Kaneto Uekama

In Vitro and In Vivo gene delivery mediated by Lactosylated Dendrimer/α-Cyclodextrin Conjugates (G2) into Hepatocytes

The purpose of this study is to evaluate in vitro and in vivo gene delivery efficiency of polyamidoamine (PAMAM) starburst dendrimer (generation 2, G2) conjugates with alpha-cyclodextrin (alpha-CDE (G2)) bearing lactose (Lac-alpha-CDE) with various degrees of substitution of the lactose moiety (DSL) as a novel hepatocyte-selective carrier in hepatocytes. Lac-alpha-CDE (DSL 2.6) was found to have much higher gene transfer activity than dendrimer, alpha-CDE, Lac-alpha-CDE (DSL 1.2, 4.6, 6.2 and 10.2) and lactosylated dendrimer (Lac-dendrimer, DSL 2.4) in HepG2 cells, which are dependent on the expression of cell-surface asialoglycoprotein receptor (ASGP-R), reflecting the cellular association of the plasmid DNA (pDNA) complexes. The physicochemical properties of pDNA complex with Lac-alpha-CDE (DSL 2.6) were almost comparable to that with alpha-CDE. Lac-alpha-CDE (DSL 2.6) provided negligible cytotoxicity up to a charge ratio of 150 in HepG2 cells. Lac-alpha-CDE (DSL 2.6) provided gene transfer activity higher than jetPEI-Hepatocyte to hepatocytes with much less changes of blood chemistry values 12h after intravenous administration in mice. These results suggest the potential use of Lac-alpha-CDE (DSL 2.6) as a non-viral vector for gene delivery toward hepatocytes.

Involvement of PI3K-Akt-Bad pathway in apoptosis induced by 2,6-di-O-methyl-β-cyclodextrin, not 2,6-di-O-methyl-α-cyclodextrin, through cholesterol depletion from lipid rafts on plasma membranes in cells

Cyclodextrins (CyDs), which are widely used to increase the solubility of drug in pharmaceutical fields, are known to induce hemolysis and cytotoxicity at high concentrations. However, it is still not unclear whether cell death induced by CyDs is apoptosis or not. Therefore, in the present study, we investigated the effects of various kinds of CyDs on apoptosis in the cells such as NR8383 cells, A549 cells and Jurkat cells. Of various CyDs, methylated CyDs inducted cell death under the present experimental conditions, but hydroxypropylated CyDs or sulfobutyl ether-beta-CyD (SBE7-beta-CyD) did not. Of methylated CyDs, 2,6-di-O-methyl-beta-cyclodextrin (DM-beta-CyD) and 2,3,6-tri-O-methyl-beta-cyclodextrin (TM-beta-CyD) markedly caused apoptosis in NR8383 cells, A549 cells and Jurkat cells, through cholesterol depletion in cell membranes. In sharp contrast, 2,6-di-O-methyl-alpha-cyclodextrin (DM-alpha-CyD) and methyl-beta-cyclodextrin (M-beta-CyD) induced cell death in an anti-apoptotic mechanism. DM-beta-CyD induced apoptosis through the inhibition of the activation of PI3K-Akt-Bad pathway. Neither p38 MAP kinase nor p53 was contributed to the induction of apoptosis by DM-beta-CyD. Additionally, DM-beta-CyD significantly decreased mitochondrial transmembrane potential, and then caused the release of cytochrome c from mitochondria to cytosol in NR8383 cells. Furthermore, we confirmed that down-regulation of pro-caspase-3 and activation of caspase-3 after incubation with DM-beta-CyD. These results suggest that of methylated CyDs, DM-beta-CyD, not DM-alpha-CyD, induces apoptosis through the PI3K-Akt-Bad pathway, resulting from cholesterol depletion in lipid rafts of cell membranes.

Inhibitory effect of siRNA complexes with polyamidoamine dendrimer/α-cyclodextrin conjugate (generation 3, G3) on endogenous gene expression.

In the present study, we prepared the small interfering RNA (siRNA) complexes with polyamidoamine (PAMAM) dendrimer (G3) conjugate with α-cyclodextrin (α-CDE (G3)), and examined the physicochemical properties, serum resistance, in vitro RNAi effects on endogenous gene expression, cytotoxicity, interferon response, hemolytic activity, cellular association and intracellular distribution. In addition, these results were compared to the siRNA complexes with the commercial transfection reagents such as linear polyethyleneimine (PEI), Lipofectamine™2000 (L2) and RNAiFect™ (RF). α-CDE (G3) interacted with siRNA, and suppressed siRNA degradation by serum. The siRNA complex with α-CDE (G3) showed the potent RNAi effects against Lamin A/C and Fas expression with negligible cytotoxicity and hemolytic activity, compared to those of the transfection reagents in Colon-26-luc cells and NIH3T3-luc cells. Cell-death patterns induced by siRNA polyplexes with α-CDE (G3) and PEI were different from siRNA lipoplexes with L2 and RF. α-CDE (G3) delivered fluorescent-labeled siRNA to cytoplasm, not nucleus, after transfection in NIH3T3-luc cells. Taken together, α-CDE (G3) could be potentially used as a siRNA carrier to provide the RNAi effect on endogenous gene expression with negligible cytotoxicity.

Reduction of bitterness of antihistaminic drugs by complexation with β-cyclodextrins.

Reduction of bitterness of antihistaminic drugs by cyclodextrin (CyD) complexation was examined. The stability constant (Kc) of the 1:1 CyD inclusion complexes with antihistaminic drugs increased in the order of 2-hydroxypropyl-β-CyD (HP-β-CyD) ≈ β-CyD > γ-CyD > α-CyD for diphenhydramine and epinastine, and HP-β-CyD ≈ β-CyD > α-CyD > γ-CyD for hydroxyzine, cetirizine, and dl-chlorpheniramine. The inclusion complexes inhibited the adsorption of antihistaminic drugs to lipid membrane using liposomes, as the magnitude of Kc increased. From human gustatory sensation tests, β-CyD and HP-β-CyD potently suppressed the bitterness of antihistaminic drugs in a dose-dependent manner. Further, an artificial taste sensor analysis revealed that β-CyD and HP-β-CyD inhibited the bitterness of antihistaminic drugs in solution. The results suggest that CyDs suppress the bitterness of antihistaminic drugs in solutions through the formation of inclusion complexes. These results may provide useful information for masking or elimination of bitterness of drugs using CyDs.

5-Fluorouracil acetic acid/β-cyclodextrin conjugates: Drug release behavior in enzymatic and rat cecal media

5-Fluorouracil-1-acetic acid (5-FUA) was prepared and covalently conjugated to beta-cyclodextrin (beta-CyD) through ester or amide linkage, and the drug release behavior of the conjugates in enzymatic solutions and rat cecal contents were investigated. The 5-FUA/beta-CyD ester conjugate was slowly hydrolyzed to 5-FUA in aqueous solutions (half lives (t(1/2))=38 and 17h at pH 6.8 and 7.4, respectively, at 37 degrees C), whereas the amide conjugate was hardly hydrolyzed at these physiological conditions, but hydrolyzed only in strong alkaline solutions (>0.1M NaOH) at 60 degrees C. Both ester and amide conjugates were degraded in solutions of a sugar-degrading enzyme, alpha-amylase, to 5-FUA/maltose and triose conjugates, but the release of 5-FUA was only slight in alpha-amylase solutions. In solutions of an ester-hydrolyzing enzyme, carboxylic esterase, the ester conjugate was hydrolyzed to 5-FUA at the same rate as that in the absence of the enzyme, whereas the amide conjugate was not hydrolyzed by the enzyme. On the other hand, 5-FUA was rapidly released when the ester conjugate was firstly hydrolyzed by alpha-amylase, followed secondly by carboxylic esterase. The results indicated that the ester conjugate was hydrolyzed to 5-FUA in a consecutive manner, i.e. it was firstly hydrolyzed to the small saccharide conjugates, such as the maltose conjugate, by alpha-amylase, and the resulting small saccharide conjugates having less steric hindrance was susceptible to the action of carboxylic esterase, giving 5-FUA. The in vitro release behavior of the ester conjugate was clearly reflected in the hydrolysis in rat cecal contents and in the in vivo release after oral administration to rats.

Evaluation of carboxymethyl-β-cyclodextrin with acid function: Improvement of chemical stability, oral bioavailability and bitter taste of famotidine

The objective of the present study was to evaluate the potential influence of carboxymethyl-beta-cyclodextrin (CM-beta-CyD) on the aqueous solubility, chemical stability and oral bioavailability of famotidine (FMT) as well as on its bitter taste. We examined the effect of the CM-beta-CyD on the acidic degradation of FMT compared with that for sulfobutyl-ether-beta-cyclodextrin (SBE-beta-CyD). The potential use of CM-beta-CyD for orally disintegrating tablets (ODTs) was evaluated in vitro and in vivo. A taste perception study was also carried out. A strong stabilizing influence of CM-beta-CyD was observed against the acidic degradation, in sharp contrast to SBE-beta-CyD which induced a weird destabilizing effect on FMT. (13)C NMR was used to investigate the interaction mode between FMT and the 2 CyDs. In vivo study of ODTs indicated a significant increase in C(max), AUC and oral bioavailability in the case of FMT-CM-beta-CyD tablets, compared with plain drug tablets. However, no significant difference in T(max) and t(1/2) was observed. CM-beta-CyD complexation appears to be an acceptable strategy for enhancing the oral bioavailability of FMT owing to its dramatic effect on the aqueous solubility and chemical stability of the drug. In addition, it has a pronounced effect on masking the bitter taste of FMT.

Slow-release system of pegylated lysozyme utilizing formation of polypseudorotaxanes with cyclodextrins

Poly(ethylene glycol) (PEG, MW 2200) chains were introduced into lysozyme molecule. The resulting pegylated lysozyme formed polypseudorotaxanes with alpha- and gamma-cyclodextrins (alpha- and gamma-CyDs, respectively), by inserting one PEG chain in the alpha-CyD cavity and two PEG chains in the gamma-CyD cavity. The pegylated lysozyme/CyD polypseudorotaxanes were less soluble in water and the release rate of the pegylated protein decreased in the order of the pegylated lysozyme>the gamma-CyD polypseudorotaxane>the alpha-CyD polypseudorotaxane. The enzymatic activity of the pegylated lysozyme released from the polypseudorotaxanes was the same as that of the pegylated protein alone, indicating no decrease in the activity through the polypseudorotaxane formation. The results indicate that the pegylated lysozyme/CyD polypseudorotaxanes can work as a slow-release system, and the polypseudorotaxane formation with CyDs may serve as a new strategy for the preparation of slow-release system of pegylated proteins and peptides.

Potential use of folate-polyethylene glycol (PEG)-appended dendrimer (G3) conjugate with α-cyclodextrin as DNA carriers to tumor cells

We previously reported that polyamidoamine STARBURST dendrimer (generation 3, G3) (dendrimer) conjugate with α-cyclodextrin (α-CyD) having an average degree of substitution of 2.4 of α-CyD (α-CDE) provided remarkable aspects as novel carriers for DNA and small-interfering RNA. To develop novel α-CDE derivatives with tumor cell specificity, we prepared folate-appended α-CDEs (Fol-α-CDEs) and folate-polyethylene glycol (PEG)-appended α-CDEs (Fol-PαCs) with the various degrees of substitution of folate (DSF), and evaluated in vitro and in vivo gene transfer activity, cytotoxicity, cellular association and physicochemical properties. In vitro gene transfer activity of Fol-α-CDEs (G3, DSF 2, 5 or 7) was lower than that of α-CDE (G3) in KB cells, folate receptor (FR)-overexpressing cancer cells. Of the three Fol-PαCs (G3, DSF 2, 5 or 7), Fol-PαC (G3, DSF 5) had the highest gene transfer activity in KB cells. The activity of Fol-PαC (G3, DSF 5) was significantly higher than that of α-CDE (G3) in KB cells, but not in A549 cells, FR-negative cells. Negligible cytotoxicity of the plasmid DNA (pDNA) complex with Fol-PαC (G3, DSF 5) was observed in KB cells or A549 cells up to a charge ratio of 100/1 (carrier/pDNA). The cellular association of the pDNA complex with Fol-PαC (G3, DSF 5) could be mediated by FR on KB cells, resulting in its efficient cellular uptake. Fol-PαC (G3, DSF 5) had a higher binding affinity with folate-binding protein than α-CDE (G3), although the physicochemical properties of pDNA complex with Fol-PαC (G3, DSF 5) were almost comparable to that with α-CDE (G3), although the onset charge ratio and the compaction ability of Fol-PαC (G3, DSF 5) were slightly different. Fol-PαC (G3, DSF 5) tended to show a higher gene transfer activity than α-CDE (G3) 12u2009h after intratumoral administration in mice. These results suggest that Fol-PαC (G3, DSF 5), not Fol-α-CDEs, could be potentially used as a FR-overexpressing cancer cell-selective DNA carrier.

Enhancement of the Aqueous Solubility and Masking the Bitter Taste of Famotidine Using Drug/SBE-β-CyD/Povidone K30 Complexation Approach

The objective of the present study was to evaluate the potential of ternary system (comprised of famotidine, beta-cyclodextrin (beta-CyD) or its derivatives and a hydrophilic polymer) as an approach for enhancing the aqueous solubility and masking the bitter taste of famotidine. The aqueous solubility of famotidine increased in the presence of beta-CyDs, particularly sulfobutyl ether beta-CyD (SBE-beta-CyD), and it was further enhanced by the combination of SBE-beta-CyD and polyvinyl pyrrolidone (Povidone) K30. The solid binary (drug-beta-CyDs) and ternary (drug-beta-CyDs-Povidone K30) systems were prepared by the kneading and freeze-drying methods. The dissolution rates of these solid systems were much faster than that of the drug alone. A taste perception study was carried out, initially using a taste sensory machine and subsequently on human volunteers to evaluate the taste masking ability of the ternary complexation. Our results indicated that the combination of SBE-beta-CyD and Povidone K30 is effective not only in the enhancement of the solubility and dissolution rate of famotidine, but also in masking of the bitter taste of the drug. This technique may be of value for the pharmaceutical industries, especially in preparation of rapidly disintegrating tablets dealing with bitter drugs to improve patient compliance and thus effective pharmacotherapy.

Some pharmaceutical and inclusion properties of 2-hydroxybutyl-β- cyclodextrin derivative

2-Hydroxybutyl-β-cyclodextrins (HB-β-CyDs) with different degrees of substitution (D.S.) were prepared and their physicochemical and biological properties and solubilizing abilities were studied and compared with those of 2-hydroxypropyl-β-cyclodextrin (HP-β-CyD). The surface activity of HB-β-CyD was higher than that of HP-β-CyD (D.S. 5.6) and increased with its concentration and D.S. The moisture sorption of HB-β-CyD (D.S. 5.5) was less than that of HP-β-CyD (D.S. 5.6), because of the introduction of hydrophobic hydroxybutyl groups in a molecule. The hemolytic activity (rabbit erythrocytes) decreased in the order of 2,6-di-O-methyl-β-cyclodextrin (DM-β-CyD)>methyl-β-cyclodextrin (M-β-CyD)>HB-β-CyD (D.S. 5.5)>β-CyD>HP-β-CyD (D.S. 5.6). The hemolytic activity of HB-β-CyD increased with D.S. and HB-β-CyD induced echinocyte (or crenation), as well as DM-β-CyD does. It was suggested from the solubility study of membrane components that HB-β-CyD interacted predominantly with cholesterol in erythrocytes, resulting in the hemolysis. The inclusion ability of HB-β-CyD was higher than that of HP-β-CyD (D.S. 5.6), especially for poorly water-soluble drugs with long linear structures such as biphenylylacetic acid and flurbiprofen (FP). For example, HB-β-CyD formed the inclusion complex with FP in a molar ratio of 1:1, by including the biphenyl moiety in the host cavity. The dissolution rate of FP/HB-β-CyD (D.S. 5.5) complex was faster than that of HP-β-CyD (D.S. 5.6) complex. The results suggested that HB-β-CyDs have considerable pharmaceutical potential and can work as a fast-dissolving carrier for poorly water-soluble drugs.