Optimization and Evaluation of Novel Antifungal Agents for the Treatment of Fungal Infection.

Due to the increased morbidity and mortality by fungal infections and the emergence of severe antifungal resistance, there is an urgent need for new antifungal agents. Here, we screened for antifungal activity in our in-house library through the minimum inhibitory concentration test and derived two hit compounds with moderate antifungal activities. The hit compounds' antifungal activities and drug-like properties were optimized by substituting various aryl ring, alkyl chain, and methyl groups. Among the optimized compounds, 22h was the most promising candidate with good drug-like properties and exhibited potent fast-acting fungicidal antifungal effects against various fungal pathogens and synergistic antifungal activities with some known antifungal drugs. Additionally, 22h was further confirmed to disturb fungal cell wall integrity by activating multiple cell wall integrity pathways. Furthermore, 22h exerted significant antifungal efficacy in both the subcutaneous infection mouse model and ex vivo human nail infection model.

KDS2010, a Newly Developed Reversible MAO-B Inhibitor, as an Effective Therapeutic Candidate for Parkinson's Disease.

Monoamine oxidase-B (MAO-B) is a well-established therapeutic target for Parkinson's disease (PD); however, previous clinical studies on currently available irreversible MAO-B inhibitors have yielded disappointing neuroprotective effects. Here, we tested the therapeutic potential of KDS2010, a recently synthesized potent, selective, and reversible MAO-B inhibitor in multiple animal models of PD. We designed and synthesized a series of α-aminoamide derivatives and found that derivative KDS2010 exhibited the highest potency, specificity, reversibility, and bioavailability (> 100%). In addition, KDS2010 demonstrated significant neuroprotective and anti-neuroinflammatory efficacy against nigrostriatal pathway destruction in the mouse MPTP model of parkinsonism. Treatment with KDS2010 also alleviated parkinsonian motor dysfunction in 6-hydroxydopamine-induced and A53T mutant α-synuclein overexpression rat models of PD. Moreover, KDS2010 showed virtually no toxicity or side effects in non-human primates. KDS2010 could be a next-generation therapeutic candidate for PD.

Four-week repeated dose oral toxicity study of KDS2010, a novel selective monoamine oxidase B inhibitor, in Sprague Dawley rats.

Repeated dose oral toxicity and toxicokinetic of KDS2010, a new drug for Parkinson's disease, was investigated after 4-week repeated oral administration at 30, 50, 75, or 100 mg/kg/day in rats. Body weight and body weight gain decreased in rats of both sexes in the 75 and 100 mg/kg groups, and food consumption was reduced in male rats of the 75 and 100 mg/kg male groups. Histological alterations were observed in the kidney (urothelial hyperplasia, inflammatory cell infiltration in the renal pelvis, tubular vacuolation/degeneration, basophilic tubules, and hyaline droplets in the proximal tubules) of the 75 and 100 mg/kg male groups and the 50 and 100 mg/kg female groups. The 75 and 100 mg/kg male groups showed adverse effect in the testes (degeneration/exfoliation of germ cells, seminiferous tubules atrophy) and epididymis (cellular debris, oligospermia). These changes were partially recovered after a 2-week recovery period. However, basophilic tubules and hyaline droplets in the proximal tubules in the kidney and germ cell degeneration/exfoliation in the testis were not recovered. In toxicokinetics study, systemic exposure to KDS2010 increased proportionally in both sexes by in a dose -dependent manner. In addition, repeated administration for 4 weeks led to increased tendency of systemic exposure in both sexes compared with that in Day 1. In conclusion, KDS2010 was shown to target the kidney and testis with a no-observed-adverse-effect level of 50 and 30 mg/kg/day for males and females, respectively.

Nrf2 activator via interference of Nrf2-Keap1 interaction has antioxidant and anti-inflammatory properties in Parkinson's disease animal model.

Parkinson's disease (PD) is a neurodegenerative disorder characterized by abnormal movement, including slowed movements, shuffling gait, lack of balance, and tremor. Oxidative stress has been shown to play a decisive role in dopaminergic neuronal cell death in PD. The nuclear factor E2-related factor 2 (Nrf2)-Kelch-like ECH-associated protein 1 (Keap1) signaling pathway provides the main defense system against oxidative stress by inducing the expression of antioxidant enzyme genes. Direct interference in the Keap1-Nrf2 protein-protein interaction (PPI) has emerged as an effective strategy for Nrf2 activation. Therefore, we searched for novel Nrf2 activators that can disrupt Nrf2-Keap1 interaction by using a virtual screening approach and identified a potent Nrf2 activator, KKPA4026. KKPA4026 was confirmed to induce the expression of the Nrf2-dependent antioxidant enzymes heme oxygenase-1, glutamate-cysteine ligase catalytic subunit, glutamate-cysteine ligase regulatory subunit, and NAD(P)H:quinone oxidoreductase 1 in BV-2 cells. Furthermore, KKPA4026 showed anti-inflammatory effects in an Nrf2-dependent manner. In a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced mouse model of PD, KKPA4026 effectively attenuated PD-associated behavioral deficits and protected dopaminergic neurons. In summary, we identified KKPA4026 as a novel Nrf2 activator and suggested that Nrf2 activation through interference with the Nrf2-Keap1 interaction may be effective for PD treatment.

Aberrant Tonic Inhibition of Dopaminergic Neuronal Activity Causes Motor Symptoms in Animal Models of Parkinson's Disease.

Current pharmacological treatments for Parkinson's disease (PD) are focused on symptomatic relief, but not on disease modification, based on the strong belief that PD is caused by irreversible dopaminergic neuronal death. Thus, the concept of the presence of dormant dopaminergic neurons and its possibility as the disease-modifying therapeutic target against PD have not been explored. Here we show that optogenetic activation of substantia nigra pars compacta (SNpc) neurons alleviates parkinsonism in acute PD animal models by recovering tyrosine hydroxylase (TH) from the TH-negative dormant dopaminergic neurons, some of which still express DOPA decarboxylase (DDC). The TH loss depends on reduced dopaminergic neuronal firing under aberrant tonic inhibition, which is attributed to excessive astrocytic GABA. Blocking the astrocytic GABA synthesis recapitulates the therapeutic effect of optogenetic activation. Consistently, SNpc of postmortem PD patients shows a significant population of TH-negative/DDC-positive dormant neurons surrounded by numerous GABA-positive astrocytes. We propose that disinhibiting dormant dopaminergic neurons by blocking excessive astrocytic GABA could be an effective therapeutic strategy against PD.

A novel chalcone derivative as Nrf2 activator attenuates learning and memory impairment in a scopolamine-induced mouse model.

Alzheimer's disease is a common neurodegenerative disease characterized by progressive degeneration and neuronal cell death, resulting in neural network dysfunction. As the underlying mechanisms, oxidative damage and neuroinflammation have been reported to contribute to the onset and deterioration of Alzheimer's disease. The nuclear factor E2-related factor 2-antioxidant responsive element signaling pathway is a pivotal cellular defense mechanism against oxidative stress. Nrf2, a transcription factor, regulates the cellular redox balance and is primarily involved in anti-inflammatory responses. In this study, we synthesized novel chalcone derivatives and found a highly potent Nrf2 activator, compound 20a. Compound 20a confirmed to activate Nrf2 and induce expression of the Nrf2-dependent enzymes HO-1 and GCLC at both mRNA and protein levels. It also suppressed the production of nitric oxide and downregulated inflammatory mediators in BV-2 microglial cells. We found that compound 20a effectively increased the expression level and the activity of superoxide dismutase in both BV-2 microglial cells and brain hippocampus region of the scopolamine-induced mouse model. In addition, compound 20a effectively recovered the learning and memory impairment in a scopolamine-induced mouse model.

Newly developed reversible MAO-B inhibitor circumvents the shortcomings of irreversible inhibitors in Alzheimer's disease.

Monoamine oxidase-B (MAO-B) has recently emerged as a potential therapeutic target for Alzheimer's disease (AD) because of its association with aberrant γ-aminobutyric acid (GABA) production in reactive astrocytes. Although short-term treatment with irreversible MAO-B inhibitors, such as selegiline, improves cognitive deficits in AD patients, long-term treatments have shown disappointing results. We show that prolonged treatment with selegiline fails to reduce aberrant astrocytic GABA levels and rescue memory impairment in APP/PS1 mice, an animal model of AD, because of increased activity in compensatory genes for a GABA-synthesizing enzyme, diamine oxidase (DAO). We have developed a potent, highly selective, and reversible MAO-B inhibitor, KDS2010 (IC50 = 7.6 nM; 12,500-fold selectivity over MAO-A), which overcomes the disadvantages of the irreversible MAO-B inhibitor. Long-term treatment with KDS2010 does not induce compensatory mechanisms, thereby significantly attenuating increased astrocytic GABA levels and astrogliosis, enhancing synaptic transmission, and rescuing learning and memory impairments in APP/PS1 mice.

Synthesis and evaluation of biaryl derivatives for structural characterization of selective monoamine oxidase B inhibitors toward Parkinson's disease therapy.

Benzyloxyphenyl moiety is a common structure of highly potent, selective and reversible inhibitors of monoamine oxidase B (MAO-B), safinamide and sembragiline. We synthesized 4-(benzyloxy)phenyl and biphenyl-4-yl derivatives including halogen substituents on the terminal aryl unit. In addition, we modified the carbon linker between amine group and the biaryl linked unit. Among synthesized compounds, 12c exhibited the most potent and selective MAO-B inhibitory effect (hMAO-B IC50: 8.9 nM; >10,000-fold selectivity over MAO-A) as a competitive inhibitor. In addition, 12c showed greater MAO-B inhibitory activity and selectivity compared to well-known MAO-B inhibitors such as selegiline, safinamide and sembragiline. In the MPTP-induced mouse model of Parkinson's disease (PD), 12c significantly protected the tyrosine hydroxylase (TH)-immunopositive DAergic neurons and attenuated the PD-associated behavioral deficits. This study suggests characteristic structures as a MAO-B inhibitor that may provide a good insight for the development of therapeutic agents for PD.

Screening, Synthesis, and In Vitro Evaluation of Vinyl Sulfones as Inhibitors of Complement-Dependent Cytotoxicity in Neuromyelitis Optica.

Neuromyelitis optica (NMO) is a demyelinating autoimmune disease of the optic nerve and spinal cord triggered by binding of NMO-specific immunoglobulin G (NMO-IgG) auto-antibodies to the water channel aquaporin-4 (AQP4) in astrocytes. To find potential NMO therapeutics, a screening system was established and used to identify inhibitors of NMO-IgG-mediated complement-dependent cytotoxicity (CDC). The screening of approximately 400 compounds yielded potent hit compounds with inhibitory effects against CDC in U87-MG cells expressing human AQP4. Derivatives of the hit compounds were synthesized and evaluated for their inhibition of CDC. Of the small molecules synthesized, (E)-1-(2-((4-methoxyphenyl)sulfonyl)vinyl)-[4-[(3-trifluoromethyl)phenyl] methoxy]benzene (5 c) showed the most potent activity in both stably transfected U87-MG cells and mice-derived astrocytes. The results of this study suggest that 5 c, which targets NMO-IgG-specific CDC, may be useful as a research tool and a potential candidate for therapeutic development for the treatment of NMO.

Synthesis of a series of unsaturated ketone derivatives as selective and reversible monoamine oxidase inhibitors.

We have synthesized three categories of α,ß-unsaturated carbonyl derivatives and evaluated their MAO-A and MAO-B inhibitory activities. Among them, compound 10b including α,ß-unsaturated ketone group showed the most potent and selective MAO-B inhibitory activity (IC50 human MAO-B 16 nM, >6000-fold selective vs MAO-A) and compound 10b exhibited good reversibility compared with selegiline, a well-known irreversible MAO-B inhibitor. However, both α,ß-unsaturated amide and ester derivatives exhibited weaker MAO-B inhibition potencies. The docking studies provided insights into the possible binding modes and the key interaction sites of the synthesized MAO-B inhibitors.

A novel compound VSC2 has anti-inflammatory and antioxidant properties in microglia and in Parkinson's disease animal model.

BACKGROUND AND PURPOSE: Neuroinflammation through microglial activation is involved in the pathogenesis of neurodegenerative diseases including Parkinson's disease (PD), a major neurodegenerative disorder characterized by dopaminergic neuronal death in the substantia nigra. We examined our novel synthetic compound VSC2 for its anti-inflammatory properties towards development of a PD therapy. EXPERIMENTAL APPROACH: We tested the effects of VSC2 on production of various NF-κB-dependent proinflammatory molecules and Nrf2-dependent antioxidant enzymes in BV-2 microglia and in vivo. KEY RESULTS: The vinyl sulfone compound, VSC2, most effectively suppressed the production of NO in LPS-activated microglia. It also down-regulated expression of inducible NOS (iNOS), COX-2, IL-1ß and TNF-α and inhibited nuclear translocalization and transcriptional activity of NF-κB. VSC2 increased total and nuclear Nrf2 levels, induced Nrf2 transcriptional activity and was bound to Keap1 with high affinity. Expression of the Nrf2-regulated antioxidant enzyme genes NAD(P)H quinone oxidoreducase-1 (NQO-1), haem oxygenase-1 (HO-1) and glutamylcysteine ligase (GCL) were up-regulated by VSC2. In the MPTP mouse model of PD, oral administration of VSC2 decreased the number of activated microglia in the substantia nigra, lowered the levels of iNOS, COX-2 and IL-1ß, and protected the dopaminergic neurons. VSC2 also elevated the levels of NQO1, HO-1, GCL and Nrf2 in the nigrostriatal area. CONCLUSIONS AND IMPLICATIONS: VSC2 has both anti-inflammatory and antioxidant properties and prevented neuroinflammation in microglia and in an animal model of PD. This suggests VSC2 as a potential candidate for PD therapy.

Discovery of vinyl sulfones as a novel class of neuroprotective agents toward Parkinson's disease therapy.

Although the etiology of Parkinson's disease (PD) remains elusive, recent studies suggest that oxidative stress contributes to the cascade leading to dopaminergic (DAergic) neurodegeneration. The Nrf2 signaling is the main pathway responsible for cellular defense system against oxidative stress. Nrf2 is a transcription factor that regulates environmental stress response by inducing expression of antioxidant enzyme genes. We have synthesized novel vinyl sulfone derivatives. They exhibited a broad range of activities in inducing HO-1, whose gene expression is under the control of Nrf2. Among them, compound 12g was confirmed to activate Nrf2 and induce expression of the Nrf2-dependent antioxidant enzymes NQO1, GCLC, GLCM, and HO-1, at both mRNA and protein levels in DAergic neuronal cells. This was accompanied by protection of DAergic neurons in both in vitro and MPTP-induced in vivo models of PD. In addition, compound 12g effectively resulted in attenuation of the PD-associated behavioral deficits in the mouse model.