Synthesis, characterization and potential application of monoacyl-cyclodextrins

Area of Science:

• Carbohydrate Chemistry
• Supramolecular Chemistry
• Organic Synthesis

Background:

• Direct regioselective cyclodextrin (CD) acylation is challenging, often necessitating complex synthetic routes.
• Existing methods for preparing CD monoesters are varied, but achieving specific regioselectivity remains a hurdle.

Purpose of the Study:

• To develop a straightforward, one-step method for the regioselective synthesis of monoacylated cyclodextrins (CDs).
• To investigate the influence of solvents and reaction conditions on acylation regioselectivity.
• To evaluate the potential of synthesized monoacylated CDs as carriers for silibinin.

Main Methods:

• One-step acylation of alpha-, beta-, and gamma-CDs using acyclic or aromatic carboxylic acid derivatives.
• Exploitation of beta-CD's ability to complex cupric ions for regioselective acylation in water.
• Preparation of long-chain aliphatic monoesters in DMF.
• Characterization using NMR spectroscopy (1H, 13C, 2D) and thermal analysis.

Main Results:

• High regioselectivity in beta-CD acylation was achieved using cupric ion complexation in water with benzoyl, cinnamoyl, and phenyl acetyl chlorides.
• Optimal conditions for preparing long-chain aliphatic monoesters of alpha-, beta-, and gamma-CDs were identified in DMF.
• NMR studies confirmed the precise location of esterification.
• Monoacylated CDs demonstrated utility as carriers for silibinin, forming characterized inclusion complexes.

Conclusions:

• Solvent choice and reaction conditions are critical determinants of acylation regioselectivity in CDs.
• The developed one-step method offers a simplified approach to synthesizing regioselectively monoacylated CDs.
• Monoacylated CDs show promise as effective carriers for drug molecules like silibinin.