Effect of maceligan on the systemic exposure of paclitaxel: in vitro and in vivo evaluation.

This study investigated the effect of macelignan on the P-glycoprotein-mediated drug efflux as well as CYP3A4-mediated drug metabolism and subsequently its in vivo implication on the bioavailability of paclitaxel. The inhibition effect of macelignan on the CYP3A4-mediated metabolism was negligible over the concentration range of 0.01-100muM in rat liver microsome while approximately 33% inhibition was observed at 100muM in human liver microsome, implying that the interaction of macelignan with CYP3A4 might be insignificant at the physiologically achievable concentrations. In contrast, macelignan (20muM) increased the cellular accumulation of paclitaxel by approximately 1.7-fold in NCI/ADR-RES cells overexpressing P-gp, while it did not alter the cellular accumulation of paclitaxel in OVCAR-8 cells lacking P-gp. The effect of macelignan on the systemic exposure of paclitaxel was also examined in rats after the intravenous and oral administration of paclitaxel in the presence and the absence of macelignan. The concurrent use of macelignan significantly (p<0.05) enhanced the oral exposure of paclitaxel in rats while it did not affect the intravenous pharmacokinetics of paclitaxel, implying that macelignan might be more effective to improve the intestinal absorption rather than reducing hepatic elimination. In conclusion, macelignan appeared to be effective to improve the cellular accumulation as well as oral exposure of paclitaxel mainly via the inhibition of P-gp-mediated cellular efflux, suggesting that the concomitant use of macelignan may provide a therapeutic benefit in improving the anticancer efficacy of paclitaxel.

Drug development for Alzheimer's disease: recent progress.

Alzheimer's disease, the most common cause of dementia, is characterized by two major pathological hallmarks: amyloid plaques and neurofibrillary tangles. Based on these two indicators, an amyloid cascade hypothesis was proposed, and accordingly, most current therapeutic approaches are now focused on the removal of ß-amyloid peptides (Aß from the brain. Additionally, strategies for blocking tau hyperphosphorylation and aggregation have been suggested, including the development of drugs that can block the formation of tangles. However, there are no true disease-modifying drugs in the current market, though many drugs based on theories other than Aß and tau pathology are under development. The purpose of this review was to provide information on the current development of AD drugs and to discuss the issues related to drug development.

Macelignan: a new modulator of P-glycoprotein in multidrug-resistant cancer cells.

The effect of macelignan, a phytoestrogen, on P-gp function was investigated using multidrug resistant cancer cells overexpressing P-gp (NCI/ADR-RES) and the fluorescent P-gp substrates, daunorubicin and rhodamine 123. Macelignan (40 microM) increased the cellular accumulation of daunorubicin by approximately threefold in NCI/ADR-RES cells, whereas it did not alter the cellular accumulation of daunorubicin in MCF-7/sensitive cells. Similarly, the presence of macelignan also enhanced significantly (P < 0.05) the cellular accumulation of rhodamine 123 in a concentration-dependent manner in NCI/ADR-RES cells. Furthermore, cancer cells were more susceptible to the cytotoxicity of vinblastine, a P-gp substrate, in the presence of macelignan. Those results suggest that macelignan has inhibitory effects on P-gp mediated cellular efflux. However, P-gp activity did not affect the cellular accumulation of macelignan itself. Taken all together, macelignan was identified as a novel inhibitor of P-gp activity and may be a promising lead compound for the rational design of more efficacious drugs to reverse multidrug resistance in cancer.

Macelignan attenuates LPS-induced inflammation and reduces LPS-induced spatial learning impairments in rats.

Previous studies have shown that macelignan has anti-inflammatory and neuroprotective effects. Subsequently, in the current study, we demonstrate that oral administrations of macelignan reduce the hippocampal microglial activation induced by chronic infusions of lipopolysaccharide (LPS) into the fourth ventricle of Fisher-344 rat brains. A Morris water maze was used to evaluate the status of the hippocampal-dependent spatial learning in control rats with an artificial cerebrospinal fluid infusion, rats with chronic LPS infusions, and rats with chronic LPS infusions and oral administrations of macelignan. The rats with chronic LPS infusions showed spatial memory impairments relative to the control rats in the performance of the memory task. Daily administration of macelignan reduced the spatial memory impairments induced by the chronic LPS infusions. The results indicate that macelignan may possess therapeutic potential for the prevention of Alzheimer's disease.

Determination of macelignan in rat plasma by high-performance liquid chromatography with ultraviolet detection.

A high-performance liquid chromatographic method was developed for the determination of macelignan in rat plasma and applied to the pharmacokinetic study of macelignan in rats. Chromatographic separation was achieved on a conventional ODS column with the mobile phase of water: acetonitrile: methanol = 35:32.5:32.5 (v/v/v %). The flow rate of isocratic elution was 1 mL/min and peaks were detected at 240 nm. The limit of detection was 10 ng/mL and the limit of quantitation was 20 ng/mL. The calibration curve was linear over the concentration range of 50-5000 ng/mL. Intra-and inter-day precision for the assay over the concentration range was below 10 % and the accuracy ranged between 96.0-107% for intra-day and 98.8-114% for inter-day, respectively. The method was applied to the single dose pharmacokinetic study of macelignan in rats and the results showed that this HPLC method was adequate to support the in vivo pharmacokinetic study of macelignan.

Human vesicular glutamate transporters functionally complement EAT-4 in C. elegans.

The vesicular glutamate transporter (VGLUT) transports glutamate into pre-synaptic vesicles. Three isoforms of VGLUT have been identified in humans, but their functional differences remain largely unknown. EAT-4 is the only homologue of human VGLUT in C. elegans. Here we report that mutants of eat-4 exhibit hyperforaging behavior and that each of the isoforms of human VGLUT functionally rescues the defects in eat-4 worms.

Overexpression of BACE1 stimulates spontaneous basal secretion in PC12 cells.

Although alterations in the function of the neurotransmitter system have been implicated in the pathology of Alzheimer's disease (AD), the mechanisms that underlie this pathological change are not well understood. Beta-site amyloid precursor protein cleaving enzyme 1 (BACE1) is a key protease in the generation of beta-amyloid, an important trigger protein in the pathogenesis of AD. The expression and activity of BACE1 are increased in the brains of sporadic AD patients, and a role for BACE1 in neurotransmission has been suggested recently. This study examines whether BACE1 plays a role in regulated exocytosis in PC12 cells. Treatment of PC12 cells with a beta-secretase inhibitor reduced stimulus-dependent secretion of neurotransmitters, suggesting a potential role of BACE1 in regulated exocytosis. Using transfected human growth hormone as a reporter for a regulated secretory pathway in PC12 cells, we found that the transient overexpression of BACE1 increased basal secretion in the absence of a stimulus and reduced stimulus-dependent secretion in intact PC12 cells. In digitonin-permeabilized PC12 cells, an overexpression of BACE1 enhanced the Ca2+-independent and ATP-independent component of the secretory pathway. Furthermore, expression of the glycosylation-deficient mutant of BACE1, BACE1N354Q, led to an elevation of basal secretions over that by BACE1 wild-type, suggesting a role of BACE1 glycosylation in basal secretion. These results demonstrate an unknown role for BACE1 in secretion, and suggest that elevated levels of BACE1 in AD brains may contribute to the altered neurotransmitter pathology of AD through stimulation of spontaneous basal secretion under resting conditions.

Antioxidant and anti-inflammatory activities of the methanolic extract of Neorhodomela aculeate in hippocampal and microglial cells.

The antioxidant and anti-inflammatory properties of the marine red alga Neorhodomela aculeate (N. aculeata) Masuda were investigated with neuronal and microglial cells. Extracts of N. aculeata had potent neuroprotective effects on glutamate-induced neurotoxicity and inhibited reactive oxygen species (ROS) generation in the murine hippocampal HT22 cell line. Also, extracts of N. aculeata inhibited H2O2-induced lipid peroxidation in rat brain homogenates. The properties of the extract as an anti-inflammatory agent were investigated in microglial activation by interferon-gamma (IFN-gamma): it reduced the inducible nitric oxide synthase that consequently resulted in the reduction of nitric oxide. These results suggest that the marine red alga N. aculeata could be considered as a potential source for reducing reactive oxygen species and inflammation related to neurological diseases.

Putative therapeutic agents for the learning and memory deficits of people with Down syndrome.

Mental retardation is the most common and debilitating condition for individuals with Down syndrome (DS). The hyper-activation of DYRK1A by overexpression causes significant learning and memory deficits in DS-model mice. Thus far, no mechanism-based drug has been developed to address this. After a combination of in silico and in vitro screenings, two DYRK1A inhibitors were isolated that are active in a cell-based assay. Further optimization could lead to a novel drug discovery that could address DS learning and memory deficits.

Ulva conglobata, a marine algae, has neuroprotective and anti-inflammatory effects in murine hippocampal and microglial cells.

It has been reported that inflammatory processes are associated with the pathophysiology of Alzheimer's disease (AD), and the treatment of AD using anti-inflammatory agents slows the progress of AD. Marine algae have been utilized in food products as well as in medicine products for a variety of purposes. In this study, we investigated the neuroprotective effects of methanol extracts of Ulva conglobata (U. conglobata), a marine algae, on glutamate-induced neurotoxicity in the murine hippocampal HT22 cell line and the anti-inflammatory effects on interferon gamma (IFN-gamma)-induced microglial activation in BV2 cells. U. conglobata methanol extracts significantly attenuated the neurotoxicity induced by glutamate in HT22 cells and inhibited nitric oxide production induced by IFN-gamma in BV2 cells. U. conglobata methanol extract treatments were also examined and it was found that they almost completely suppressed the expression of the proinflammatory enzyme cyclooxygenase 2 (COX-2) and inducible nitric oxide synthase (iNOS). These results suggest that U. conglobata possesses therapeutic potential for combating neurodegenerative diseases associated with neuroinflammation.

DYRK1A BAC transgenic mice show altered synaptic plasticity with learning and memory defects.

Among the various phenotypes seen in Down syndrome (DS), mental retardation is the most common and most debilitating condition suffered by individuals with DS. The DYRK1A gene on human chromosome 21q22.2 encodes a subfamily of protein kinases that displays dual substrate specificities and is known to play a critical role in neurodevelopment. To study DS mental retardation, we have generated transgenic mice that contain only one copy of the complete human DYRK1A gene in a bacterial artificial chromosome. The transgenic mice showed significant impairment in hippocampal-dependent memory tasks in a Morris water maze. Interestingly, we observed shifts in both long-term potentiation and long-term depression, which suggests a role for DYRK1A in bidirectional synaptic plasticity. These mice represent the most clinically relevant DYRK1A mouse model to date and provide us a valuable tool for the in vivo study of mechanisms that underlie the learning and memory deficit in DS.

Antioxidant and antiinflammatory activities of xanthorrhizol in hippocampal neurons and primary cultured microglia.

Xanthorrhizol, a natural sesquiterpenoid isolated from the rhizome of Curcuma xanthorrhiza Roxb (Zingiberaceae), has antibacterial activities and protective effects against cisplatin-induced hepatotoxicity. In this study, we investigated the activities of xanthorrhizol as an antioxidant or antiinflammatory agent using neuronal and microglial cells. Xanthorrhizol had potent neuroprotective effects on glutamate-induced neurotoxicity and reactive oxygen species (ROS) generation in the murine hippocampal HT22 cell line. Also, xanthorrhizol inhibited H(2)O(2)-induced lipid peroxidation in rat brain homogenates. The properties of xanthorrhizol as an antiinflammatory agent were investigated in microglial activation by lipopolysaccharide. It reduced the expression of cyclooxygenase-2 and the inducible nitric oxide synthase, which consequently resulted in the reduction of nitric oxide. The production of proinflammatory cytokines, such as interleukin-6 and tumor necrosis factor-alpha in activated microglial cells, was reduced by xanthorrhizol. These results suggest that xanthorrhizol could be an effective candidate for the treatment of Alzheimer's disease- and other neurological disease-related ROS and inflammation.

Anti-oxidant and anti-inflammatory activities of macelignan in murine hippocampal cell line and primary culture of rat microglial cells.

Epidemiological studies suggest that the treatments of anti-inflammatory agents and anti-oxidants slow the progress of neurological diseases. Lignans are anti-oxidants and phytoestrogens found in a variety of plants. In this study, we investigated the neuroprotective effect of macelignan on glutamate-induced neurotoxicity and reactive oxygen species (ROS) in murine hippocampal HT22 cell line. Macelignan significantly attenuated the ROS production and neurotoxicity induced by glutamate in HT22 cell. Also, the properties of macelignan as an anti-inflammatory agent were investigated in microglials activation by lipopolysaccharide (LPS). It potently suppressed the expression of cyclooxygenase-2 and inducible nitric oxide synthase, that consequently resulted in the reduction of nitric oxide in LPS-treated microglial cells. It also significantly suppressed the production of pro-inflammatory cytokine tumor necrosis factor-alpha and interleukin-6. These results suggest that macelignan possesses therapeutic potentials against neurodegenerative diseases with oxidative stress and neuroinflammation.