Cyclodextrin complexes of reduced bromonoscapine in guar gum microspheres enhance colonic drug delivery.
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ABSTRACT: Here, we report improved solubility and enhanced colonic delivery of reduced bromonoscapine (Red-Br-Nos), a cyclic ether brominated analogue of noscapine, upon encapsulation of its cyclodextrin (CD) complexes in bioresponsive guar gum microspheres (GGM). Phase-solubility analysis suggested that Red-Br-Nos complexed with ?-CD and methyl-?-CD in a 1:1 stoichiometry, with a stability constant (Kc) of 2.29 × 10(3) M(-1) and 4.27 × 10(3) M(-1). Fourier transforms infrared spectroscopy indicated entrance of an O-CH? or OCH?-C?H?-OCH? moiety of Red-Br-Nos in the ?-CD or methyl-?-CD cavity. Furthermore, the cage complex of Red-Br-Nos with ?-CD and methyl-?-CD was validated by several spectral techniques. Rotating frame Overhauser enhancement spectroscopy revealed that the Ha proton of the OCH?-C?H?-OCH? moiety was closer to the H? proton of ?-CD and the H? proton of the methyl-?-CD cavity. The solubility of Red-Br-Nos in phosphate buffer saline (PBS, pH ? 7.4) was improved by ?10.7-fold and ?21.2-fold when mixed with ?-CD and methyl-?-CD, respectively. This increase in solubility led to a favorable decline in the IC?? by ?2-fold and ?3-fold for Red-Br-Nos-?-CD-GGM and Red-Br-Nos-methyl-?-CD-GGM formulations respectively, compared to free Red-Br-Nos-?-CD and Red-Br-Nos-methyl-?-CD in human colon HT-29 cells. GGM-bearing drug complex formulations were found to be highly cytotoxic to the HT-29 cell line and further effective with simultaneous continuous release of Red-Br-Nos from microspheres. This is the first study to showing the preparation of drug-complex loaded GGMS for colon delivery of Red-Br-Nos that warrants preclinical assessment for the effective management of colon cancer.
SUBMITTER: Madan J
PROVIDER: S-EPMC4255741 | biostudies-literature | 2014 Dec
REPOSITORIES: biostudies-literature
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