Hydroxybenzoic Acid Derivatives as Dual-Target Ligands: Mitochondriotropic Antioxidants and Cholinesterase Inhibitors

The mitochondriotropic antioxidants AntiOxBEN2 and AntiOxCIN4 are structurally-similar but differentially alter energy homeostasis in human skin fibroblasts

Mitochondrial dysfunction and increased reactive oxygen species (ROS) generation play an import role in different human pathologies. In this context, mitochondrial targeting of potentially protective antioxidants by their coupling to the lipophilic triphenylphosphonium cation (TPP) is widely applied. Employing a six‑carbon (C6) linker, we recently demonstrated that mitochondria-targeted phenolic antioxidants derived from gallic acid (AntiOxBEN2) and caffeic acid (AntiOxCIN4) counterbalance oxidative stress in primary human skin fibroblasts by activating ROS-protective mechanisms. Here we demonstrate that C6-TPP (but not AntiOxBEN2 and AntiOxCIN4) induce cell death in human skin fibroblasts. This indicates that C6-TPP cytoxocity is counterbalanced by the antioxidant moieties of AntiOxBEN2 and AntiOxCIN4. Remarkably, C6-TPP and AntiOxBEN2 (but not AntiOxCIN4) induced a glycolytic switch, as exemplified by a reduced cellular oxygen consumption rate (OCR), increased extracellular acidification rate (ECAR), elevated extracellular lactate levels, and higher protein levels of glucose transporter 1 (GLUT-1). This switch involved activation of AMP-activated protein kinase (AMPK) and fully compensated for the loss in mitochondrial ATP production by sustaining cellular ATP content. When glycolytic switch induction was prevented (i.e. by using a glucose-free, galactose-containing medium), AntiOxBEN2 induced cell death whereas AntiOxCIN4 did not. We conclude that, despite their similar chemical structure and antioxidant capacity, AntiOxBEN2 and AntiOxCIN4 display both common (redox-adaptive) and specific (bioenergetic-adaptive) effects.

Assisted Reproduction Technologies (ART): Impact of Mitochondrial (Dys)function and Antioxidant Therapy

In the last decades, major changes in ecosystems related to industrial development and environmental modifications have had a direct impact on mammalian fertility, as well as on biodiversity. It is widely demonstrated that all these changes impair reproductive function. Several studies have connected the increase of reactive oxygen species (ROS) generated in mitochondria to the recently identified decline of fertility due to various factors, including heat stress. The study of antioxidants, and especially of mitochondria targeted antioxidants, has been focused on identifying more efficient and less toxic therapies that could circumvent fertility problems. These antioxidants can be derived from natural compounds in the diet and delivered to the mitochondria in more effective forms, providing a much more natural therapy. The use of mitochondriotropic diet-based antioxidants in assisted reproductive technologies (ART) may be an important way to overcome low fertility, allowing the conservation of animal biodiversity and productivity. This paper provides a concise review of the current state of the art on this topic, with a particular focus on the antioxidants mitoquinone, AntiOxBEN2, AntiOxCIN4, urolithin A and piperine, and their effects on bovine and other animal species.

Co-administration of Ceratonia siliqua extract nanoparticles promotes the oral bioavailability and neurotherapeutic efficacy of donepezil in a dementia model

BACKGROUND

This study aimed to assess the herb-drug interactions between crude/silver nanoparticle (SNP)-loaded carob extract (Car, NCar, respectively) and donepezil-HCl (DPZ) and their impact on neurotherapeutic outcomes in a dementia model.

METHODS

Carob pods were subjected to ethanol extraction, and their phytoconstituents were chromatographically analysed. SNP-loaded extract was synthesized and characterized, and dementia-like symptoms were induced in Wistar rats by repeated dosing with 175 mg/kg AlCl3 for 60 days, after which the animals were treated with Car, NCar, DPZ, and combinations of Car/NCar-DPZ for 30 days. The effect of carob formulations on DPZ bioavailability was in-silico profiled and the herb-drug interactions were mathematically assessed as combination indices.

RESULTS

Different formulations significantly improved cognitive/spatial memory functions, restored dysregulated brain redox and cholinergic functions, and markedly inhibited cholinesterase, as reflected by the reduction/absence of amyloid plaques and neurofibrillary tangles. In silico profiling of the major phytoconstituents revealed their non-P-glycoprotein substrate nature and CYP3A4, 2C19, and 2C9 inhibition, which might have improved the oral bioavailability of DPZ. The combination index calculations revealed strong synergy between DPZ and both carob formulations, with the strongest effect exhibited by the DPZ/NCar combination.

CONCLUSION

The co-administration of carob extract/SNPs represents a promising approach for enhancing the neurotherapeutic efficacy of DPZ.

Mechanistic insights into the potential role of dietary polyphenols and their nanoformulation in the management of Alzheimer's disease

Alzheimer's disease (AD) is a very common neurodegenerative disorder associated with memory loss and a progressive decline in cognitive activity. The two major pathophysiological factors responsible for AD are amyloid plaques (comprising amyloid-beta aggregates) and neurofibrillary tangles (consisting of hyperphosphorylated tau protein). Polyphenols, a class of naturally occurring compounds, are immensely beneficial for the treatment or management of various disorders and illnesses. Naturally occurring sources of polyphenols include plants and plant-based foods, such as fruits, herbs, tea, vegetables, coffee, red wine, and dark chocolate. Polyphenols have unique properties, such as being the major source of anti-oxidants and possessing anti-aging and anti-cancerous properties. Currently, dietary polyphenols have become a potential therapeutic approach for the management of AD, depending on various research findings. Dietary polyphenols can be an effective strategy to tackle multifactorial events that occur with AD. For instance, naturally occurring polyphenols have been reported to exhibit neuroprotection by modulating the Aβ biogenesis pathway in AD. Many nanoformulations have been established to enhance the bioavailability of polyphenols, with nanonization being the most promising. This review comprehensively provides mechanistic insights into the neuroprotective potential of dietary polyphenols in treating AD. It also reviews the usability of dietary polyphenol as nanoformulation for AD treatment.

Repurposing immune boosting and anti-viral efficacy of Parkia bioactive entities as multi-target directed therapeutic approach for SARS-CoV-2: exploration of lead drugs by drug likeness, molecular docking and molecular dynamics simulation methods

The COVID-19 pandemic has caused adverse health (severe respiratory, enteric and systemic infections) and environmental impacts that have threatened public health and the economy worldwide. Drug repurposing and small molecule multi-target directed herbal medicine therapeutic approaches are the most appropriate exploration strategies for SARS-CoV-2 drug discovery. This study identified potential multi-target-directed Parkia bioactive entities against SARS-CoV-2 receptors (S-protein, ACE2, TMPRSS2, RBD/ACE2, RdRp, MPro, and PLPro) using ADMET, drug-likeness, molecular docking (AutoDock, FireDock and HDOCK), molecular dynamics simulation and MM-PBSA tools. One thousand Parkia bioactive entities were screened out by virtual screening and forty-five bioactive phytomolecules were selected based on favorable binding affinity and acceptable pharmacokinetic and pharmacodynamics properties. The binding affinity values of Parkia phyto-ligands (AutoDock: -6.00--10.40 kcal/mol; FireDock: -31.00--62.02 kcal/mol; and HDOCK: -150.0--294.93 kcal/mol) were observed to be higher than the reference antiviral drugs (AutoDock: -5.90--9.10 kcal/mol; FireDock: -35.64--59.35 kcal/mol; and HDOCK: -132.82--211.87 kcal/mol), suggesting a potent modulatory action of Parkia bioactive entities against the SARS-CoV-2. Didymin, rutin, epigallocatechin gallate, epicatechin-3-0-gallate, hyperin, ursolic acid, lupeol, stigmasta-5,24(28)-diene-3-ol, ellagic acid, apigenin, stigmasterol, and campesterol strongly bound with the multiple targets of the SARS-CoV-2 receptors, inhibiting viral entry, attachment, binding, replication, transcription, maturation, packaging and spread. Furthermore, ACE2, TMPRSS2, and MPro receptors possess significant molecular dynamic properties, including stability, compactness, flexibility and total binding energy. Residues GLU-589, and LEU-95 of ACE2, GLN-350, HIS-186, and ASP-257 of TMPRSS2, and GLU-14, MET-49, and GLN-189 of MPro receptors contributed to the formation of hydrogen bonds and binding interactions, playing vital roles in inhibiting the activity of the receptors. Promising results were achieved by developing multi-targeted antiviral Parkia bioactive entities as lead and prospective candidates under a small molecule strategy against SARS-CoV-2 pathogenesis. The antiviral activity of Parkia bioactive entities needs to be further validated by pre-clinical and clinical trials.

Efficacy of Novel Quaternary Ammonium and Phosphonium Salts Differing in Cation Type and Alkyl Chain Length against Antibiotic-Resistant Staphylococcus aureus

Antibacterial resistance poses a critical public health threat, challenging the prevention and treatment of bacterial infections. The search for innovative antibacterial agents has spurred significant interest in quaternary heteronium salts (QHSs), such as quaternary ammonium and phosphonium compounds as potential candidates. In this study, a library of 49 structurally related QHSs was synthesized, varying the cation type and alkyl chain length. Their antibacterial activities against Staphylococcus aureus, including antibiotic-resistant strains, were evaluated by determining minimum inhibitory/bactericidal concentrations (MIC/MBC) ≤ 64 µg/mL. Structure-activity relationship analyses highlighted alkyl-triphenylphosphonium and alkyl-methylimidazolium salts as the most effective against S. aureus CECT 976. The length of the alkyl side chain significantly influenced the antibacterial activity, with optimal chain lengths observed between C10 and C14. Dose-response relationships were assessed for selected QHSs, showing dose-dependent antibacterial activity following a non-linear pattern. Survival curves indicated effective eradication of S. aureus CECT 976 by QHSs at low concentrations, particularly compounds 1e, 3e, and 5e. Moreover, in vitro human cellular data indicated that compounds 2e, 4e, and 5e showed favourable safety profiles at concentrations ≤ 2 µg/mL. These findings highlight the potential of these QHSs as effective agents against susceptible and resistant bacterial strains, providing valuable insights for the rational design of bioactive QHSs.

Phytochemicals and quaternary phosphonium ionic liquids: Connecting the dots to develop a new class of antimicrobial agents

INTRODUCTION

The infections by multidrug-resistant bacteria are a growing threat to human health, and the efficacy of the available antibiotics is gradually decreasing. As such, new antibiotic classes are urgently needed.

OBJECTIVES

This study aims to evaluate the antimicrobial activity, safety and mechanism of action of phytochemical-based triphenylphosphonium (TPP+) conjugates.

METHODS

A library of phytochemical-based TPP+ conjugates was repositioned and extended, and its antimicrobial activity was evaluated against a panel of Gram-positive (methicillin-resistant Staphylococcus aureus - MRSA) and Gram-negative bacteria (Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Acinetobacter baumannii) and fungi (Candida albicans, Cryptococcus neoformans var. grubii). The compounds' cytotoxicity and haemolytic profile were also evaluated. To unravel the mechanism of action of the best compounds, the alterations in the surface charge, bacterial membrane integrity, and cytoplasmic leakage were assessed.

RESULTS

Structure-activity-toxicity data revealed the contributions of the different structural components (phenolic ring, carbon-based spacers, carboxamide group, alkyl linker) to the compounds' bioactivity and safety. Dihydrocinnamic derivatives 5 m and 5n stood out as safe, potent and selective antibacterial agents against S. aureus (MIC < 0.25 µg/mL; CC50 > 32 µg/mL; HC10 > 32 µg/mL). Mechanistic studies suggest that the antibacterial activity of compounds 5 m and 5n may result from interactions with the bacterial cell wall and membrane.

CONCLUSIONS

Collectively, these studies demonstrate the potential of phytochemical-based TPP+ conjugates as a new class of antibiotics.

Discovery of Novel Tryptanthrin Derivatives with Benzenesulfonamide Substituents as Multi-Target-Directed Ligands for the Treatment of Alzheimer's Disease

Based on the multi-target-directed ligands (MTDLs) approach, two series of tryptanthrin derivatives with benzenesulfonamide substituents were evaluated as multifunctional agents for the treatment of Alzheimer's disease (AD). In vitro biological assays indicated most of the derivatives had good cholinesterase inhibitory activity and neuroprotective properties. Among them, the target compound 4h was considered as a mixed reversible dual inhibitor of acetylcholinesterase (AChE, IC50 = 0.13 ± 0.04 μM) and butyrylcholinesterase (BuChE, IC50 = 6.11 ± 0.15 μM). And it could also potentially prevent the generation of amyloid plaques by inhibiting self-induced Aβ aggregation (63.16 ± 2.33%). Molecular docking studies were used to explore the interactions of AChE, BuChE, and Aβ. Furthermore, possessing significant anti-neuroinflammatory potency (NO, IL-1β, TNF-α; IC50 = 0.62 ± 0.07 μM, 1.78 ± 0.21 μM, 1.31 ± 0.28 μM, respectively) reduced ROS production, and chelated biometals were also found in compound 4h. Further studies showed that 4h had proper blood-brain barrier (BBB) permeability and suitable in vitro metabolic stability. In in vivo study, 4h effectively ameliorated the learning and memory impairment of the scopolamine-induced AD mice model. These findings suggested that 4h may be a promising compound for further development as a multifunctional agent for the treatment of AD.

Pyrimidines: Molecular docking and inhibition studies on carbonic anhydrase and cholinesterases

Alzheimer's disease (AD) is a neurodegenerative disorder. The disease is characterized by dementia, memory impairment, cognitive impairment, and speech impairment. Cholinesterases (ChEs; AChE, acetylcholinesterase and BChE, butyrylcholinesterase) inhibitors and their benefits of cholinergic replacement in the treatment of AD have been researched and documented by scientists in various ways to date. Recent studies prove that human carbonic anhydrases (hCAs) are also one of the important targets in the treatment of AD. Therefore, the development of new agents that can simultaneously modulate the various mechanisms or targets involved in the AD pathway may be a powerful strategy to treat AD, the current disease. Considering these data, the effects of the pyrimidines (1-7) were investigated in this study for the discovery and development of multitargeted ChEs and hCAs inhibitors associated with AD. In addition, the molecular docking analysis of the 4-amino-2-choloropyrimidine (2) was performed to understand the binding interactions on the active site of the enzyme. All compounds (1-7) showed satisfactory enzyme inhibitory potency in micromolar concentrations against AChE, BChE, hCAI, and hCAII with K_I values ranging from 0.099 to 0.241 μM, from 1.324 to 3.418 μM, from 0.201 to 0.884 μM, from 1.867 to 3.913 μM, respectively. Due to their ChEs and hCAs inhibition, these compounds (1-7) may be considered as leads for investigations in neurodegenerative diseases. All these results revealed that the 4-amino-5,6-dichloropyrimidine (7) (K_I value of 0.201 ± 0.041 μM for hCA I), the 4-amino-6-hydroxypyrimidine (4) (K_I value of 1.867 ± 0.296 μM for hCA II), the 4-amino-5,6-dichloropyrimidine (7) (K_I value of 0.099 ± 0.008 μM for AChE), and the 4-amino-2-chloropyrimidine (2) (K_I value of 1.324 ± 0.273 μM for BChE) from the pyrimidines in this series were the most promising derivatives, as they exhibited a good multifunctional inhibition at all experimental levels and in the in silico validation against these enzymes, for the treatment of AD.

The Therapeutic Potential of the Endocannabinoid System in Age-Related Diseases

The endocannabinoid system (ECS) dynamically regulates many aspects of mammalian physiology. ECS has gained substantial interest since growing evidence suggests that it also plays a major role in several pathophysiological conditions due to its ability to modulate various underlying mechanisms. Furthermore, cannabinoids, as components of the cannabinoid system (CS), have proven beneficial effects such as anti-inflammatory, immunomodulatory, neuromodulatory, antioxidative, and cardioprotective effects. In this comprehensive review, we aimed to describe the complex interaction between CS and most common age-related diseases such as neuro-degenerative, oncological, skeletal, and cardiovascular disorders, together with the potential of various cannabinoids to ameliorate the progression of these disorders. Since chronic inflammation is postulated as the pillar of all the above-mentioned medical conditions, we also discuss in this paper the potential of CS to ameliorate aging-associated immune system dysregulation.

Targeting Hydroxybenzoic Acids to Mitochondria as a Strategy to Delay Skin Ageing: An In Vitro Approach

Targeting antioxidants to mitochondria is considered a promising strategy to prevent cellular senescence and skin ageing. In this study, we investigate whether four hydroxybenzoic acid-based mitochondria-targeted antioxidants (MitoBENs, MB1-4) could be used as potential active ingredients to prevent senescence in skin cells. Firstly, we evaluated the chemical stability, cytotoxicity, genotoxicity and mitochondrial toxicity of all compounds. We followed this by testing the antioxidant protective capacity of the two less toxic compounds on human skin fibroblasts. We then assessed the effects of the best hit on senescence, inflammation and mitochondrial remodeling on a 3D skin cell model, while also testing its mutagenic potential. Cytotoxicity and mitochondrial toxicity rankings were produced: MB3 < MB4 ≃ MB1 < MB2 and MB3 < MB1 < MB4 < MB2, respectively. These results suggest that pyrogallol-based compounds (MB2 and MB4) have lower cytotoxicity. The pyrogallol derivative, MB2, containing a 6-carbon spacer, showed a more potent antioxidant protective activity against hydrogen peroxide cytotoxicity. In a 3D skin cell model, MB2 also decreased transcripts related to senescence. In sum, MB2’s biological safety profile, good chemical stability and lack of mutagenicity, combined with its anti-senescence effect, converts MB2 into a good candidate for further development as an active ingredient for skin anti-ageing products.

Flaxseed Ethanol Extracts’ Antitumor, Antioxidant, and Anti-Inflammatory Potential

The antitumoral, antioxidant, and anti-inflammatory effects of flaxseed ethanol extract was screened. Phytochemical analysis was performed by measuring the total phenolic content and by HPLC-DAD-ESI MS. In vitro antiproliferative activity was appreciated by MMT test of four adenocarcinomas and two normal cell lines. In vitro, antioxidant activity was evaluated by DPPH, FRAP, H₂O₂, and NO scavenging tests. The in vivo growth inhibitory activity against Ehrlich ascites carcinoma (EAC) in female BALB/c mice was determined using the trypan blue test. In EAC mice serum and ascites total oxidative status, total antioxidant reactivity, oxidative stress index, malondialdehyde, total thiols, total nitrites, 3-nitrotyrosine, and NFkB were measured. The phytochemical analysis found an significant content of phenols, with lignans having the highest concentration. The extract had an significant in vitro antioxidant effect and different inhibitory effects on different cell lines. After treatment of EAC mice with flaxseeds extract, body weight, ascites volume and viable tumour cell count, serum and ascites oxidative stress, and inflammatory markers decreased significantly. The ethanol flaxseeds extract has potential antiproliferative activity against some ovary and endometrial malignant cells and EAC. This effect can be attributed to the phenols content, and its antioxidant and anti-inflammatory activity.

Effect of a Novel Hydroxybenzoic Acid Based Mitochondria Directed Antioxidant Molecule on Bovine Sperm Function and Embryo Production

Sperm cells are particularly vulnerable to reactive oxygen species (ROS), impairing their fertilizing ability. Our objective was to study the effect of a novel mitochondrial-directed antioxidant, AntiOxBEN2, on bovine sperm function. This antioxidant was added to the semen capacitation medium (CAP), during the swim-up process, and to the fertilization medium (FERT) during the co-incubation of matured oocytes and capacitated spermatozoa, in concentrations of 0 (control), 1, and 10 µM. After the swim-up, sperm motility (CASA and visual analysis), vitality (eosin-nigrosin), mitochondrial membrane potential (JC1), intracellular ROS, adenosine triphosphate (ATP) levels, and basal metabolism (Seahorse Xfe96) were evaluated. Embryo development and quality were also assessed. Higher cleavage rates were obtained when 1 µM AntiOxBEN2 were added to CAP and FERT media (compared to control, p < 0.04). A positive effect of AntiOxBEN2 on intracellular ROS reduction (p = 0.01), on the increment of mitochondrial membrane potential (p ≤ 0.003) and, consequently, on the sperm quality was identified. However, the highest dose impaired progressive motility, ATP production, and the number of produced embryos. The results demonstrate a beneficial effect of AntiOxBEN2 (1 µM) on sperm capacitation and fertilization processes, thus improving embryonic development. This may constitute a putative novel therapeutic strategy to improve the outcomes of assisted reproductive techniques (ART).

A Report on Multi-Target Anti-Inflammatory Properties of Phytoconstituents from Monochoria hastata (Family: Pontederiaceae)

This study aims to investigate the potential analgesic properties of the crude extract of Monochoria hastata (MH) leaves using in vivo experiments and in silico analysis. The extract, in a dose-dependent manner, exhibited a moderate analgesic property (~54% pain inhibition in acetic acid-induced writhing test), which is significant (** p < 0.001) as compared to the control group. The complex inflammatory mechanism involves diverse pathways and they are inter-connected. Therefore, multiple inflammatory modulator proteins were selected as the target for in silico analysis. Computational analysis suggests that all the selected targets had different degrees of interaction with the phytochemicals from the extract. Rutin (RU), protocatechuic acid (PA), vanillic acid (VA), and ferulic acid (FA) could regulate multiple targets with a robust efficiency. None of the compounds showed selectivity to Cyclooxygenase-2 (COX-2). However, regulation of COX and lipoxygenase (LOX) cascade by PA can reduce non-steroidal analgesic drugs (NSAIDs)-related side effects, including asthma. RU showed robust regulation of cytokine-mediated pathways like RAS/MAPK and PI3K/NF-kB by inhibition of EGFR and IKBα (IKK), which may prevent multi-organ failure due to cytokine storm in several microbial infections, for example, SARS-CoV-2. Further investigation, using in vivo and in vitro experiments, can be conducted to develop multi-target anti-inflammatory drugs using the isolated compounds from the extract.

Tetrahydroxystilbene glucoside protects against sodium azide-induced mitochondrial dysfunction in human neuroblastoma cells

Objective

Mitochondrial dysfunction is evident in the early stage of Alzheimer’s disease (AD). Therefore development of drugs that protect mitochondrial function is a promising strategy for AD. The present work was to investigate the effects of 2, 3, 5, 4′-Tetrahydroxystilbene-2-O-β-d-glucosides (TSG) on a mitochondrial dysfunction cell model induced by sodium azide and elucidate the underlying mechanisms.

Methods

Mitochondrial membrane potential (MMP) was detected by a fluorescence method. Cellular adenosine triphosphate (ATP) level was measured using a firefly luciferase-based kit. Reactive oxygen species (ROS) was detected using dichlorofluorescin diacetate (DCFH-DA). The expression levels of Bcl-2 and Bax were measured by Western blotting assay. Flow cytometry was utilized to measure apoptosis.

Results

Pretreatment of TSG (25–200 μmol/L) for 24 h significantly elevated MMP and ATP content, reduced ROS level and Bax/Bcl-2 ratio, and inhibited apoptosis in SH-SY5Y cells exposed to sodium azide.

Conclusion

These results suggest that TSG protects SH-SY5Y cells against sodium azide-induced mitochondrial dysfunction and apoptosis. These findings are helpful to understand the protective effect of TSG on mitochondria, which are involved in the early stage of AD.

Fine-Tuning the Biological Profile of Multitarget Mitochondriotropic Antioxidants for Neurodegenerative Diseases

Neurotransmitter depletion and mitochondrial dysfunction are among the multiple pathological events that lead to neurodegeneration. Following our previous studies related with the development of multitarget mitochondriotropic antioxidants, this study aims to evaluate whether the π-system extension on the chemical scaffolds of AntiOXCIN2 and AntiOXCIN3 affects their bioactivity and safety profiles. After the synthesis of four triphenylphosphonium (TPP⁺) conjugates (compounds 2–5), we evaluated their antioxidant properties and their effect on neurotransmitter-metabolizing enzymes. All compounds were potent equine butyrylcholinesterase (eqBChE) and moderate electric eel acetylcholinesterase (eeAChE) inhibitors, with catechols 4 and 5 presenting lower IC₅₀ values than AntiOXCIN2 and AntiOXCIN3, respectively. However, differences in the inhibition potency and selectivity of compounds 2–5 towards non-human and human cholinesterases (ChEs) were observed. Co-crystallization studies with compounds 2–5 in complex with human ChEs (hChEs) showed that these compounds exhibit different binging modes to hAChE and hBChE. Unlike AntiOXCINs, compounds 2–5 displayed moderate human monoamine oxidase (hMAO) inhibitory activity. Moreover, compounds 4 and 5 presented higher ORAC-FL indexes and lower oxidation potential values than the corresponding AntiOXCINs. Catechols 4 and 5 exhibited broader safety windows in differentiated neuroblastoma cells than benzodioxole derivatives 2 and 3. Compound 4 is highlighted as a safe mitochondria-targeted antioxidant with dual ChE/MAO inhibitory activity. Overall, this work is a contribution for the development of dual therapeutic agents addressing both mitochondrial oxidative stress and neurotransmitter depletion.

Chemical Profiling, Antioxidant, Anticholinesterase, and Antiprotozoal Potentials of Artemisia copa Phil. (Asteraceae)

Artemisia copa Phil. (Asteraceae) (known as copa-copa) is a native species of Chile used as an infusion in traditional medicine by Atacameños people in the Altiplano, highlands of northern Chile. In this research, we have investigated for the first time the cholinesterase inhibition potential against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), and the chemical profiling of the infusions prepared from the aerial parts of A. copa by high resolution spectrometry. In addition, total phenolic, total flavonoid content, antioxidant (DPPH, FRAP, and ORAC) and antiprozoal activity were tested. Artemisia copa showed good inhibitory activity against AChE and BChE (3.92 ± 0.08 µg/ml and 44.13 ± 0.10 µg/ml). The infusion displayed a total phenolics content of 155.6 ± 2.9 mg of gallic acid equivalents/g and total flavonoid content of 5.5 ± 0.2 mg quercetin equivalents/g. Additionally, trypanocidal activity against Trypanosoma cruzi was found (LD₅₀ of 131.8 µg/ml). Forty-seven metabolites were detected in the infusion of A. copa including several phenolic acids and flavonoids which were rapidly identified using ultrahigh performance liquid chromatography orbitrap mass spectrometry analysis (UHPLC-Orbitrap-MS) for chemical profiling. The major compounds identified in the infusions were studied by molecular docking against AChE and BChE. The UHPLC-MS fingerprints generated can be also used for the authentication of these endemic species. These findings reveal that A. copa infusions can be used as beverages with protective effects.

Molecular Hybridization as a Tool in the Design of Multi-target Directed Drug Candidates for Neurodegenerative Diseases

Neurodegenerative Diseases (NDs) are progressive multifactorial neurological pathologies related to neuronal impairment and functional loss from different brain regions. Currently, no effective treatments are available for any NDs, and this lack of efficacy has been attributed to the multitude of interconnected factors involved in their pathophysiology. In the last two decades, a new approach for the rational design of new drug candidates, also called multitarget-directed ligands (MTDLs) strategy, has emerged and has been used in the design and for the development of a variety of hybrid compounds capable to act simultaneously in diverse biological targets. Based on the polypharmacology concept, this new paradigm has been thought as a more secure and effective way for modulating concomitantly two or more biochemical pathways responsible for the onset and progress of NDs, trying to overcome low therapeutical effectiveness. As a complement to our previous review article (Curr. Med. Chem. 2007, 14 (17), 1829-1852. https://doi.org/10.2174/092986707781058805), herein we aimed to cover the period from 2008 to 2019 and highlight the most recent advances of the exploitation of Molecular Hybridization (MH) as a tool in the rational design of innovative multifunctional drug candidate prototypes for the treatment of NDs, specially focused on AD, PD, HD and ALS.

Novel benzoic acid derivatives: Synthesis and biological evaluation as multitarget acetylcholinesterase and carbonic anhydrase inhibitors

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by dementia, memory impairment, cognitive dysfunction, and speech impairment. The utility of cholinergic replacement by acetylcholinesterase (AChE) inhibitors in AD treatment has been well documented so far. Recently, studies have also evidenced that human carbonic anhydrases (hCAs) serve as an important target for AD treatment. In this direction, the improvement of new multitarget drugs, which can simultaneously modulate several mechanisms or targets included in the AD pathway, may be a potent strategy to treat AD. In light of these data for understanding and developing AD-related multitarget AChE and hCAs inhibitors, in this study, novel methylene-aminobenzoic acid and tetrahydroisoquinolynyl-benzoic acid derivatives (4a-g and 6a-g) were designed. The synthesized analogs were experimentally validated for their effects by in vitro and direct enzymatic tests. Also, the compounds were subjected to in silico monitoring with Schrödinger Suite software to assign binding affinities of potential derivatives based on Glide XP scoring, molecular mechanics-generalized Born surface area computing, and validation by molecular docking. The results revealed that 6c (1,3-dimethyldihydropyrimidine-2,4-(1H,3H)-dione-substituted, K_I  value of 33.00 ± 0.29 nM), 6e (cyclohexanone-substituted, K_I  value of 18.78 ± 0.09 nM), and 6f (2,2-dimethyl-1,3-dioxan-4-one-substituted, K_I  value of 13.62 ± 0.21 nM) from the benzoic acid derivatives in this series were the most promising derivatives, as they exhibited a good multifunctional inhibition at all experimental levels and in the in silico validation against hCA I, hCA II, and AChE, respectively, for the treatment of AD.

A small-molecule ARTS mimetic promotes apoptosis through degradation of both XIAP and Bcl-2

Many human cancers over-express B cell lymphoma 2 (Bcl-2) or X-linked inhibitor of apoptosis (IAP) proteins to evade cell death. The pro-apoptotic ARTS (Sept4_i2) protein binds directly to both Bcl-2 and XIAP and promotes apoptosis by stimulating their degradation via the ubiquitin-proteasome system (UPS). Here we describe a small molecule, A4, that mimics the function of ARTS. Microscale thermophoresis assays showed that A4 binds XIAP, but not cellular inhibitor of apoptosis protein 1 (cIAP1). A4 binds to a distinct ARTS binding pocket in the XIAP-BIR3 (baculoviral IAP repeat 3) domain. Like ARTS, A4 stimulated poly-ubiquitylation and UPS-mediated degradation of XIAP and Bcl-2, but not cIAP1, resulting in caspase-9 and -3 activation and apoptosis. In addition, over-expression of XIAP rescued HeLa cells from A4-induced apoptosis, consistent with the idea that A4 kills by antagonizing XIAP. On the other hand, treatment with the SMAC-mimetic Birinapant induced secretion of tumour necrosis factor-α (TNFα) and killed ~50% of SKOV-3 cells, and addition of A4 to Birinapant-treated cells significantly reduced secretion of TNFα and blocked Birinapant-induced apoptosis. This suggests that A4 acts by specifically targeting XIAP. The effect of A4 was selective as peripheral blood mononuclear cells and normal human breast epithelial cells were unaffected. Furthermore, proteome analysis revealed that cancer cell lines with high levels of XIAP were particularly sensitive to the killing effect of A4. These results provide proof of concept that the ARTS binding site in XIAP is "druggable". A4 represents a novel class of dual-targeting compounds stimulating apoptosis by UPS-mediated degradation of important anti-apoptotic oncogenes.

Discovery of Helminthosporin, an Anthraquinone Isolated from Rumex abyssinicus Jacq as a Dual Cholinesterase Inhibitor

Natural products have extensively contributed toward the discovery of new leads for Alzheimer's disease. During our search for new inhibitors of cholinesterase enzymes from natural sources, the ethyl acetate (EtOAc) extract of Rumex abyssinicus Jacq was identified as a dual cholinesterase inhibitor with IC₅₀ values of 2.7 and 11.4 μg/mL against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), respectively. The phytochemical investigation of the EtOAc extract has resulted in isolation of four anthraquinones, namely, helminthosporin, emodin, chrysophanol, and physcion, amongst which the helminthosporin has been isolated for the first time from Rumex sp. All isolated secondary metabolites have displayed significant inhibition of EeAChE with IC₅₀ values of 2.63, 15.21, 33.7, and 12.16 μM, respectively. In addition, the helminthosporin was also found to inhibit BChE with an IC₅₀ value of 2.99 μM. The enzyme kinetic study has indicated that helminthosporin inhibits AChE and BChE in a noncompetitive manner with k _i values of 10.3 and 12.3 μM, respectively. The results of molecular modeling and propidium iodide displacement assay have revealed that helminthosporin occupies the peripheral anionic site of the active site gorge of AChE. In the PAMPA-BBB permeability assay, helminthosporin was found to possess high BBB permeability (P _e = 6.16 × 10^-6 cm/s). In a nutshell, helminthosporin has been identified as a brain permeable dual cholinesterase inhibitor, and thus its further synthetic exploration is warranted for optimization of its potency.

Alzheimer's Disease Pharmacotherapy in Relation to Cholinergic System Involvement

Alzheimer’s disease, a major and increasing global health challenge, is an irreversible, progressive form of dementia, associated with an ongoing decline of brain functioning. The etiology of this disease is not completely understood, and no safe and effective anti-Alzheimer’s disease drug to prevent, stop, or reverse its evolution is currently available. Current pharmacotherapy concentrated on drugs that aimed to improve the cerebral acetylcholine levels by facilitating cholinergic neurotransmission through inhibiting cholinesterase. These compounds, recognized as cholinesterase inhibitors, offer a viable target across key sign domains of Alzheimer’s disease, but have a modest influence on improving the progression of this condition. In this paper, we sought to highlight the current understanding of the cholinergic system involvement in Alzheimer’s disease progression in relation to the recent status of the available cholinesterase inhibitors as effective therapeutics.

Optimizing the Synthetic Route of Chromone-2-carboxylic Acids: A Step forward to Speed-Up the Discovery of Chromone-Based Multitarget-Directed Ligands

6-Bromochromone-2-carboxylic acid (3) was synthesized by a microwave-assisted process. The optimization of the reaction was performed varying parameters, such as type of base/number of reagent equivalents, solvent, temperature and reaction time. The yield of the reaction was improved to 87%. The new synthetic route is versatile as several chromone-2-carboxylic acids (compounds 4B-10B) were obtained with good yields (54-93%). Only in the case of the nitro substituent (compound 11B), an ester was obtained instead of the desired carboxylic acid. Following this synthetic route chromone carboxylic acids can be attained with a high degree of purity, without the need of the tedious and expensive purification processes through column chromatography. The reaction is safe, cost-effective, fast and robust, and can be used in the development of concise and diversity-oriented libraries based on chromone scaffold. The overall study can be looked as a step forward to speed-up the discovery of chromone-based multitarget-directed ligands.

Catechol thioethers with physiologically active fragments: Electrochemistry, antioxidant and cryoprotective activities

A number of asymmetrical thioethers based on 3,5-di-tert-butylcatechol containing sulfur atom bonding with physiologically active groups in the sixth position of aromatic ring have been synthesized and the electrochemical properties, antioxidant, cryoprotective activities of new thioethers have been evaluated. Cyclic voltammetry was used to estimate the oxidation potentials of thioethers in acetonitrile. The electrooxidation of compounds at the first stage leads to the formation of o-benzoquinones. The antioxidant activities of the compounds were determined using 2,2'-diphenyl-1-picrylhydrazyl radical (DPPH) assay, experiments on the oxidative damage of the DNA, the reaction of 2,2'-azobis(2-amidinopropane hydrochloride) (AAPH) induced glutathione depletion (GSH), the process of lipid peroxidation of rat liver (Wistar) homogenates in vitro, and iron(II) chelation test. Compounds 1-9 have greater antioxidant effectiveness than 3,5-di-tert-butylcatechol (CatH₂) in all assays. The variation of physiologically active groups at sulfur atom allows to regulate lipophilic properties and antioxidant activity of compounds. Thioethers 3, 4 and 7 demonstrate the combination of radical scavenging, antioxidant activity and iron(II) binding properties. The researched compounds 1-9 were studied as possible cryoprotectants of the media for cryopreservation of the Russian sturgeon sperm. Novel cryoprotective additives in cryomedium reduce significantly the content of membrane-permeating agent (DMSO). A cryoprotective effect of an addition of the catechol thioethers depends on the structure of groups at sulfur atom. The cryoprotective properties of compounds 3, 4 and 7 are caused by combination of catechol fragment, bonded by a thioether linker with a long hydrocarbon chain and a terminal ionizable group or with a biologically relevant acetylcysteine residue.

Benzoic acid-derived nitrones: A new class of potential acetylcholinesterase inhibitors and neuroprotective agents

The discovery of new chemical entities endowed with potent and selective acetylcholinesterase (AChE) and/or butyrylcholinesterase (BChE) inhibitory activity is still a relevant subject for Alzheimer's disease therapy. Therefore, a small library of benzoic based amide nitrones (compounds 24 to 42) was synthesized and screened toward cholinesterase enzymes. SAR studies showed that the tert-butyl moiety is the most favourable nitrone pattern. In general, tert-butyl derivatives effectively inhibited AChE, being compound 33 the most potent (IC₅₀ = 8.3 ± 0.3 μM; Ki 5.2 μM). The data pointed to a non-competitive inhibition mechanism of action, which was also observed for the standard donepezil. None of compounds showed BChE inhibitory activity. Molecular modelling studies provided insights into the enzyme-inhibitor interactions and rationalised the experimental data, confirming that the binding mode of nitrones 33 and 38 towards AChE has the most favourable binding free energy. The tert-butylnitrones 33 and 38 were not cytotoxic on different cell lines (SH-SY5Y and HepG2). Moreover, compound 33 was able to prevent t-BHP-induced oxidative stress in SH-SY5Y differentiated cells. Due to its AChE selectivity and promising cytoprotective properties, as well as its appropriate drug-like profile pointing toward blood-brain barrier permeability, compound 33 is proposed as a valid lead for a further optimization step.

Reconsideration of Anticholinesterase Therapeutic Strategies against Alzheimer's Disease

Alzheimer's disease (AD) is well-known as a severe neurodegeneration disease involving complicated etiologies, and cholinesterase inhibition remain the prevailing mode of clinical intervention in AD management. Although most clinically applied cholinesterase inhibitors (ChEIs) achieve limited clinical outcomes, research on the central cholinergic system is still thriving. Recently, an impressive amount of knowledge regarding novel acetylcholinesterase functions, as well as the close association between the central cholinergic system and other key elements for AD pathogenesis, has accumulated, highlighting that this field still has great potential for future drug development. In contrast to the overwhelmingly disappointing clinical therapeutic effects of various disease-modifying drug candidates, interesting evidence has continued to emerge over the past 20 years from the wealth of preclinical and clinical data on the usage of ChEIs, indicating underestimated clinical benefits due to physician ambivalence, a lack of persistent treatment, and inappropriate medication times or doses. Here we pinpoint several topics fit for future attention, focusing on the updated cholinergic hypothesis, especially the pleiotropic relationships with key pathogenetic signaling pathways and functions in AD, as well as possible novel therapeutic strategies, including novel ChEIs and cholinesterase inhibition-based innovative multifunctional therapeutic candidates. We intend to strengthen the future value of the precise application of cholinergic drugs, especially novel ChEIs, as a cornerstone pharmacological approach to AD treatment, either alone or in combination with other targets, to relieve symptoms and to modify disease progression.