Sesquiterpenes from Oplopanax horridus

Area of Science:

• Natural Product Chemistry
• Medicinal Chemistry
• Phytochemistry

Background:

• Oplopanax horridus (devil's club) is an ethnobotanical source with reported medicinal properties.
• Investigating the chemical constituents of O. horridus is crucial for identifying novel bioactive compounds.

Purpose of the Study:

• To isolate and characterize new compounds from O. horridus with anti-tuberculosis (anti-TB) activity.
• To elucidate the structures of novel nerolidol derivatives and assess their contribution to the plant's bioactivity.

Main Methods:

• Isolation of compounds using countercurrent chromatography.
• Structure elucidation through extensive spectroscopic analysis, including 1H NMR and MS data.
• Evaluation of anti-TB activity against Mycobacterium tuberculosis.

Main Results:

• Isolation of two new heterocyclic nerolidol derivatives, neroplomacrol (1) and neroplofurol (2), along with known compounds oplopandiol (3), falcarindiol (4), and sesamin (5).
• Identification of a novel 3,10-oxanonacyclic ring system in neroplomacrol (1).
• Polyynes 3 and 4 were identified as the main anti-TB active principles, showing synergistic effects with the new sesquiterpenes 1 and 2.

Conclusions:

• Neroplomacrol and neroplofurol are novel compounds with potential anti-TB activity.
• 1H NMR fingerprints and MS data are effective for dereplication of isolates at submilligram levels.
• The synergistic activity of O. horridus extracts against Mycobacterium tuberculosis is attributed to a complex interplay between polyynes and new sesquiterpenes.