Synthesis and Physicochemical Characterization of Folate−Cyclodextrin Bioconjugate for Active Drug Delivery

Abstract

beta-Cyclodextrin-poly(ethylene glycol)-folic acid conjugate (CD-PEG-FA) was synthesized according to a two-step procedure: (1). synthesis of CD-PEG-NH(2) by reaction of monotosyl-activated beta-cyclodextrin with excess of 700 Da diamino-PEG; (2). synthesis of CD-PEG-FA by reaction of CD-PEG-NH(2) with succinimidyl ester-activated folic acid. The CD-PEG-NH(2) intermediate was purified by precipitation in acetone, and the CD-PEG-FA by gel permeation and C-18 reversed-phase chromatography. Both CD-PEG-NH(2) and CD-PEG-FA were analyzed by mass spectrometry, (1)H NMR, and UV-vis spectroscopy. All analytical methods confirmed the theoretical composition of the conjugates: the CD-PEG-NH(2) intermediate was composed of CD and PEG in the molar ratio of 1:1, and the CD-PEG-FA was composed of beta-cyclodextrin, PEG, and folic acid in the molar ratio of 1:1:1. The CD-PEG-FA conjugate was highly soluble in buffer (>42 mM) as compared to the unmodified beta-cyclodextrin (16.3 mM). Phase solubility diagrams of beta-estradiol revealed that drug solubility increases from 11 microM in buffer to 600 microM in the presence of beta-cyclodextrins and 5900 microM with CD-PEG-FA. However, the affinity of beta-estradiol for beta-cyclodextrins decreased about 4 times with PEG and folic acid conjugation. Stability studies carried out using chlorambucil confirmed that the conjugate partially prevents drug degradation in buffer, although this effect was considerably lower than that obtained with beta-cyclodextrin. Computer modeling studies showed that the folic acid linked to the beta-cyclodextrins through a PEG spacer could partially interact with the cyclodextrin cavity. Finally, CD-PEG-FA displayed reduced hemolytic effect as compared to unmodified beta-cyclodextrin.

Synthesis and characterization of a colloidal novel folic acid–β-cyclodextrin conjugate for targeted drug delivery

“…FA has also been conjugated to polyethyleneglycol (PEG) to successfully deliver a wide variety of compounds including chemotherapeutic agents, oligonucleotides, photosensitizers, polymers and dendrimers [9]. The synthesis of a b-cyclodextrin-polyethyleneglycol-folic acid conjugate (CD-PEG-FA) has been reported by Caliceti et al CD-PEG-FA was obtained from the reaction between CD-PEG-NH2 and FA [10]. The conjugate with FA was proposed as an active tumour targeting molecule [11].…”

Potential Use of Cyclodextrins as Drug Carriers and Active Pharmaceutical Ingredients

“…Therefore a number of FA-conjugated CyDs have been designed as tumor-targeting drug carriers. 27,28) However, most of the studies have been performed only in vitro. Thereby, there are few reports that achieved targeting of anticancer drug in vivo using FA-conjugated CyDs.…”

Polysaccharide-Based Anticancer Prodrugs

“…The CD-PEG-FA conjugate was obtained according to a two-step procedure which includes the synthesis of CD-PEG-NH 2 by reaction of mono-tosyl activated β-cyclodextrin with 700 Da diamino-PEG followed by the folic acid conjugation to the free amino group of CD-PEG-NH 2 [157].…”