Effects of Carbazole Derivatives on Neurite Outgrowth and Hydrogen Peroxide-Induced Cytotoxicity in Neuro2a Cells

Design, synthesis and neuroprotective evaluation of nitrogen heterocyclic and triazole derivatives of sarracinic acid

Novel sarracinic acid derivatives bearing triazole or N-heterocyclic moiety were prepared via two separate reaction schemes. The triazoles and the N-heterocyclic derivatives were synthesised using standard click chemistry approach and amination of 2-bromoethyl ester of sarracinic acid respectively. All the synthesised derivatives were screened for in vitro neuroprotective activity against corticosterone induced impairment in neuroblastoma cell line SH-SY5Y. Two analogs SA-2 and SA-12 exhibited strong neuroprotective activity. The cell viability, after high dose corticosterone induced cell death, increased remarkably with the pre treatment of SA-2 and SA-12. The in vitro biological activity of SA-2 and SA-12 was verified through docking studies. The docking studies were in good agreement with the biological results. SA-2 and SA-12 showed strong binding affinities with the target protein having ΔGb = -8.88 and -7.52; inhibition constant (ki) = 3.08 nM and 30.9 nM respectively.

A Potential Strategy for Treatment of Neurodegenerative Disorders by Regulation of Adult Hippocampal Neurogenesis in Human Brain

Abstract:

Adult hippocampal neurogenesis is a multistage mechanism that continues throughout the lifespan of human and non-human mammals. These adult-born neurons in the central nervous system (CNS) play a significant role in various hippocampus-dependent processes, including learning, mood regulation, pattern recognition, etc. Reduction of adult hippocampal neurogenesis, caused by multiple factors such as neurological disorders and aging, would impair neuronal proliferation and differentiation and result in memory loss. Accumulating studies have indicated that functional neuron impairment could be restored by promoting adult hippocampal neurogenesis. In this review, we summarized the small molecules that could efficiently promote the process of adult neurogenesis, particularly the agents that have the capacity of crossing the blood-brain barrier (BBB), and showed in vivo efficacy in mammalian brains. This may pave the way for the rational design of drugs to treat humnan neurodegenerative disorders in the future.

Total synthesis of pyrrolo[2,3-c]quinoline alkaloid: trigonoine B

The first total synthesis of the pyrrolo[2,3-c]quinoline alkaloid trigonoine B (1) was accomplished via a six-step sequence involving the construction of an N-substituted 4-aminopyrrolo[2,3-c]quinoline framework via electrocyclization of 2-(pyrrol-3-yl)benzene containing a carbodiimide moiety as a 2-azahexatriene system. The employed six-step sequence afforded trigonoine B (1) in 9.2% overall yield. The described route could be employed for the preparation of various N-substituted 4-aminopyrroloquinolines with various biological activities.

Protective effects of butein on corticosterone-induced cytotoxicity in Neuro2A cells

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Butein protected Neuro2A cells from CORT-induced apoptosis via mitochondrial dysfunction, caspase-3 activation, and DNA damage.

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CORT suppressed retinoic acid-induced neurite outgrowth in Neuro2A cells.

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Butein inhibited CORT-suppressed neurite outgrowth in Neuro2A cells.

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High doses of butein induced cytotoxicity in Neuro2A cells.

A functional understanding of the relationship between glucocorticoids and neuronal apoptosis induced by the production of reactive oxygen species (ROS) may lead to a novel strategy for the treatment or prevention of depression. Previous reports suggest that butein, a type of flavonoids, may be a potent candidate against depression-related neuronal cell apoptosis caused by oxidative stress; however, the protective effects of butein on damaged corticosterone (CORT)-treated neuronal cells has not been elucidated. In the present study, we examined the protective effect of butein on CORT-induced cytotoxicity and neurite growth during cell differentiation of mouse neuroblastoma Neuro2A (N2A) cells. Moreover, the effect on cultured cells by high concentrations of butein was confirmed. Our results demonstrate that CORT treatment significantly decreases cell viability and induces cell death. CORT was suggested to induce apoptosis via mitochondrial dysfunction and caspase-3 activation; this apoptosis may be attributed to DNA damage by ROS generation, found in this study to be significantly inhibited by pretreatment with butein. We found that CORT produced significant growth suppression of retinoic acid-induced neurite outgrowth in N2A cells; however, butein significantly increased neurite length and induced dose-dependent apoptotic cytotoxicity in N2A cells. This study suggests that low concentration of butein can prevent CORT-induced cytotoxicity in N2A cells, and provides preliminary results supporting some of the beneficial roles of butein in neuroprotection.

Citrus Auraptene Induces Expression of Brain-Derived Neurotrophic Factor in Neuro2a Cells

(1) Background: Our published data have indicated that 1) auraptene (AUR), a citrus ingredient, has neuroprotective effects on the mouse brain, owing to its ability to suppress inflammation, such as causing a reduction in hyperactivation of microglia and astrocytes; 2) AUR has the ability to trigger phosphorylation (activation) of extracellular signal-related kinase (ERK) and cAMP response element-binding protein (CREB) in neuronal cells; 3) AUR has the ability to induce glial cell line-derived neurotrophic factor (GDNF) synthesis/secretion in rat C6 glioma cells. The well-established fact that the ERK-CREB pathway plays an important role in the production of neurotrophic factors, including GDNF and brain-derived neurotrophic factor (BDNF), prompted us to investigate whether AUR would also have the ability to induce BDNF expression in neuronal cells. (2) Methods: Mouse neuroblastoma neuro2a cells were cultured and the effects of AUR on BDNF mRNA expression and protein content were evaluated by RT-PCR and ELISA, respectively. (3) Results: The levels of BDNF mRNA and secreted BDNF were significantly increased by AUR in a dose- and time-dependent manner in neuro2a cells. (4) Conclusion: The induction of BDNF in neuronal cells might be, in part, one of the mechanisms accounting for the neuroprotective effects of AUR.

Accelerative effects of carbazole-type alkaloids from Murraya koenigii on neurite outgrowth and their derivative's in vivo study for spatial memory

Murraya koenigii is a medicinal plant that contains several carbazole-type alkaloids as its characteristic constituents. Blood-brain barrier permeable constituents of M. koenigii accelerated neurite outgrowth in PC-12 cells. Nine compounds were isolated from M. koenigii and their effects on neurite outgrowth were examined. Murrayamine-E (8) at 10 μM showed significant effect. Focusing on the carbazole skeleton, we synthesized derivatives to attenuate cytotoxicity. 9-Benzyl-9H-carbazol-4-ol (15) exhibited strong neurite outgrowth accelerative effect. In addition, the novel object recognition test and the Morris water maze test were performed to evaluate memory improvement of 15 in APdE9 mice. Compound 15 tended to improve spatial memory in the Morris water maze test. These results suggest that carbazole derivative 15 would be a seed compound for Alzheimer's disease drug.

Citrus Auraptene Induces Glial Cell Line-Derived Neurotrophic Factor in C6 Cells

We previously demonstrated that auraptene (AUR), a natural coumarin derived from citrus plants, exerts anti-inflammatory effects in the brain, resulting in neuroprotection in some mouse models of brain disorders. The present study showed that treatment with AUR significantly increased the release of glial cell line-derived neurotrophic factor (GDNF), in a dose- and time-dependent manner, by rat C6 glioma cells, which release was associated with increased expression of GDNF mRNA. These results suggest that AUR acted as a neuroprotective agent in the brain via not only its anti-inflammatory action but also its induction of neurotrophic factor. We also showed that (1) the AUR-induced GDNF production was inhibited by U0126, a specific inhibitor of mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK) 1/2, and by H89, a specific inhibitor of protein kinase A (PKA); and (2) AUR induced the phosphorylation of cAMP response element-binding protein (CREB), a transcription factor located within the nucleus. These results suggest that AUR-stimulated gdnf gene expression was up-regulated through the PKA/ERK/CREB pathway in C6 cells.