Implications of critical node-dependent unidirectional cross-talk of Plasmodium SUMO pathway proteins.

The endoparasitic pathogen, Plasmodium falciparum (Pf), modulates protein-protein interactions to employ post-translational modifications like SUMOylation to establish successful infections. The interaction between E1 and E2 (Ubc9) enzymes governs species specificity in the Plasmodium SUMOylation pathway. Here, we demonstrate that a unidirectional cross-species interaction exists between Pf-SUMO and human E2, whereas Hs-SUMO1 failed to interact with Pf-E2. Biochemical and biophysical analyses revealed that surface-accessible aspartates of Pf-SUMO determine the efficacy and specificity of SUMO-Ubc9 interactions. Furthermore, we demonstrate that critical residues of the Pf-Ubc9 N terminus are responsible for diminished Hs-SUMO1 and Pf-Ubc9 interaction. Mutating these residues to corresponding Hs-Ubc9 residues restores electrostatic, π-π, and hydrophobic interactions and allows efficient cross-species interactions. We suggest that, in comparison with human counterparts, Plasmodium SUMO and Ubc9 proteins have acquired critical changes on their surfaces as nodes, which Plasmodium can use to exploit the host SUMOylation machinery.

Decreased Expression of Cerebral Dopamine Neurotrophic Factor in Platelets of Probable Alzheimer Patients.

BACKGROUND: Alzheimer disease (AD) patients experience progressive neurological and cognitive decline attributed to neurodegeneration. Cerebral dopamine neurotrophic factor (CDNF) has been identified to protect and rescue neurons in various preclinical neurodegeneration models. The expression of this protein occurs in both the central nervous system and peripheral blood. Blood platelets exhibit several biochemical impairments similar to the brain tissues of patients with neurological disorders. This study examines CDNF mRNA expression in human blood platelets in healthy subjects and Alzheimer-probable patients. METHODS: Platelets were extracted from whole blood from patients. mRNA was extracted to synthesize cDNA and quantify CDNF gene expression from 21 Alzheimer-probable patients and 73 healthy age-matched control subjects using real-time qPCR. Grouping analysis of the data with regard to sex was conducted. RESULTS: CDNF mRNA expression was significantly decreased in Alzheimer-probable patients relative to the control subjects (P<0.05). Further analysis demonstrated reduced CDNF expression in male Alzheimer-probable patients compared with their age and sex-matched controls (P<0.05). However, no change in female subjects was observed. Interestingly, there is a lower level of CDNF expression in the female control group relative to the control male group (P<0.05). CONCLUSION: Alzheimer-probable male patients demonstrated significant reductions in CDNF expression, suggesting that CDNF plays a significant role in the pathogenesis of AD. In addition, it may assist in diagnosing male Alzheimer patients.

Novel mechanism of action for the mood stabilizer lithium.

BACKGROUND: Bipolar Disorder (BD) is associated with a decrease in cellular resilience. Despite the half a century old discovery of lithium's efficacy for the treatment of BD, its exact mechanisms remain elusive. Accumulating data suggest that lithium's cytoprotective properties involve the modulation of several UPR proteins, such as GRP78. Mesencephalic astrocyte-derived neurotrophic factor (MANF) is an endoplasmic reticulum resident protein that regulates proteostasis through directly interacting with GRP78. The purpose of this study was to determine whether lithium increases MANF expression using cellular and rodent models and, if so, to elucidate the cellular mechanisms of action. PROCEDURE: Mouse striatal neuroblasts were treated with PBS, lithium, or lithium + Activator Protein-1 (AP-1) inhibitor for 24-72 hours. Once cells were harvested, mRNA was extracted. In vivo experiments included, intraperitoneal injections of lithium or saline to male Sprague Dawley rats twice daily for 14 consecutive days. Following drug treatment, brain tissue was isolated, and mRNA was extracted from various regions. MANF gene expression was measured using RT-qPCR. RESULTS: In vitro studies showed lithium-treated cells displayed a significant increase in MANF mRNA expression compared to controls. In contrast, cells treated with lithium and AP-1 inhibitor showed no increase in expression. Similarly, in vivo studies revealed that lithium-treated rats compared to controls had a significant increase in MANF expression in the PFC and striatum. CONCLUSION: Taken together, these data suggest that lithium's therapeutic mechanism involves the maintenance of ER homeostasis via increased MANF gene expression mediated by the AP-1 transcription factor.

Decreased Expression of Cerebral Dopamine Neurotrophic Factor in Platelets of Stroke Patients.

BACKGROUND: Cerebral dopamine neurotrophic factor plays a critical role in repairing and maintaining healthy neurons in pathological conditions such as stroke. However, the association between cerebral dopamine neurotrophic factor expression and stroke has only recently been investigated in preclinical models and is rarely described in human studies. OBJECTIVES: The aims of this were to examine neurological alterations mirrored in human blood platelet cerebral dopamine neurotrophic factor gene expression. Cerebral dopamine neurotrophic factor is expressed in both the central nervous system and peripheral blood. Blood platelets are often used to model neuronal behavior because they exhibit biochemical impairments similar to brain tissues of patients with neurological disorders. METHODS: RNA was isolated from platelets and cDNA was synthesized to quantify cerebral dopamine neurotrophic factor gene expression of 36 stroke patients compared to 72 healthy aged-matched controls through real-time PCR. Further grouping analyses of data with regard to age, sex, and medication history were performed. RESULTS: Cerebral dopamine neurotrophic factor gene expression was significantly reduced in stroke patients relative to control subjects (P = .013). Subsequent analysis revealed a significant difference in expression between males and females within the control group (P = .026). Decreased cerebral dopamine neurotrophic factor expression was only observed in male stroke patients compared to their sex-matched controls (P = .008). Grouping stroke patients based on their medication history did not significantly alter cerebral dopamine neurotrophic factor gene expression. CONCLUSIONS: Further studies investigating cerebral dopamine neurotrophic factor expression could be directed towards the interplay of the central nervous system, hematopoietic derivatives, and utilizing cerebral dopamine neurotrophic factor as a therapeutic tool.

Reduced expression of synapsin II in a chronic phencyclidine preclinical rat model of schizophrenia.

Schizophrenia is a mental disorder characterized by positive symptoms, negative symptoms, and cognitive dysfunction. Phencyclidine (PCP)-a N-methyl-D-aspartate (NMDA) receptor antagonist-induces symptoms indistinguishable from those of schizophrenia. A reduction of the phosphoprotein synapsin II has also been implicated in schizophrenia and has a well-known role in the maintenance of the presynaptic reserve pool and vesicle mobilization. This study assessed the behavioral and biochemical outcomes of chronic NMDA receptor antagonism in rodents and its implications for the pathophysiology of schizophrenia. Sprague Dawley rats received saline or chronic PCP (5 mg/kg/day) for 14 days via surgically implanted Alzet® osmotic mini-pumps. Following the treatment period, rats were tested with a series of behavioral paradigms, including locomotor activity, social interaction, and sensorimotor gating. Following behavioral assessment, the medial prefrontal cortex (mPFC) of all rats was isolated for synapsin II protein analysis. Chronic PCP treatment yielded a hyper-locomotive state (p = 0.0256), reduced social interaction (p = 0.0005), and reduced pre-pulse inhibition (p < 0.0001) in comparison to saline-treated controls. Synapsin IIa (p < 0.0001) and IIb (p < 0.0071) levels in the mPFC of chronically treated PCP rats were reduced in comparison to the saline group. Study results confirm that rats subject to chronic PCP treatment display behavioral phenotypes similar to established preclinical animal models of schizophrenia. Reduction of synapsin II expression in this context implicates the role of this protein in the pathophysiology of schizophrenia and sheds light on the longer-term consequences of NMDA receptor antagonism facilitated by chronic PCP treatment.

Cell Permeating Nano-Complexes of Amphiphilic Polyelectrolytes Enhance Solubility, Stability, and Anti-Cancer Efficacy of Curcumin.

Many hydrophobic drugs encounter severe bioavailability issues owing to their low aqueous solubility and limited cellular uptake. We have designed a series of amphiphilic polyaspartamide polyelectrolytes (PEs) that solubilize such hydrophobic drugs in aqueous medium and enhance their cellular uptake. These PEs were synthesized through controlled (∼20 mol %) derivatization of polysuccinimide (PSI) precursor polymer with hydrophobic amines (of varying alkyl chain lengths, viz. hexyl, octyl, dodecyl, and oleyl), while the remaining succinimide residues of PSI were opened using a protonable and hydrophilic amine, 2-(2-amino-ethyl amino) ethanol (AE). Curcumin (Cur) was employed as a representative hydrophobic drug to explore the drug-delivery potential of the resulting PEs. Unprecedented enhancement in the aqueous solubility of Cur was achieved by employing these PEs through a rather simple protocol. In the case of PEs containing oleyl/dodecyl residues, up to >65000× increment in the solubility of Cur in aqueous medium could be achieved without requiring any organic solvent at all. The resulting suspensions were physically and chemically stable for at least 2 weeks. Stable nanosized polyelectrolyte complexes (PECs) with average hydrodynamic diameters (DH) of 150-170 nm (without Cur) and 220-270 nm (after Cur loading) were obtained by using submolar sodium polyaspartate (SPA) counter polyelectrolyte. The zeta potential of these PECs ranged from +36 to +43 mV. The PEC-formation significantly improved the cytocompatibility of the PEs while affording reconstitutable nanoformulations having up to 40 wt % drug-loading. The Cur-loaded PECs were readily internalized by mammalian cells (HEK-293T, MDA-MB-231, and U2OS), majorly through clathrin-mediated endocytosis (CME). Cellular uptake of Cur was directly correlated with the length of the alkyl chain present in the PECs. Further, the PECs significantly improved nuclear transport of Cur in cancer cells, resulting in their death by apoptosis. Noncancerous cells were completely unaffected under this treatment.

Brain Targeting of a Water Insoluble Antipsychotic Drug Haloperidol via the Intranasal Route Using PAMAM Dendrimer.

Delivery of therapeutics to the brain is challenging because many organic molecules have inadequate aqueous solubility and limited bioavailability. We investigated the efficiency of a dendrimer-based formulation of a poorly aqueous soluble drug, haloperidol, in targeting the brain via intranasal and intraperitoneal administration. Aqueous solubility of haloperidol was increased by more than 100-fold in the developed formulation. Formulation was assessed via different routes of administration for behavioral (cataleptic and locomotor) responses, and for haloperidol distribution in plasma and brain tissues. Dendrimer-based formulation showed significantly higher distribution of haloperidol in the brain and plasma compared to a control formulation of haloperidol administered via intraperitoneal injection. Additionally, 6.7 times lower doses of the dendrimer-haloperidol formulation administered via the intranasal route produced behavioral responses that were comparable to those induced by haloperidol formulations administered via intraperitoneal injection. This study demonstrates the potential of dendrimer in improving the delivery of water insoluble drugs to brain.

In situ-gelling hydrophobized starch nanoparticle-based nanoparticle network hydrogels for the effective delivery of intranasal olanzapine to treat brain disorders.

Intranasal (IN) delivery offers potential to deliver antipsychotic drugs with improved efficacy to the brain. However, the solubilization of such drugs and the frequency of required re-application both represent challenges to its practical implementation in treating various mental illnesses including schizophrenia. Herein, we report a sprayable nanoparticle network hydrogel (NNH) consisting of hydrophobically-modified starch nanoparticles (SNPs) and mucoadhesive chitosan oligosaccharide lactate (COL) that can gel in situ within the nasal cavity and release ultra-small penetrative SNPs over time. Hydrophobization of the SNPs enables enhanced uptake and prolonged release of poorly water soluble drugs such as olanzapine from the NNH depot through mucous and ultimately into the brain via the nose-to-brain (N2B) pathway. The hydrogel shows high in vitro cytocompatibility in mouse striatal neuron and human primary nasal cell lines and in vivo efficacy in an amphetamine-induced pre-clinical rat schizophrenia model, with IN-delivered NNH hydrogels maintaining successful attenuation of locomotor activity for up to 4 h while all other tested treatments (drug-only IN or conventional intraperitoneal delivery) failed to attenuate at any time point past 0.5 h. As such, in situ-gelling NNHs represent a safe excipient for the IN delivery of hydrophobic drugs directly to the brain using customized SNPs that exhibit high penetration and drug complexing properties to maximize effective drug delivery.

Development of peptidomimetic ligands of Pro-Leu-Gly-NH(2) as allosteric modulators of the dopamine D(2) receptor.

A variety of stable, small-molecule peptidomimetic ligands have been developed to elucidate the mechanism by which the neuropeptide Pro-Leu-Gly-NH(2) (PLG) modulates dopaminergic neurotransmission. Photoaffinity labeling ligands based upon PLG peptidomimetics have been used to establish that PLG binds to the D(2) dopamine receptor at a site that is different from the orthosteric site, thus making PLG and its peptidomimetics allosteric modulators of the dopamine receptor. Through the design, synthesis and pharmacological evaluation of conformationally constrained peptidomimetics containing lactam, bicyclic, and spiro-bicyclic scaffolds, support was provided for the hypothesis that the bioactive conformation of PLG is a type II ß-turn. In addition, studies with peptidomimetics designed to mimic either a type VI ß-turn or polyproline II helix conformation yielded molecules that were able to modulate dopamine receptors because of their ability to place the carboxamide NH(2) pharmacophore in the same topological space as that seen in the type II ß-turn. Extensive studies with the spiro-bicyclic PLG peptidomimetics also established that both positive and negative modes of modulation were possible for the same series of peptidomimetics simply as a result of minor differences in the stereochemistry about the bridgehead carbon within the scaffold. This information was used to transform existing positive modulators into negative modulators, which demonstrated that small structural changes in the spiro-bicyclic dopamine receptor modulators are capable of causing major changes in the modulatory activity of PLG peptidomimetics.

Ketamine-induced neurotoxicity is mediated through endoplasmic reticulum stress in vitro in STHdhQ7/Q7 cells.

Ketamine has traditionally been used as a dissociative anesthetic agent and more recently as a treatment for treatment-resistant depression. However, there is growing concern over the increased use of ketamine in recreational and therapeutic settings due to the potential neurotoxic effects. Recent studies have demonstrated that ketamine is cytotoxic in several cell types, such as fibroblasts, hepatocytes, uroepithelial cells, and adult induced pluripotent stem cells (iPSCs). Ketamine has been shown to dysregulate calcium signalling, increase reactive oxygen species (ROS) production, and impair mitochondrial function, ultimately leading to apoptosis. However, it is unclear whether endoplasmic reticulum (ER) stress plays a role in ketamine associated neurotoxicity in striatal neurons. Disruption to ER homeostasis can initiate ER-mediated cell death, which has been implicated in several neurodegenerative diseases. Thus, the purpose of this study was to determine whether ketamine's neurotoxic effects involve an ER stress-dependent pathway and to elucidate the underlying mechanisms involved in its neurotoxic effects. Mouse striatal cells were treated with various concentrations of ketamine (10 µM, 100 µM, 1 mM) or DMEM for 9-72 hrs. Cell viability was assessed using the MTT assay, and changes in gene expression of ER stress markers were evaluated using RT-qPCR. MTT results revealed that 1 mM ketamine decreased cell viability in striatal cells after 24 h of treatment. Gene expression studies complemented these findings such that ketamine upregulated pro-apoptotic ER stress markers, including X-box binding protein 1 (XBP1), activating transcription factor 4 (ATF4), and C/EBP homologous protein (CHOP) and downregulated pro-survival ER stress proteins such as GRP78, MANF and CDNF. Ketamine activated all three stress sensing pathways including PERK, IRE1, and ATF6. Taken together, our results show that ketamine-induced neurotoxicity is mediated through an ER stress-dependent apoptotic pathway.

Using the Intranasal Route to Administer Drugs to Treat Neurological and Psychiatric Illnesses: Rationale, Successes, and Future Needs.

While the intranasal administration of drugs to the brain has been gaining both research attention and regulatory success over the past several years, key fundamental and translational challenges remain to fully leveraging the promise of this drug delivery pathway for improving the treatment of various neurological and psychiatric illnesses. In response, this review highlights the current state of understanding of the nose-to-brain drug delivery pathway and how both biological and clinical barriers to drug transport using the pathway can been addressed, as illustrated by demonstrations of how currently approved intranasal sprays leverage these pathways to enable the design of successful therapies. Moving forward, aiming to better exploit the understanding of this fundamental pathway, we also outline the development of nanoparticle systems that show improvement in delivering approved drugs to the brain and how engineered nanoparticle formulations could aid in breakthroughs in terms of delivering emerging drugs and therapeutics while avoiding systemic adverse effects.

SARS-CoV-2 spike E156G/Δ157-158 mutations contribute to increased infectivity and immune escape.

Breakthrough infections by emerging SARS-CoV-2 variants raise significant concerns. Here, we sequence-characterized the spike gene from breakthrough infections that corresponded to B.1.617 sublineage. Delineating the functional impact of spike mutations revealed that N-terminal domain (NTD)-specific E156G/Δ157-158 contributed to increased infectivity and reduced sensitivity to vaccine-induced antibodies. A six-nucleotide deletion (467-472) in the spike-coding region introduced this change in the NTD. We confirmed the presence of E156G/Δ157-158 from cases concurrently screened, in addition to other circulating spike (S1) mutations such as T19R, T95I, L452R, E484Q, and D614G. Notably, E156G/Δ157-158 was present in more than 90% of the sequences reported from the USA and UK in October 2021. The spike-pseudotyped viruses bearing a combination of E156G/Δ157-158 and L452R exhibited higher infectivity and reduced sensitivity to neutralization. Notwithstanding, the post-recovery plasma robustly neutralized viral particles bearing the mutant spike. When the spike harbored E156G/Δ157-158 along with L452R and E484Q, increased cell-to-cell fusion was also observed, suggesting a combinatorial effect of these mutations. Our study underscores the importance of non-RBD changes in determining infectivity and immune escape.

Curcumin prevents haloperidol-induced development of abnormal oro-facial movements: possible implications of Bcl-XL in its mechanism of action.

Curcumin (Curcuma Longa Linn), the active component of turmeric, has been shown to be effective in ameliorating several stress and drug-induced disorders in rats and humans. However, it is unclear whether short term curcumin administration can prevent the abnormal oro-facial movements (AOFM) which develop following blockade of dopamine D2 receptors by antagonist such as Haloperidol. The objective of this study is to determine whether short term treatment with curcumin along with Haloperidol can prevent the development of AOFM in rats. Male Sprague Dawley rats were administered curcumin at 200 mg/kg, and Haloperidol at 2 mg/kg daily for 2 weeks, and AOFMs and locomotor activity were assessed at baseline, day 7 and day 14. By day 14, rats receiving concurrent curcumin administration had a significant reduction in the incidence of Haloperidol-induced AOFMs, but no change on the Haloperidol-induced hypolocomotion. There was no spiked increase in locomotor activity in absence of challenge with dopamine D2 receptor agonist. The exact mechanism by which curcumin attenuates AOFMs remains unknown, therefore, we performed a proteomic analysis of the striatal samples obtained from control and curcumin treated groups. A number of proteins were altered by curcumin, among them an antiapoptotic protein, Bcl-XL, was significantly upregulated. These results suggest that curcumin may be a promising treatment to prevent the development of AOFMs and further suggest some therapeutic value in the treatment of movement disorders.

Vesicular stomatitis virus inhibits mitotic progression and triggers cell death.

Vesicular stomatitis virus (VSV) infects and kills a wide range of cell types; however, the mechanisms involved in VSV-mediated cell death are not fully understood. Here we show that VSV infection interferes with mitotic progression, resulting in cell death. This effect requires the interaction of VSV matrix (M) protein with the Rae1-Nup98 complex in mitosis, which is associated with a subset of ribonucleoproteins (RNPs). VSV displaced Rae1 from spindle poles, caused spindle abnormalities and triggered substantial cell death during metaphase. These effects were attenuated in cells infected with VSV expressing a mutant M protein that does not bind efficiently to the Rae1-Nup98-RNP complex. In cells that progressed to late mitosis, M protein prevented proper nuclear formation and chromatin decondensation. VSV is an oncolytic (anti-tumour) agent as it preferentially replicates and kills tumour cells. As tumour cells have a high mitotic index, VSV-mediated mitotic cell death probably contributes to its oncolytic activity.

The Effect of PAOPA, a Novel Allosteric Modulator of Dopamine D2 Receptors, on Signaling Proteins Following Sub-Chronic Administration in Rats.

BACKGROUND: Allosteric modulators of G-protein coupled receptors regulate receptor activity by binding to sites other than the active site and have emerged as a new and highly desirable class of drugs. PAOPA (3(R)-[(2(S)-pyrrolidinylcarbonyl)amino]-2-oxo-1-pyrrolidineacetamide), a peptidomimetic analog of L-prolyl-L-leucyl-glycinamide, is a potent dopamine D2 receptor allosteric modulator. PAOPA has shown therapeutic effects in pre-clinical models of schizophrenia and extrapyramidal dysfunction. OBJECTIVE: In this study, we sought to examine the biomolecular underpinnings of PAOPA's therapeutic outcomes in pre-clinical models of schizophrenia. METHODS: Following sub-chronic (daily for 7 days) administration of PAOPA, we assessed levels of dopamine D2 receptors, receptor kinases (GRK2 (G protein-coupled receptor kinase 2) and Arrestin- 3), and phosphorylated mitogen-activated protein kinase (MAPKs), namely, extracellular signal- regulated kinases (ERK1/2) in the hippocampus, medial pre-frontal cortex, nucleus accumbens, pre-frontal cortex, and dorsal striatum via protein quantification. RESULTS: Following 7 days of daily PAOPA treatment, we observed decreased GRK2 and increased dopamine D2 receptor expression in the dorsal striatum. These findings potentially underscore the therapeutic mechanism of action of PAOPA for the positive-like symptoms of schizophrenia in pre-clinical animal models. Additionally, we observed a decline in GRK2 in the hippocampus and an increase in phosphorylated ERK1 in the pre-frontal cortex, suggesting a role of PAOPA in treating cognitive and/or affective dysfunction in pre-clinical models. CONCLUSION: While further studies are required to elucidate the mechanism of action of PAOPA, this study discusses prior investigations and develops an early framework to describe the therapeutic mechanism of action of PAOPA.

Therapeutic effects of TP5, a Cdk5/p25 inhibitor, in in vitro and in vivo models of Parkinson's disease.

Parkinson's Disease (PD) is a chronic progressive neurodegenerative disease. Current treatments for PD are symptomatic and only increase striatal dopamine levels. Proactive neuroprotective approaches that slow the progression of PD and maintain appropriate dopamine neuron populations are needed to treat the disease. One suggested mechanism contributing to the pathology of PD involves the binding of cyclin-dependent kinase 5 (Cdk5) to p25, creating a hyperactivated complex to induce cell death. The objective of this study is to investigate the neuroprotective and neurorestorative properties of Truncated Peptide 5 (TP5), a derivative of the p35 activator involved in Cdk5 regulation, via the inhibition of Cdk5/p25 complex function. SH-SY5Y cell line and the nematode Caenorhabditis elegans were exposed to paraquat (PQ), an oxidative stressor, to induce Parkinsonian phenotypes. TP5 was administered prior to PQ exposure to determine its neuroprotective effects and, in further experiments, after PQ exposure to examine its neurorestorative effects. In the SH-SY5Y cell line, TP5 was found to have neuroprotective effects using a cell viability assay and demonstrated neuroprotective and neurorestorative effects in C. elegans by examining dopaminergic neurons and dopamine-dependent behaviour. TP5 decreased elevated Cdk5 activation in worms that were exposed to PQ. TP5's inhibition of Cdk5/p25 hyperactivity led to the protection of dopamine neurons in these PD models. This suggests that TP5 can act as a potential therapeutic drug towards PD.

C. elegans electrotaxis behavior is modulated by heat shock response and unfolded protein response signaling pathways.

The nematode C. elegans is a leading model to investigate the mechanisms of stress-induced behavioral changes coupled with biochemical mechanisms. Our group has previously characterized C. elegans behavior using a microfluidic-based electrotaxis device, and showed that worms display directional motion in the presence of a mild electric field. In this study, we describe the effects of various forms of genetic and environmental stress on the electrotactic movement of animals. Using exposure to chemicals, such as paraquat and tunicamycin, as well as mitochondrial and endoplasmic reticulum (ER) unfolded protein response (UPR) mutants, we demonstrate that chronic stress causes abnormal movement. Additionally, we report that pqe-1 (human RNA exonuclease 1 homolog) is necessary for the maintenance of multiple stress response signaling and electrotaxis behavior of animals. Further, exposure of C. elegans to several environmental stress-inducing conditions revealed that while chronic heat and dietary restriction caused electrotaxis speed deficits due to prolonged stress, daily exercise had a beneficial effect on the animals, likely due to improved muscle health and transient activation of UPR. Overall, these data demonstrate that the electrotaxis behavior of worms is susceptible to cytosolic, mitochondrial, and ER stress, and that multiple stress response pathways contribute to its preservation in the face of stressful stimuli.

In situ-gelling starch nanoparticle (SNP)/O-carboxymethyl chitosan (CMCh) nanoparticle network hydrogels for the intranasal delivery of an antipsychotic peptide.

Existing oral or injectable antipsychotic drug delivery strategies typically demonstrate low bioavailability to targeted brain regions, incentivizing the development of alternative delivery strategies. Delivery via the nasal cavity circumvents multiple barriers for reaching the brain but requires drug delivery vehicles with very specific properties to be effective. Herein, we report in situ-gelling and degradable bulk nanoparticle network hydrogels consisting of oxidized starch nanoparticles (SNPs) and carboxymethyl chitosan (CMCh) that enable intranasal delivery via spray, high nasal mucosal retention, and functional controlled release of the peptide drug PAOPA, a positive allosteric modulator of dopamine D2 receptor. PAOPA-loaded SNP-CMCh hydrogels can alleviate negative symptoms like behavioural abnormalities associated with schizophrenia (i.e. decreased social interaction time) for up to 72 h in an MK-801-induced pre-clinical rat model of schizophrenia at a low drug dosage (0.5 mg/kg); in comparison, conventional PAOPA administration via the intraperitoneal route requires twice the PAOPA dose to achieve a therapeutic effect that persists for only a few hours. This strategy offers potential for substantially decreasing re-administration frequencies and overall drug doses (and thus side-effects) of a range of potential antipsychotic drugs via a minimally-invasive administration route.

Structural determinants for the inhibitory ligands of orotidine-5'-monophosphate decarboxylase.

In recent years, orotidine-5'-monophosphate decarboxylase (ODCase) has gained renewed attention as a drug target. As a part of continuing efforts to design novel inhibitors of ODCase, we undertook a comprehensive study of potent, structurally diverse ligands of ODCase and analyzed their structural interactions in the active site of ODCase. These ligands comprise of pyrazole or pyrimidine nucleotides including the mononucleotide derivatives of pyrazofurin, barbiturate ribonucleoside, and 5-cyanouridine, as well as, in a computational approach, 1,4-dihydropyridine-based non-nucleoside inhibitors such as nifedipine and nimodipine. All these ligands bind in the active site of ODCase exhibiting distinct interactions paving the way to design novel inhibitors against this interesting enzyme. We propose an empirical model for the ligand structure for rational modifications in new drug design and potentially new lead structures.

Amphiphilic Small-Molecule Assemblies to Enhance the Solubility and Stability of Hydrophobic Drugs.

Amphiphilic assemblies made from diverse synthetic building blocks are well known for their biomedical applications. Here, we report the synthesis of gemini-type amphiphilic molecules that form stable assemblies in water. The assembly property of molecule M2 in aqueous solutions was first inferred from peak broadening observed in the proton NMR spectrum. This was supported by dynamic light scattering and transmission electron microscopy analysis. The assembly formed from M2 (M2agg) was used to solubilize the hydrophobic drugs curcumin and doxorubicin at physiological pH. M2agg was able to effectively solubilize curcumin as well as protect it from degradation under UV irradiation. Upon solubilization in M2agg, curcumin showed excellent cell permeability and higher toxicity to cancer cells over normal cells, probably because of enhanced cellular uptake and increased stability. M2agg also showed pH-dependent release of doxorubicin, resulting in controlled toxicity on cancer cell lines, making it a promising candidate for the selective delivery of drugs to cancer cells.