Ceramicines U-Z from Chisocheton ceramicus and structure-antimalarial activity relationship study

Area of Science:

• Natural Product Chemistry
• Medicinal Chemistry
• Pharmacology

Background:

• Ceramicines, a class of limonoids from Chisocheton ceramicus, possess known biological activities.
• The Malaysian plant Chisocheton ceramicus is a source of diverse limonoid compounds.

Purpose of the Study:

• To isolate and characterize new ceramicine limonoids from Chisocheton ceramicus barks.
• To evaluate the antimalarial activity of novel ceramicines against Plasmodium falciparum.
• To investigate the structure-activity relationships (SAR) of ceramicines for antimalarial efficacy.

Main Methods:

• Isolation and purification of limonoids using chromatographic techniques.
• Structure elucidation of new compounds via 1D and 2D Nuclear Magnetic Resonance (NMR) spectroscopy.
• Determination of absolute configurations using Circular Dichroism (CD) spectroscopy.
• In vitro antimalarial activity assay against Plasmodium falciparum (3D7 strain).

Main Results:

• Six new limonoids, ceramicines U-Z (1-6), were identified, featuring a cyclopentanone[α]phenanthrene ring system with a β-furyl moiety.
• Ceramicine W (3) exhibited significant antimalarial activity with an IC50 value of 1.2 µM against Plasmodium falciparum 3D7.
• Structure-activity relationship analysis indicated that the B ring and adjacent functional groups are crucial for antimalarial potency.
• Bulky, equatorially oriented ester substituents at C-7 and C-12 positions were found to substantially enhance antimalarial activity.

Conclusions:

• The study successfully identified novel ceramicine limonoids with potent antimalarial properties.
• Ceramicine W represents a promising lead compound for further antimalarial drug development.
• Understanding the SAR of ceramicines provides valuable insights for designing more effective antimalarial agents targeting Plasmodium falciparum.