Synthesis and antioxidant activity of a procyanidin B3 analogue.

Proanthocyanidin, an oligomer of catechin, is a natural antioxidant and a potent inhibitor of lectin-like oxidized LDL receptor-1, which is involved in the pathogenesis of arteriosclerosis. We synthesized proanthocyanidin analogue 1, in which the geometry of one catechin molecule in procyanidin B3, a dimer of (+)-catechin, is constrained to be planar. The antioxidant activities of the compounds were evaluated in terms of their capacities to scavenge galvinoxyl radicals, and results demonstrate that while procyanidin was 3.8 times more potent than (+)-catechin, the radical scavenging activity of proanthocyanidin analogue 1 was further increased to 1.9 times that of procyanidin B3. This newly designed proanthocyanidin analogue 1 may be a promising lead compound for the treatment of arteriosclerosis and related cerebrovascular diseases.

Inhibition of amyloid fibril formation and cytotoxicity by caffeic acid-conjugated amyloid-ß C-terminal peptides.

Amyloid-ß (Aß) deposition and oxidative stress observed in the brains of patients with Alzheimer's disease (AD) are important targets for therapeutic intervention. In this study, we conjugated the antioxidants caffeic acid (CA) and dihydrocaffeic acid (DHCA) to Aß1-42 C-terminal motifs (Aßx-42: x=38, 40) to synthesize CA-Aßx-42 and DHCA-Aßx-42, respectively. Among the compounds, CA-Aß38-42 exhibited potent inhibitory activity against Aß1-42 aggregation and scavenged Aß1-42-induced intracellular oxidative stress. Moreover, CA-Aß38-42 significantly protected human neuroblastoma SH-SY5Y cells against Aß1-42-induced cytotoxicity, with an IC50 of 4µM. These results suggest that CA-Aß38-42 might be a potential lead for the treatment of AD.

Design, synthesis, and evaluation of Trolox-conjugated amyloid-ß C-terminal peptides for therapeutic intervention in an in vitro model of Alzheimer's disease.

Two hallmarks of Alzheimer's disease (AD) observed in the brains of patients with the disease include oxidative injury and deposition of protein aggregates comprised of amyloid-ß (Aß) variants. To inhibit these toxic processes, we synthesized antioxidant-conjugated peptides comprised of Trolox and various C-terminal motifs of Aß variants, TxAßx-n (x=34, 36, 38, 40; n=40, 42, 43). Most of these compounds were found to exhibit anti-aggregation activities. Among them, TxAß36-42 significantly inhibited Aß1-42 aggregation, showed potent antioxidant activity, and protected SH-SY5Y cells from Aß1-42-induced cytotoxicity. Thus, this method represents a promising strategy for developing multifunctional AD therapeutic agents.

A survey of mental health literacy in parents and guardians of teenagers.

Introduction: Parents and guardians (hereafter caregivers) of teenagers need high levels of mental health literacy (MHL) to manage mental health problems arising in teenagers in their care. Previous studies assessing MHL levels in caregivers of teenagers have reported mixed results, making it difficult to clearly estimate caregiver MHL levels. This study aimed to investigate MHL levels in Japanese caregivers of regular teenagers. Methods: Responses from caregivers (n = 1,397) of students entering junior and senior high schools to a self-administered online questionnaire were analyzed. The questionnaire assessed (a) knowledge about mental health/illnesses and (b) attitudes towards mental health problems in teens in their care (e.g., recognition of depression as a medical illness and intention to engage in helping behaviors). Results: The average proportion of correct answers to the knowledge questions (n = 7) was 55.4%; about one tenth (9.2%) of caregivers correctly answered only one or none of the questions. Few caregivers correctly answered about the life-time prevalence of any mental illnesses (46.1%) and appropriate sleep duration for teenagers' health (16.5%). The proportions of caregivers who had the intention to listen to the teen in their care, consult another person, and seek professional medical help if the teen suffered from depression were 99.5%, 91.5% and 72.7%, respectively. Conclusions: Many teenagers' caregivers appeared to be willing to help the teens in their care if they were suffering from mental health problems. However, there was much room for improvement in knowledge on mental health/illnesses and intention to seek help from medical professionals. Efforts toward better education should be made.

Increased Expression of NPM1 Suppresses p27Kip1 Function in Cancer Cells.

p27Kip1, a major cyclin-dependent kinase inhibitor, is frequently expressed at low levels in cancers, which correlates with their malignancy. However, in this study, we found a qualitative suppression of p27 overexpressed in some cancer cells. By proteomic screening for factors interacting with p27, we identified nucleophosmin isoform 1 (NPM1) as a novel p27-interacting factor and observed that NPM1 protein was expressed at high levels in some cancer cells. NPM1 overexpression in normal cells suppressed p27 function, and conversely, NPM1 knockdown in cancer cells restored the function in vitro. Furthermore, the tumors derived from cancer cells carrying the combination of p27 overexpression and NPM1 knockdown constructs showed significant suppression of growth as compared with those carrying other combinations in mouse xenograft models. These results strongly suggest that increased expression of NPM1 qualitatively suppresses p27 function in cancer cells.

Biodistribution and metabolism of the anti-influenza drug [11C]oseltamivir and its active metabolite [11C]Ro 64-0802 in mice.

INTRODUCTION: Oseltamivir phosphate (Tamiflu) is an orally active anti-influenza drug, which is hydrolyzed by esterase to its carboxylate metabolite Ro 64-0802 with potent activity to inhibit the influenza virus. The abnormal behavior and death associated with the use of oseltamivir have developed into a major problem in Japan where Tamiflu is often prescribed for seasonal influenza. It is critical to determine the amount of oseltamivir and Ro 64-0802 in the human brain and to elucidate the relationship between their amounts and neuropsychiatric side effects. The aim of this study was to evaluate [(11)C]oseltamivir and [(11)C]Ro 64-0802 in mice as promising positron emission tomography (PET) ligands for measuring their amounts in living brains. METHODS: Whole-body biodistribution of [(11)C]oseltamivir and [(11)C]Ro 64-0802 was determined in mice using the dissection method and micro-PET. In vitro and in vivo metabolite assay was performed in the plasma and brain of mice. RESULTS: Between 1 and 60 min after injection of [(11)C]oseltamivir and [(11)C]Ro 64-0802, 0.20-0.06% and 0.39-0.03% ID/g were detected in the mouse brains, respectively (dissection method). Radioactivity concentrations in the living brains between 0 and 90 min after injection were measured at standardized uptake values of 0.25-0.05 for [(11)C]oseltamivir and 0.38-0.02 for [(11)C]Ro 64-0802 (micro-PET). In vivo metabolite assay demonstrated the presence of [(11)C]oseltamivir and [(11)C]Ro 64-0802 in the brains after [(11)C]oseltamivir injection. CONCLUSION: This study determined the distribution and metabolism of [(11)C]oseltamivir and [(11)C]Ro 64-0802 in mice. PET could be used to measure their amounts in the living brain and to elucidate the relationship between the amounts in the brain and the side effects of Tamiflu in the central nervous system.

Tyrosol Reduces Amyloid-ß Oligomer Neurotoxicity and Alleviates Synaptic, Oxidative, and Cognitive Disturbances in Alzheimer's Disease Model Mice.

Soluble amyloid-ß (Aß) oligomers (AßOs), which elicit neurotoxicity and synaptotoxicity, are thought to play an initiating role in the pathology of Alzheimer's disease (AD). Since AßOs are a key therapeutic target, we attempted to identify natural agents that reduce AßO neurotoxicity. Using an assay system in which primary cultured neurons are treated with AßOs, we found that Rhodiola rosea extracts and one of its main constituents, tyrosol, significantly inhibited AßO-induced caspase-3 activation. We then assessed the in vivo efficacy of tyrosol by oral administration of the compound into AD model (5XFAD) transgenic and non-transgenic mice from either 2 or 4 to 7 months of age. In both paradigms, tyrosol treatment did not affect body weights of mice. Immunohistochemical analysis revealed that the immunoreactivity of spinophilin, a dendritic synaptic protein, was significantly reduced in three hippocampal subregions of vehicle-treated AD mice compared with non-transgenic mice, which was reversed in tyrosol-treated AD mice. Tyrosol treatment also prevented the enhancement of 4-hydroxy-2-nonenal immunoreactivity in the hippocampal CA3 region of AD mice. By contrast, tyrosol administration did not affect Aß accumulation, as evaluated by immunohistochemical and biochemical analyses. Moreover, the Barnes maze test showed that tyrosol administration modestly mitigated spatial memory impairment in AD mice. These findings collectively indicate that the natural agent tyrosol protects neurons against AßO neurotoxicity in vitro and ameliorates synaptic disturbance, oxidative stress responses, and cognitive impairment in vivo. We thus suggest that tyrosol is potentially an effective, safe, and unique drug candidate for AD.

Radiosyntheses of two positron emission tomography probes: [11C]Oseltamivir and its active metabolite [11C]Ro 64-0802.

Oseltamivir phosphate (Tamiflu, 1.H(3)PO(4) is an orally active anti-influenza drug, which is hydrolyzed by esterase to its carboxylate metabolite Ro 64-0802 (2) with potent activity inhibiting neuraminidase. In this study, for the first time, we synthesized carbon-11-labeled oseltamivir ([(11)C]1) and Ro 64-0802 ([(11)C]2) as two novel positron emission tomography probes and demonstrated that [(11)C]1 had twofold higher radioactivity concentration in the mouse brains than [(11)C]2.

An automated voxel-based method for calculating the reference value for a brain tumour metabolic index using 18F-FDG-PET and 11C-methionine PET.

OBJECTIVE: The tumour-to-normal ratio (T/N) is a representative index reflecting brain tumour activity by 18F-fluorodeoxyglucose (FDG) and 11C-methionine (MET) PET. We proposed a new automated method of calculating the normal reference value (N-value) for use as the denomination of T/N. This method uses voxel-based analysis of FDG- and MET-PET images. We compared the results of this method with those of the standard region-of-interest (ROI) method. METHODS: Data sets were obtained from 32 patients with newly diagnosed glioma and 13 patients with recurrent brain tumour. Our methods were as follows: (1) FDG-PET and MET-PET images were co-registered. (2) The areas where the FDG uptake was higher than a set threshold were selected. (3) For the corresponding areas of MET-PET images, mode and mean voxel values were calculated as tentative MET N-values. (4) Applying the same coordinates to FDG-PET, the voxel values were averaged and used as tentative FDG N-values. (5) The threshold of FDG-PET and whether to use the mode or the mean voxel values were computationally optimized using learning data sets. (6) Applying the optimal threshold and either the mode or mean, N-values of FDG and MET were finally determined. RESULTS: N-values determined by our automated method showed excellent agreement with those determined by a manual ROI method (ICC(2,1) > 0.78). These values were significantly correlated with mean manual N-values (p < 0.001). CONCLUSIONS: Our new method shows sufficiently good agreement with the standard method and can provide a more objective metabolic index.

Synthesis, in vitro and in vivo pharmacology of a C-11 labeled analog of CP-101,606, (+/-)threo-1-(4-hydroxyphenyl)-2-[4-hydroxy-4-(p-[11C]methoxyphenyl)piperidino]-1-propanol, as a PET tracer for NR2B subunit-containing NMDA receptors.

A carbon-11 labeled methoxyl analog of CP-101,606, (+/-)threo-1-(4-hydroxyphenyl)-2-[4-hydroxy-4-(p-[11C]methoxyphenyl)piperidino]-1-propanol [(+/-)[11C]1], was synthesized as a new subtype-selective PET radioligand for NMDA receptors. The in vitro binding studies using rat brain slices demonstrated that (+/-)[11C]1 shows an extremely high-specific binding to the NR2B subunit of NMDA receptors. In contrast to the in vitro binding, the in vivo binding to mouse and monkey brains showed no apparent specific localization of the radioactivity in any of the brain regions. Metabolism and physicochemical properties such as the lipophilicity of (+/-)[11C]1 seemed unlikely to affect the in vivo (+/-)[11C]1 binding. Among the various endogenous ligands acting at the NMDA receptors, polyamines (spermine and spermidine) and divalent cations (Mg(2+,) Zn(2+,) and Ca(2+)) strongly inhibited the in vitro (+/-)[11C]1 binding. Thus, the present studies point to the possibility that the polyamines and cations behave as endogenous inhibitors for (+/-)[11C]1 binding, leading to the loss of the specific binding in vivo.

Pd2(dba)3/P(MeNCH2CH2)3N·HCl-mediated Stille cross-coupling of [1-11C]acetyl chloride with aryl and heteroaryl stannanes.

INTRODUCTION: Developments in the Stille cross-coupling of [1-11C]acetyl chloride with tributylphenylstannane mediated by the Pd2(dba)3/P(MeNCH2CH2)3N·HClsystem are reported. METHODS: The reaction conditions for the cross-coupling of [1-11C]acetyl chloride with tributylphenylstannane were optimized, and the reaction scope was investigated. RESULTS: The cross-couplings of [1-11C]acetyl chloride with a range of aryl and heteroaryl stannanes were performed with good to excellent radiochemical conversions using the developed method. CONCLUSIONS: A highly efficient method for the Stille cross-coupling of [1-11C]acetyl chloride with organostannanes was demonstrated. It is anticipated that our method will be an attractive addition to the carbon-11-labeling procedures available for the synthesis of positron emission tomography probes.

Determination of radioactivity in infant, juvenile and adult rat brains after injection of anti-influenza drug [¹¹C]oseltamivir using PET and autoradiography.

Oseltamivir phosphate (Tamiflu(®)) is an orally active anti-influenza drug, which is hydrolyzed to its metabolite Ro 64-0802 inhibiting the influenza virus with potent activity. The abnormal behavior of young influenza patients associated with the use of oseltamivir has developed to a social problem in countries where Tamiflu is often prescribed. It is important to determine the amount of oseltamivir in the brain and to elucidate the relationship between its presence and neuropsychiatric side effects. The aim of this study was to determine the radioactivity in the infant, juvenile and adult rat brains after injection of [(11)C]oseltamivir into the rats using PET and autoradiography. After injection of this radioligand, the highest radioactivity was found in the infant brain and the radioactivity level decreased with age. Ex vivo autoradiography on the infant brain displayed a relatively higher radioactivity in the cerebellum than that in the cerebrum. Pretreatment with cyclosporin A (an inhibitor for P-glycoprotein) increased the brain radioactivity. These results give helpful insights into elucidating why the neuropsychiatric side effects of oseltamivir occur in young patients.

Use of a novel radiometric method to assess the inhibitory effect of donepezil on acetylcholinesterase activity in minimally diluted tissue samples.

BACKGROUND AND PURPOSE: Cholinesterase inhibitors have been widely used for the treatment of patients with dementia. Monitoring of the cholinesterase activity in the blood is used as an indicator of the effect of the cholinesterase inhibitors in the brain. The selective measurement of cholinesterase with low tissue dilution is preferred for accurate monitoring; however, the methods have not been established. Here, we investigated the effect of tissue dilution on the action of cholinesterase inhibitors using a novel radiometric method with selective substrates, N-[(14)C]methylpiperidin-4-yl acetate ([(14)C]MP4A) and (R)-N- [(14)C]methylpiperidin-3-yl butyrate ([(14)C]MP3B_R), for AChE and butyrylcholinesterase (BChE) respectively. EXPERIMENTAL APPROACH: We investigated the kinetics of hydrolysis of [(14)C]-MP4A and [(14)C]-MP3B_R by cholinesterases, and evaluated the selectivity of [(14)C]MP4A and [(14)C]MP3B_R for human AChE and BChE, respectively, compared with traditional substrates. Then, IC(50) values of cholinesterase inhibitors in minimally diluted and highly diluted tissues were measured with [(14)C]MP4A and [(14)C]MP3B_R. KEY RESULTS: AChE and BChE activities were selectively measured as the first-order hydrolysis rates of [(14)C]-MP4A and [(14)C]MP3B_R respectively. The AChE selectivity of [(14)C]MP4A was an order of magnitude higher than traditional substrates used for the AChE assay. The IC(50) values of specific AChE and BChE inhibitors, donepezil and ethopropazine, in 1.2-fold diluted human whole blood were much higher than those in 120-fold diluted blood. In addition, the IC(50) values of donepezil in monkey brain were dramatically decreased as the tissue was diluted. CONCLUSIONS AND IMPLICATIONS: This method would effectively monitor the activity of cholinesterase inhibitors used for therapeutics, pesticides and chemical warfare agents.

Efficient and reproducible synthesis of [1-11C]acetyl chloride using the loop method.

[1-(11)C]Acetyl chloride ([(11)C]AcCl), an important [(11)C]acylating agent, was synthesized by reacting [(11)C]CO(2) with methylmagnesium bromide coated on the inner surface of a polyethylene loop (loop method). By optimizing the reaction conditions and synthesis parameters, [1-(11)C]phenylacetate and [1-(11)C]benzylacetate were produced from [(11)C]AcCl in high radiochemical yield and specific activity.

Synthesis and brain regional distribution of [11C]NPS 1506 in mice and rat: an N-methyl-D-aspartate (NMDA) receptor antagonist.

NPS 1506 [3-fluoro-gamma-(3-fluorophenyl)-N-methylbenzenepropamine] is representative of a non-psychotomimetic class of N-methyl-D-aspartate (NMDA) receptor antagonists. [11C]NPS 1506 was prepared at high radiochemical purity (>98%) with a specific activity of around 50 GBq/micromol at the end of synthesis by methylation of the desmethyl precursor with [11C]methyl iodide in the presence of NaH. Biodistribution of [11C]NPS 1506 in mice and rat demonstrated that uptake into the brain was rapid and occurred at high levels. [11C]NPS 1506 showed no appreciable specific binding in rodent brains under in vivo conditions, possibly because of both a large non-specific bound fraction and low in vitro binding affinity for NMDA receptors.