Labdane and Clerodane Diterpenoids from Colophospermum mopane

Area of Science:

• Natural Product Chemistry
• Phytochemistry
• Medicinal Chemistry

Background:

• Colophospermum mopane (Mopane) is a significant plant in Southern Africa.
• Diterpenoids are a class of natural products with diverse biological activities.

Purpose of the Study:

• To isolate and characterize diterpenoids from Colophospermum mopane.
• To evaluate the antimicrobial potential of these compounds and extracts.

Main Methods:

• Isolation and structural elucidation of diterpenoids using spectroscopic methods (NMR, HRESIMS).
• Determination of absolute configurations via X-ray diffraction, modified Mosher's method, and electronic circular dichroism.
• Antimicrobial activity testing using minimum inhibitory concentration (MIC) assays.

Main Results:

• Eleven diterpenoids were isolated, including nine new compounds: five labdanes (1-5), one isolabdane (6), and five clerodanes (7-11).
• The leaf extract exhibited notable activity against Staphylococcus aureus (125 μg/mL).
• Compound 11 demonstrated potent antimicrobial activity against Escherichia coli and Staphylococcus aureus (15.6 μg/mL) and Enterococcus faecalis (31.3 μg/mL).

Conclusions:

• Colophospermum mopane seeds, husks, and leaves are a source of novel diterpenoids.
• Compound 11 is a promising candidate for further investigation as an antimicrobial agent.