Naturally Occurring Chalcones with Aggregation-Induced Emission Enhancement Characteristics

Area of Science:

• Photophysics and Spectroscopy
• Natural Product Chemistry
• Medicinal Chemistry

Background:

• Chalcones are natural compounds with diverse biological activities.
• Aggregation-induced emission enhancement (AIEE) is a phenomenon with potential applications in sensing and imaging.
• Understanding the structure-property relationships of natural chalcones is crucial for developing new functional molecules.

Purpose of the Study:

• To investigate the spectroscopic and structural features of five natural chalcones.
• To identify chalcones exhibiting aggregation-induced emission enhancement (AIEE).
• To evaluate the antioxidant and neuroprotective potential of these chalcones.

Main Methods:

• Spectroscopic techniques: UV-vis, fluorescence spectroscopy.
• Structural analysis: Scanning electron microscopy (SEM), single-crystal X-ray diffraction (XRD).
• Biological assays: Free radical scavenging (DPPH), acetylcholinesterase (AChE), and butyrylcholinesterase (BuChE) inhibition.

Main Results:

• Cardamonin (CA) and 2'-hydroxy-4,4',6'-trimethoxychalcone (HCH) demonstrated effective AIEE behavior.
• Licochalcone A (LIC) exhibited high fluorescence quantum yield and Stokes shift in polar solvents and solid state.
• Licochalcone A displayed the most potent antioxidant (DPPH IC50 29%) and neuroprotective (AChE IC50 23.41 μM, BuChE IC50 42.28 μM) activities.

Conclusions:

• The study establishes a relationship between the photophysical properties and biological activities of natural chalcones.
• Licochalcone A is a promising candidate for developing AIEE-based biosensors and therapeutic agents.
• Structural modifications can be guided by these findings to design novel AIEE molecules for biological applications.