Cassane diterpenes from Caesalpinia platyloba

Area of Science:

• Natural Product Chemistry
• Organic Chemistry
• Phytochemistry

Background:

• Caesalpinia platyloba is a plant species known to produce bioactive compounds.
• Diterpenes are a class of organic compounds with diverse biological activities.
• Cassane diterpenes represent a specific structural class within diterpenoids.

Purpose of the Study:

• To isolate and characterize cassane diterpenes from the dichloromethane extract of Caesalpinia platyloba leaves.
• To determine the absolute configurations of the isolated diterpenes.
• To chemically correlate the isolated compounds with known related structures.

Main Methods:

• Extraction of plant material using dichloromethane.
• Isolation of compounds using chromatographic techniques.
• Structure elucidation using Nuclear Magnetic Resonance (NMR) spectroscopy (1D and 2D).
• Determination of absolute configurations via comparison of experimental and DFT-calculated Vibrational Circular Dichroism (VCD) spectra.

Main Results:

• Three cassane diterpenes, (-)-(5S,6R,8S,9S,10R,14R)-6-acetoxyvouacapane (1), (-)-(5S,6R,8S,9S,10R,12Z,14R)-6-acetoxycassa-12,15-diene (3), and (-)-(5S,6R,8S,9S,10R,13E)-6-acetoxycassa-13,15-diene (4), were isolated.
• Compound 1 was chemically correlated with compounds 2, 5, and 6.
• The absolute configurations of six diterpenes (1-6) were established.
• Reassignment of chemical shifts for compounds 2 and 5 was performed based on 2D NMR data.

Conclusions:

• The study successfully identified and characterized novel cassane diterpenes from Caesalpinia platyloba.
• The application of VCD spectroscopy proved effective for determining absolute configurations.
• The findings contribute to the understanding of the chemical diversity of cassane diterpenes and their natural sources.