Chun-Ho Wong - Academia.edu (original) (raw)

Papers by Chun-Ho Wong

Significance Small CAG (sCAG) RNAs are neurotoxic, but their role in polyglutamine degeneration r... more Significance Small CAG (sCAG) RNAs are neurotoxic, but their role in polyglutamine degeneration remains to be fully elucidated. We observed that cellular expression of sCAGs is sufficient to induce neuronal DNA damage and discovered that the transcript level of NUDT16 was reduced in HD models. The NUDT16 protein has previously been linked to the DNA damage pathway. At the structural level, sCAGs form double-stranded CAG–CUG heteroduplex RNA with NUDT16 transcript which led to its gene silencing. We showed that the bisamidinium-based compound DB213 specifically interacts with duplex CAG RNA; consequently, both NUDT16 expression and DNA damage were rescued in HD mice. Our findings describe a pathogenic pathway that induces DNA damage in polyglutamine degeneration and demonstrate its therapeutic potential. DNA damage plays a central role in the cellular pathogenesis of polyglutamine (polyQ) diseases, including Huntington’s disease (HD). In this study, we showed that the expression of u...

Journal of Pharmaceutical and Biomedical Analysis

Drug Metabolism and Pharmacokinetics

Journal of Biological Chemistry

Edited by Joseph M. Jez Polyglutamine (polyQ) diseases are a group of dominantly inherited neurod... more Edited by Joseph M. Jez Polyglutamine (polyQ) diseases are a group of dominantly inherited neurodegenerative disorders caused by the expansion of an unstable CAG repeat in the coding region of the affected genes. Hallmarks of polyQ diseases include the accumulation of misfolded protein aggregates, leading to neuronal degeneration and cell death. PolyQ diseases are currently incurable, highlighting the urgent need for approaches that inhibit the formation of disaggregate cytotoxic polyQ protein inclusions. Here, we screened for bisamidine-based inhibitors that can inhibit neuronal polyQ protein inclusions. We demonstrated that one inhibitor, AQAMAN, prevents polyQ protein aggregation and promotes de-aggregation of self-assembled polyQ proteins in several models of polyQ diseases. Using immunocytochemistry, we found that AQAMAN significantly reduces polyQ protein aggregation and specifically suppresses polyQ protein-induced cell death. Using a recombinant and purified polyQ protein (thioredoxin-Huntingtin-Q46), we further demonstrated that AQAMAN interferes with polyQ self-assembly, preventing polyQ aggregation, and dissociates preformed polyQ aggregates in a cell-free system. Remarkably, AQAMAN feeding of Drosophila expressing expanded polyQ disease protein suppresses polyQ-induced neurodegeneration in vivo. In addition, using inhibitors and activators of the autophagy pathway, we demonstrated that AQAMAN's cytoprotective effect against polyQ toxicity is autophagy-dependent. In summary, we have identified AQAMAN as a potential therapeutic for combating polyQ protein toxicity in polyQ diseases. Our findings further highlight the importance of the autophagy pathway in clearing harmful polyQ proteins. Polyglutamine (polyQ) 3 diseases are a group of diseases characterized by an unstable CAG repeat expansion in the coding region of the affected genes, which in turn produces abnormal proteins with long stretches of polyQ tracts (1, 2). This group of diseases include Huntington's disease (HD), spinal and bulbar muscular atrophy (SBMA), dentatorubral pallidoluysian atrophy, and a number of spinocerebellar ataxias, including Machado-Joseph disease (MJD, also known as SCA3) (1, 2). Toxic proteins with polyQ stretches have a tendency to aggregate and form neuronal inclusions (3). The accumulation of aggregated and misfolded proteins induces endoplasmic reticulum (ER) stress (4, 5), leading to neuronal dysfunction and cell death (6), which subsequently contributes to the pathogenesis of polyQ diseases, including HD (7), SBMA (8), and MJD (9). When the ER is under stress from deleterious unfolded proteins, the unfolded protein response (UPR) pathway is activated in the cell to transduce appropriate signals from the cytoplasm to the nucleus, which in turn induces the expression of numerous molecular chaperones and folding enzymes for the ER to cope with the stress condition (10, 11). Apart from managing unfolded proteins, the UPR pathway is also closely related to autophagy, which is an essential catabolic mechanism involving the degradation of misfolded proteins and damaged organelles through the lysosomal pathway (12, 13). Accumulating evidence indicates that persistent ER stress in neurodegenerative diseases often results

European Journal of Pharmaceutical Sciences

The AAPS journal, Dec 27, 2017

Intranasal administration could be an attractive alternative route of administration for the deli... more Intranasal administration could be an attractive alternative route of administration for the delivery of drugs to the central nervous system (CNS). However, there are always doubts about the direct transport of therapeutics from nasal cavity to the CNS since there are only limited studies on the understanding of direct nose-to-brain transport. Therefore, this study aimed to (1) investigate the existence of nose-to-brain transport of intranasally administered HIV-1 replication inhibitor DB213 and (2) assess the direct nose-to-brain transport of unbound HIV-1 replication inhibitor DB213 quantitatively by a pharmacokinetic approach. Plasma samples were collected up to 6 h post-dosing after administration via intranasal or intravenous route at three bolus doses. In the brain-uptake study, the plasma, whole brain, and cerebrospinal fluid (CSF) were sampled between 15 min and 8 h post-dosing. All samples were analyzed with LC/MS/MS. Plasma, CSF, and brain concentration versus time profile...

International journal of pharmaceutics, Jan 25, 2018

DB213 is an HIV-1 replication inhibitor targeting the Central Nervous System for the treatment of... more DB213 is an HIV-1 replication inhibitor targeting the Central Nervous System for the treatment of HIV-associated neurocognitive disorders. Current study aims to develop an in situ thermosensitive gelling system for intranasal delivery of DB213 facilitated by Statistical Design of Experiment (DoE) to conduct a more efficient experimentation by extracting the maximum amount of information from limited experiments. In our current study, information was extracted from twenty-five experimental designs from MODDESoftware and a mathematical model was successfully developed to predict formulations to achieve desired performance as well as to analyze relationships between the amount of Pluronic F-127, Pluronic F-68, Chitosan, DB213 and the performances of in situ thermosensitive gels. Based on DoE, in situ thermosensitive gels of 1% DB213 (F1) and 5% DB213 (F2) were developed for further in vivo bioavailability and brain uptake evaluations in Sprague-Dawley rats and C57BL/6 mice, respectivel...

ChemMedChem, Jul 1, 2016

Myotonic dystrophy is the most common form of adult-onset muscular dystrophy, originating in a CT... more Myotonic dystrophy is the most common form of adult-onset muscular dystrophy, originating in a CTG repeat expansion in the DMPK gene. The expanded CUG transcript sequesters MBNL1, a key regulator of alternative splicing, leading to the misregulation of numerous pre-mRNAs. We report an RNA-targeted agent as a possible lead compound for the treatment of myotonic dystrophy type 1 (DM1) that reveals both the promise and challenges for this type of small-molecule approach. The agent is a potent inhibitor of the MBNL1-rCUG complex with an inhibition constant (Ki ) of 25±8 nm, and is also relatively nontoxic to HeLa cells, able to dissolve nuclear foci, and correct the insulin receptor splicing defect in DM1 model cells. Moreover, treatment with this compound improves two separate disease phenotypes in a Drosophila model of DM1: adult external eye degeneration and larval crawling defect. However, the compound has a relatively low maximum tolerated dose in mice, and its cell uptake may be l...

Burns : journal of the International Society for Burn Injuries, Jan 17, 2016

Burn-induced hypertrophic scars are disfiguring and can be associated with severe and intractable... more Burn-induced hypertrophic scars are disfiguring and can be associated with severe and intractable pruritus. No effective treatment modalities are currently available for symptomatic control of pruritus for most patients. We assessed the effect of the Antipruritic Hydrogel (CQ-01) in the symptomatic treatment of severe and intractable pruritus associated with burn-induced hypertrophic scars in a prospective, multicenter, controlled trial. A pilot study was conducted in healthy adult volunteers to identify the most appropriate hydrogel formulation. A selected preparation called Chongqing No. 1 (CQ-01; a guar gum-based hydrogel impregnated with peppermint oil, menthol, and methyl salicylate by a nanoemulsion), showed an excellent symptomatic relief in an exploratory study in 2 patients with intractable pruritus. A statistically powered, prospective, multicenter, controlled study was then conducted in 74 patients to evaluate the efficacy and safety of a 24-h application of CQ-01 compare...

Journal of pharmaceutical and biomedical analysis, Jan 14, 2016

The current study aims to investigate the pharmacokinetics and brain uptake of HIV-1 replication ... more The current study aims to investigate the pharmacokinetics and brain uptake of HIV-1 replication inhibitor DB213 via a developed LC/MS/MS analytical method. A sensitive, selective, accurate and reliable LC/MS/MS method for determination and quantification of DB213 in rat plasma and brain was developed and validated. A triple quadrupole mass spectrometer equipped with electrospray ionization (ESI) source was applied for the detection of DB213 and benzamidine (Internal Standard). The analytes were quantified by using multiple reaction monitoring (MRM) mode with m/z 333.4→86.1 and m/z 121.2→104 for DB213 and benzamidine respectively. Chromatographic separation of DB213 and benzamidine was achieved on a SunFire C8 (4.6×250mm, i.d. 5μm) analytical column with gradient elution of a mobile phase consisted of acetonitrile and 20mM ammonium formate buffer (containing 0.5% formic acid). The method achieved good linearity from 1.95∼1000ng/ml (r(2)=0.999) in plasma and 0.98∼125ng/ml (r(2)=0.999...

ChemMedChem, 2014

The front cover picture shows small molecules (yellow) entering a diseased cell and then its nucl... more The front cover picture shows small molecules (yellow) entering a diseased cell and then its nucleus. The molecules selectively bind to a toxic CCUG RNA transcript (purple) that causes myotonic dystrophy type 2. Binding by this potential therapeutic agent (structure shown in white) disrupts the MBNL1-rCCUGexp interaction and frees the key alternative splicing regulator MBNL (blue) to perform it normal function. For more details, see the Full Paper by Steven C. Zimmerman et al. on p. 2455 ff.

ChemMedChem, 2014

Myotonic dystrophy type 2 (DM2) is caused by an expansion of CCTG repeats in the zinc-finger prot... more Myotonic dystrophy type 2 (DM2) is caused by an expansion of CCTG repeats in the zinc-finger protein gene (ZNF9). Transcribed CCUG repeats sequester muscleblind-like protein 1 (MBNL1), an important alternative splicing regulator, preventing its normal function, leading to the disease phenotype. We describe a series of ligands that disrupt the MBNL1-r(CCUG)n interaction as potential lead agents for developing DM2 therapeutics. A previously reported triaminopyrimidine-acridine conjugate was a moderate inhibitor in vitro, however it proved to be poorly water-soluble and not cell-permeable. To improve its therapeutic potential, the new set of ligands maintained the key triaminopyrimidine recognition unit but replaced the acridine intercalator with a bisamidinium groove binder. The optimized ligands exhibit low micromolar inhibition potency to MBNL1-r(CCUG)8. Importantly, the ligands are the first to show the ability to disrupt the MBNL1-r(CCUG)n foci in DM2 model cell culture and exhibi...

Organic Letters, 2006

spectra for structural characterization were recorded on a Bruker Avance DPX300 (1 H: 300 MHz; 13... more spectra for structural characterization were recorded on a Bruker Avance DPX300 (1 H: 300 MHz; 13 C: 75.5 MHz) or DRX500 (1 H: 500 MHz) spectrometer. 1 H NMR spectra for dimerization studies were recorded on a Bruker Avance 600 (1 H: 600 MHz) or DRX500 (1 H: 500 MHz) spectrometer. Unless otherwise stated, all NMR measurements were carried out in CDCl 3 at 25 °C. Chemical shifts were reported as parts per million (ppm) in δ scale using solvent residual peak (1 H: δ = 7.26; 13 C: δ = 77.16) as internal standard. Coupling constants (J) were reported in hertz. Mass spectra were obtained on a ThermoFinnigan MAT 95 XL double focusing sector mass spectrometer with electron impact (EI), fast atom bombardment (FAB), or electron spray ionization (ESI) technique. Vapor pressure osmometric (VPO) measurements were performed on a Knauer vapor pressure osmometer K-7000 at 30 °C using CHCl 3 as solvent. FT-IR spectra were obtained on a Shimadzu FTIR-8400S spectrophotometer with NaCl plate. Gel permeation chromatographic (GPC) measurements were performed on Waters ® Styragel columns (HR1, HR2, HR3, and HR4 7.8 × 300 mm in serial) at 40 °C using THF as eluent (flow rate = 1.0 mL/min) on a Water ® HPLC 515 pump equipped with a Waters ® 486 tunable UV absorbance detector. Melting points were measured on an Electrothermal ® 9100 digital melting point apparatus and were uncorrected. Elemental analyses were carried out at MEDAC Ltd.,

Nucleic Acids Research, 2011

Myotonic dystrophy type 2 (DM2) is an incurable neuromuscular disease caused by expanded CCUG rep... more Myotonic dystrophy type 2 (DM2) is an incurable neuromuscular disease caused by expanded CCUG repeats that may exhibit toxicity by sequestering the splicing regulator MBNL1. A series of triaminotriazine-and triaminopyrimidine-based small molecules (ligands 1-3) were designed, synthesized and tested as inhibitors of the MBNL1-CCUG interaction. Despite the structural similarities of the triaminotriazine and triaminopyrimidine units, the triaminopyrimidine-based ligands bind with low micromolar affinity to CCUG repeats (K d $ 0.1-3.6 mM) whereas the triaminotriazine ligands do not bind CCUG repeats. Importantly, these simple and small triaminopyrimidine ligands exhibit both strong inhibition (K i $ 2 mM) of the MBNL1-CCUG interaction and high selectivity for CCUG repeats over other RNA targets. These experiments suggest these compounds are potential lead agents for the treatment of DM2.

Molecular Pharmaceutics, 2011

This paper develops a structure-activity relationship understanding of the way in which surfactan... more This paper develops a structure-activity relationship understanding of the way in which surfactant-like dendrons with hydrophilic spermine surface groups and a variety of lipophilic units at their focal points can self-assemble and subsequently bind to DNA with high affinity. The choice of functional group at the focal point of the dendron and the high tunability of the molecular structure have a very significant impact on DNA binding. Mesoscale modeling of the mode of dendron self-assembly provides a direct insight into how the mode of self-assembly exerts its effect on the DNA binding process. In particular, the hydrophobic unit controls the number of dendrons in the self-assembled micellar structures, and hence their diameters and surface charge density. The DNA binding affinity correlates with the surface charge density of the dendron aggregates. Furthermore, these structure-activity effects can also be extended to cellular gene delivery, as surface charge density plays a role in controlling the extent of endosomal escape. It is reported that higher generation dendrons, although binding DNA less strongly than the self-assembling lower generation dendrons, are more effective for transfection. The impact of the lipophilic group at the focal point is less significant for the DNA binding ability of these larger dendrons, which is predominantly controlled by the spermine surface groups, but it does modify the levels of gene transfection. Significant synergistic effects on gene delivery were observed when employing combinations of the dendrons and polyethyleneimine (PEI, 25 kDa), with transfection becoming possible at low loading levels where the two components would not transfect individually, giving practically useful levels of gene delivery.

Macromolecules, 2010

A series of G1− G3 supramolecular dendronized polymers 6 bearing dimeric 2-ureido-4-pyrimidinone ... more A series of G1− G3 supramolecular dendronized polymers 6 bearing dimeric 2-ureido-4-pyrimidinone (UPy) units on the main chain and aliphatic hydrocarbon dendrons as side chain appendages was prepared. Because of the high crystallinity and poor solubility of ...

Journal of the American Chemical Society, 2014

A working hypothesis for the pathogenesis of myotonic dystrophy type 1 (DM1) involves the aberran... more A working hypothesis for the pathogenesis of myotonic dystrophy type 1 (DM1) involves the aberrant sequestration of an alternative splicing regulator, MBNL1, by expanded CUG repeats, r(CUG) exp. It has been suggested that a reversal of the myotonia and potentially other symptoms of the DM1 disease can be achieved by inhibiting the toxic MBNL1r(CUG) exp interaction. Using rational design, we discovered an RNA-groove binding inhibitor (ligand 3) that contains two triaminotriazine units connected by a bisamidinium linker. Ligand 3 binds r(CUG) 12 with a low micromolar affinity (K d = 8 ± 2 μM) and disrupts the MBNL1-r(CUG) 12 interaction in vitro (K i = 8 ± 2 μM). In addition, ligand 3 is cell and nucleus permeable, exhibits negligible toxicity to mammalian cells, dissolves MBNL1-r(CUG) exp ribonuclear foci, and restores misregulated splicing of IR and cTNT in a DM1 cell culture model. Importantly, suppression of r(CUG) exp RNA-induced toxicity in a DM1 Drosophila model was observed after treatment with ligand 3. These results suggest ligand 3 as a lead for the treatment of DM1.

Significance Small CAG (sCAG) RNAs are neurotoxic, but their role in polyglutamine degeneration r... more Significance Small CAG (sCAG) RNAs are neurotoxic, but their role in polyglutamine degeneration remains to be fully elucidated. We observed that cellular expression of sCAGs is sufficient to induce neuronal DNA damage and discovered that the transcript level of NUDT16 was reduced in HD models. The NUDT16 protein has previously been linked to the DNA damage pathway. At the structural level, sCAGs form double-stranded CAG–CUG heteroduplex RNA with NUDT16 transcript which led to its gene silencing. We showed that the bisamidinium-based compound DB213 specifically interacts with duplex CAG RNA; consequently, both NUDT16 expression and DNA damage were rescued in HD mice. Our findings describe a pathogenic pathway that induces DNA damage in polyglutamine degeneration and demonstrate its therapeutic potential. DNA damage plays a central role in the cellular pathogenesis of polyglutamine (polyQ) diseases, including Huntington’s disease (HD). In this study, we showed that the expression of u...

Journal of Pharmaceutical and Biomedical Analysis

Drug Metabolism and Pharmacokinetics

Journal of Biological Chemistry

Edited by Joseph M. Jez Polyglutamine (polyQ) diseases are a group of dominantly inherited neurod... more Edited by Joseph M. Jez Polyglutamine (polyQ) diseases are a group of dominantly inherited neurodegenerative disorders caused by the expansion of an unstable CAG repeat in the coding region of the affected genes. Hallmarks of polyQ diseases include the accumulation of misfolded protein aggregates, leading to neuronal degeneration and cell death. PolyQ diseases are currently incurable, highlighting the urgent need for approaches that inhibit the formation of disaggregate cytotoxic polyQ protein inclusions. Here, we screened for bisamidine-based inhibitors that can inhibit neuronal polyQ protein inclusions. We demonstrated that one inhibitor, AQAMAN, prevents polyQ protein aggregation and promotes de-aggregation of self-assembled polyQ proteins in several models of polyQ diseases. Using immunocytochemistry, we found that AQAMAN significantly reduces polyQ protein aggregation and specifically suppresses polyQ protein-induced cell death. Using a recombinant and purified polyQ protein (thioredoxin-Huntingtin-Q46), we further demonstrated that AQAMAN interferes with polyQ self-assembly, preventing polyQ aggregation, and dissociates preformed polyQ aggregates in a cell-free system. Remarkably, AQAMAN feeding of Drosophila expressing expanded polyQ disease protein suppresses polyQ-induced neurodegeneration in vivo. In addition, using inhibitors and activators of the autophagy pathway, we demonstrated that AQAMAN's cytoprotective effect against polyQ toxicity is autophagy-dependent. In summary, we have identified AQAMAN as a potential therapeutic for combating polyQ protein toxicity in polyQ diseases. Our findings further highlight the importance of the autophagy pathway in clearing harmful polyQ proteins. Polyglutamine (polyQ) 3 diseases are a group of diseases characterized by an unstable CAG repeat expansion in the coding region of the affected genes, which in turn produces abnormal proteins with long stretches of polyQ tracts (1, 2). This group of diseases include Huntington's disease (HD), spinal and bulbar muscular atrophy (SBMA), dentatorubral pallidoluysian atrophy, and a number of spinocerebellar ataxias, including Machado-Joseph disease (MJD, also known as SCA3) (1, 2). Toxic proteins with polyQ stretches have a tendency to aggregate and form neuronal inclusions (3). The accumulation of aggregated and misfolded proteins induces endoplasmic reticulum (ER) stress (4, 5), leading to neuronal dysfunction and cell death (6), which subsequently contributes to the pathogenesis of polyQ diseases, including HD (7), SBMA (8), and MJD (9). When the ER is under stress from deleterious unfolded proteins, the unfolded protein response (UPR) pathway is activated in the cell to transduce appropriate signals from the cytoplasm to the nucleus, which in turn induces the expression of numerous molecular chaperones and folding enzymes for the ER to cope with the stress condition (10, 11). Apart from managing unfolded proteins, the UPR pathway is also closely related to autophagy, which is an essential catabolic mechanism involving the degradation of misfolded proteins and damaged organelles through the lysosomal pathway (12, 13). Accumulating evidence indicates that persistent ER stress in neurodegenerative diseases often results

European Journal of Pharmaceutical Sciences

The AAPS journal, Dec 27, 2017

Intranasal administration could be an attractive alternative route of administration for the deli... more Intranasal administration could be an attractive alternative route of administration for the delivery of drugs to the central nervous system (CNS). However, there are always doubts about the direct transport of therapeutics from nasal cavity to the CNS since there are only limited studies on the understanding of direct nose-to-brain transport. Therefore, this study aimed to (1) investigate the existence of nose-to-brain transport of intranasally administered HIV-1 replication inhibitor DB213 and (2) assess the direct nose-to-brain transport of unbound HIV-1 replication inhibitor DB213 quantitatively by a pharmacokinetic approach. Plasma samples were collected up to 6 h post-dosing after administration via intranasal or intravenous route at three bolus doses. In the brain-uptake study, the plasma, whole brain, and cerebrospinal fluid (CSF) were sampled between 15 min and 8 h post-dosing. All samples were analyzed with LC/MS/MS. Plasma, CSF, and brain concentration versus time profile...

International journal of pharmaceutics, Jan 25, 2018

DB213 is an HIV-1 replication inhibitor targeting the Central Nervous System for the treatment of... more DB213 is an HIV-1 replication inhibitor targeting the Central Nervous System for the treatment of HIV-associated neurocognitive disorders. Current study aims to develop an in situ thermosensitive gelling system for intranasal delivery of DB213 facilitated by Statistical Design of Experiment (DoE) to conduct a more efficient experimentation by extracting the maximum amount of information from limited experiments. In our current study, information was extracted from twenty-five experimental designs from MODDESoftware and a mathematical model was successfully developed to predict formulations to achieve desired performance as well as to analyze relationships between the amount of Pluronic F-127, Pluronic F-68, Chitosan, DB213 and the performances of in situ thermosensitive gels. Based on DoE, in situ thermosensitive gels of 1% DB213 (F1) and 5% DB213 (F2) were developed for further in vivo bioavailability and brain uptake evaluations in Sprague-Dawley rats and C57BL/6 mice, respectivel...

ChemMedChem, Jul 1, 2016

Myotonic dystrophy is the most common form of adult-onset muscular dystrophy, originating in a CT... more Myotonic dystrophy is the most common form of adult-onset muscular dystrophy, originating in a CTG repeat expansion in the DMPK gene. The expanded CUG transcript sequesters MBNL1, a key regulator of alternative splicing, leading to the misregulation of numerous pre-mRNAs. We report an RNA-targeted agent as a possible lead compound for the treatment of myotonic dystrophy type 1 (DM1) that reveals both the promise and challenges for this type of small-molecule approach. The agent is a potent inhibitor of the MBNL1-rCUG complex with an inhibition constant (Ki ) of 25±8 nm, and is also relatively nontoxic to HeLa cells, able to dissolve nuclear foci, and correct the insulin receptor splicing defect in DM1 model cells. Moreover, treatment with this compound improves two separate disease phenotypes in a Drosophila model of DM1: adult external eye degeneration and larval crawling defect. However, the compound has a relatively low maximum tolerated dose in mice, and its cell uptake may be l...

Burns : journal of the International Society for Burn Injuries, Jan 17, 2016

Burn-induced hypertrophic scars are disfiguring and can be associated with severe and intractable... more Burn-induced hypertrophic scars are disfiguring and can be associated with severe and intractable pruritus. No effective treatment modalities are currently available for symptomatic control of pruritus for most patients. We assessed the effect of the Antipruritic Hydrogel (CQ-01) in the symptomatic treatment of severe and intractable pruritus associated with burn-induced hypertrophic scars in a prospective, multicenter, controlled trial. A pilot study was conducted in healthy adult volunteers to identify the most appropriate hydrogel formulation. A selected preparation called Chongqing No. 1 (CQ-01; a guar gum-based hydrogel impregnated with peppermint oil, menthol, and methyl salicylate by a nanoemulsion), showed an excellent symptomatic relief in an exploratory study in 2 patients with intractable pruritus. A statistically powered, prospective, multicenter, controlled study was then conducted in 74 patients to evaluate the efficacy and safety of a 24-h application of CQ-01 compare...

Journal of pharmaceutical and biomedical analysis, Jan 14, 2016

The current study aims to investigate the pharmacokinetics and brain uptake of HIV-1 replication ... more The current study aims to investigate the pharmacokinetics and brain uptake of HIV-1 replication inhibitor DB213 via a developed LC/MS/MS analytical method. A sensitive, selective, accurate and reliable LC/MS/MS method for determination and quantification of DB213 in rat plasma and brain was developed and validated. A triple quadrupole mass spectrometer equipped with electrospray ionization (ESI) source was applied for the detection of DB213 and benzamidine (Internal Standard). The analytes were quantified by using multiple reaction monitoring (MRM) mode with m/z 333.4→86.1 and m/z 121.2→104 for DB213 and benzamidine respectively. Chromatographic separation of DB213 and benzamidine was achieved on a SunFire C8 (4.6×250mm, i.d. 5μm) analytical column with gradient elution of a mobile phase consisted of acetonitrile and 20mM ammonium formate buffer (containing 0.5% formic acid). The method achieved good linearity from 1.95∼1000ng/ml (r(2)=0.999) in plasma and 0.98∼125ng/ml (r(2)=0.999...

ChemMedChem, 2014

The front cover picture shows small molecules (yellow) entering a diseased cell and then its nucl... more The front cover picture shows small molecules (yellow) entering a diseased cell and then its nucleus. The molecules selectively bind to a toxic CCUG RNA transcript (purple) that causes myotonic dystrophy type 2. Binding by this potential therapeutic agent (structure shown in white) disrupts the MBNL1-rCCUGexp interaction and frees the key alternative splicing regulator MBNL (blue) to perform it normal function. For more details, see the Full Paper by Steven C. Zimmerman et al. on p. 2455 ff.

ChemMedChem, 2014

Myotonic dystrophy type 2 (DM2) is caused by an expansion of CCTG repeats in the zinc-finger prot... more Myotonic dystrophy type 2 (DM2) is caused by an expansion of CCTG repeats in the zinc-finger protein gene (ZNF9). Transcribed CCUG repeats sequester muscleblind-like protein 1 (MBNL1), an important alternative splicing regulator, preventing its normal function, leading to the disease phenotype. We describe a series of ligands that disrupt the MBNL1-r(CCUG)n interaction as potential lead agents for developing DM2 therapeutics. A previously reported triaminopyrimidine-acridine conjugate was a moderate inhibitor in vitro, however it proved to be poorly water-soluble and not cell-permeable. To improve its therapeutic potential, the new set of ligands maintained the key triaminopyrimidine recognition unit but replaced the acridine intercalator with a bisamidinium groove binder. The optimized ligands exhibit low micromolar inhibition potency to MBNL1-r(CCUG)8. Importantly, the ligands are the first to show the ability to disrupt the MBNL1-r(CCUG)n foci in DM2 model cell culture and exhibi...

Organic Letters, 2006

spectra for structural characterization were recorded on a Bruker Avance DPX300 (1 H: 300 MHz; 13... more spectra for structural characterization were recorded on a Bruker Avance DPX300 (1 H: 300 MHz; 13 C: 75.5 MHz) or DRX500 (1 H: 500 MHz) spectrometer. 1 H NMR spectra for dimerization studies were recorded on a Bruker Avance 600 (1 H: 600 MHz) or DRX500 (1 H: 500 MHz) spectrometer. Unless otherwise stated, all NMR measurements were carried out in CDCl 3 at 25 °C. Chemical shifts were reported as parts per million (ppm) in δ scale using solvent residual peak (1 H: δ = 7.26; 13 C: δ = 77.16) as internal standard. Coupling constants (J) were reported in hertz. Mass spectra were obtained on a ThermoFinnigan MAT 95 XL double focusing sector mass spectrometer with electron impact (EI), fast atom bombardment (FAB), or electron spray ionization (ESI) technique. Vapor pressure osmometric (VPO) measurements were performed on a Knauer vapor pressure osmometer K-7000 at 30 °C using CHCl 3 as solvent. FT-IR spectra were obtained on a Shimadzu FTIR-8400S spectrophotometer with NaCl plate. Gel permeation chromatographic (GPC) measurements were performed on Waters ® Styragel columns (HR1, HR2, HR3, and HR4 7.8 × 300 mm in serial) at 40 °C using THF as eluent (flow rate = 1.0 mL/min) on a Water ® HPLC 515 pump equipped with a Waters ® 486 tunable UV absorbance detector. Melting points were measured on an Electrothermal ® 9100 digital melting point apparatus and were uncorrected. Elemental analyses were carried out at MEDAC Ltd.,

Nucleic Acids Research, 2011

Myotonic dystrophy type 2 (DM2) is an incurable neuromuscular disease caused by expanded CCUG rep... more Myotonic dystrophy type 2 (DM2) is an incurable neuromuscular disease caused by expanded CCUG repeats that may exhibit toxicity by sequestering the splicing regulator MBNL1. A series of triaminotriazine-and triaminopyrimidine-based small molecules (ligands 1-3) were designed, synthesized and tested as inhibitors of the MBNL1-CCUG interaction. Despite the structural similarities of the triaminotriazine and triaminopyrimidine units, the triaminopyrimidine-based ligands bind with low micromolar affinity to CCUG repeats (K d $ 0.1-3.6 mM) whereas the triaminotriazine ligands do not bind CCUG repeats. Importantly, these simple and small triaminopyrimidine ligands exhibit both strong inhibition (K i $ 2 mM) of the MBNL1-CCUG interaction and high selectivity for CCUG repeats over other RNA targets. These experiments suggest these compounds are potential lead agents for the treatment of DM2.

Molecular Pharmaceutics, 2011

This paper develops a structure-activity relationship understanding of the way in which surfactan... more This paper develops a structure-activity relationship understanding of the way in which surfactant-like dendrons with hydrophilic spermine surface groups and a variety of lipophilic units at their focal points can self-assemble and subsequently bind to DNA with high affinity. The choice of functional group at the focal point of the dendron and the high tunability of the molecular structure have a very significant impact on DNA binding. Mesoscale modeling of the mode of dendron self-assembly provides a direct insight into how the mode of self-assembly exerts its effect on the DNA binding process. In particular, the hydrophobic unit controls the number of dendrons in the self-assembled micellar structures, and hence their diameters and surface charge density. The DNA binding affinity correlates with the surface charge density of the dendron aggregates. Furthermore, these structure-activity effects can also be extended to cellular gene delivery, as surface charge density plays a role in controlling the extent of endosomal escape. It is reported that higher generation dendrons, although binding DNA less strongly than the self-assembling lower generation dendrons, are more effective for transfection. The impact of the lipophilic group at the focal point is less significant for the DNA binding ability of these larger dendrons, which is predominantly controlled by the spermine surface groups, but it does modify the levels of gene transfection. Significant synergistic effects on gene delivery were observed when employing combinations of the dendrons and polyethyleneimine (PEI, 25 kDa), with transfection becoming possible at low loading levels where the two components would not transfect individually, giving practically useful levels of gene delivery.

Macromolecules, 2010

A series of G1− G3 supramolecular dendronized polymers 6 bearing dimeric 2-ureido-4-pyrimidinone ... more A series of G1− G3 supramolecular dendronized polymers 6 bearing dimeric 2-ureido-4-pyrimidinone (UPy) units on the main chain and aliphatic hydrocarbon dendrons as side chain appendages was prepared. Because of the high crystallinity and poor solubility of ...

Journal of the American Chemical Society, 2014

A working hypothesis for the pathogenesis of myotonic dystrophy type 1 (DM1) involves the aberran... more A working hypothesis for the pathogenesis of myotonic dystrophy type 1 (DM1) involves the aberrant sequestration of an alternative splicing regulator, MBNL1, by expanded CUG repeats, r(CUG) exp. It has been suggested that a reversal of the myotonia and potentially other symptoms of the DM1 disease can be achieved by inhibiting the toxic MBNL1r(CUG) exp interaction. Using rational design, we discovered an RNA-groove binding inhibitor (ligand 3) that contains two triaminotriazine units connected by a bisamidinium linker. Ligand 3 binds r(CUG) 12 with a low micromolar affinity (K d = 8 ± 2 μM) and disrupts the MBNL1-r(CUG) 12 interaction in vitro (K i = 8 ± 2 μM). In addition, ligand 3 is cell and nucleus permeable, exhibits negligible toxicity to mammalian cells, dissolves MBNL1-r(CUG) exp ribonuclear foci, and restores misregulated splicing of IR and cTNT in a DM1 cell culture model. Importantly, suppression of r(CUG) exp RNA-induced toxicity in a DM1 Drosophila model was observed after treatment with ligand 3. These results suggest ligand 3 as a lead for the treatment of DM1.