naphthoquinones and Parkinson-Disease

Tobacco and its use was discovered by Christopher Columbus in parallel with the discovery of America. Soon after, tobacco became a known medicinal plant in Europe. Its harmful effects were gradually discovered, especially those of tobacco smoke, and now it is considered a toxic plant. Tobacco leaf has a monograph in German "Hagers Enzyklopädie derArzneistoffe und Drogen", which describes its old, already not valid, medicinal use and clearly shows the toxic effects. Epidemiological studies indicate about 50% lower incidence of Parkinson's disease in smokers than in non-smokers. In turn, studies of the brains of smokers using positron emission tomography showed significantly decreased level of monoamine oxidase B--an enzyme which degrades dopamine--the neurotransmitter which the significant insufficiency of about 80-85%, is responsible for the symptoms of Parkinson's disease. From the tobacco leaves there were isolated MAO-B inhibitors--naphthoquinone--2,3,6-trimethyl-1,4-naphthoquinone and diterpenoid -trans,trans-farnesol, which occur also in tobacco smoke. In the last decade many papers have appeared on the neuroprotective activity of nicotine, the best known component of tobacco. through the effect of this compound on specific nicotinic cholinergic receptors (nAChRs), which interacts with nigrostriatal dopaminergic system as well as the possibility of using nicotine for the treatment of Parkinson's disease and other neurodegenerative diseases. Moreover, tobacco was also found to contain inhibitors of neuronal nitric oxide synthase (nNOS). Tobacco cannot be considered a medicinal plant, but some compounds occurring in that plant may find therapeutic use.

Topics: Animals; Brain; Comorbidity; Humans; Monoamine Oxidase; Naphthoquinones; Neuroprotective Agents; Nicotiana; Nicotine; Nitric Oxide Synthase Type I; Parkinson Disease; Phytotherapy; Plants, Medicinal; Receptors, Nicotinic; Smoking

There is an unmet need to better control motor complications in Parkinson's disease (PD). Naftazone, which exhibits glutamate release inhibition properties, has shown antiparkinsonian and antidyskinetic activity in preclinical models of PD and in a clinical proof of concept study.. We conducted a double-blind randomized placebo-controlled cross-over trial in PD patients with motor fluctuations and dyskinesia testing naftazone 160 mg/day versus placebo for 14 days. The two co-primary endpoints were the area under curve (AUC) of motor (MDS-UPDRS part III) and dyskinesia (AIMS) scores during an acute levodopa challenge performed at the end of each period. Secondary endpoints were UDysRS and axial symptoms scores during the challenge; AIMS, UDysRS, and time spent with or without dyskinesia the day before the challenge. The primary analysis was performed in the per protocol population.. Sixteen patients were included in the analysis. There was no difference between naftazone and placebo for the AUC of MDS-UPDRS III (-89, 95%CI[-1071; 893], p = 0.85), and AIMS (70, 95%CI[-192; 332], p = 0.57). At the end of treatment periods, AIMS score tended to be lower with naftazone than placebo (4.4 ± 3.4 versus 6.7 ± 4.4, p = 0.07), but UDysRS scores and other secondary outcomes were not different. Naftazone was safe and well tolerated.. This study did not confirm previous results on the efficacy of naftazone on dyskinesia nor motor fluctuations highlighting the problem of translating results obtained in preclinical models into clinical trials. Further investigation of naftazone may be conducted in PD with longer treatment duration.

Topics: Aged; Antiparkinson Agents; Cross-Over Studies; Dopamine Agents; Double-Blind Method; Dyskinesia, Drug-Induced; Female; Humans; Levodopa; Male; Middle Aged; Naphthoquinones; Parkinson Disease; Treatment Outcome

To explore for the first time the tolerability and efficacy of naftazone in patients with Parkinson's disease (PD). Proof-of-concept, randomized, double-blind, placebo-controlled, multiple-cross-over n-of-1 study in patients with PD with wearing-off and dyskinesias. Naftazone was titrated up to 120 mg/day during an initial single-blind dose-finding phase. Seven patients entered the placebo-controlled phase (four consecutive 28-day cross-overs). Three outcome measures were used to collect preliminary indices of efficacy: (i) 48-h ON-OFF diaries; (ii) Unified PD Rating Scale (UPDRS) part III while ON; (iii) seven-point Likert scale to assess "patients' discomfort caused by dyskinesias" (Q1) and 'disability during OFF-periods' (Q2). A 'responder' analysis (proportion of patients with mean treatment effect [naftazone minus placebo] favoring naftazone over the 4 cross-over periods) was used. Treatment effects were derived from mixed-effects anova. On diaries, 5/7 patients responded to naftazone for 'ON-time with troublesome dyskinesia' (reduced time, treatment effect: -49 [95% CI: -93/-4] min, P = 0.03), 6/7 regarding 'ON-time without troublesome dyskinesia' (increased time, treatment effect: 35 [-19/88], P = 0.2). No trend was observed for 'OFF' time. There were 7/7 'responders' regarding UPDRSIII (reduced score, treatment effect: -2.1[-4.5/0.2], P = 0.08). The 7-point scales did not show clear trends in favor of naftazone (3/7 responders for Q1 and 4/7 for Q2). Four of the seven patients reported adverse events after randomization, mostly related to the CNS (mild: 2, severe: 2). These pilot findings are consistent with preclinical data in primates and support the hypothesis that naftazone may have antiparkinsonian and antidyskinetic effects in humans that deserve further clinical investigation.

Topics: Aged; Antiparkinson Agents; Cross-Over Studies; Double-Blind Method; Dyskinesias; Female; Humans; Male; Naphthoquinones; Parkinson Disease; Pilot Projects; Placebos; Single-Blind Method; Treatment Outcome

α-Synuclein (αSyn) is an intrinsically disordered protein and its abnormal aggregation into amyloid fibrils is the main hallmark of Parkinson's disease (PD). The disruption of preformed αSyn fibrils using small molecules is considered as a potential strategy for PD treatment. Recent experiments have reported that naphthoquinone-dopamine hybrids (NQDA), synthesized by naphthoquinone (NQ) and dopamine (DA) molecules, can significantly disrupt αSyn fibrils and cross the blood-brain barrier. To unravel the fibril-disruptive mechanisms at the atomic level, we performed microsecond molecular dynamics simulations of αSyn fibrils in the absence and presence of NQDA, NQ, DA, or NQ+DA molecules. Our simulations showed that NQDA reduces the β-sheet content, disrupts K45-E57 and E46-K80 salt-bridges, weakens the inter-protofibril interaction, and thus destabilizes the αSyn fibril structure. NQDA has the ability to form cation-π and H-bonding interactions with K45/K80, and form π-π stacking interactions with Y39/F94. Those interactions between NQDA and αSyn fibrils play a crucial role in disaggregating αSyn fibrils. Moreover, we found that NQDA has a better fibril destabilization effect than that of NQ, DA, and NQ+DA molecules. This is attributed to the synergistic fibril-binding effect between NQ and DA groups in NQDA molecules. The DA group can form strong π-π stacking interactions with aromatic residues Y39/F94 of the αSyn fibril, while the DA molecule cannot. In addition, NQDA can form stronger cation-π interactions with residues K45/K80 than those of both NQ and DA molecules. Our results provide the molecular mechanism underlying the disaggregation of the αSyn fibril by NQDA and its better performance in fibril disruption than NQ, DA, and NQ+DA molecules, which offers new clues for the screening and development of promising drug candidates to treat PD.

Topics: alpha-Synuclein; Amyloid; Dopamine; Humans; Naphthoquinones; Parkinson Disease

Parkinson's disease (PD) is the second most common neurodegenerative disorder. Shikonin plays protective roles in age-associated diseases. Therefore, we investigate the biological functions of shikonin and its mechanisms involved in PD pathogenesis. The neurotoxin, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) was used to mimic PD-like conditions in animal models. The learning and memory capacities were assessed by Morris water-maze test, pole test, locomotor activity test and rotarod test. Neuroinflammation was determined by measuring the levels of tumour necrosis factor α (TNF-α), interleukin (IL)-1β, IL-6, inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). The quantification of superoxide dismutase, malondialdehyde and glutathione in substantia nigra was performed to estimate oxidative damage. Histopathologic changes were examined by haematoxylin and eosin staining. Immunofluorescence staining was conducted to determine the activation of astrocytes, tyrosine hydroxylase (TH)-positive neurons, and nuclear translocation of p65. Immunohistochemistry was performed to evaluate dopamine transporter (DAT)-positive neurons. Protein levels were measured by western blotting. Shikonin alleviates the cognitive and behavioural impairments. The death of dopaminergic neurons in nigra was attenuated by shikonin. The MPTP-induced neuroinflammation and oxidative stress in substantia nigra were alleviated by shikonin administration. Shikonin ameliorated the neuronal damage in nigra and inhibited the activation of astrocyte. Shikonin modulated the protein kinase B (Akt)/extracellular regulated kinase (ERK)/c-Jun N-terminal kinase (JNK)/nuclear factor κB (NF-κB) pathways. Shikonin ameliorates dopaminergic neuronal apoptosis by inhibiting oxidative stress and neuroinflammation via the Akt/ERK/JNK/NF-κB pathways in PD. The study has several limitations. First, in a previous study, levels of phosphorylated ERK were increased by MPTP. In our current study, we observed decreased p-ERK in nigra following MPTP treatment. Therefore, further investigation in the mechanisms of shikonin against PD progression is required. Second, the biological functions of shikonin need more exploration, including mitochondrial function and autophagy. Moreover, specific molecular targets for shikonin remain uncertain.

Topics: 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine; Animals; Cyclooxygenase 2; Disease Models, Animal; Dopamine Plasma Membrane Transport Proteins; Glutathione; Interleukin-6; JNK Mitogen-Activated Protein Kinases; Malondialdehyde; Mice; Mice, Inbred C57BL; Naphthoquinones; Neuroinflammatory Diseases; Neurotoxins; NF-kappa B; Nitric Oxide Synthase Type II; Oxidative Stress; Parkinson Disease; Proto-Oncogene Proteins c-akt; Superoxide Dismutase; Tumor Necrosis Factor-alpha; Tyrosine 3-Monooxygenase

Accumulation and aggregation of the intrinsically disordered protein α-synuclein (α-Syn) into amyloid fibrils are hallmarks of a series of heterogeneous neurodegenerative disorders, known as synucleinopathies and most notably Parkinson's disease (PD). The crucial role of α-Syn aggregation in PD makes it an attractive target for the development of disease-modifying therapeutics that would inhibit α-Syn aggregation or disrupt its preformed fibrillar assemblies. To this end, we have designed and synthesized two naphthoquinone-dopamine-based hybrid small molecules, NQDA and Cl-NQDA, and demonstrated their ability to inhibit in vitro amyloid formation by α-Syn using ThT assay, CD, TEM, and Congo red birefringence. Moreover, these hybrid molecules efficiently disassembled preformed fibrils of α-Syn into nontoxic species, as evident from LUV leakage assay. NQDA and Cl-NQDA were found to have low cytotoxicity and they attenuated the toxicity induced by α-Syn towards SH-SY5Y neuroblastoma cells. NQDA was found to efficiently cross an in vitro human blood-brain barrier model. These naphthoquinone-dopamine based derivatives can be an attractive scaffold for therapeutic design towards PD.

Topics: alpha-Synuclein; Amyloid; Dopamine; Humans; Naphthoquinones; Parkinson Disease

Parkinson disease (PD) is a chronic neurodegenerative disease characterized by a slow and progressive degeneration of dopaminergic neurons in substantia nigra. The pathophysiological mechanisms underlying PD remain unclear. Pin1, a major peptidyl-prolyl isomerase, has recently been associated with certain diseases. Notably, Ryo et al. (Ryo, A., Togo, T., Nakai, T., Hirai, A., Nishi, M., Yamaguchi, A., Suzuki, K., Hirayasu, Y., Kobayashi, H., Perrem, K., Liou, Y. C., and Aoki, I. (2006) J. Biol. Chem. 281, 4117-4125) implicated Pin1 in PD pathology. Therefore, we sought to systematically characterize the role of Pin1 in PD using cell culture and animal models. To our surprise we observed a dramatic up-regulation of Pin1 mRNA and protein levels in dopaminergic MN9D neuronal cells treated with the parkinsonian toxicant 1-methyl-4-phenylpyridinium (MPP(+)) as well as in the substantia nigra of the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD mouse model. Notably, a marked expression of Pin1 was also observed in the substantia nigra of human PD brains along with a high co-localization of Pin1 within dopaminergic neurons. In functional studies, siRNA-mediated knockdown of Pin1 almost completely prevented MPP(+)-induced caspase-3 activation and DNA fragmentation, indicating that Pin1 plays a proapoptotic role. Interestingly, multiple pharmacological Pin1 inhibitors, including juglone, attenuated MPP(+)-induced Pin1 up-regulation, α-synuclein aggregation, caspase-3 activation, and cell death. Furthermore, juglone treatment in the MPTP mouse model of PD suppressed Pin1 levels and improved locomotor deficits, dopamine depletion, and nigral dopaminergic neuronal loss. Collectively, our findings demonstrate for the first time that Pin1 is up-regulated in PD and has a pathophysiological role in the nigrostriatal dopaminergic system and suggest that modulation of Pin1 levels may be a useful translational therapeutic strategy in PD.

Topics: 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine; 1-Methyl-4-phenylpyridinium; Animals; Apoptosis; Brain; Cells, Cultured; Dopaminergic Neurons; Gene Expression; Humans; Immunoblotting; Immunohistochemistry; Male; Mice; Mice, Inbred C57BL; Motor Activity; Naphthoquinones; Neurotoxins; NIMA-Interacting Peptidylprolyl Isomerase; Parkinson Disease; Parkinson Disease, Secondary; Peptidylprolyl Isomerase; RNA Interference; RNA-Directed DNA Polymerase; Substantia Nigra; Up-Regulation