Neurite Outgrowth Activity Research Articles

Impact of Ecklonia radiata extracts on the neuroprotective activities against amyloid beta (Aβ1-42) toxicity and aggregation

Abstract The impact of extract composition on the neuroprotective activities of Ecklonia radiata was investigated in multiple neuroprotective assays in vitro. A total of six fractions (crude extract (CE), phlorotannin (PT), polysaccharide (PS), free sugar (FS), low molecular weight (LM), and high molecular weight (HM)) prepared from E. radiata were used to determine their effects against Aβ1-42 and oxidative stress in neuronal cell line PC-12. Only three fractions (CE, PS, and HM) demonstrated cytotoxicity in at least the highest concentration (100 μg/mL) tested in PC-12 cells. All fractions inhibited apoptosis induced by Aβ1-42 and enhanced neurite outgrowth activity. With the exception of HM, other fractions inhibited the aggregation of Aβ1-42 and demonstrated antioxidant activity against the toxicity induced by hydrogen peroxide. This study highlights the potential of using brown seaweed E. radiata components for improving neuroprotective activities. Such extracts could be potentially used as functional food or dietary supplements to support neurological function.

Crafting Carbazole-Based Vorinostat and Tubastatin-A-like Histone Deacetylase (HDAC) Inhibitors with Potent in Vitro and in Vivo Neuroactive Functions.

Small-molecule inhibitors of HDACs (HDACi) induce hyperacetylation of histone and nonhistone proteins and have emerged as potential therapeutic agents in most animal models tested. The established HDACi vorinostat and tubastatin-A alleviate neurodegenerative and behavioral conditions in animal models of neuropsychiatric disorders restoring the neurotrophic milieu. In spite of the neuroactive pharmacological role of HDACi (vorinostat and tubastatin-A), they are limited by efficacy and toxicity. Considering these limitations and concern, we have designed novel compounds 3–11 as potential HDACi based on the strategic crafting of the key pharmacophoric elements of vorinostat and tubastatin-A into architecting a single molecule. The molecules 3–11 were synthesized through a multistep reaction sequence starting from carbazole and were fully characterized by NMR and mass spectral analysis. The novel molecules 3–11 showed remarkable pan HDAC inhibition and the potential to increase the levels of acetyl H3 and acetyl tubulin. In addition, few novel HDAC inhibitors 4–8, 10, and 11 exhibited significant neurite outgrowth-promoting activity with no observable cytotoxic effects, and interestingly, compound 5 has shown comparably more neurite growth than the parent compounds vorinostat and tubastatin-A. Also, compound 5 was evaluated for possible mood-elevating effects in a chronic unpredictable stress model of Zebrafish. It showed potent anxiolytic and antidepressant-like effects in the novel tank test and social interaction test, respectively. Furthermore, the potent in vitro and in vivo neuroactive compound 5 has shown selectivity for class II over class I HDACs. Our results suggest that the novel carbazole-based HDAC inhibitors, crafted with vorinostat and tubastatin-A pharmacophoric moieties, have potent neurite outgrowth activity and potential to be developed as therapeutics to treat depression and related psychiatric disorders.

The Methylene-Cycloalkylacetate (MCA) Scaffold in Terpenyl Compounds with Potential Pharmacological Activities

Recently, the methylene-cycloakylacetate (MCA) scaffold has been reported as a potential pharmacophore for neurite outgrowth activity. In this work, natural diterpenes that embed MCA fragments are reviewed, as they are major components of Halimium viscosum: ent-halimic acid, the prototype for these bioactive compounds. Herein, structures, sources, and activities for the natural diterpenes, as well as their synthetic derivatives of interest, are reviewed.

Leonurine promotes neurite outgrowth and neurotrophic activity by modulating the GR/SGK1 signaling pathway in cultured PC12 cells.

Depression is a common psychiatric disorder that affects almost 10% of children and adolescents worldwide. Numerous synthetic chemical antidepressants used to treat depression have adverse side effects. Therefore, new therapeutic approaches for depression treatment are urgently needed. Leonurus cardiaca has recently been shown to be effective for the treatment of nervous system diseases such as depression, but its mechanism is not clear. In this study, we aimed to reveal the mechanism underlying leonurine’s antidepressant activity. Leonurine was used to treat corticosterone-induced PC12 cells to examine its effect on neurite outgrowth and neurotrophic factors after treatment with the inhibitor of glucocorticoid receptor (GR) and serum-inducible and glucocorticoid-inducible kinase 1 (SGK1). Methyl thiazolyl tetrazolium assays were used to evaluate the viability of cells. High content analysis was used to detect cell area, total neurite length, maximum neurite length, and expression of GR, SGK1, brain-derived neurotrophic factor (BDNF), neurotrophic factor-3 (NT-3), and B-cell lymphoma-2 (BCL-2). The results showed that leonurine increased cell viability in a concentration-dependent manner, with the maximal prosurvival effect at 60 μM. Leonurine increased cell area, total neurite length, and maximum neurite length of corticosterone-induced PC12 cells, increased the expression of GR, BDNF, NT-3, and BCL-2, and decreased the expression of SGK1. After treatment with GR inhibitor RU486, the expressions of GR, BDNF, NT-3, and BCL-2 were significantly decreased and SGK1 was increased. In contrast, treatment with GSK650394 had the opposite effect of RU486. Our data indicate that leonurine promotes neurite outgrowth and neurotrophic activity in cultured PC12 cells, and its potential mechanism may involve the GR/SGK1 signaling pathway.

In vitro studies of the neuroprotective activities of astaxanthin and fucoxanthin against amyloid beta (Aβ1-42) toxicity and aggregation

Amyloid beta (Aβ) can aggregate and form plaques, which are considered as one of the major hallmarks of Alzheimer's disease. This study aims to directly compare the neuroprotective activities in vitro of two marine-derived carotenoids astaxanthin and fucoxanthin that have shown a spectrum of biological activities, including neuroprotection. The in vitro neuroprotective activities were investigated against Aβ1-42-mediated toxicity in pheochromocytoma (PC-12) neuronal cells using the MTT cell viability assay, anti-apoptotic, antioxidant and neurite outgrowth activities; as well as inhibition against Aβ1-42 fibrillization in the Thioflavin T (ThT) assay of fibril kinetics and via transmission electron microscopic (TEM) evaluation of fibril morphology. The results demonstrated that both astaxanthin and fucoxanthin exhibited multi-neuroprotective effects favouring fucoxanthin over astaxanthin supporting neuroprotective roles of marine-derived carotenoids as potential novel dementia prevention or therapeutic strategies.

Targeting Ubiquitin Proteasome Pathway with Traditional Chinese Medicine for Treatment of Spinocerebellar Ataxia Type 3.

Nine autosomal dominant spinocerebellar ataxias (SCAs) are caused by an abnormal expansion of CAG trinucleotide repeats that encodes a polyglutamine (polyQ) tract within different genes. Accumulation of aggregated mutant proteins is a common feature of polyQ diseases, leading to progressive neuronal dysfunction and degeneration. SCA type 3 (SCA3), the most common form of SCA worldwide, is characterized by a CAG triplet expansion in chromosome 14q32.1 ATXN3 gene. As accumulation of the mutated polyQ protein is a possible initial event in the pathogenic cascade, clearance of aggregated protein by ubiquitin proteasome system (UPS) has been proposed to inhibit downstream detrimental events and suppress neuronal cell death. In this study, Chinese herbal medicine (CHM) extracts were studied for their proteasome-activating, polyQ aggregation-inhibitory and neuroprotective effects in GFPu and ATXN3/Q -GFP 293/SH-SY5Y cells. Among the 14 tested extracts, 8 displayed increased proteasome activity, which was confirmed by 20S proteasome activity assay and analysis of ubiquitinated and fused GFP proteins in GFPu cells. All the eight extracts displayed good aggregation-inhibitory potential when tested in ATXN3/Q -GFP 293 cells. Among them, neuroprotective effects of five selected extracts were shown by analyses of polyQ aggregation, neurite outgrowth, caspase 3 and proteasome activities, and ATXN3-GFP, ubiquitin, BCL2 and BAX protein levels in neuronal differentiated ATXN3/Q -GFP SH-SY5Y cells. Finally, enhanced proteasome function, anti-oxidative activity and neuroprotection of catalpol, puerarin and daidzein (active constituents of Rehmannia glutinosa and Pueraria lobata) were demonstrated in GFPu and/or ATXN3/Q -GFP 293/SH-SY5Y cells. This study may have therapeutic implication in polyQ-mediated disorders.

Fellutamide B Synthetic Path Intermediates with in Vitro Neuroactive Function Shows Mood-Elevating Effect in Stress-Induced Zebrafish Model.

Fellutamide B is reported to have cytotoxic and proteasome inhibitory activity. Interestingly, fellutamide B and its simplified analogues have also been observed for the neurotrophic activity by stimulating the synthesis and secretion of neurotrophins. Owing to the interesting structural and potent neurotrophic role of fellutamide B (a lipopeptide aldehyde), we have assessed the synthetic path intermediates (compounds A–D) of fellutamide B for their neuroactive potential (in vitro and in vivo). We have observed few compounds (comp #A–D) to have potential neurite outgrowth activity in Neuro2a cells with no observable negative effect on the cell viability. In addition, most compounds (comp #A, C, and D) have shown neurogenic activity ex vivo in hippocampal neurosphere culture, with increased acetyl H3 and acetyl H4 induction ability (comp #C). Furthermore, the intermediate product comp #C has shown anxiolytic and antidepressant-like activity in novel tank test and social interaction test, in the chronic unpredictable stress model of zebrafish mood disorder, inducing BDNF gene expression in the telencephalon region of the fish brain. Our results thus demonstrate that the fellutamide B synthetic path intermediates have potential neurotrophic, neurogenic, and mood-elevating effects and thus good prospect to be developed as potential therapeutics to treat psychiatric disorders.

PO-314 ALK inhibitor, ceritinib, abrogates activation of the novel ALK-I1171T mutation in neuroblastoma

IntroductionMutations in the kinase domain of Anaplastic Lymphoma Kinase (ALK) are undoubtedly implicated in the pathogenesis of the childhood cancer, neuroblastoma. However, clinical response of ALK positive neuroblastoma patients to the first generation ALK inhibitor has been rather disappointing.Here we report the appearance of a novel ALK mutation in neuroblastoma together with other chromosomal aberrations that mediate neuroblastoma initiation and progression.Material and methodsGenomic tumour DNA from biopsy samples were extracted and exome sequencing was performed through paired-end sequencing on Illumina plateforms.The novel ALK-I1171T mutant was biochemically analysed by western blot and neurite-outgrowth assay in PC12 cells, and foci formation assay in NIH3T3 cells.Results and discussionsAnalyses of genomic tumour DNA from biopsy samples initially showed an 11q deletion, 17q gain with a mutation of the ALK gene at protein position 1171, which mediate an amino acid change from isoleucine to threonine. We show that mutation of I1171 to threonine generates a potent gain-of-function mutant, as observed in two independent systems. Firstly, in PC12 cell lines expressing ALK-I1171T display ligand independent activation of ALK, neurite outgrowth and further downstream signalling activation. Secondly, ALK-I1171T meditate foci formation in a NIH3T3 transformation analysis. Finally, pharmacological inhibition of ALK-I1171T employing ceritinib, an FDA approved ALK inhibitor show 14-fold better ability to abrogate ALK-I1171T compared with crizotinib.ConclusionThis study suggests that ceritinib presents a viable therapeutic option for ALK-positive neuroblastoma.

Differences in Neuritogenic Activity and Signaling Activation of Madecassoside, Asiaticoside, and Their Aglycones in Neuro-2a cells.

Madecassoside (MS) and asiaticoside (AS) along with their aglycones, madecassic acid (MA) and asiatic acid (AA), are considered the major neuroactive triterpenoid constituents of Centella asiatica. In this study, we aimed to compare MS, AS, MA, and AA for their neurite outgrowth activities and mechanisms in Neuro-2a cells. Immunofluorescent cell staining showed MS and AS significantly increased the percentage of neurite-bearing cells (%NBC) and the neurite length with higher potency than MA and AA. The triterpenoid glycosides induced sustained extracellular signal-regulated protein kinases 1 and 2 (ERK1/2) phosphorylation, while their aglycones activated only transient signaling of ERK1/2. Suppression of ERK1/2 activation significantly abolished not only cAMP response element-binding protein (CREB) phosphorylation but also the increment of %NBC and neurite length in MS- and AS-treated cells. Inhibition of ERK phosphorylation did not produce similar blockage of CREB activation and neurite outgrowth in MA- and AA-treated cells. On the other hand, inactivation of protein kinase B (Akt) resulted in a suppression of neurite lengthening in all studied triterpenoids. This is the first study discerning the different signaling pathways of neurite outgrowth activity induced by C. asiatica triterpenoid glycosides and aglycones. Neurite outgrowth activity of the glycosides MS and AS was found to involve the activation of sustained ERK phosphorylation leading to CREB activation, while ERK activation was not associated with MA- and AA-induced neurite outgrowth. In addition, Akt activation was evident to be more involved in neurite elongation process.

Neuron-Macrophage Co-cultures to Activate Macrophages Secreting Molecular Factors with Neurite Outgrowth Activity

There is strong evidence that macrophages can participate in the regeneration or repair of injured nervous system. Here, we describe a protocol in which macrophages are induced to produce conditioned medium (CM) that promotes neurite outgrowth. Adult dorsal root ganglion (DRG) neurons are acutely dissociated and plated. After the neurons are stably attached, peritoneal macrophages are co-cultured on a cell culture insert overlaid on the same well. Dibutyryl cyclic AMP (db-cAMP) is applied to the co-cultures for 24 h, after which the cell culture insert containing the macrophages is moved to another well to collect CM for 72 h. The CM from the co-cultures treated with db-cAMP, when applied to a separate adult DRG neuron culture, exhibits robust neurite outgrowth activity. The CM obtained from the db-cAMP-treated cultures consisting of single cell type alone, either DRG neuron or peritoneal macrophage, did not exhibit neurite outgrowth activity. This indicates that the interaction between neurons and macrophages is indispensable for the activation of macrophages secreting molecular factors with neurite outgrowth activity into CM. Thus, our co-culture paradigm will also be useful to study intercellular signaling in the neuron-macrophage interaction to stimulate the macrophages to be endowed with a pro-regenerative phenotype.

Neuron-Macrophage Co-cultures to Activate Macrophages Secreting Molecular Factors with Neurite Outgrowth Activity.

There is strong evidence that macrophages can participate in the regeneration or repair of injured nervous system. Here, we describe a protocol in which macrophages are induced to produce conditioned medium (CM) that promotes neurite outgrowth. Adult dorsal root ganglion (DRG) neurons are acutely dissociated and plated. After the neurons are stably attached, peritoneal macrophages are co-cultured on a cell culture insert overlaid on the same well. Dibutyryl cyclic AMP (db-cAMP) is applied to the co-cultures for 24 h, after which the cell culture insert containing the macrophages is moved to another well to collect CM for 72 h. The CM from the co-cultures treated with db-cAMP, when applied to a separate adult DRG neuron culture, exhibits robust neurite outgrowth activity. The CM obtained from the db-cAMP-treated cultures consisting of single cell type alone, either DRG neuron or peritoneal macrophage, did not exhibit neurite outgrowth activity. This indicates that the interaction between neurons and macrophages is indispensable for the activation of macrophages secreting molecular factors with neurite outgrowth activity into CM. Thus, our co-culture paradigm will also be useful to study intercellular signaling in the neuron-macrophage interaction to stimulate the macrophages to be endowed with a pro-regenerative phenotype.

Abstract B40: A novel activating I1171T ALK mutation in neuroblastoma responds better to ceritinib compare to the first generation inhibitor crizotinib

Abstract Mutations in the kinase domain of Anaplastic Lymphoma Kinase (ALK) have been suggested to be important players in the genetics and progression of the childhood tumor neuroblastoma. Here we report the appearance of a novel ALK mutation in neuroblastoma together with other chromosomal aberrations that mediate neuroblastoma initiation and progression. Analyses of genomic tumor DNA from biopsy samples initially showed an 11q minus, 17q gain with a mutation of the ALK gene at protein position 1171, which mediate an amino acid change from isoleucine to threonine. We show that mutation of I1171 to threonine generates a potent gain-of-function mutant, as observed in two independent systems. Firstly, in PC12 cell lines expressing ALKI1171T display ligand independent activation of ALK, neurite outgrowth and further downstream signaling activation. Secondly, ALKI1171T meditate foci formation in a NIH3T3 transformation analysis. Finally, pharmacological inhibition of ALKI1171T employing ceritinib, an FDA approved ALK inhibitor show 14-fold better ability to abrogate ALKI1171T compared with crizotinib. Citation Format: Joachim T. Siaw, Jikui Guan, Tommy Martinsson, Magnus Hansson, Per Kogner, Ruth Palmer. A novel activating I1171T ALK mutation in neuroblastoma responds better to ceritinib compare to the first generation inhibitor crizotinib [abstract]. In: Proceedings of the AACR International Conference: New Frontiers in Cancer Research; 2017 Jan 18-22; Cape Town, South Africa. Philadelphia (PA): AACR; Cancer Res 2017;77(22 Suppl):Abstract nr B40.

Effects of a defined xeno-free medium on the growth and neurotrophic and angiogenic properties of human adult stem cells

BackgroundThe growth properties and neurotrophic and angiogenic effects of human mesenchymal stromal cells (MSCs) cultured in a defined xeno-free, serum-free medium (MesenCult-XF) were investigated. MethodsHuman MSCs from adipose tissue (ASCs) and bone marrow (BMSCs) were cultured in Minimum Essential Medium-alpha (α-MEM) containing fetal calf serum or in MesenCult-XF. Proliferation was measured over 10 passages and the colony-forming unit (CFU) assay and expression of cluster of differentiation (CD) surface markers were determined. Neurite outgrowth and angiogenic activity of the MSCs were determined. ResultsAt early passage, both ASCs and BMSCs showed better proliferation in MesenCult-XF compared with standard α-MEM–containing serum. However, CFUs were significantly lower in MesenCult-XF. ASCs cultured in MesenCult-XF continued to expand at faster rates than cells grown in serum. BMSCs showed morphological changes at late passage in MesenCult-XF and stained positive for senescence β-galactosidase activity. Expression levels of CD73 and CD90 were similar in both cell types under the various culture conditions but CD105 was significantly reduced at passage 10 in MesenCult-XF. In vitro stimulation of the cells enhanced the expression of brain-derived neurotrophic factor (BDNF), vascular endothelial growth factor (VEGF-A) and angiopoietin-1. Stimulated ASCs grown in MesenCult-XF evoked the longest neurite outgrowth in a neuron co-culture model. Stimulated BMSCs grown in MesenCult-XF produced the most extensive network of capillary-like tube structures in an in vitro angiogenesis assay. ConclusionsASCs and BMSCs exhibit high levels of neurotrophic and angiogenic activity when grown in the defined serum-free medium indicating their suitability for treatment of various neurological conditions. However, long-term expansion in MesenCult-XF might be restricted to ASCs.

Di-n-butyl phthalate exposure negatively influences structural and functional neuroplasticity via Rho-GTPase signaling pathways

Di-n-butyl phthalate (DBP) has been reported to cause disruptions in hippocampal plasticity, but its specific mechanism has not yet been ascertained. In this research, a mouse model of chronic DBP exposure was generated by intragastric administration of DBP (10, 50, or 250°mg/kg/d) for 5 weeks. Chronic exposure to high concentrations of DBP (250°mg/kg/d) induced a spatial learning deficit in the Morris water maze in male mice. By determining the activity of Rho-GTPase signaling pathways in the hippocampal tissues, we found that DBP exposure inhibited the activity of Rac1/PAK1/LIMK1 but activated RhoA/ROCK/LIMK2 signaling and eventually suppressed cofilin activity by phosphorylation. Consistent with this, the differential activation was also observed in the acute exposure model of neuronal cells generated by incubation with DBP (100°ng/ml, 1, 10, or 100°μg/ml) for 72 hours. Moreover, acute exposure to high concentrations of DBP (100°μg/ml) altered cell morphology by inhibiting neurite outgrowth. A ROCK inhibitor, but not inhibitors of Rac1 or PAK1, reversed the inhibition of DBP to the activity of cofilin and neurite outgrowth in cells. These findings provide the first evidence that DBP exposure results in impairment of neuroplasticity by differential regulation of Rho-GTPase signaling pathways.

Synthesis and Neurotrophic Activity Studies of Illicium Sesquiterpene Natural Product Analogues.

Neurotrophic natural products hold potential as privileged structures for the development of therapeutic agents against neurodegeneration. However, only a few studies have been conducted to investigate a common pharmacophoric motif and structure-activity relationships (SARs). Here, an investigation of structurally more simple analogues of neurotrophic sesquiterpenes of the illicium family is presented. A concise synthetic route enables preparation of the carbon framework of (±)-Merrilactone A and (±)-Anislactone A/B on a gram scale. This has allowed access to a series of structural analogues by modification of the core structure, including variation of oxidation levels and alteration of functional groups. In total, 15 derivatives of the natural products have been synthesized and tested for their neurite outgrowth activities. Our studies indicate that the promising biological activity can be retained by structurally simpler natural product analogues, which are accessible by a straightforward synthetic route.

Frontispiece: Competent Route to Unsymmetric Dimer Architectures: Total Syntheses of (−)‐Lycodine and (−)‐Complanadines A and B, and Evaluation of Their Neurite Outgrowth Activities

Frontispiece: Competent Route to Unsymmetric Dimer Architectures: Total Syntheses of (−)‐Lycodine and (−)‐Complanadines A and B, and Evaluation of Their Neurite Outgrowth Activities

Potent mechanism-based sirtuin-2-selective inhibition by an in situ-generated occupant of the substrate-binding site, "selectivity pocket" and NAD+-binding site.

Sirtuin 2 (SIRT2), a member of the NAD+-dependent histone deacetylase family, has recently received increasing attention due to its potential involvement in neurodegenerative diseases and the progression of cancer. Potent and selective SIRT2 inhibitors thus represent desirable biological probes. Based on the X-ray crystal structure of SIRT2 in complex with a previously reported weak inhibitor (6), we identified in this study the potent mechanism-based inactivator KPM-2 (36), which is selective toward SIRT2. Compound 36 engages in a nucleophilic attack toward NAD+ at the active site of SIRT2, which affords a stable 36-ADP-ribose conjugate that simultaneously occupies the substrate-binding site, the "selectivity pocket" and the NAD+-binding site. Moreover, 36 exhibits antiproliferative activity in cancer cells and remarkable neurite outgrowth activity. This strategy for the selective inhibition of SIRT2 should allow further probing of the biology of SIRT2, and promote the development of new disease treatment strategies.

Competent Route to Unsymmetric Dimer Architectures: Total Syntheses of (-)-Lycodine and (-)-Complanadines A and B, and Evaluation of Their Neurite Outgrowth Activities.

Valuable synthetic routes to the Lycopodium alkaloid lycodine (1) and its unsymmetric dimers, complanadines A (4) and B (5), have been developed. Regioselective construction of the bicyclo[3.3.1]nonane core structure of lycodine was achieved by a remote functionality-controlled Diels-Alder reaction and subsequent intramolecular Mizoroki-Heck reaction. A key coupling reaction of the lycodine units, pyridine N-oxide (66) and aryl bromide (65), through C-H arylation at the C1 position of 66 provided the unsymmetric dimer structure at a late stage of the synthesis. This strategy greatly simplified the construction of the dimeric architecture and functionalization. Complanadines A (4) and B (5) were synthesized by adjusting the oxidation level of the bipyridine mono-N-oxide (67). The diverse utility of this common intermediate (67) suggests a possible biosynthetic pathway of complanadines in Nature. Both enantiomers of lycodine (1) and complanadines A (4) and B (5) were prepared in sufficient quantities for biological evaluation. The effect on neuron differentiation of PC-12 cells upon treatment with culture medium, in which human astrocytoma cells had been cultured in the presence of 1, 4, or 5 was evaluated.

Pharmacological Activities and Applications of Spicatoside A.

Liriopogons (Liriope and Opiopogon) species are used as a main medicinal ingredient in several Asian countries. The Liriopes Radix (tuber, root of Liriope platyphylla) has to be a promising candidate due to their source of phytochemicals. Steroidal saponins and their glycosides, phenolic compounds, secondary metabolites are considered of active constituents in Liriopes Radix. Spicatoside A, a steroidal saponin, could be more efficacious drug candidate in future. In this review, we summarized the available knowledge on phytochemical and pharmacological activities for spicatoside A. It significantly suppressed the level of NF-κB, NO, iNOS, Cox-2, IL-1β, IL-6 and MAPKs in LPS-stimulated inflammation. The production of MUC5AC mucin was increased. MMP-13 expression was down-regulated in IL-1β-treated cells and reduced glycosaminoglycan release from IL-1α-treated cells. The neurite outgrowth activity, PI3K, Akt, ERK1/2, TrkA and CREB phosphorylation and neurotropic factors such as NGF and BDNF were upregulated with increased latency time. It also showed cell growth inhibitory activity on various carcinoma cells. From this, spicatoside A exerts anti-inflammation, anti-asthma, anti-osteoclastogenesis, neurite outgrowth, memory consolidation and anticancer activities. Further studies are needed on spicatoside A in order to understand mechanisms of action to treat various human diseases.

Negletein as a neuroprotectant enhances the action of nerve growth factor and induces neurite outgrowth in PC12 cells.

Negletein has been shown to have therapeutic potential for inflammation-associated diseases, but its effect on neurite outgrowth is still unknown. The present study showed that negletein alone did not trigger PC12 cells to differentiate and extend neurites. When compared with the cells in the untreated control, a significant (P<0.05) induction and a higher neurite outgrowth activity was observed when the cells were cotreated with negletein (10µM) and a low dose of nerve growth factor (NGF; 5ng/mL). The neurite outgrowth process was blocked by the tyrosine kinase receptor (Trk) inhibitor, K252a, suggesting that the neuritogenic effect was NGF-dependent. Negletein (10µM) together with NGF (5ng/mL) enhanced the phosphorylation of extracellular signal-regulated kinases (ERKs), protein kinase B (Akt), and cAMP response element-binding protein (CREB). The growth associated protein-43 (GAP-43) and the NGF level were also upregulated by negletein (10µM) and a low dose of NGF (5ng/mL). Negletein at nanomolar concentration also was found to be sufficient to mediate the survival of serum-deprived PC12 cells up to 72h. Taken together, negletein might be useful as an efficient bioactive compound to protect neurons from cell death and promote neuritogenesis. © 2016 BioFactors, 42(6):591-599, 2016.