Interplay among Conformation, Intramolecular Hydrogen Bonds, and Chameleonicity in the Membrane Permeability and Cyclophilin A Binding of Macrocyclic Peptide Cyclosporin O Derivatives.

A macrocyclic peptide scaffold with well-established structure-property relationship is desirable for tackling undruggable targets. Here, we adopted a natural macrocycle, cyclosporin O (CsO) and its derivatives (CP1-3), and evaluated the impact of conformation on membrane permeability, cyclophilin A (CypA) binding, and the pharmacokinetic (PK) profile. In nonpolar media, CsO showed a similar conformation to cyclosporin A (CsA), a well-known chameleonic macrocycle, but less chameleonic behavior in a polar environment. The weak chameleonicity of CsO resulted in decreased membrane permeability; however, the more rigid conformation of CsO was not detrimental to its PK profile. CsO exhibited a higher plasma concentration than CsA, which resulted from minimal CypA binding and lower accumulation in red blood cells and moderate oral bioavailability (F = 12%). Our study aids understanding of CsO, a macrocyclic peptide that is less explored than CsA but with greater potential for diversity generation and rational design.

Discovery of a novel 9-position modified second-generation anti-HCV candidate via bioconversion and semi-synthesis of FR901459.

Evidence that hepatitis C virus (HCV) utilizes cellular cyclophilin proteins in the virus replication cycle has increased attention on cyclophilin inhibitors as attractive therapeutic targets in the treatment of HCV. Previous reports have described a number of non-immunosuppressive cyclophilin inhibitors, most of which require many synthetic steps for their preparation. Sasamura et al. have previously reported the isolation of bioconversion derivative 4. This analog is a convenient starting point for optimization due to the presence of the readily modifiable primary hydroxyl group and because it shows moderate anti-HCV activity and decreased immunosuppressive activity. We have also established an efficient C-alkylation reaction at the 3-position. Through a detailed structure-activity relationship study, we discovered a new type of clinical candidate 14 which requires a short synthetic process and has potent anti-HCV activity and reduced immunosuppressive activity, as well as improved aqueous solubility and pharmacokinetics.

Phospholipid Cyclosporine Prodrugs Targeted at Inflammatory Bowel Disease (IBD) Treatment: Design, Synthesis, and in Vitro Validation.

Novel phospholipid (PL)-cyclosporine conjugates were prepared and studied as potential prodrugs for inflammatory bowel disease (IBD). Our approach relies on phospholipase A2 (PLA2 ), which is overexpressed in the inflamed intestinal tissues, as the prodrug activator to potentially release cyclosporine at the site of inflammation. PL-cyclosporine prodrug conjugates with methylene linkers of various lengths between the sn-2 position of the PL and cyclosporine were synthesized and evaluated for in vitro activation. Surprisingly, despite previous work indicating that conjugates with six methylene linkers between the lipid and drug would suffer rapid enzymatic hydrolysis, with cyclosporine this was not observed. However, compounds with longer linkers (n=10, 12 methylene units) display complete release of the drug by PLA2 -catalyzed hydrolysis, thus demonstrating the importance and profound impact of structural fine-tuning. This study represents a proof-of-concept for our hypothesis and a first step towards a truly targeted IBD treatment with cyclosporine that could be administered throughout the GI tract.

Development of an efficient semisynthetic modification of FR901459 via a novel regioselective N, O-acyl migration.

HCV utilizes cellular protein cyclophilins in the virus replication cycle and cyclophilin inhibitors have become a new class of anti-HCV agents. In our screening of natural products, we identified a unique cyclosporin analogue, FR901459, as a cyclophilin inhibitor with potent anti-HCV activity. In this work, we developed an efficient synthetic methodology to prepare FR901459 derivatives via an N, O-acyl migration reaction. This method allows us to efficiently manipulate the amino acid residues at the 3 position while avoiding lengthy total synthesis for each compound. By using this methodology, we discovered 4, which has superior anti-HCV activity and decreased immunosuppressive activity compared to FR901459.

Cyclosporine A Suppresses the Malignant Progression of Oral Squamous Cell Carcinoma in vitro.

BACKGROUND: The Oral Squamous Cell Carcinoma (OSCC) is one of the most frequent cancer types. Failure of treatment of OSCC is potentially lethal because of local recurrence, regional lymph node metastasis, and distant metastasis. Chemotherapy plays a vital role through suppression of tumorigenesis. Cyclosporine A (CsA), an immunosuppressant drug, has been efficiently used in allograft organ transplant recipients to prevent rejection, and also has been used in a subset of patients with autoimmunity related disorders. The present study aims to investigate novel and effective chemotherapeutic drugs to overcome drug-resistance in the treatment of OSCC. METHODS: Cells were incubated in the standard way. Cell viability was assayed using the MTT assay. Cell proliferation was determined using colony formation assay. The cell cycle assay was performed using flow cytometry. Apoptosis was assessed using fluorescence-activated cell sorting after stained by the Annexin V-fluorescein isothiocyanate (FITC). Cell migration and invasion were analyzed using wound healing assay and tranwell. The effect of COX-2, c-Myc, MMP-9, MMP-2, and NFATc1 protein expression was determined using Western blot analysis while NFATc1 mRNA expression was determined by RT-PCR. RESULTS: In vitro studies indicated that CsA inhibited partial OSCC growth by inducing cell cycle arrest, apoptosis, and the migration and invasion of OSCC cells. We also demonstrated that CsA could inhibit the expression of NFATc1 and its downstream genes COX-2, c-Myc, MMP-9, and MMP-2 in OSCC cells. Furthermore, we analyzed the expression of NFATc1 in head and neck cancer through the Oncomine database. The data was consistent with the experimental findings. CONCLUSION: The present study initially demonstrated that CsA could inhibit the progression of OSCC cells and can mediate the signal molecules of NFATc1 signaling pathway, which has strong relationship with cancer development. That explains us CsA has potential to explore the possibilities as a novel chemotherapeutic drug for the treatment of OSCC.

Development of a cyclosporin A derivative with excellent anti-hepatitis C virus potency.

Synthetic modification of cyclosporin A at P3-P4 positions led to the discovery of NIM258, a next generation cyclophilin inhibitor with excellent anti-hepatitis C virus potency, with decreased transporter inhibition, and pharmacokinetics suitable for coadministration with other drugs. Herein is disclosed the evolution of the synthetic strategy to from the original medicinal chemistry route, designed for late diversification, to a convergent and robust development synthesis. The chiral centers in the P4 fragment were constructed by an asymmetric chelated Claisen rearrangement in the presence of quinidine as the chiral ligand. Identification of advanced crystalline intermediates enabled practical supply of key intermediates. Finally, macrocyclization was carried out at 10% weight concentration by a general and unconventional "slow release" concept.

Preparation and in vitro/in vivo evaluation of cyclosporin A-loaded nanodecorated ocular implants for subconjunctival application.

In terms of ocular drug delivery, biodegradable implant systems have several advantages including the ability to provide constant drug concentration at the target site, no necessity for surgical removal, and minimum systemic side effects. Cyclosporin A (CsA) is a neutral, hydrophobic, cyclic peptide of amino acids that frequently used for dry eye disease treatment. The aim of this study was to develop a nanoparticle-loaded implant system for sustained-release CsA delivery following subconjunctival implantation. Poly(lactide-co-glycolide) (85:15) or poly-ε-caprolactone (PCL) were used to prepare two different nanoparticle formulations. These nanoparticles loaded into PCL or poly(lactide-co-caprolactone) implant formulations were prepared by two different methods, which were molding and electrospinning. Size and zeta potential of nanoparticles were determined and the morphology of the formulations were investigated by scanning electron microscopy. CsA-loading efficiencies were calculated and the in vitro degradation and in vitro release studies were performed. MTT test was also performed using L929 fibroblast cells to evaluate the cytotoxicity of the formulations. PCL-PCL-NP-I formulation was implanted to Swiss Albino mice with induced dry eye syndrome to evaluate the efficacy. In vitro release studies showed that the release from the formulations continues between 30 and 60 days, and the cell viability was found to be 77.4%-99.0%. In vivo studies showed that healing is significantly faster in the presence of the selected implant formulation. Results indicated that nanodecorated implants are promising ocular carriers for controlled-release CsA application.

Anti-inflammatory effects of extracellular cyclosporins are exclusively mediated by CD147.

Leukocyte trafficking and recruitment is a critical process in host immune surveillance and in inflammatory diseases. Extracellular cyclophilins (eCyps) have been identified as a novel class of chemotactic mediators. The impact of eCyp/CD147 interactions for the recruitment of leukocytes during inflammation was analyzed using a structurally simplified cell-impermeable eCyp inhibitor. This compound was highly effective at inhibiting leukocyte migration toward CypA in vitro as well as in the recruitment of leukocytes during inflammation in a mouse model of experimentally induced peritonitis and delayed-type hypersensitivity reaction. By using CD147-/- mice in combination with the cell-impermeable eCyp inhibitor, we were able to show that the action of eCyps in inflammation is exclusively mediated by interaction with CD147. Our findings suggest that blocking eCyps may be an effective therapeutic target for reducing inflammatory diseases associated with leukocyte recruitment.

Characterization and stability studies of a novel liposomal cyclosporin A prepared using the supercritical fluid method: comparison with the modified conventional Bangham method.

A novel method to prepare cyclosporin A encapsulated liposomes was introduced using supercritical fluid of carbon dioxide (SCF-CO(2)) as an antisolvent. To investigate the strength of the newly developed SCF-CO(2) method compared with the modified conventional Bangham method, particle size, zeta potential, and polydispersity index (PDI) of both liposomal formulations were characterized and compared. In addition, entrapment efficiency (EE) and drug loading (DL) characteristics were analyzed by reversed-phase high-performance liquid chromatography. Significantly larger particle size and PDI were revealed from the conventional method, while EE (%) and DL (%) did not exhibit any significant differences. The SCF-CO(2) liposomes were found to be relatively smaller, multilamellar, and spherical with a smoother surface as determined by transmission electron microscopy. SCF-CO(2) liposomes showed no significant differences in their particle size and PDI after more than 3 months, whereas conventional liposomes exhibited significant changes in their particle size. The initial yield (%), EE (%), and DL (%) of SCF-CO(2) liposomes and conventional liposomes were 90.98 ± 2.94, 92.20 ± 1.36, 20.99 ± 0.84 and 90.72 ± 2.83, 90.24 ± 1.37, 20.47 ± 0.94, respectively, which changed after 14 weeks to 86.65 ± 0.30, 87.63 ± 0.72, 18.98 ± 0.22 and 75.04 ± 8.80, 84.59 ± 5.13, 15.94 ± 2.80, respectively. Therefore, the newly developed SCF-CO(2) method could be a better alternative compared with the conventional method and may provide a promising approach for large-scale production of liposomes.

Small-molecular inhibitors of Ca²âº-induced mitochondrial permeability transition (MPT) derived from muscle relaxant dantrolene.

A structure consisting of substituted hydantoin linked to a 5-(halophenyl)furan-2-yl group via an amide bond was identified as a promising scaffold for development of low-molecular-weight therapeutic agents to treat vascular dysfunction, including ischemia/reperfusion injury. Among the compounds synthesized, 5-(3,5-dichlorophenyl)-N-{2,4-dioxo-3-[(pyridin-3-yl)methyl]imidazolidin-1-yl}-2-furamide (17) possessed the most potent inhibitory activity against Ca(2+)-induced mitochondrial swelling. The structural development, synthesis and structure-activity relationship of these compounds are described.

A fascinating journey into history: exploration of the world of isonitriles en route to complex amides.

We describe herein our recent explorations in the field of isonitrile chemistry. An array of broadly useful coupling methodologies has been developed for the formation of peptidyl and glycopeptidyl amide bonds. We further describe the application of these methods to the syntheses of complex systems, including the cyclic peptide cyclosporine A, constrained peptide systems, and heterocycles.

Synthesis and biological evaluation of [D-lysine]8cyclosporin A analogs as potential anti-HCV agents.

An efficient synthesis of [D-lysine](8)cyclosporin A has been developed. Several analogs of [D-lysine](8)cyclosporin A have been synthesized and show promising anti-HCV activity, particularly compounds 39 and 43, which each exhibit an anti-HCV EC(50)<200 nM, and are each ≥50-fold less immunosuppressive than cyclosporin A.

Total synthesis of cyclosporine: access to N-methylated peptides via isonitrile coupling reactions.

Recent developments in the use of isonitriles to furnish secondary and tertiary amide bond formations have been applied to a novel total synthesis of the important cyclic polypeptide cyclosporine A. Specifically, the disclosed synthetic route demonstrates the utility of microwave-mediated carboxylic acid isonitrile couplings, thioacid isonitrile couplings at ambient temperature, and isonitrile-mediated couplings of carboxylic acids and thioacids with amines to form challenging amide bonds.

Mucoadhesive effect of thiolated PEG stearate and its modified NLC for ocular drug delivery.

This study was to develop a thiolated non-ionic surfactant, cysteine-polyethylene glycol stearate (Cys-PEG-SA), for the assembling of nanoparticulate ocular drug delivery system with mucoadhesive property. Cys-PEG-SA was synthesized in two steps reaction involving a new derivative intermediate formation of p-nitrophenylcarbonyl-PEG-SA (pNP-PEG-SA). Up to 369.43+/-25.54 mumol free thiol groups per gram of the conjugates was reached. The nanostructured lipid carrier (NLC) loaded cyclosporine A (CyA) was prepared by melt-emulsification method. The mucoadhesive NLC (Cys-NLC) was obtained by incubating NLC emulsion with Cys-PEG-SA. The mucoadhesive properties of these nanocarriers were examined by using mucin particles method. The particle size or zeta potential of the porcine mucin particles were changed with the added concentration of Cys-PEG-SA, and the disulphide bond breaker cysteine significantly reduced the adhesion of Cys-NLC to mucin particles (P<0.05), whereas PEG-SA and NLC did not alternate the properties of the mucin particles. When Cys-NLC was administered topically to the rabbit eye, the encapsulated cyclosporine was found to remain on the ocular surface in the cul-de-sac for up to 6 h, both precorneal retention time and concentration were dramatically increased (P<0.05), compared with the NLC without thiomer modification.

Inhibition of human immunodeficiency virus type 1 replication in human cells by Debio-025, a novel cyclophilin binding agent.

Debio-025 is a synthetic cyclosporine with no immunosuppressive capacity but a high inhibitory potency against cyclophilin A (CypA)-associated cis-trans prolyl isomerase (PPIase) activity. A lack of immunosuppressive effects compared to that of cyclosporine was demonstrated both in vitro and in vivo. For three cyclosporines, the inhibitory potential against PPIase activity was quantitatively correlated with that against human immunodeficiency virus type 1 (HIV-1) replication. Debio-025 selectively inhibited the replication of HIV-1 in a CD4+ cell line and in peripheral blood mononuclear cells: potent activity was demonstrated against clinical isolates of various HIV-1 subtypes, including isolates with multidrug resistance to reverse transcriptase and protease inhibitors. Simian immunodeficiency virus and HIV-2 strains were generally resistant to inhibition by Debio-025; however, some notable exceptions of sensitive HIV-2 clinical isolates were detected. In two-drug combination studies, additive inhibitory effects were found between Debio-025 and 19 clinically used drugs of different classes. Clinical HIV-1 isolates that are naturally resistant to Debio-025 and that do not depend on CypA for infection were identified. Comparison of the amino acid sequences of the CypA binding domain of the capsid (CA) protein from Debio-025-sensitive and -resistant HIV-1 isolates indicated that resistance was mostly associated with an H87Q/P exchange. Mechanistically, cyclosporines competitively inhibit the binding of CypA to the HIV-1 CA protein, which is an essential interaction required for early steps in HIV-1 replication. By real-time PCR we demonstrated that early reverse transcription is reduced in the presence of Debio-025 and that late reverse transcription is almost completely blocked. Thus, Debio-025 seems to interfere with the function of CypA during the progression/completion of HIV-1 reverse transcription.

Synthesis and neurotrophic activity of nonimmunosuppressant cyclosporin A derivatives.

In order to exploit cyclophilin as a potential target for neurological drug design, we demonstrate in this presentation that several nonimmunosuppressant analogues of cyclosporin A, modified at the various positions in the 'effector' domain, are equipotent nerve growth agents compared to cyclosporin A. Our results suggest that neurotrophic activity of cyclosporin A and its derivatives resides in the binding domain, and binding to cyclophilin and/or inhibiting rotamase activity may be a necessity for neurotrophic effects of cyclophilin ligands.

[Cyclosporine 2% eye drops preparation]. / Préparation d'un collyre de ciclosporine à 2%

PURPOSE: Cyclosporine administration is very effective in the case of immunological diseases of the cornea, conjunctive or uvea. Moreover, it is widely used in the case of high-risk rejection corneal transplantation. We present a preparation of cyclosporine 2% eye drops. METHODS: Cyclosporine 2% eye drops are prepared following a particular formulation including one part commercially available cyclosporine oral solution (Sandimmun) diluted in four parts of sterile castor oil. Manufacturing procedures maintain the sterile state of the preparation with a laminar airflow hood placed in a particulate controlled room, with pharmacists, technicians and clerical personnel wearing sterile clothes. Physical and chemical monitoring during and after manufacture for each batch guarantees the process and minimizes the risk of batch rejection. Chemical analysis of cyclosporine is conducted using a validated stability-indicating high-performance liquid chromatographic assay (reverse-phase). Blood dosages taken after the first administration at the 24th hour (after administration of the 6th drop) check for systemic integration. RESULTS: Cyclosporine 2% eye drops are fairly stable: 12 months after manufacturing, concentrations result in levels not statistically different from concentrations measured the day of preparation. After a daily regimen of six drops in the eye, cyclosporine 2% eye drops have a very low systemic bioavailability, because the blood concentrations only reach the detection limit of the fluorescence polarization immunoassay used for cyclosporine drug monitoring. This explains the absence of systemic toxicity. CONCLUSION: Cyclosporine 2% eye drops can be available in the hospital pharmacy. The eye drops are stable at room temperature and can be delivered up to 12 months after manufacture. No local adverse effects have been noted, probably in relation with the very low concentration of ethanol in the ocular preparation.

Preparation of biodegradable cyclosporine nanoparticles by high-pressure emulsification-solvent evaporation process.

The cyclic endecapeptide cyclosporine (CsA), a potent immunosuppressive drug, was incorporated into biodegradable poly (DL-lactide-co-gylcolide) (DL-PLG) 50/50, 65/35 and PEG 5000-70/30 DL-PLG to improve the oral bioavailability and pharmacokinetics. Nanoparticles were prepared by a high-pressure emulsification-solvent evaporation (HPESE) process. The CsA-loaded nanoparticles were evaluated for particle size, zeta potential, surface morphology by scanning electron microscopy (SEM), thermal characterizations by differential scanning calorimetry (DSC), encapsulation efficiency (E.E.%) and in vitro release. The amount of CsA loaded into the nanoparticles was determined using high-performance liquid chromatography (HPLC) at a detection wavelength of 210 nm. The mobile phase was acetonitrile-water (70:30% v/v) and flow rate was set at 1.5 ml min(-1). The photon correlation spectroscopy showed that the particles size were <250 nm and polydispersity index (PI) <0.14. The zeta potential was positive for 200 mg and negative for 400 mg of polymer composition, respectively. The SEM micrographs revealed that the nanoparticles were spherical and smooth. The drug loading was between 82% and 92%. Differential scanning calorimetry (DSC) studies did not show the melting endotherm for CsA in the drug-loaded nanoparticles. In-vitro release in intestinal fluid pH 6.8 (USP XXIV) showed a cumulative percent release of 30-45% CsA in 8 h. The physicochemical properties showed that the DL-PLG and PEG-DLPLG nanoparticles could be an effective carrier for oral CsA delivery. The reported method is easy, reproducible and can be automated for batch scale production.