Synthesis of linear, beta-cyclodextrin-based polymers and their camptothecin conjugates

Area of Science:

• Polymer Chemistry
• Drug Delivery
• Bioconjugation

Background:

• Beta-cyclodextrin (beta-CD) derivatives offer potential for drug delivery applications.
• Camptothecin (CPT) is a potent anti-cancer drug with poor aqueous solubility.
• Developing effective CPT delivery systems is crucial for improving its therapeutic efficacy.

Purpose of the Study:

• To synthesize novel beta-cyclodextrin-based polymers with pendant carboxylate functionality.
• To conjugate camptothecin (CPT) to these polymers to create prodrugs with enhanced solubility and controlled release.
• To evaluate the in vitro anti-cancer activity and release kinetics of the CPT prodrugs.

Main Methods:

• Synthesis of a beta-cyclodextrin diamino acid derivative and its condensation with PEG comonomers to form high molecular weight polymers.
• Conjugation of CPT derivatives to the synthesized polymers.
• Solubility, drug release kinetics (in plasma and at varying pH), and in vitro cytotoxicity (MTT assay) assessments.

Main Results:

• Novel, highly water-soluble beta-cyclodextrin-based polymers (M(w) > 50 kDa) with pendant carboxylate groups were synthesized.
• CPT solubility was increased by over three orders of magnitude upon conjugation.
• Prodrugs demonstrated accelerated CPT release in plasma, suggesting enzymatic cleavage, and pH-dependent hydrolysis rates.
• In vitro assays showed cell-line dependent cytotoxicity for CPT conjugates, with low toxicity for the parent polymer.

Conclusions:

• The developed beta-cyclodextrin-based polymers serve as effective carriers for CPT, significantly improving its solubility and enabling controlled release.
• The prodrugs exhibit promising anti-cancer activity, with release mechanisms influenced by enzymatic and pH factors.
• These findings highlight the potential of these novel polymer-CPT conjugates for cancer therapy.