• Determination of absolute configuration for key compounds using the Mosher ester method.

Main Results:

• Isolation of six new cis,cis-germacranolide-type sesquiterpene lactones (compounds 1-6).
• Discovery of three compounds (1-3) possessing an unusual 3,4-epoxy functionality.
• Identification of two new melampolides (compounds 7 and 8).
• Confirmation of a trans C-8 lactone ring closure in all isolated compounds.

Conclusions:

• The study successfully identified eight novel sesquiterpene lactones from Mikania thapsoides.
• The findings highlight the rich and unique chemical profile of this plant species.
• The elucidated structures contribute to the understanding of sesquiterpene lactone diversity and biosynthesis.