Histidyl-Proline Diketopiperazine Isomers as Multipotent Anti-Alzheimer Drug Candidates

Cyclic dipeptides administered by both parenteral and oral routes are suggested as promising candidates for the treatment of neurodegeneration-related pathologies. In this study, we tested Cyclo (His-Pro) isomers (cHP1-4) for their anti-Alzheimer potential using a differentiated human neuroblastoma cell line (SH-SY5Y) as an Alzheimer’s disease (AD) experimental model. The SH-SY5Y cell line was differentiated by the application of all-trans retinoic acid (RA) to obtain mature neuron-like cells. Amyloid-beta 1-42 (Aβ_1-42) peptides, the main effector in AD, were administered to the differentiated cell cultures to constitute the in vitro disease model. Next, we performed cell viability analyses 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and lactate dehydrogenase (LDH) release assays) to investigate the neuroprotective concentrations of cyclodipeptides using the in vitro AD model. We evaluated acetylcholinesterase (AChE), α- and β-secretase activities (TACE and BACE1), antioxidant potency, and apoptotic/necrotic properties and performed global gene expression analysis to understand the main mechanism behind the neuroprotective features of cHP1-4. Moreover, we conducted sister chromatid exchange (SCE), micronucleus (MN), and 8-hydroxy-2′-deoxyguanosine (8-OHdG) analyses to evaluate the genotoxic damage potential after applications with cHP1-4 on cultured human lymphocytes. Our results revealed that cHP1-4 isomers provide a different degree of neuroprotection against Aβ_1-42-induced cell death on the in vitro AD model. The applications with cHP1-4 isomers altered the activity of AChE but not the activity of TACE and BACE1. Our analysis indicated that the cHP1-4 increased the total antioxidant capacity without altering total oxidative status levels in the cellular AD model and that cHP1-4 modulated the alterations of gene expressions by Aβ_1-42 exposure. We also observed that cHP1-4 exhibited noncytotoxic and non-genotoxic features in cultured human whole blood cells. In conclusion, cHP1-4 isomers, especially cHP4, have been explored as novel promising therapeutics against AD.

Carvacrol Prodrugs with Antimicrobial Activity Loaded on Clay Nanocomposites

Background: Carvacrol, an essential oil with antimicrobial activity against a wide range of pathogens, and its water soluble carvacrol prodrugs (WSCP1-3) were intercalated into montmorillonite (VHS) interlayers to improve their stability in physiological media and promote their absorption in the intestine. Methods: Intercalation of prodrugs by cation exchange with montmorillonite interlayer counterions was verified by X-ray powder diffraction and confirmed by Fourier transform infrared spectroscopy and thermal analysis. Results: In vitro release studies demonstrated that montmorillonite successfully controlled the release of the adsorbed prodrugs and promoted their bioactivation only in the intestinal tract where carvacrol could develop its maximum antimicrobial activity. The amount of WSCP1, WSCP2, and WSCP3 released from VHS were 38%, 54%, and 45% at acid pH in 120 min, and 65%, 78%, and 44% at pH 6.8 in 240 min, respectively. Conclusions: The resultant hybrids successfully controlled conversion of the prodrugs to carvacrol, avoiding premature degradation of the drug.

Viscoelastic behaviour of hyaluronic acid formulations containing carvacrol prodrugs with antibacterial properties

In this paper, we report the development and viscoelastic properties of hyaluronic acid formulations (HA₅, HA₃₀, and HA₆₀, containing 0.5, 3, and 6% HA, respectively) loaded with carvacrol prodrugs (WSCP_S) with antibacterial properties. Notably, antimicrobial studies revealed that WSCP1-2 in both HA₅ and HA₃₀ formulations showed the best minimum inhibitory concentration (MIC) values against Enterococcus faecium (128 mg/L) and Enterococcus faecalis (256 mg/L) compared to those of carvacrol alone or in formulations with HA. Moreover, rheological analyses showed that HA₃₀ composites exhibited a semi-solid consistency, while HA₅ formulations possessed a fluid consistency. Considering these data, HA₃₀ is a useful formulation which guarantees a good percentage of prodrug release (e.g., 30 and 60% for WSCP1 and 2, respectively) as well as a texture suitable for topical administration to treat wounds and/or skin infections.

Novel anti-Alzheimer phenol-lipoyl hybrids: Synthesis, physico-chemical characterization, and biological evaluation

To date, drugs that hit a single target are inadequate for the treatment of neurodegenerative diseases, such as Alzheimer's or Parkinson's diseases. The development of multitarget ligands, able to interact with the different pathways involved in the progession of these disorders, represents a great challenge for medicinal chemists. In this context, we report here the synthesis and biological evaluation of phenol-lipoyl hybrids (SV1-13), obtained via a linking strategy, to take advantage of the synergistic effect due to the antioxidant portions and anti-amyloid properties of the single constituents present in the hybrid molecule. Biological results showed that SV5 and SV10 possessed the best protective activity against Aβ_1-42 induced neurotoxicity in differentiated SH-SY5Y cells. SV9 and SV10 showed remarkable antioxidant properties due to their ability to counteract the damage caused by H₂O₂ in SHSY-5Y-treated cells. Hovewer, SV5, showing moderate antioxidant and good neuroprotective activities, resulted the best candidate for further experiments since it also resulted stable both simulated and plasma fluids.

Modulation of Apoptotic Cell Death and Neuroprotective Effects of Glutathione-L-Dopa Codrug Against H2O2-Induced Cellular Toxicity

The L-3,4-dihydroxyphenylalanine (LD) is the gold standard drug currently used to manage Parkinson’s disease (PD) and to control its symptoms. However, LD could cause disease neurotoxicity due to the generation of pro-oxidant intermediates deriving from its autoxidation. In order to overcome this limitation, we have conjugated LD to the natural antioxidant glutathione (GSH) to form a codrug (GSH-LD). Here we investigated the effect of GSH-LD on H₂O₂-induced cellular toxicity in undifferentiated and differentiated lymphoma U-937 and dopaminergic neuroblastoma SH-SY5Y cell lines, used respectively as models to study the involvement of macrophages/microglia and dopaminergic neurons in PD. We analyzed the effect of GSH-LD on apoptosis and cellular oxidative stress, both considered strategic targets for the prevention and treatment of neurodegenerative diseases. Compared to LD and GSH, GSH-LD had a stronger effect in preventing hydrogen peroxide (H₂O₂) induced apoptosis in both cell lines. Moreover, GSH-LD was able to preserve cell viability, cellular redox status, gluthation metabolism and prevent reactive oxygen species (ROS) formation, in a phosphinositide 3-kinase (PI3K)/kinase B (Akt)-dependent manner, in a neurotoxicity cellular model. Our findings indicate that the GSH-LD codrug offers advantages deriving from the additive effect of LD and GSH and it could represent a promising candidate for PD treatment.

Role of Dietary Supplements in the Management of Parkinson's Disease

The use of food supplements or functional food has significantly increased in the past decades, especially to compensate both the modern lifestyle and the food shortages of the industrialized countries. Despite food supplements are habitually intended to correct nutritional deficiencies or to support specific physiological functions, they are often combined with common drug therapies to improve the patient's health and/or mitigate the symptoms of many chronic diseases such as cardiovascular diseases, cystic fibrosis, cancer, liver and gastrointestinal diseases. In recent years, increased attentions are given to the patient's diet, and the use of food supplements and functional food rich in vitamins and antioxidants plays a very important role in the treatment and prevention of neurodegenerative diseases such as Parkinson's disease (PD). Natural compounds, phytochemicals, vitamins, and minerals can prevent, delay, or alleviate the clinical symptoms of PD in contrast to some of the main physiopathological mechanisms involved in the development of the disease, like oxidative stress, free radical formation, and neuroinflammation. The purpose of this review is to collect scientific evidences which support the use of specific biomolecules and biogenic elements commonly found in food supplements or functional food to improve the clinical framework of patients with PD.

Synthesis and biological evaluation of novel analogues of Gly-l-Pro-l-Glu (GPE) as neuroprotective agents

This study investigated the anti-inflammatory effects of novel pseudotripeptides (GPE 1-3) as potential candidates to counteract neuroinflammation processes in Alzheimer's disease. GPE 1-3 pseudotripeptides are synthetic derivatives of Gly-l-Pro-l-Glu (GPE), the N-terminal tripeptide of IGF-1, obtained through the introduction of isosteres of the amidic bond (aminomethylene unit) to increase the metabolic stability of the native tripeptide. The results showed that all synthetic derivatives possessed higher half-lives (t_1/2 > 4 h) than GPE (t_1/2 = 30 min) in human plasma and had good water solubility. The biological results demonstrated that GPE 1-3 had protective properties in several experimental models of treated THP-1 cells. Notably, the novel pseudotripeptides influenced inflammatory cytokine expression (IL-1β, IL-18, and TNF-α) in Aβ_25-35-, PMA-, and LPS-treated THP-1 cells. In PMA-differentiated THP-1 macrophages, both GPE 1 and GPE 3 reduced the expression levels of all selected cyto-chemokines, even though GPE 3 showed the best neuroprotective properties.

Cyclo(His-Pro) inhibits NLRP3 inflammasome cascade in ALS microglial cells

Neuroinflammation, i.e. self-propelling progressive cycle of microglial activation and neuron damage, as well as improper protein folding, are recognized as major culprits of neurodegenerative diseases, such as amyotrophic lateral sclerosis (ALS). Mutations in several proteins have been linked to ALS pathogenesis, including the G93A mutation in the superoxide dismutase 1 (SOD1) enzyme. SOD1(G93A) mutant is prone to aggregate thus inducing both oxidative stress and neuroinflammation. In this study we used hSOD1(G93A) microglial cells to investigate the effects of the antioxidant and anti-inflammatory cyclic dipeptide (His-Pro) on LPS-induced inflammasome activation. We found that cyclo(His-Pro) inhibits NLRP3 inflammasome activation by reducing protein nitration via reduction in NO and ROS levels, indicative of lower peroxynitrite generation by LPS. Low levels in peroxynitrite are related to NF-κB inhibition responsible for iNOS down-regulation and NO dampening. On the other hand, cyclo(His-Pro)-mediated ROS attenuation, not linked to Nrf2 activation in this cellular model, is ascribed to increased soluble SOD1 activity due to the up-regulation of Hsp70 and Hsp27 expression. Conclusively, our results, besides corroborating the anti-inflammatory properties of cyclo(His-Pro), highlight a novel role of the cyclic dipeptide as a proteostasis regulator, and therefore a good candidate for the treatment of ALS and other misfolding diseases.

Carvacrol reduces adipogenic differentiation by modulating autophagy and ChREBP expression

Objective

Obesity is the result of white adipose tissue accumulation where excess of food energy is stored to form triglycerides. De novo lipogenesis (DNL) is the continuous process of new fat production and is driven by the transcription factor ChREBP. During adipogenesis, white adipocytes change their morphology and the entire cell volume is occupied by one large lipid droplet. Recent studies have implicated an essential role of autophagy in adipogenic differentiation, cytoplasmic remodelling and mitochondria reorganization. The phenolic monoterpenoid carvacrol (2-methyl-5-[1-methylethyl]phenol), produced by numerous aromatic plants, has been shown to reduce lipid accumulation in murine 3T3-L1 cells during adipogenic differentiation by modulating genes associated with adipogenesis and inflammation. Therefore, the aim of this study was to evaluate whether carvacrol could affect autophagy and ChREBP expression during adipogenic differentiation.

Methods

The study was carried on by using the murine 3T3-L1 and the human WJ-MSCs (Wharton’s jelly-derived mesenchymal stem cells) cell lines. Cells undergoing adipogenic differentiation were untreated or treated with carvacrol. Adipogenic differentiation was assessed by analyzing cellular lipid accumulation with Oil-Red O staining and by ultrastructural examination with TEM. Autophagy was evaluated by western immunoblotting of autophagy markers LC3B and p62/SQSTM and by ultrastructural examination of autophagic bodies. Autophagic flux was evaluated by using autophagy inhibitor cloroquine (CQ). ChREBP expression levels was assessed by both western blotting and immunoelectron microscopy and ChREBP activity by analysis of adipogenic target genes expression.

Results

We found that carvacrol reduced adipogenic differentiation of about 40% and 30% in, respectively, 3T3-L1 and in WJ-MSCs cells. The effect of carvacrol on adipogenic differentiation correlated with both reduction of autophagy and reduction of ChREBP expression.

Conclusion

The results support the notion that carvacrol, through its effect on autophagy (essential for adipocyte maturation) and on ChREBP activity, could be used as a valuable adjuvant to reduce adipogenic differentiation.

Chelating and antioxidant properties of l-Dopa containing tetrapeptide for the treatment of neurodegenerative diseases

Neurodegenerative diseases share a common pathogenetic mechanism involving aggregation and deposition of misfolded proteins, oxidative stress, metal dyshomeostasis, and glutamate exicitotoxicity, which lead to progressive dysfunction of central nervous system (CNS). A potential strategy to counteract these deleterious events at neuronal level is represented by the employment of a novel class of multi-target therapeutic agents that selectively and simultaneously hit these targets In this paper, we report the metal binding and antioxidant properties of a novel metal-protein attenuating peptide, GSH-LD, a tetrapeptide obtained by linking glutathione, a well-known antioxidant tripeptide, to L-Dopa. Results demonstrated that GSH-LD possesses chelating capabilities in order to selectively target the excess of metals without interfere with metal-containing antioxidant enzymes. Moreover, antioxidant assays revealed a large contribution of GSH-LD to restore the antioxidant defences of damaged neuronal cells.

Synthesis and Antioxidant Properties of Novel Memantine Derivatives

BACKGROUND

Medicinal chemistry methodologies are presently used to develop multifunctional molecules which simultaneously reduce oxidative stress, excitotoxicity, metal dyshomeostasis, and neuroinflammation that characterize neuropathological conditions, such as Alzheimer's Disease.

RESULTS

Memantine (MEM) derivatives 1-6 were designed and synthesized as novel multifunctional entities with antioxidant and neuroprotective capabilities to manage neurodegenerative diseases, such as Alzheimer's Disease. In vitro neuroprotective studies were performed by using astroglial GL15 cell line to assess antioxidant capability of MEM derivatives 1-6.

CONCLUSION

Our outcomes showed that compounds 1 and 5 (at the concentration of 10 μM), containing as antioxidant portion residues of N-acetyl-Cys-OH and N-acetyl-Cys(Allyl)-OH, respectively, revealed a significant neuroprotective activity against oxidative stress, as assessed by NBT assays.

Effect of MRJF4 on C6 Glioma Cells Proliferation and Migration

BACKGROUND

MRJF4, a novel haloperidol metabolite II prodrug, was obtained through the esterification of the secondary hydroxyl group of haloperidol metabolite II with 4-phenylbutyric acid. The activities of (±)-MRJF4 and its two enantiomers [(+)-MRJF4 and (-)-MRJF4] as tumor specific inducers of pro-apoptotic genes were evaluated on malignant C6 glioma cells. In particular, changes in Nf-κB signaling pathway, activity of nitric oxide synthases (NOS), metalloproteinases (MMPs), and membrane adhesion proteins were investigated.

RESULTS

IκBα reduced phosphorylation and iNOS lowered activity could be correlated with the previously demonstrated decreased proliferation and tumor progression of C6 cells upon 24 h of treatment with all the three compounds. Integrin β1 decreased expression, at the same experimental time, seems to support lower C6 cells migrative capability and the consequent reduced invasiveness of these cells upon treatment with (±)-MRJF4 and its enantiomers.

CONCLUSION

These results suggest that this multi-target prodrug and its two enantiomers might be a valuable clinical tool for the treatment of metastatic glioblastoma.

(R)-α-Lipoyl-Gly-l-Pro-l-Glu dimethyl ester as dual acting agent for the treatment of Alzheimer's disease

In this study, effects of LA-GPE (R-α-Lipoyl-Gly-l-Pro-l-Glu dimethyl ester) and GPE (Gly-L-Pro-L-Glu) on the cytotoxic action of Aβ_1-42 were tested with differentiated human neuroblastoma SH-SY5Y cells as cellular Alzheimer model via measurements of mitochondrial viability (MTT assay) and lactate dehydrogenase release (LDH assay). Effects of LA-GPE and GPE on acetylcholinesterase (AChE) activity, total antioxidant capacity (TAC) and total oxidative status (TOS) levels, and neural cell apoptosis and necrosis were also determined. In addition, biological safety of these novel formulations was evaluated in human blood cells using different cytotoxicity and genotoxicity assays. Our results indicated that both compounds could block Aβ_1-42 induced cell death. LA-GPE reduced Aβ-induced AChE activity and oxidative stress, suggesting it as a multifunctional compound potentially valuable for the treatment of Alzheimer's disease (AD).

Nanoencapsulation strategies for the delivery of novel bifunctional antioxidant/σ1 selective ligands

Nowadays sigma-1 receptors are considered as new therapeutic objectives for central nervous system neurodegenerative diseases. Among different molecules, alpha lipoic acid has been identified as a natural potent antioxidant drug, whose therapeutic efficacy is limited by its many drawbacks, such as fast metabolism, poor bioavailability and high physico-chemical instability. Alfa-lipoic acid derivatives have been recently developed demonstrating their neuroprotective activity and effectiveness in different types of oxidative stress. In this work, two derivatives containing an amide or an ester functional group with different lipophilicity, were selected for their important affinity for sigma-1 receptors. Herein, in order to improve the in vitro stability and antioxidant effectiveness of alpha-lipoic acid derivatives, we focused our efforts in the nanoencapsulation strategies. Aqueous-core nanocapsules for the delivery of the hydrophilic compound and nanostructured lipid carrier for the lipophilic derivative, were properly designed and prepared using a direct or inverse eco-friendly organic solvent-free procedure. All nanosystems were characterized in terms of mean size, polydispersity, stability, morphology, encapsulation efficiency and in vitro release profiles. In order to evaluate the nanocarriers biocompatibility and antioxidant effectiveness, in vitro biological studies (cell viability, total antioxidant capacity and total oxidative status) were developed on primary human whole blood cell cultures, on both unloaded and derivatives-loaded nanodevices.

Gold nanoparticles as scaffolds for poor water soluble and difficult to vehiculate antiparkinson codrugs

We report the facile and non-covalent preparation of gold nanoparticles (AuNPs) stabilized by an antiparkinson codrug based on lipoic acid (LA). The obtained AuNPs appear stable in both dimethyl sulfoxide and fetal bovine serum and able to load an amount of codrug double the weight of gold. These NPs were demonstrated to be safe and biocompatible towards primary human blood cells and human neuroblastoma cells, one of the most widely used cellular models to study dopaminergic neural cells, therefore are ideal drug carriers for difficult to solubilize molecules. Very interestingly, the codrug-stabilized AuNPs were shown to reduce the accumulation of reactive oxygen species in SH-SY5Y cells treated with LD and did not change total oxidant status levels in cultured human blood cells, thus confirming the antioxidant role of LA although bound to AuNPs. The characterization of AuNPs in terms of loading and stability paves the way for their use in biomedical and pharmacological applications.

Toxicity assessment of hydroxyapatite nanoparticles in rat liver cell model in vitro

Hydroxyapatite nanoparticles (HAP NPs) are widely used for preparations of biomedical and biotechnological fields such as drug delivery, gene therapy, and molecular imaging. However, the current toxicological knowledge about HAP NPs is relatively limited. The present study was designed to investigate the toxicity potentials of various concentrations (0–1000 µg cm−2) of HAP NPs in cultured primary rat hepatocytes. Cell viability was detected by 3-(4,5-dimethyl-thiazol-2-yl) 2,5-diphenyltetrazolium bromide (MTT) assay and lactate dehydrogenase (LDH) release, while total antioxidant capacity (TAC) and total oxidative stress (TOS) levels were determined to evaluate the oxidative injury. The DNA damage was also analyzed via scoring liver micronuclei rates and determining 8-oxo-2-deoxyguanosine (8-OH-dG) levels. The results of MTT and LDH assays showed that the higher concentrations of dispersed HAP NPs (300, 500, and 1000 µg cm−2) decreased cell viability. Also, HAP NPs increased TOS (500 and 1000 µg cm−2) levels and decreased TAC (300, 500, and 1000 µg cm−2) levels in cultured hepatocytes. On the basis of increasing doses, the NPs as depending on dose caused significant increases of the number of micronucleated hepatocytes and 8-OH-dG levels as compared to control culture. Furthermore, the highest concentration of HAP NPs (1000 µg cm−2) exhibited cytotoxic activity. Based on these results, HAP NPs have a dose-dependent toxic effect in rat hepatocytes. Further extensive research in this field is promising and reasonable.