Undifferentiated and differentiated PC12 cells protected by huprines against injury induced by hydrogen peroxide

New thiourea and benzamide derivatives of 2-aminothiazole as multi-target agents against Alzheimer's disease: Design, synthesis, and biological evaluation

In this study, two series of compounds were designed and synthesized, bearing thiourea and benzamide derivatives at position 2 of 4-subtituted-2-aminothiazole, respectively. Then, the inhibition potency of all final compounds for cholinesterase enzymes were evaluated. Among the thiourea derivatives, 3c (IC50 = 0.33 μM) was identified as the most potent and selective butyrylcholinesterase inhibitor. Additionally, benzamide derivative 10e (AChE IC50 = 1.47 and BChE IC50 = 11.40 μM) was found as a dual cholinesterase inhibitor. The type of inhibition for both compounds was determined by kinetic studies and the results showed that the compounds were mixed type inhibitors. Moreover, all title compounds were investigated in terms of their antioxidant (DPHH, ORAC) and metal chelator activities. In addition, the neuroprotective effects of selected compounds (3c, 3e, 6c, 6e and 10e) against H₂O₂-induced damage in the PC12 cell line were tested. The experimental findings demonstrated that thiourea-derived 6e (40.4 %) and benzamide-derived 10e (37.8 %) have a neuroprotective effect of about half as ferulic acid at 10 μM. Subsequently, the cytotoxicity of selected compounds was examined by the MTT assay, and the compounds were found not to have cytotoxic effect on the PC12 cell line in 24 h. Additionally, compounds 6e and 10e were also found to be more effective in inhibiting the release of IL-1β, IL-6, TNF-α and NO compared to other selected compounds in this study.

Neuroprotective Potential of Ellagic Acid: A Critical Review

Ellagic acid (EA) is a dietary polyphenol present in various fruits, vegetables, herbs, and nuts. It exists either independently or as part of complex structures, such as ellagitannins, which release EA and several other metabolites including urolithins following absorption. During the past few decades, EA has drawn considerable attention because of its vast range of biological activities as well as its numerous molecular targets. Several studies have reported that the oxidative stress-lowering potential of EA accounts for its broad-spectrum pharmacological attributes. At the biochemical level, several mechanisms have also been associated with its therapeutic action, including its efficacy in normalizing lipid metabolism and lipidemic profile, regulating proinflammatory mediators, such as IL-6, IL-1β, and TNF-α, upregulating nuclear factor erythroid 2-related factor 2 and inhibiting NF-κB action. EA exerts appreciable neuroprotective activity by its free radical-scavenging action, iron chelation, initiation of several cell signaling pathways, and alleviation of mitochondrial dysfunction. Numerous in vivo studies have also explored the neuroprotective attribute of EA against various neurotoxins in animal models. Despite the increasing number of publications with experimental evidence, a critical analysis of available literature to understand the full neuroprotective potential of EA has not been performed. The present review provides up-to-date, comprehensive, and critical information regarding the natural sources of EA, its bioavailability, metabolism, neuroprotective activities, and underlying mechanisms of action in order to encourage further studies to define the clinical usefulness of EA for the management of neurological disorders.

Human adipose derived stem cell exosomes enhance the neural differentiation of PC12 cells

Human adipose stem cells (hADSCs) are proper cell sources for tissue regeneration. They mainly mediate their therapeutic effects through paracrine factors as exosomes. The exosomes contents are protein, lipid and RNA. Exosomes are effective in restoring the function of neurons and astrocytes in neurodegenerative diseases, and improve the therapeutic outcomes. We investigated the effect of hADSCs derived exosomes on survival and neural differentiation of PC12 cells in vitro. The isolated hADSCs, were characterized by flow cytometry. Exosomes were separated from hADSC-condition medium using Exo-spinTM kit and characterized by DLS and TEM. Then acridine orange staining was performed to confirm entrance of exosomes into PC12 cells. PC12 cells were treated with culture medium containing NGF and exosome. Cell viability was assessed by MTT assay, and neural differentiation by ICC technique and qRT-PCR. TEM and DLS data confirmed the isolation of exosomes according to their size (30-100 nm) and acridine orange staining indicated entrance of exosomes to target cells. MTT assay showed that cell viability was significantly increased in exosome treated group. ICC technique revealed that the expression of Map2 was superior in the exosome treated group. Based on qRT-PCR data, Map2 and β-tub III gene expression was increased in the exosome treated group. Significant expression of Gfap was seen in the NGF and NGF/EXO treated groups. Present study indicated that hADSCs derived exosomes might enhance cell viability and promote neuronal differentiation and expression of mature neural marker in PC12 cells.

Effects of Ginsenoside Rg3 on Inhibiting Differentiation, Adipogenesis, and ER Stress-Mediated Cell Death in Brown Adipocytes

Objectives

Ginsenoside Rg3 (Rg3), a main active component of Panax ginseng, has various therapeutic properties in literatures, and it has been studied for its potential use in obesity control due to its antiadipogenic effects in white adipocytes. However, little is known about its effects on brown adipocytes.

Methods

The mechanisms through which Rg3 inhibits differentiation, adipogenesis, and ER stress-mediated cell death in mouse primary brown adipocytes (MPBAs) are explored.

Results

Rg3 significantly induced cytotoxicity in differentiated MPBAs but not in undifferentiated MPBAs. Rg3 treatment downregulated the expression of differentiation and adipogenesis markers and the level of perilipin in MPBAs while upregulating the expression of lipolytic Kruppel-like factor genes. Rg3 also induced lipolysis and efflux of triglycerides from MPBAs and subsequently increased proinflammatory cytokine levels. Notably, Rg3 treatment resulted in elevation of ER stress and proapoptotic markers in MPBAs.

Conclusions

Our results demonstrate that Rg3 is able to selectively exert cytotoxicity in differentiated MPBAs while leaving undifferentiated MPBAs intact, resulting in the induction of ER stress and subsequent cell death in MPBAs via regulation of various genes related to adipocyte differentiation, adipogenesis, lipolysis, and inflammation. These results indicate that further studies on the potential therapeutic applications of Rg3 are warranted.

Ajmalicine and Reserpine: Indole Alkaloids as Multi-Target Directed Ligands Towards Factors Implicated in Alzheimer's Disease

Alzheimer’s disease (AD) is a multifactorial disorder characterized by exponential loss of memory and cognitive deficit involving several disease modifying targets (amyloid beta, beta-secretase, monoaminoxidase-B, and cholinesterase). The present study explores multi-target directed ligand approach using secondary metabolite reserpine (RES) and ajmalicine (AJM) obtained from Rauwolfia serpentina roots. Novel LCMS and HPLC methods were developed for identification and quantification of reserpine and ajmalicine. In vitro enzyme inhibition assays were performed to evaluate anti-cholinesterase, β-site amyloid cleaving enzyme (BACE-1) inhibition and monoamine oxidase-B (MAO-B) inhibition, further analyzed with in silico analysis. Anti-amyloidogenic potential was studied using anti-aggregation studies along with TEM and circular dichroism (CD) analysis. In vitro neuroprotective potential against Aβ toxicity and anti-oxidative stress was demonstrated using PC12 cell cultures. Reserpine is a more potent dual cholinesterase inhibitor than ajmalicine (IC₅₀ values of 1.7 μM (AChE) and 2.8 μM (BuChE)). The anti-aggregation activity of reserpine (68%) was more than ajmalicine (56%). Both compounds demonstrated neuroprotective activity against Aβ42 (92%) and H₂O₂ (93%) induced toxicity in PC12 cells against controls. Phytocompounds also inhibited MAO-B and BACE-1 enzymes in concentration dependent manner. Molecular docking studies indicated the strong binding of compounds to the catalytic site of targets. This novel study demonstrated that reserpine and ajmalicine as a multi-target directed ligand that have disease modifying potential for amelioration of AD.

Anti-Neuroinflammatory Property of Phlorotannins from Ecklonia cava on Aβ25-35-Induced Damage in PC12 Cells

Alzheimer disease (AD) is a neurodegenerative disorder characterized by excessive accumulation of amyloid-beta peptide (Aβ) and progressive loss of neurons. Therefore, the inhibition of Aβ-induced neurotoxicity is a potential therapeutic approach for the treatment of AD. Ecklonia cava is an edible brown seaweed, which has been recognized as a rich source of bioactive derivatives, mainly phlorotannins. In this study, phlorotannins including eckol, dieckol, 8,8'-bieckol were used as potential neuroprotective candidates for their anti-apoptotic and anti-inflammatory effects against Aβ25-35-induced damage in PC12 cells. Among the tested compounds, dieckol showed the highest effect in both suppressing intracellular oxidative stress and mitochondrial dysfunction and activation of caspase family. Three phlorotannins were found to inhibit TNF-α, IL-1β and PGE₂ production at the protein levels. These result showed that the anti-inflammatory properties of our compounds are related to the down-regulation of proinflammatory enzymes, iNOS and COX-2, through the negative regulation of the NF-κB pathway in Aβ25-35-stimulated PC12 cells. Especially, dieckol showed the strong anti-inflammatory effects via suppression of p38, ERK and JNK. However, 8,8'-bieckol markedly decreased the phosphorylation of p38 and JNK and eckol suppressed the activation of p38. Therefore, the results of this study indicated that dieckol from E. cava might be applied as a drug candidate for the development of new generation therapeutic agents against AD.

Behavioural effects of novel multitarget anticholinesterasic derivatives in Alzheimer's disease

The current pharmacological approach to Alzheimer's disease (AD) treatment, mostly based on acetylcholinesterase inhibitors (AChEIs), is being revisited, especially in terms of the temporal frames and the potential benefits of their noncanonic actions, raising the question of whether inhibitors of AChE might also act in a disease-modifying manner. Besides, in the last decades, the pharmacophoric moieties of known AChEIs have been covalently linked to other pharmacophores in the pursuit of multitarget hybrid molecules that are expected to induce long-lasting amelioration of impaired neurotransmission and clinical symptoms but also to exert disease-modifying effects. Our research consortium has synthesized and defined the pharmacological profile of new AChEIs derivatives of potential interest for the treatment of AD. Among these, huprines and derivatives have been characterized successfully. Huprine X, a reversible AChE inhibitor, designed by molecular hybridization of tacrine and huperzine A, has been shown to affect the amyloidogenic process in vitro, and the AD-related neuropathology in vivo in mice models of the disease. More recently, we have shown that a group of donepezil-huprine heterodimers exerts a highly potent and selective inhibitory action on AChE both in vitro and ex vivo, simultaneously interacting with both peripheral and catalytic binding sites, and inhibiting the β-amyloid aggregation, whereas some levetiracetam-huprine hybrids have been shown to reduce epileptiform activity, neuroinflammation and amyloid burden in an animal model of AD. Here, we summarize the behavioural correlates of these noncanonic actions as assessed in three distinct biological scenarios: middle-age, cognitive deficits associated with ageing and AD-like phenotype in mice. Besides the improvement in the hallmark cognitive symptomatology without inducing side effects, these drugs have shown to be able to modulate emotional and anxiety-like behaviours or to reduce spontaneous seizures, all of them related to the so-called 'behavioural and psychological symptoms of dementia'. Overall, the studies show that these novel multitarget anticholinesterasics exert noncanonic actions providing symptomatic and disease-modifying benefits of potential interest for the management of AD.

Huprine X Attenuates The Neurotoxicity Induced by Kainic Acid, Especially Brain Inflammation

Huprine X (HX) is a synthetic anticholinesterasic compound that exerts a potent inhibitory action on acetylcholinesterase (AChE) activity, an agonist effect on cholinergic receptors, neuroprotective activity in different neurotoxicity models in vivo and in vitro and cognition enhancing effects in non-transgenic (C57BL/6) and transgenic (3xTg-AD, APPswe) mice. In this study, we assessed the ability of HX (0.8 mg/kg, 21 days) to prevent the damage induced by kainic acid (KA; 28 mg/kg) regarding apoptosis, glia reactivity and neurogenesis in mouse brain. KA administration significantly modified the levels of pAkt1, Bcl2, pGSK3β, p25/p35, increased the glial cell markers and reduced the neurogenesis process. We also observed that pre-treatment with HX significantly reduced the p25/p35 ratio and increased synaptophysin levels, which suggests a protective effect against apoptosis and an improvement of neuroplasticity. The increase in GFAP (88%) and Iba-1 (72%) induced by KA was totally prevented by HX pre-treatment, underlying a relevant anti-inflammatory action of the anticholinesterasic drug. Our findings highlight the potential of HX, in particular, and of AChEIs, in general, to treat a number of diseases that course with both cognitive deficits and chronic inflammatory processes.

Neuroprotective activity of two active chemical constituents from Tinospora hainanensis

OBJECTIVE

To determine the chemical structure of the new compound and investigate the protective effects of Tinosporaic acid A and B towards in-vitro neuro.

METHODS

The structures of two new compounds were established by analyzing its 1D and 2D NMR spectra as well as HRESIMS. Their neuroprotective effects with respect to the antioxidant properties were evaluated by radical scavenging tests and hydrogen peroxide-injured oxidative stress model in PC12 cell lines. Cell morphology of treated PC12 cells was observed by phase contrast microscopy. In-vitro MTT assay, lactate dehydrogenase activity assay and oxidative stress markers (intracellular ROS production, MDA level, and caspase-3 activity) were used to evaluate the protective effects against hydrogen peroxide induced cytotoxicity in PC12 cells.

RESULTS

The two new compounds, named Tinosporaic acid A and B, were isolated and identified from the stem bark of Tinospora hainanensis. Cell viability studies identified a representative concentration for each extract that was subsequently used to measure oxidative stress markers. Both extracts were able to reverse the oxidative damage caused by hydrogen peroxide, thus promoting PC12 cells survival. The concentration of Tinosporaic acid A and B were 86.34 μg/mL and 22.06 μg/mL respectively, which is neuroprotective for EC50. The results indicated that both of them significantly attenuated hydrogen peroxide-induced neurotoxicity.

CONCLUSION

The two new compounds isolated from ethanol extracts of Tinospora hainanensis are the promising natural ones with neuroprotective activity and needed for further research.

Chemosensitivity of U251 Cells to the Co-treatment of D-Penicillamine and Copper: Possible Implications on Wilson Disease Patients

D-Penicillamine (PA), a copper chelator, and one of the recommended drugs for treatment of Wilson disease (WD) has been reported to worsen the symptoms of patients with neurologic presentations. However, the cause of this paradoxical response has not been fully elucidated and requires further investigations. Accordingly, we have studied the in vitro effect of Copper (Cu) and/or PA treatment on human glioblastoma U251 cells as an in vitro model of Cu cytotoxicity. Treatment of U251 cells with either Cu or PA exerted no significant effect on their morphology, viability or ROS level. In contrast, co-treatment with Cu-PA caused a decrease in viability, altered glutathione and ceruloplasmin expression coupled with marked increase in ROS; depolarization of mitochondrial membrane potential; and an increase in Sub G0 phase; along with alpha-Fodrin proteolysis. These findings along with the absence of LDH release in these assays, suggest that combined Cu-PA exposure induced apoptosis in U251 cells. In addition, pre-/or co-treatment with antioxidants showed a protective effect, with catalase being more effective than N-acetyl cysteine or trolox in restoring viability and reducing generated ROS levels. By comparison, a similar analysis using other cell lines showed that rat PC12 cells were resistant to Cu and/or PA treatment, while the neuroblastoma cell line SH-SY5Y was sensitive to either compound alone, resulting in decreased viability and increased ROS level. Taken together, this study shows that glioblastoma U251 cells provide a model for Cu-PA cytotoxicity mediated by H₂O₂. We postulate that PA oxidation in presence of Cu yields H₂O₂ which in turn permeates the plasma membrane and induced apoptosis. However, other cell lines exhibited different responses to these treatments, potentially providing a model for cell type- specific cytotoxic responses in the nervous system. The sensitivity of different neural and glial cell types to Cu-PA treatment may therefore underlie the neurologic worsening occurring in some PA-treated WD patients. Our results also raise the possibility that the side effects of PA treatment might be reduced or prevented by administering antioxidants.

The Effects of Ellagic Acid upon Brain Cells: A Mechanistic View and Future Directions

Ellagic acid (EA, 2,3,7,8-tetrahydroxy-chromeno; C14H6O8) is a polyphenol derived from fruits (pomegranates, berries) and nuts. EA exhibits antioxidant capacity and induces anti-inflammatory actions in several mammalian tissues. EA has been characterized as a possible neuroprotective agent, but the number of reports is still limited to conclude whether and how EA exerts neuroprotection in humans. In this regard, performing additional studies considering the potential beneficial and/or toxicological roles for EA on brain cells would be an important step towards fully understanding of when and how EA may be securely utilized by humans as a neuroprotective agent. The aim of the present work is to discuss data related to the neuronal and glial effects of EA and the mechanisms underlying such events. Moreover, future directions are suggested as a potential guide to be utilized by researchers interested in investigating the neuronal and glial actions of EA hereafter.

In vitro studies of primary explosive blast loading on neurons

In a military setting, traumatic brain injury (TBI) is frequently caused by blast waves that can trigger a series of neuronal biochemical changes. Although many animal models have been used to study the effects of primary blast waves, elucidating the mechanisms of damage in a whole-animal model is extremely complex. In vitro models of primary blast, which allow for the deconvolution of mechanisms, are relatively scarce. It is largely unknown how structural damage at the cellular level impacts the functional activity at variable time scales after the TBI event. A novel in vitro system was developed to probe the effects of explosive blast (ranging from ∼25 to 40 psi) on dissociated neurons. PC12 neurons were cultured on laminin-coated substrates, submerged underwater, and subjected to single and multiple blasts in a controlled environment. Changes in cell membrane permeability, viability, and cell morphology were evaluated. Significant increases in axonal beading were observed in the injured cells. In addition, although cell death was minimal after a single insult, cell viability decreased significantly following repeated blast exposure.

Prediction of multi-target networks of neuroprotective compounds with entropy indices and synthesis, assay, and theoretical study of new asymmetric 1,2-rasagiline carbamates

In a multi-target complex network, the links (L_ij) represent the interactions between the drug (d_i) and the target (t_j), characterized by different experimental measures (K_i, K_m, IC₅₀, etc.) obtained in pharmacological assays under diverse boundary conditions (c_j). In this work, we handle Shannon entropy measures for developing a model encompassing a multi-target network of neuroprotective/neurotoxic compounds reported in the CHEMBL database. The model predicts correctly >8300 experimental outcomes with Accuracy, Specificity, and Sensitivity above 80%–90% on training and external validation series. Indeed, the model can calculate different outcomes for >30 experimental measures in >400 different experimental protocolsin relation with >150 molecular and cellular targets on 11 different organisms (including human). Hereafter, we reported by the first time the synthesis, characterization, and experimental assays of a new series of chiral 1,2-rasagiline carbamate derivatives not reported in previous works. The experimental tests included: (1) assay in absence of neurotoxic agents; (2) in the presence of glutamate; and (3) in the presence of H₂O₂. Lastly, we used the new Assessing Links with Moving Averages (ALMA)-entropy model to predict possible outcomes for the new compounds in a high number of pharmacological tests not carried out experimentally.