Inhibitory effects of novel hydrophilic cyclodextrin derivatives on nitric oxide production in macrophages stimulated with lipopolysaccharide

Supramolecular Pharmaceutical Sciences: A Novel Concept Combining Pharmaceutical Sciences and Supramolecular Chemistry with a Focus on Cyclodextrin-Based Supermolecules

Supramolecular chemistry is an extremely useful and important domain for understanding pharmaceutical sciences because various physiological reactions and drug activities are based on supramolecular chemistry. However, it is not a major domain in the pharmaceutical field. In this review, we propose a new concept in pharmaceutical sciences termed "supramolecular pharmaceutical sciences," which combines pharmaceutical sciences and supramolecular chemistry. This concept could be useful for developing new ideas, methods, hypotheses, strategies, materials, and mechanisms in pharmaceutical sciences. Herein, we focus on cyclodextrin (CyD)-based supermolecules, because CyDs have been used not only as pharmaceutical excipients or active pharmaceutical ingredients but also as components of supermolecules.

Role of lipid microdomains in TLR-mediated signalling

Over the last twenty years, evidence has been provided that the plasma membrane is partitioned with microdomains, laterally mobile in the bilayer, providing the necessary microenvironment to specific membrane proteins for signalling pathways to be initiated. We discuss here the importance of such microdomains for Toll-like receptors (TLR) localization and function. First, lipid microdomains favour recruitment and clustering of the TLR machinery partners, i.e. receptors and co-receptors previously identified to be required for ligand recognition and signal transmission. Further, the presence of the so-called Cholesterol Recognition Amino-Acid Consensus (CRAC) sequences in the intracellular juxtamembrane domain of several Toll-like receptors suggests a direct role of cholesterol in the activation process. This article is part of a Special Issue entitled: Lipid-protein interactions.

Cyclodextrins, blood-brain barrier, and treatment of neurological diseases

Biological barriers are the main defense systems of the homeostasis of the organism and protected organs. The blood-brain barrier (BBB), formed by the endothelial cells of brain capillaries, not only provides nutrients and protection to the central nervous system but also restricts the entry of drugs, emphasizing its importance in the treatment of neurological diseases. Cyclodextrins are increasingly used in human pharmacotherapy. Due to their favorable profile to form hydrophilic inclusion complexes with poorly soluble active pharmaceutical ingredients, they are present as excipients in many marketed drugs. Application of cyclodextrins is widespread in formulations for oral, parenteral, nasal, pulmonary, and skin delivery of drugs. Experimental and clinical data suggest that cyclodextrins can be used not only as excipients for centrally acting marketed drugs like antiepileptics, but also as active pharmaceutical ingredients to treat neurological diseases. Hydroxypropyl-β-cyclodextrin received orphan drug designation for the treatment of Niemann-Pick type C disease. In addition to this rare lysosomal storage disease with neurological symptoms, experimental research revealed the potential therapeutic use of cyclodextrins and cyclodextrin nanoparticles in neurodegenerative diseases, stroke, neuroinfections and brain tumors. In this context, the biological effects of cyclodextrins, their interaction with plasma membranes and extraction of different lipids are highly relevant at the level of the BBB.

Effect of 18β-glycyrrhetinic acid and hydroxypropyl γcyclodextrin complex on indomethacin-induced small intestinal injury in mice

Non-steroidal anti-inflammatory drugs (NSAIDs)-induced small intestinal injury is a serious clinical event with recent advances of diagnostic technologies, but a successful therapeutic method to treat such injuries is still lacking. Licorice, a traditional herbal medicine, and its derivatives have been widely used for the treatment of a variety of diseases due to their extensive biological actions. However, it is unknown whether these derivatives have an effect on NSAIDs-induced small intestinal damage. Previously, the anti-inflammatory effects of three compounds extracted from the licorice root, glycyrrhizin, 18β-glycyrrhetinic acid, and dipotassium glycyrrhizinate, were compared in vitro cell culture. The most prominent inhibitory effect on the tumor necrosis factor-α (TNF-α) production was observed with the administration of 18β-glycyrrhetinic acid as an active metabolite of glycyrrhizin. In this study, a complex compound of 18β-glycyrrhetinic acid and hydroxypropyl γcyclodextrin was examined to improve the oral bioavailability. After administration of this complex to indomethacin treated mice, a significantly high plasma concentration of 18β-glycyrrhetinic acid was detected using the tandem mass spectrometry coupled with the HPLC. Furthermore, the complex form of 18β-glycyrrhetinic acid and hydroxypropyl γcyclodextrin reduced mRNA expressions of TNF-α, interleukin (IL)-1β, and IL-6, which was histologically confirmed in the improvement of indomethacin-induced small intestinal damage. These results suggest that the complex of 18β-glycyrrhetinic acid and hydroxypropyl γcyclodextrin has the potential therapeutic value for preventing the adverse effects of indomethacin-induced small intestinal injury.

Inhibitory effects of 2,6-di-O-methyl-alpha-cyclodextrin on poly I:C signaling in macrophages

In the present study, we examined the effects of alpha-cyclodextrin (alpha-CyD), 2-hydroxypropyl-alpha-cyclodextrin (HP-alpha-CyD) and 2,6-di-O-methyl-alpha-cyclodextrin (DM-alpha-CyD) on the nitric oxide (NO) and interferon-beta (IFN-beta) production in murine and human macrophages stimulated with Poly I:C and CpG-DNA, toll-like receptor 3 (TLR3) and TLR9 ligands, respectively. DM-alpha-CyD significantly inhibited NO production in RAW264.7 cells and U937 cells differentiated by phorbol myristate acetate (PMA), murine and human macrophage-like cell lines, respectively, stimulated with Poly I:C without cytotoxicity, but neither alpha-CyD nor HP-alpha-CyD did. Meanwhile, the three alpha-CyDs did not inhibit NO production in RAW264.7 cells stimulated with CpG-DNA. DM-alpha-CyD inhibited inducible NO synthase (iNOS) and IFN-beta expression upon stimulation with Poly I:C. Furthermore, DM-alpha-CyD markedly decreased the cellular uptake of Poly I:C in RAW264.7 cells. Therefore, DM-alpha-CyD may be useful as a potent inhibitor for excess activation of macrophages stimulated with Poly I:C.

Evaluation of polyamidoamine dendrimer/alpha-cyclodextrin conjugate (generation 3, G3) as a novel carrier for small interfering RNA (siRNA)

As the first step toward an evaluation of the potential use of the PAMAM dendrimer (G3) conjugate with alpha-cyclodextrin (alpha-CDE) for a small interfering RNA (siRNA) carrier, the ternary complexes of alpha-CDE or the transfection reagents such as Lipofactamine 2000 (L2), TransFast (TF) and Lipofectin (LF) with plasmid DNA (pDNA) and siRNA were prepared, and their RNAi effects, cytotoxicity, physicochemical properties and intracellular distribution were compared. Here the pGL2 control vector (pGL2) and pGL3 control vector (pGL3) encoding the firefly luciferase gene and the two corresponding siRNAs (siGL2 and siGL3) were used. The ternary complexes of pGL3/siGL3/alpha-CDE showed the potent RNAi effects with negligible cytotoxicity compared to those of the transfection reagents in various cells. alpha-CDE strongly interacted with both pDNA and siRNA, and suppressed siRNA degradation by serum, compared to those of the transfection reagents. alpha-CDE allowed fluorescent labeled siRNA to distribute in cytoplasm, whereas the transfection reagents resided in both nucleus and cytoplasm in NIH3T3 cells. Furthermore, the binary complex of siRNA/alpha-CDE provided the significant RNAi effect in NIH3T3 cells transiently and stably expressing luciferase gene. These results suggest that alpha-CDE may be utilized as a novel carrier for siRNA.

Effect of 2,6-di-O-methyl-alpha-cyclodextrin on hemolysis and morphological change in rabbit's red blood cells

The effects of 2,6-di-O-methyl-alpha-cyclodextrin (DM-alpha-CyD) on hemolysis and morphological changes in rabbit's red blood cells (RBC) were examined, compared with those of alpha-cyclodextrin (CyD) and 2-hydoxypropyl-alpha-cyclodextrin (HP-alpha-CyD). The hemolytic activity of alpha-CyDs increased in the order of HP-alpha-CyD<alpha-CyD<DM-alpha-CyD. The three alpha-CyDs induced morphological changes of RBC from discocyte to stomatocyte. At the same concentration (3mM) of alpha-CyDs, DM-alpha-CyD and alpha-CyD released phospholipids, rather than cholesterol, and DM-alpha-CyD markedly released proteins from RBC membranes, compared to alpha-CyD and HP-alpha-CyD. The treatment of RBC with DM-alpha-CyD lowered the extent of a fluorescent sphingomyelin analogue from lipid rafts of RBC membranes in a concentration-dependent manner. These results suggest that DM-alpha-CyD has higher hemolytic and morphological change activity than alpha-CyD and HP-alpha-CyD through more extraction of phospholipids including sphingomyelin and proteins, not cholesterol, from RBC membranes than alpha-CyD and HP-alpha-CyD.

Inhibitory effects of dimethylacetyl-beta-cyclodextrin on lipopolysaccharide-induced macrophage activation and endotoxin shock in mice

The potential use of hydrophilic cyclodextrins (CyDs) as an inhibitor for lipopolysaccharide (LPS) was examined. Of the five CyDs used in this study, dimethylacetyl-beta-cyclodextrin (DMA7-beta-CyD) had greater inhibitory activity than other CyDs against the production of nitric oxide (NO) and various proinflammatory cytokines including tumor necrosis factor-alpha (TNF-alpha) in murine macrophages stimulated with two serotypes of LPS and lipid A. The inhibitory effect of DMA7-beta-CyD on NO production was also observed in macrophages stimulated with lipoteichoic acid (LTA), but not peptidoglycan (PGN), polyinosinic-polycytidylic acid (poly I:C) or CpG oligonucleotide (CpG-ODN). Several studies have suggested that the inhibitory effects of DMA7-beta-CyD could be ascribed to the interaction with LPS. Simultaneous administration of DMA7-beta-CyD not only intraperitoneally but also intravenously and intraperitoneal injection of aqueous solution containing LPS and d-galactosamine in murine endotoxin shock model suppressed fatality. Also, DMA7-beta-CyD decreased blood level of TNF-alpha as well as serum levels of aspartate transaminase (AST) and alanine transaminase (ALT) in mice. In conclusion, DMA7-beta-CyD may have promise as a new therapeutic agent for endotoxin shock induced by LPS.

Design and evaluation of cyclodextrin-based drug formulation

The pharmaceutically useful cyclodextrins (CyDs) are classified into hydrophilic, hydrophobic, and ionic derivatives. Because of the multi-functional characteristics and bioadaptability, these CyDs are capable of alleviating the undesirable properties of drug molecules through the formation of inclusion complexes or the form of CyD/drug conjugates. This review outlines the current application of CyDs in design and evaluation of CyD-based drug formulation, focusing on their ability to enhance the drug absorption across biological barriers, the ability to control the rate and time profiles of drug release, and the ability to deliver a drug to a targeted site.

Involvement of CD14 in the inhibitory effects of dimethyl-α-cyclodextrin on lipopolysaccharide signaling in macrophages

The potential use of alpha-cyclodextrin and its hydrophilic alpha-cyclodextrin derivatives (alpha-CyDs) as antagonists against lipopolysaccharide (LPS), which stimulates the nitric oxide (NO) and tumor necrosis factor-alpha (TNF-alpha) production as well as nuclear factor-kappaB (NF-kappaB) activation in macrophages was examined. Of three alpha-CyDs used in the present study, 2,6-di-O-methyl-alpha-CyD (DM-alpha-CyD) had greater inhibitory activity than did the other CyDs against NO and TNF-alpha production through an impairment of gene expression in macrophage cell lines and primary macrophages stimulated with LPS and lipid A in a concentration-dependent manner. Concomitantly, DM-alpha-CyD inhibited NF-kappaB translocation into nucleus. These inhibitory effects of DM-alpha-CyD could be attributed to the release of CD14 from lipid rafts caused by an efflux of phospholipids, but not cholesterol. These results suggest that DM-alpha-CyD may have promise as a potent and unique antagonist for excess activation of macrophages stimulated with LPS.

[Pharmaceutical application of cyclodextrins as multi-functional drug carriers]

Owing to the increasingly globalized nature of the cyclodextrin (CyD)-related science and technology, development of the CyD-based pharmaceutical formulation is rapidly progressing. The pharmaceutically useful CyDs are classified into hydrophilic, hydrophobic, and ionic derivatives. Because of the multi-functional characteristics and bioadaptability, these CyDs are capable of alleviating the undesirable properties of drug molecules through the formation of inclusion complexes or the form of CyD/drug conjugates. This review outlines the current application of CyDs in drug delivery and pharmaceutical formulation, focusing on the following evidences. 1) The hydrophilic CyDs enhance the rate and extent of bioavailability of poorly water-soluble drugs. 2) The amorphous CyDs such as 2-hydroxypropyl-beta-CyD are useful for inhibition of polymorphic transition and crystallization rates of drugs during storage. 3) The delayed release formulation can be obtained by the use of enteric type CyDs such as O-carboxymethyl-O-ethyl-beta-CyD. 4) The hydrophobic CyDs are useful for modification of the release site and/or time profile of water-soluble drugs with prolonged therapeutic effects. 5) The branched CyDs are particularly effective in inhibiting the adsorption to hydrophobic surface of containers and aggregation of polypeptide and protein drugs. 6) The combined use of different CyDs and/or pharmaceutical additives can serve as more functional drug carriers, improving efficacy and reducing side effects. 7) The CyD/drug conjugates may provide a versatile means for the constructions of not only colonic delivery system but also site-specific drug release system, including gene delivery. On the basis of the above-mentioned knowledge, the advantages and limitations of CyDs in the design of advanced dosage forms will be discussed.