Mitochondria-Targeted Protective Compounds in Parkinson's and Alzheimer's Diseases

Hypericum perforatum: a comprehensive review on pharmacognosy, preclinical studies, putative molecular mechanism, and clinical studies in neurodegenerative diseases

The herb Hypericum perforatum, also referred to as St. John's wort, has drawn a lot of interest because of its potential therapeutic benefits in treating neurodegenerative illnesses. Due to the absence of effective therapies, illnesses like Alzheimer's and Parkinson's disease pose an increasing worldwide health concern. Because of its wide variety of phytochemicals, especially hyperforin, and hypericin, Hypericum perforatum is well known for its neuroprotective properties. These substances have proven to be able to affect different cellular processes linked to neurodegeneration. They can act as anti-inflammatory, antioxidant, and neurotransmitter system regulators, which may help halt neurodegenerative illnesses' progression. The use of Hypericum perforatum extracts and its contents has shown encouraging results in research on animal models of neurodegenerative disorders. These advantages include higher nerve cell survival, lowered oxidative stress, and higher cognitive performance. Underscoring its versatile potential to combat neurodegeneration, Hypericum perforatum has neuroprotective mechanisms that modulate neuroinflammation and prevent apoptotic pathways. In conclusion, Hypericum perforatum shows tremendous promise as a potential treatment for neurological illnesses due to its wide variety of phytochemicals. To completely comprehend its specific mechanisms of action and turn these discoveries into efficient clinical therapies, additional research is needed. Investigating Hypericum perforatum's function in neurodegenerative disorders may present new opportunities for the advancement of ground-breaking therapeutic strategies.

The emerging role of ATP as a cosolute for biomolecular processes

ATP is an important small molecule that appears at outstandingly high concentration within the cellular medium. Apart from its use as a source of energy and a metabolite, there is increasing evidence for important functions as a cosolute for biomolecular processes. Owned to its solubilizing kosmotropic triphosphate and hydrophobic adenine moieties, ATP is a versatile cosolute that can interact with biomolecules in various ways. We here use three models to categorize these interactions and apply them to review recent studies. We focus on the impact of ATP on biomolecular solubility, folding stability and phase transitions. This leads us to possible implications and therapeutic interventions in neurodegenerative diseases.

Caffeine improves mitochondrial function in PINK1B9-null mutant Drosophila melanogaster

Mitochondrial dysfunction plays a central role in Parkinson's disease (PD) and can be triggered by xenobiotics and mutations in mitochondrial quality control genes, such as the PINK1 gene. Caffeine has been proposed as a secondary treatment to relieve PD symptoms mainly by its antagonistic effects on adenosine receptors (ARs). Nonetheless, the potential protective effects of caffeine on mitochondrial dysfunction could be a strategy in PD treatment but need further investigation. In this study, we used high-resolution respirometry (HRR) to test caffeine's effects on mitochondrial dysfunction in PINK1^B9-null mutants of Drosophila melanogaster. PINK1 loss-of-function induced mitochondrial dysfunction in PINK1^B9-null flies observed by a decrease in O₂ flux related to oxidative phosphorylation (OXPHOS) and electron transfer system (ETS), respiratory control ratio (RCR) and ATP synthesis compared to control flies. Caffeine treatment improved OXPHOS and ETS in PINK^B9-null mutant flies, increasing the mitochondrial O₂ flux compared to untreated PINK^B9-null mutant flies. Moreover, caffeine treatment increased O₂ flux coupled to ATP synthesis and mitochondrial respiratory control ratio (RCR) in PINK 1^B9-null mutant flies. The effects of caffeine on respiratory parameters were abolished by rotenone co-treatment, suggesting that caffeine exerts its beneficial effects mainly by stimulating the mitochondrial complex I (CI). In conclusion, we demonstrate that caffeine may improve mitochondrial function by increasing mitochondrial OXPHOS and ETS respiration in the PD model using PINK1 loss-of-function mutant flies.

Pathological and Therapeutic Advances in Parkinson's Disease: Mitochondria in the Interplay

Parkinson's disease (PD) is the second most common neurodegenerative illness majorly affecting the population between the ages of 55 to 65 years. Progressive dopaminergic neuronal loss and the collective assemblage of misfolded alpha-synuclein in the substantia nigra, remain notable neuro-pathological hallmarks of the disease. Multitudes of mechanistic pathways have been proposed in attempts to unravel the pathogenesis of PD but still, it remains elusive. The convergence of PD pathology is found in organelle dysfunction where mitochondria remain a major contributor. Mitochondrial processes like bioenergetics, mitochondrial dynamics, and mitophagy are under strict regulation by the mitochondrial genome and nuclear genome. These processes aggravate neurodegenerative activities upon alteration through neuroinflammation, oxidative damage, apoptosis, and proteostatic stress. Therefore, the mitochondria have grabbed a central position in the patho-mechanistic exploration of neurodegenerative diseases like PD. The management of PD remains a challenge to physicians to date, due to the variable therapeutic response of patients and the limitation of conventional chemical agents which only offer symptomatic relief with minimal to no disease-modifying effect. This review describes the patho-mechanistic pathways involved in PD not only limited to protein dyshomeostasis and oxidative stress, but explicit attention has been drawn to exploring mechanisms like organelle dysfunction, primarily mitochondria and mitochondrial genome influence, while delineating the newer exploratory targets such as GBA1, GLP, LRRK2, and miRNAs and therapeutic agents targeting them.

Mitochondria - Nucleus communication in neurodegenerative disease. Who talks first, who talks louder?

Mitochondria - nuclear coadaptation has been central to eukaryotic evolution. The dynamic dialogue between the two compartments within the context of multiorganellar interactions is critical for maintaining cellular homeostasis and directing the balance survival-death in case of cellular stress. The conceptualisation of mitochondria - nucleus communication has so far been focused on the communication from the mitochondria under stress to the nucleus and the consequent signalling responses, as well as from the nucleus to mitochondria in the context of DNA damage and repair. During ageing processes this dialogue may be better viewed as an integrated bidirectional 'talk' with feedback loops that expand beyond these two organelles depending on physiological cues. Here we explore the current views on mitochondria - nucleus dialogue and its role in maintaining cellular health with a focus on brain cells and neurodegenerative disease. Thus, we detail the transcriptional responses initiated by mitochondrial dysfunction in order to protect itself and the general cellular homeostasis. Additionally, we are reviewing the knowledge of the stress pathways initiated by DNA damage which affect mitochondria homeostasis and we add the information provided by the study of combined mitochondrial and genotoxic damage. Finally, we reflect on how each organelle may take the lead in this dialogue in an ageing context where both compartments undergo accumulation of stress and damage and where, perhaps, even the communications' mechanisms may suffer interruptions.

Modulation of Cellular Circadian Rhythms by Secondary Metabolites of Lichens

Background

Most mammalian cells harbor molecular circadian clocks that synchronize physiological functions with the 24-h day-night cycle. Disruption of circadian rhythms, through genetic or environmental changes, promotes the development of disorders like obesity, cardiovascular diseases, and cancer. At the cellular level, circadian, mitotic, and redox cycles are functionally coupled. Evernic (EA) and usnic acid (UA), two lichen secondary metabolites, show various pharmacological activities including anti-oxidative, anti-inflammatory, and neuroprotective action. All these effects have likewise been associated with a functional circadian clock.

Hypothesis/Purpose

To test, if the lichen compounds EA and UA modulate circadian clock function at the cellular level.

Methods

We used three different cell lines and two circadian luminescence reporter systems for evaluating dose- and time-dependent effects of EA/UA treatment on cellular clock regulation at high temporal resolution. Output parameters studied were circadian luminescence rhythm period, amplitude, phase, and dampening rate.

Results

Both compounds had marked effects on clock rhythm amplitudes and dampening independent of cell type, with UA generally showing a higher efficiency than EA. Only in fibroblast cells, significant effects on clock period were observed for UA treated cells showing shorter and EA treated cells showing longer period lengths. Transient treatment of mouse embryonic fibroblasts at different phases had only minor clock resetting effects for both compounds.

Conclusion

Secondary metabolites of lichen alter cellular circadian clocks through amplitude reduction and increased rhythm dampening.

Peanut (Arachis hypogaea) sprout prevents high-fat diet-induced cognitive impairment by improving mitochondrial function

This study was performed to evaluate the improvement effect of the ethyl acetate fraction from peanut (Arachis hypogaea) sprout (EFPS) on high-fat diet (HFD)-induced cognitive deficits in C57BL/6 mice. Mice were randomly divided four groups (n = 13) as control (normal chow), HFD, EFPS 20 (20 mg/kg of body weight; intragastric administration) and EFPS 50 (50 mg/kg of body weight; intragastric administration) groups. HFD was provide for 15 weeks excepting control group. EFPS ameliorated cognitive dysfunction in Y-maze, passive avoidance test and Morris water maze test. EFPS significantly improved glucose tolerance and serum lipid profile, and reduced body weight. EFPS ameliorated oxidative stress by regulating MDA levels and SOD activity in liver and brain tissues. In addition, EFPS restored brain mitochondrial dysfunction related to energy metabolism. Moreover, the bioactive compounds of EFPS were identified as di-caffeic acid, caffeic acid, dihydrokaempferol-hexoside, di-p-coumaroyl tartaric acid isomer and group B soyasaponins using ultra-performance liquid chromatography-quadrupole-time-of-flight (UPLC-Q-TOF) mass spectrometry. These results show that EFPS can improve cognitive functions in HFD-induced diabetic mice.

Mechanisms associated with the dysregulation of mitochondrial function due to lead exposure and possible implications on the development of Alzheimer's disease

Lead (Pb) is a multimedia contaminant with various pathophysiological consequences, including cognitive decline and neural abnormalities. Recent findings have reported an association of Pb toxicity with Alzheimer's disease (AD). Studies have revealed that mitochondrial dysfunction is a pathological characteristic of AD. According to toxicology reports, Pb promotes mitochondrial oxidative stress by lowering complex III activity in the electron transport chain, boosting reactive oxygen species formation, and reducing the cell's antioxidant defence system. Here, we review recent advances in the role of mitochondria in Pb-induced AD pathology, as well as the mechanisms associated with the mitochondrial dysfunction, such as the depolarisation of the mitochondrial membrane potential, mitochondrial permeability transition pore opening; mitochondrial biogenesis, bioenergetics and mitochondrial dynamics alterations; and mitophagy and apoptosis. We also discuss possible therapeutic options for mitochondrial-targeted neurodegenerative disease (AD).

Mitochondrial Transplantation Attenuates Cerebral Ischemia-Reperfusion Injury: Possible Involvement of Mitochondrial Component Separation

Background

Mitochondrial dysfunctions play a pivotal role in cerebral ischemia-reperfusion (I/R) injury. Although mitochondrial transplantation has been recently explored for the treatment of cerebral I/R injury, the underlying mechanisms and fate of transplanted mitochondria are still poorly understood.

Methods

Mitochondrial morphology and function were assessed by fluorescent staining, electron microscopy, JC-1, PCR, mitochondrial stress testing, and metabolomics. Therapeutic effects of mitochondria were evaluated by cell viability, reactive oxygen species (ROS), and apoptosis levels in a cellular hypoxia-reoxygenation model. Rat middle cerebral artery occlusion model was applied to assess the mitochondrial therapy in vivo. Transcriptomics was performed to explore the underlying mechanisms. Mitochondrial fate tracking was implemented by a variety of fluorescent labeling methods.

Results

Neuro-2a (N2a) cell-derived mitochondria had higher mitochondrial membrane potential, more active oxidative respiration capacity, and less mitochondrial DNA copy number. Exogenous mitochondrial transplantation increased cellular viability in an oxygen-dependent manner, decreased ROS and apoptosis levels, improved neurobehavioral deficits, and reduced infarct size. Transcriptomic data showed that the differential gene enrichment pathways are associated with metabolism, especially lipid metabolism. Mitochondrial tracking indicated specific parts of the exogenous mitochondria fused with the mitochondria of the host cell, and others were incorporated into lysosomes. This process occurred at the beginning of internalization and its efficiency is related to intercellular connection.

Conclusions

Mitochondrial transplantation may attenuate cerebral I/R injury. The mechanism may be related to mitochondrial component separation, altering cellular metabolism, reducing ROS, and apoptosis in an oxygen-dependent manner. The way of isolated mitochondrial transfer into the cell may be related to intercellular connection.

1,5-Benzodiazepin-2(3H)-ones: In Vitro Evaluation as Antiparkinsonian Agents

A new series of twenty-three 1,5-benzodiazepin-2(3H)-ones were synthesized and evaluated in the 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS), ferric reducing antioxidant power (FRAP), and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assays as a new chemotype with antioxidant and good drug-like properties. All of the derivatives showed low cytotoxicity in comparison to curcumin against the human neuroblastoma SH-SY5Y and the human hepatoma HepG2 cell lines. Experimental solubility in bio-relevant media showed a good relationship with melting points in this series. Five compounds with the best antioxidant properties showed neuroprotectant activity against H₂O₂-induced oxidative stress in the SH-SY5Y cell line. From them, derivatives 4-phenyl-1H-1,5-benzodiazepin-2(3H)-one (18) and 4-(3,4,5-trimethoxyphenyl)-1H-1,5-benzodiazepin-2(3H)-one (20) yielded good neuroprotection activity in the same neuronal cell line under 6-OHD and MPP⁺ insults as in vitro models of mitochondrial dysfunction and oxidative stress in Parkinson’s disease (PD). Both compounds also demonstrated a significant reduction of intracellular Reactive Oxygen Species (ROS) and superoxide levels, in parallel with a good improvement of the Mitochondrial Membrane Potential (ΔΨm). Compared with curcumin, compound 18 better reduced lipid peroxidation levels, malondialdehyde (MDA), in SH-SY5Y cells under oxidative stress pressure and recovered intracellular glutathione synthetase (GSH) levels. Apoptosis and caspase-3 levels of SH-SY5Y under H₂O₂ pressure were also reduced after treatment with 18. Neuroprotection in neuron-like differentiated SH-SY5Y cells was also achieved with 18. In summary, this family of 1,5-benzodiazepin-2-ones with an interesting antioxidant and drug-like profile, with low cytotoxic and good neuroprotectant activity, constitutes a new promising chemical class with high potential for the development of new therapeutic agents against PD.

Korean red ginseng decreases 1-methyl-4-phenylpyridinium-induced mitophagy in SH-SY5Y cells

OBJECTIVE

Mitophagy is known to contribute towards progression of Parkinson's disease. Korean red ginseng (KRG) is a widely used medicinal herb in East Asia, and recent studies have reported that KRG prevents 1-methyl-4-phenylpyridinium ion (MPP⁺)-induced cell death. This study was undertaken to investigate whether KRG suppresses MPP⁺-induced apoptosis and mitophagy.

METHODS

SH-SY5Y cells were incubated with KRG for 24 h, and subsequently exposed to MPP⁺. The MPP⁺-induced cell death was confirmed with the 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay, and the terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling assay. Changes in the structure and function of mitochondria were confirmed using mitotracker, MitoSOX red mitochondrial superoxide indicator, parkin, and phosphatase and tensin homolog deleted on chromosome ten-induced putative kinase 1 (PINK1) immunofluorescent staining. Western blotting was performed to evaluate the expression of apoptosis-related factors in whole cells, including Bax, Bcl-2 and cleaved caspase-3, and mitophagy-related factors in the mitochondrial fraction, including cytochrome c, parkin, PINK1, translocase of the outer membrane 20 (TOM20), p62 and Beclin 1.

RESULTS

MPP⁺ induced cell death by cytochrome c release and caspase-3 activation; however, this effect was suppressed by KRG's regulation of the expressions of Bcl-2 and Bax. Moreover, MPP⁺ exposure increased the mitochondrial expressions of parkin, PINK1, Beclin 1 and p62, and decreased TOM20, cytochrome c and Bcl-2 expressions. These MPP⁺-induced changes in the mitochondrial fraction were attenuated by treatment with KRG.

CONCLUSION

KRG effectively prevents MPP⁺-induced SH-SY5Y cell death by regulating cytochrome c release from mitochondria and PINK1/parkin-mediated mitophagy, through regulation of the Bcl-2 family.

Healthy dietary intake moderates the effects of age on brain iron concentration and working memory performance

Age-related brain iron accumulation is linked with oxidative stress, neurodegeneration and cognitive decline. Certain nutrients can reduce brain iron concentration in animal models, however, this association is not well established in humans. Moreover, it remains unknown if nutrition can moderate the effects of age on brain iron concentration and/or cognition. Here, we explored these issues in a sample of 73 healthy older adults (61-86 years old), while controlling for several factors such as age, gender, years of education, physical fitness and alcohol-intake. Quantitative susceptibility mapping was used for assessment of brain iron concentration and participants performed an N-Back paradigm to evaluate working memory performance. Nutritional-intake was assessed via a validated questionnaire. Nutrients were grouped into nutrition factors based on previous literature and factor analysis. One factor, comprised of vitamin E, lysine, DHA omega-3 and LA omega-6 PUFA, representing food groups such as nuts, healthy oils and fish, moderated the effects of age on both brain iron concentration and working memory performance, suggesting that these nutrients may slow the rate of brain iron accumulation and working memory declines in aging.

Ghrelin protects against rotenone-induced cytotoxicity: Involvement of mitophagy and the AMPK/SIRT1/PGC1α pathway

Parkinson's disease (PD) is the second most common neurodegenerative disorder, characterized by the loss of dopaminergic neurons in the substantia nigra and the deposition of Lewy bodies. Mitochondrial dysfunction, oxidative stress, and autophagy dysfunction are involved in the pathogenesis of PD. Ghrelin is a brain-gut peptide that has been reported that protected against 1-methyl-4-phenyl-1,2,3,6- tetrahydropyran (MPTP)/MPP⁺-induced toxic effects. In the present work, human neuroblastoma SH-SY5Y cells were exposed to rotenone as a PD model to explore the underlying mechanism of ghrelin. We found that ghrelin inhibited rotenone-induced cytotoxicity, mitochondrial dysfunction, and apoptosis by improving cell viability, increasing the ratio of red/green of JC-1, inhibiting the production of reactive oxidative species (ROS), and regulating Bcl-2, Bax, Cytochrome c, caspase-9, and caspase-3 expression. Besides, ghrelin promoted mitophagy accompanied by up-regulating microtubule-associated protein 1 Light Chain 3B-II/I(LC3B-II/I) and Beclin1 but decreasing the expression of p62. Moreover, ghrelin promoted PINK1/Parkin mitochondrial translocation. Additionally, we investigated that ghrelin activated the AMPK/SIRT1/PGC1α pathway and pharmacological inhibition of AMPK and SIRT1 abolished the cytoprotection of ghrelin, decreased the level of mitophagy, and PINK1/Parkin mitochondrial translocation. Taken together, our findings suggested that mitophagy and AMPK/SIRT1/PGC1α pathways were related to the cytoprotection of ghrelin. These findings provided novel insights into the underlying mechanisms of ghrelin, further mechanistic studies on preclinical and clinical levels are required to be conducted with ghrelin to avail and foresee it as a potential agent in the treatment and management of PD.

Novel brain-targeting 3-n-butylphthalide prodrugs for ischemic stroke treatment

Currently, ischemic stroke is the leading cause of disability and death worldwide, and the performance of corresponding drugs is often unsatisfactory owing to the complex pathological processes and the impediment of the blood-brain barrier (BBB). Here, we employed various tertiary amino groups, including different linear, cyclic, and bimolecular drug structures, to modify 3-n-butylphthalide (NBP), a natural product used for ischemic stroke treatment, which has poor bioavailability, to generate a series of six prodrugs. These prodrugs showed significantly improved solubility and cellular uptake, which were primarily driven by putative pyrilamine cationic transporters. They also displayed more efficient brain delivery in vivo, reaching as high as 21.5-fold brain accumulation increase compared with NBP, leading to much higher bioavailability and stronger therapeutic effects. The toxicity of these molecules is also lower or similar to that of unmodified NBP. We showed that the tertiary amino group-modified NBP prodrugs are effective and safe for treating ischemic stroke with significantly enhanced druggability; hence, they have potential for further clinical development.

Neuroprotective effects of allocryptopine-rich alkaloid extracts against oxidative stress-induced neuronal damage

BACKGROUND

Oxidative stress is a significant feature in the pathomechanism of neurodegenerative diseases. Thus, the search for an effective and safe novel antioxidant agent with neuroprotective properties has increased the interest in medicinal plant products as a bioactive phytochemical source. However, little is known about the potential effects of the medically important Glaucium corniculatum as a natural antioxidant.

OBJECTIVE

In the present study, it was aimed to investigate the anti-oxidative, anti-apoptotic, and cell cycle regulatory mechanisms underlying the neuroprotective effects of alkaloid extracts (chloroform, methanol, and water) from G. corniculatum, which was profiled for major alkaloid/alkaloids, against H₂O₂-induced neuronal damage in differentiated PC12 cells.

MATERIALS AND METHODS

The profiles of the alkaloid extracts were analyzed by GC-MS. The effects of the alkaloid extracts on intracellular ROS production, level of apoptotic cells, and cell cycle dysregulation were analyzed by flow cytometry; the effects on mRNA expression of apoptosis-related genes were also analyzed by qRT-PCR.

RESULTS

The same alkaloid components, allocryptopine, tetrahydropalmatine, and tetrahydroberberine N-oxide were obtained in all three solvents, but the ratios of the components differed according to the solvents. Allocryptopine was determined to be the major alkaloid ingredient in the alkaloid extracts, with the highest amount of allocryptopine (497 μg/mg) being found in the chloroform alkaloid extract (CAE) (*p < 0.05). The best results were obtained from CAE, which has the highest amount of allocryptopine among alkaloid extracts in all studies. CAE suppressed intracellular ROS production (5.7-fold), percentage of apoptotic cells (3.0-fold), and cells in the sub G1 phase (6.8-fold); additionally, it increased cells in the G1 phase (1.5-fold) (**p < 0.01). CAE remarkably reduced the expressions of Bax, Caspase-9/-3 mRNA (2.4-3.5-fold) while increasing the expression of Bcl-2 mRNA (3.0-fold) (*p < 0.05).

CONCLUSIONS

Our results demonstrated that alkaloid extracts from G. corniculatum, which contain allocryptopine, tetrahydropalmatine, and tetrahydroberberine N-oxide suppressed oxidative stress-induced neuronal apoptosis, possibly by suppressing the mitochondrial apoptotic pathway and regulating the cell cycle. These results are the first report that related alkaloids have played a neuroprotective role by regulating multiple mechanisms. Thus, our study indicated that these alkaloids especially allocryptopine could offer an efficient and novel strategy to explore novel drugs for neuroprotection and cognitive improvement.

Protective Effects of Silymarin Against D-Gal/LPS-Induced Organ Damage and Inflammation in Mice

AIM

Silymarin contains various flavonoids and exhibits antioxidative, anti-inflammatory, and anticancer effects, in addition to other pharmacological properties. This study explored the alleviating effect of silymarin on multiple-organ damage induced by D-galactose/lipopolysaccharide in Kunming mice.

METHODS

Kunming mice were injected intraperitoneally with D-galactose (30 mg/kg·BW)/LPS (3 μg/kg·BW) and then treated using silymarin with different doses (75 mg/kg·bw and 150 mg/kg·bw) via intragastric administration. Changes in organ indexes, pathological changes, liver-function index, biochemical indexes, molecular biological indexes, and genes related to the oxidation and inflammation of main organs were evaluated.

RESULTS

After the mice were treated with silymarin, their body weight showed no significant change, and the liver, kidney, and lung indexes of the treated mice were higher than those of the model group; meanwhile, the corresponding histopathological formation was reduced. Compared with the model group, the silymarin-treated group showed reductions in ALT, AST, and liver function indexes in the mouse serum. Silymarin treatment also increased the SOD, CAT, GSH, GSH-Px, T-AOC, IL-10, and IL-12 levels, as well as reduced the MDA, NO, IL-6, IL-1β, TNF-α, IFN-γ levels in the mouse serum and liver tissues. In addition, quantitative polymerase chain reaction analysis indicated that the mRNA expression levels of SOD1, SOD2, CAT, GSH-Px, IL-10, Nrf2, HO-1, NQO1, Trx, and IκB-α were higher in the liver tissue of the silymarin-treated mice than in those of the model group; meanwhile, the mRNA expression levels of IL-6, IL-1β, TNF-α, IFN-γ, NF-κB, NLRP3, COX2, and p38 were lower than those in the model group.

CONCLUSION

Silymarin, which exhibits antioxidative and anti-inflammatory effects, can alleviate the liver, lung, and kidney damage induced by D-galactose/lipopolysaccharide. High-dose (150 mg/kg·bw) silymarin can more effectively inhibit organ damage, compared with low-dose silymarin (75 mg/kg·bw) in Kunming mice.

Pyrroloquinoline quinone promotes mitochondrial biogenesis in rotenone-induced Parkinson's disease model via AMPK activation

Mitochondrial dysfunction is considered to be one of the important pathogenesis in Parkinson's disease (PD). We previously showed that pyrroloquinoline quinone (PQQ) could protect SH-SY5Y cells and dopaminergic neurons from cytotoxicity and prevent mitochondrial dysfunction in rotenone-induced PD models. In the present study we investigated the mechanisms underlying the protective effects of PQQ in a mouse PD model, which was established by intraperitoneal injection of rotenone (3 mg·kg-1·d-1, ip) for 3 weeks. Meanwhile the mice were treated with PQQ (0.8, 4, 20 mg·kg-1·d-1, ip) right after rotenone injection for 3 weeks. We showed that PQQ treatment dose-dependently alleviated the locomotor deficits and nigral dopaminergic neuron loss in PD mice. Furthermore, PQQ treatment significantly diminished the reduction of mitochondria number and their pathological change in the midbrain. PQQ dose-dependently blocked rotenone-caused reduction in the expression of PGC-1α and TFAM, two key activators of mitochondrial gene transcription, in the midbrain. In rotenone-injured human neuroblastoma SH-SY5Y cells, PTMScan Direct analysis revealed that treatment with PQQ (100 μM) differentially regulated protein phosphorylation; the differentially expressed phosphorylated proteins included the signaling pathways related with adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) pathway. We conducted Western blot analysis and confirmed that AMPK was activated by PQQ both in PD mice and in rotenone-injured SH-SY5Y cells. Pretreatment with AMPK inhibitor dorsomorphin (4 μM) significantly attenuated the protective effect and mitochondrial biogenesis by PQQ treatment in rotenone-injured SH-SY5Y cells. Taken together, PQQ promotes mitochondrial biogenesis in rotenone-injured mice and SH-SY5Y cells via activation of AMPK signaling pathway.

The mechanism and prevention of mitochondrial injury after exercise

With the development of society, physical activity has come to be an effective means by which people pursue good health to improve the quality of life. However, with the increase of intensity and the passage of time, exercise injury has become a hazard that can no longer be ignored. It is imperative to find effective ways to inhibit or reduce the negative effects of exercise. Mitochondria are important organelles involved in exercise and play an important role in exercise injury and prevention. Studies have found that exercise preconditioning and increased mitochondrial nutrition can effectively decrease mitochondrial damage after exercise. Against this background, some of the newest developments in this important field are reviewed here. The results discussed indicate that exercise preconditioning and supplement mitochondrial nutrition need to be increased to prevent exercise-related injuries.

Claulansine F-Donepezil Hybrids as Anti-Alzheimer's Disease Agents with Cholinergic, Free-Radical Scavenging, and Neuroprotective Activities

The multifactorial nature of Alzheimer's disease (AD) calls for the development of multitarget agents addressing key pathogenic processes. A total of 26 Claulansine F-donepezil hybrids were designed and synthesized as multitarget drugs. Among these compounds, six compounds exhibited excellent acetylcholinesterase (AChE) inhibitory activity (half maximal inhibitory concentration (IC50) 1.63-4.62 μM). Moreover, (E)-3-(8-(tert-Butyl)-3,3-dimethyl-3,11-dihydropyrano[3,2-a]carbazol-5-yl)-N-((1-(2-chlorobenzyl)piperidin-4-yl)methyl)acrylamide (6bd) exhibited better neuroprotective effects against OGD/R (oxygen-glucose deprivation/reoxygenation) than lead compound Claulansine F. Furthermore, 6bd could cross the blood-brain barrier in vitro. More importantly, compared to edaravone, 6bd had stronger free-radical scavenging activity. Molecular docking studies revealed that 6bd could interact with the catalytic active site of AChE. All of these outstanding in vitro results indicate 6bd as a leading structure worthy of further investigation.

Neuroprotective Activities of Boophone haemanthoides (Amaryllidaceae) Extract and Its Chemical Constituents

Parkinson’s disease (PD) is a neurodegenerative condition that progresses as age increases, and some of its major symptoms include tremor and postural and movement-related difficulties. To date, the treatment of PD remains a challenge because available drugs only treat the symptoms of the disease or possess serious side effects. In light of this, new treatment options are needed; hence, this study investigates the neuroprotective effects of an organic Boophone haemanthoides extract (BHE) and its bioactive compounds using an in vitro model of PD involving the toxin 1-methyl-4-phenylpyridinium (MPP⁺) and SH-SY5Y neuroblastoma cells. A total of seven compounds were isolated from BHE, viz distichamine (1), 1α,3α-diacetylnerbowdine (2), hippadine (3), stigmast-4-ene-3,6-dione (4), cholest-4-en-3-one (5), tyrosol (6), and 3-hydroxy-1-(4′-hydroxyphenyl)-1-propanone (7). Six compounds (1, 2, 4, 5, 6 and 7) were investigated, and five showed neuroprotection alongside the BHE. This study gives insight into the bioactivity of the non-alkaloidal constituents of Amaryllidaceae, since the isolated compounds and the BHE showed improved cell viability, increased ATP generation in the cells as well as inhibition of MPP⁺-induced apoptosis. Together, these findings support the claim that the Amaryllidaceae plant family could be a potential reserve of bioactive compounds for the discovery of neuroprotective agents.

A Glimmer of Hope: Maintain Mitochondrial Homeostasis to Mitigate Alzheimer's Disease

Mitochondria are classically known to be cellular energy producers. Given the high-energy demanding nature of neurons in the brain, it is essential that the mitochondrial pool remains healthy and provides a continuous and efficient supply of energy. However, mitochondrial dysfunction is inevitable in aging and neurodegenerative diseases. In Alzheimer’s disease (AD), neurons experience unbalanced homeostasis like damaged mitochondrial biogenesis and defective mitophagy, with the latter promoting the disease-defining amyloid β (Aβ) and p-Tau pathologies impaired mitophagy contributes to inflammation and the aggregation of Aβ and p-Tau-containing neurotoxic proteins. Interventions that restore defective mitophagy may, therefore, alleviate AD symptoms, pointing out the possibility of a novel therapy. This review aims to illustrate mitochondrial biology with a focus on mitophagy and propose strategies to treat AD while maintaining mitochondrial homeostasis.

Synergistic action of propolis with levodopa in the management of Parkinsonism in Drosophila melanogaster

Background The Phosphatase and tensin-induced putative kinase 1 (PINK1B9) mutant for Drosophila melanogaster is a key tool that has been used in assessing the pathology of Parkinsonism and its possible remedy. This research was targeted toward determining the effects of ethanolic extract of propolis, with levodopa therapy in the management of Parkinsonism. Method The PINK1B9 flies were divided into groups and fed with the different treatment doses of ethanoic extract of propolis. The treatment groups were subjected to 21 days of administration of propolis and the levodopa at different doses after which percentage climbing index, antioxidant activity and lifespan studies were done. Results Propolis alone improved motor activity, antioxidant and lifespan in Drosophila melanogaster than in PINK1 flies. Propolis in combination with levodopa significantly (P<0.05) improved physiological parameters at higher than lower concentrations in Parkinsonism Drosophila melanogaster demonstrating its importance in managing side effects associated with levodopa. Conclusion Propolis is a novel candidate as an alternative and integrative medicinal option to use in the management of Parkinsonism in both animals and humans at higher concentrations.

Miro, a Rho GTPase genetically interacts with Alzheimer's disease-associated genes (Tau, Aβ42 and Appl) in Drosophila melanogaster

Miro (mitochondrial Rho GTPases), a mitochondrial outer membrane protein, facilitates mitochondrial axonal transport along the microtubules to facilitate neuronal function. It plays an important role in regulating mitochondrial dynamics (fusion and fission) and cellular energy generation. Thus, Miro might be associated with the key pathologies of several neurodegenerative diseases (NDs) including Alzheimer's disease (AD). In the present manuscript, we have demonstrated the possible genetic interaction between Miro and AD-related genes such as Tau, Aβ42 and Appl in Drosophila melanogaster Ectopic expression of Tau, Aβ42 and Appl induced a rough eye phenotype, defects in phototaxis and climbing activity, and shortened lifespan in the flies. In our study, we have observed that overexpression of Miro improves the rough eye phenotype, behavioral activities (climbing and phototaxis) and ATP level in AD model flies. Further, the improvement examined in AD-related phenotypes was correlated with decreased oxidative stress, cell death and neurodegeneration in Miro overexpressing AD model flies. Thus, the obtained results suggested that Miro genetically interacts with AD-related genes in Drosophila and has the potential to be used as a therapeutic target for the design of therapeutic strategies for NDs.This article has an associated First Person interview with the first author of the paper.

Exploring the Impact of PARK2 Mutations on the Total and Mitochondrial Proteome of Human Skin Fibroblasts

Mutations in PARK2 gene are the most frequent cause of familial forms of Parkinson’s disease (PD). This gene encodes Parkin, an E3 ubiquitin ligase involved in several cellular mechanisms, including mitophagy. Parkin loss-of-function is responsible for the cellular accumulation of damaged mitochondria, which in turn determines an increment of reactive oxygen species (ROS) levels, lower ATP production, and apoptosis activation. Given the importance of mitochondrial dysfunction and mitophagy impairment in PD pathogenesis, the aim of the present study was to investigate both total and mitochondrial proteome alterations in human skin fibroblasts of PARK2-mutated patients. To this end, both total and mitochondria-enriched protein fractions from fibroblasts of five PARK2-mutated patients and five control subjects were analyzed by quantitative shotgun proteomics to identify proteins specifically altered by Parkin mutations (mass spectrometry proteomics data have been submitted to ProteomeXchange with the identifier PXD015880). Both the network-based and gene set enrichment analyses pointed out pathways in which Rab GTPase proteins are involved. To have a more comprehensive view of the mitochondrial alterations due to PARK2 mutations, we investigated the impact of Parkin loss on mitochondrial function and network morphology. We unveiled that the mitochondrial membrane potential was reduced in PARK2-mutated patients, without inducing PINK1 accumulation, even when triggered with the ionophore carbonyl cyanide m-chlorophenylhydrazone (CCCP). Lastly, the analysis of the mitochondrial network morphology did not reveal any significant alterations in PARK2-mutated patients compared to control subjects. Thus, our results suggested that the network morphology was not influenced by the mitochondrial depolarization and by the lack of Parkin, revealing a possible impairment of fission and, more in general, of mitochondrial dynamics. In conclusion, the present work highlighted new molecular factors and pathways altered by PARK2 mutations, which will unravel possible biochemical pathways altered in the sporadic form of PD.

Evaluation of the Anti-apoptotic and Anti-cytotoxic Effect of Epicatechin Gallate and Edaravone on SH-SY5Y Neuroblastoma Cells

Introduction:

Parkinson disease (PD) is the second most common neurodegenerative disease affecting older individuals with signs of motor disability and cognitive impairment. Epicatechin (EC) and edaravone have neuroprotective effects most probably due to their antioxidant activity; however, a limited number of studies have considered their role in PD. This research aimed at investigating the neuroprotective effect of EC and edaravone in a neurotoxin-induced model of PD.

Methods:

An in vitro model of PD was made by subjecting SH-SY5Y neuroblastoma cells to neurotoxin: 6-hydroxydopamine (6-OHDA) 100 μM/well. The cytoprotective effect of EC and edaravone in five concentrations on cell viability was tested using the MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide) assay. The apoptotic assay was done by annexin V and propidium iodide method using flow cytometry.

Results:

According to the MTT assay analysis, EC and edaravone had protective effects against 6-OH DA-induced cytotoxicity in SH-SY5Y neuroblastoma cells that were much more significant for edaravone and also a relative synergistic effect between EC and edaravone was observed. The apoptotic analysis showed that edaravone alone could decrease early and late apoptosis, whereas EC diminished early apoptosis, but enhanced late apoptosis and necrosis. Besides, co-treatment of edaravone and EC had a synergistic effect on decreasing apoptosis and increasing cell viability.

Conclusion:

The protective effect of edaravone on apoptosis and cytotoxicity was demonstrated clearly and EC had a synergistic effect with edaravone.

Dl-3-n-butylphthalide attenuates mouse behavioral deficits to chronic social defeat stress by regulating energy metabolism via AKT/CREB signaling pathway

Major depressive disorder (MDD) is a severe mental disorder associated with high rates of morbidity and mortality. Current first-line pharmacotherapies for MDD are based on enhancement of monoaminergic neurotransmission, but these antidepressants are still insufficient and produce significant side-effects. Consequently, the development of novel antidepressants and therapeutic targets is desired. Dl-3-n-butylphthalide (NBP) is a compound with proven efficacy in treating ischemic stroke, yet its therapeutic effects and mechanisms for depression remain unexplored. The aim of this study was to investigate the effect of NBP in a chronic social defeat stress model of depression and its underlying molecular mechanisms. Here, we examined depression-related behavior and performed a targeted metabolomics analysis. Real-time quantitative polymerase chain reaction and western blotting were used to examine key genes and proteins involved in energy metabolism and the AKT/cAMP response element-binding protein (CREB) signaling pathway. Our results reveal NBP attenuates stress-induced social deficits, anxiety-like behavior and despair behavior, and alters metabolite levels of glycolysis and tricarboxylic acid (TCA) cycle components. NBP affected gene expression of key enzymes of the TCA cycle, as well as protein expression of p-AKT and p-CREB. Our findings provide the first evidence showing that NBP can attenuate stress-induced behavioral deficits by modulating energy metabolism by regulating activation of the AKT/CREB signaling pathway.

Endoplasmic reticulum stress: A master regulator of metabolic syndrome

Endoplasmic reticulum (ER) stress, a change in the ER homeostasis, leads to initiation of the unfolded protein response (UPR). The primary functions of the UPR are to restore the ER's physiological activity and coordinate the apoptotic and adaptive responses. Pathophysiological conditions that augment ER stress include hypoxia, misfolded and/or mutated protein accumulation, and high glucose. Prolonged ER stress is a critical factor in the pathogenesis of metabolic syndrome including type 2 diabetes mellitus, cardiovascular diseases, atherosclerosis, obesity, and fatty liver disease. UPR is a complex homeostatic pathway between newly synthesized proteins and their maturation, although the regulatory mechanisms contributing to the UPR and the possible therapeutic strategies are yet to be clarified. Therefore, a comprehensive understanding of the underlying molecular mechanisms is necessary to develop therapeutic interventions targeting ER stress response. In this review, we discuss the role of ER stress and UPR signaling in the pathogenesis of metabolic syndrome, highlighting the main functions of UPR components. We have emphasized the use of novel small molecular chemical chaperones, considered as modulators of ER stress. The initial studies with these chemical chaperones are promising, but detailed studies are required to define their efficacy and adverse effects during therapeutic use in humans.

Parkinson's disease: Mechanisms, translational models and management strategies

Parkinson's disease is a progressive neurodegenerative disorder. The classical motor symptoms include resting tremors, bradykinesia, rigidity and postural instability and are accompanied by the loss of dopaminergic neurons and Lewy pathology. Diminished neurotransmitter level, oxidative stress, mitochondrial dysfunction and perturbed protein homeostasis over time worsen the disease manifestations in elderly people. Current management strategies aim to provide symptomatic relief and to slow down the disease progression. However, no pharmacological breakthrough has been made to protect dopaminergic neurons and associated motor circuitry components. Deep brain stimulation, stem cells-derived dopaminergic neurons transplantation, gene editing and gene transfer remain promising approaches for the potential management of neurodegenerative disease. Toxin or genetically induced rodent models replicating Parkinson's disease pathology are of high predictive value for translational research. This review addresses the current understanding, management strategies and the Parkinson's disease models for translational research. Preclinical research may provide powerful tools to quest the potential therapeutic and neuroprotective compounds for dopaminergic neurons and hence possible cure for the Parkinson's disease.

Role of Combined Lipoic Acid and Vitamin D3 on Astrocytes as a Way to Prevent Brain Ageing by Induced Oxidative Stress and Iron Accumulation

Brain ageing is a complex multifactorial process characterized by gradual and continuous loss of neuronal functions. It is hypothesized that at the basis of brain ageing as well as age-related diseases, there is an impairment of the antioxidant defense system leading to an increase of oxidative stress. In this study, two different biological aspects involved in brain ageing and neurodegeneration have been investigated: oxidative stress and iron accumulation damage. In primary mouse astrocytes, the stimulation with 50 μM lipoic acid (LA) and 100 nM vitamin D (vitD) was first investigated in a time-course study to determine the dosages to be used in combination and then in a permeability test using an in vitro blood-brain barrier. In a second set of experiments, the role of oxidative stress was investigated pretreating astrocytes with 200 μM H₂O₂ for 30 min. The ability of vitD and LA alone and combined together to prevent or repair the damage caused by oxidative stress was investigated after 24 h of stimulation by the MTT test, mitochondrial membrane potential measurement, and Western blot analysis. To induce neurodegeneration, cells were pretreated with 300 μM catalytic iron for 6 days and then treated with vitD and LA alone and combined for additional 6 days to investigate the protection exerted by combination, analyzing viability, ROS production, iron concentration, and activation of intracellular pathways. In our study, the combination of LA and vitD showed beneficial effects on viability of astrocytes, since the substances are able to cross the brain barrier. In addition, combined LA and vitD attenuated the H₂O₂-induced apoptosis through the mitochondrial-mediated pathway. The combination was also able to counteract the adverse conditions caused by iron, preventing its accumulation. All these data support the hypothesis of the synergistic and cooperative activity exerted by LA and vitD in astrocytes indicating a possible new strategy to slow down ageing.

P38 Mitogen-activated Protein Kinase and Parkinson's Disease

Parkinson's disease, the second major neurodegenerative disease, has created a great impact on the elder people. Although the mechanisms underlying Parkinson's disease are not fully understood, considerable evidence suggests that neuro-inflammation, oxidative stress, mitochondrial dysfunction, cell proliferation, differentiation and apoptosis are involved in the disease. p38MAPK, an important member of the mitogen-activated protein family, controls several important functions in the cell, suggesting a potential pathogenic role in PD. This review provides a brief description of the role and mechanism of p38MAPK in Parkinson's disease.

Role of purinergic receptors in the Alzheimer's disease

Etiology of the Alzheimer’s disease (AD) is not fully understood. Different pathological processes are considered, such as amyloid deposition, tau protein phosphorylation, oxidative stress (OS), metal ion disregulation, or chronic neuroinflammation. Purinergic signaling is involved in all these processes, suggesting the importance of nucleotide receptors (P2X and P2Y) and adenosine receptors (A1, A2A, A2B, A3) present on the CNS cells. Ecto-purines, ecto-pyrimidines, and enzymes participating in their metabolism are present in the inter-cellular spaces. Accumulation of amyloid-β (Aβ) in brain induces the ATP release into the extra-cellular space, which in turn stimulates the P2X7 receptors. Activation of P2X7 results in the increased synthesis and release of many pro-inflammatory mediators such as cytokines and chemokines. Furthermore, activation of P2X7 leads to the decreased activity of α-secretase, while activation of P2Y2 receptor has an opposite effect. Simultaneous inhibition of P2X7 and stimulation of P2Y2 would therefore be the efficient way of the α-secretase activation. Activation of P2Y2 receptors present in neurons, glia cells, and endothelial cells may have a positive neuroprotective effect in AD. The OS may also be counteracted via the purinergic signaling. ADP and its non-hydrolysable analogs activate P2Y13 receptors, leading to the increased activity of heme oxygenase, which has a cytoprotective activity. Adenosine, via A1 and A2A receptors, affects the dopaminergic and glutaminergic signaling, the brain-derived neurotrophic factor (BNDF), and also changes the synaptic plasticity (e.g., causing a prolonged excitation or inhibition) in brain regions responsible for learning and memory. Such activity may be advantageous in the Alzheimer’s disease.

Mitochondrial regulation by pyrroloquinoline quinone prevents rotenone-induced neurotoxicity in Parkinson's disease models

Pyrroloquinoline quinone (PQQ), a redox cofactor in the mitochondrial respiratory chain, has been reported to protect SH-SY5Y cells from cytotoxicity induced by rotenone, a mitochondrial complex I inhibitor. In this study, we aimed to investigate the mitochondrial mechanisms involved in the neuroprotection of PQQ both in vitro and in vivo. The cultured human SH-SY5Y neuroblastoma cells were exposed to different concentrations of PQQ after which the cells were treated with rotenone. Electron microscopy images showed that PQQ could prevent the mitochondrial morphology damage. The down-regulation of mitochondrial biogenesis related genes (PGC-1alpha and TFAM) and mitochondrial fission and fusion related genes (Drp1and Mfn2) in rotenone-injured SH-SY5Y cells could be inhibited by PQQ. PQQ could also promote the transposition of Drp1 and Mfn2 from cytosol to mitochondria. In addition, rotenone was injected into the left medial forebrain bundle of SD rats to establish a Parkinson's disease (PD) model in vivo, after which different doses of PQQ or Edaravone were given intraperitoneally once daily for 8 weeks. PQQ could up-regulate the mRNA levels of PGC-1alpha, TFAM, Drp-1 and Mfn2 in the midbrain of PD rats. Our findings indicated that PQQ could prevent mitochondrial dysfunction by promoting mitochondrial biogenesis and regulating mitochondrial fission and fusion, which might contribute to its neuroprotective effect in PD models.

Inhibitory Effect of Astaxanthin on Oxidative Stress-Induced Mitochondrial Dysfunction-A Mini-Review

Oxidative stress is a major contributor to the pathogenesis of various human diseases as well as to the aging process. Mitochondria, as the center of cellular metabolism and major regulators of redox balance, play a critical role in disease development and progression. Mitochondrial dysfunction involving structural and metabolic impairment is prominent in oxidative stress-related diseases. Increased oxidative stress can damage mitochondria, and subsequent mitochondrial dysfunction generates excesses of mitochondrial reactive oxygen species that cause cellular damage. Mitochondrial dysfunction also activates the mitochondrial apoptotic pathway, resulting in cellular death. Astaxanthin, a red-colored xanthophyll carotenoid, exerts an anti-oxidative and anti-inflammatory effect on various cell lines. In this manner astaxanthin maintains mitochondrial integrity under various pathological conditions. In this review, the inhibitory effects of astaxanthin on oxidative stress-induced mitochondrial dysfunction and related disease development are discussed.

Neurogenic and neuroprotective donepezil-flavonoid hybrids with sigma-1 affinity and inhibition of key enzymes in Alzheimer's disease

In this work we describe neurogenic and neuroprotective donepezil-flavonoid hybrids (DFHs), exhibiting nanomolar affinities for the sigma-1 receptor (σ1R) and inhibition of key enzymes in Alzheimer's disease (AD), such as acetylcholinesterase (AChE), 5-lipoxygenase (5-LOX), and monoamine oxidases (MAOs). In general, new compounds scavenge free radical species, are predicted to be brain-permeable, and protect neuronal cells against mitochondrial oxidative stress. N-(2-(1-Benzylpiperidin-4-yl)ethyl)-6,7-dimethoxy-4-oxo-4H-chromene-2-carboxamide (18) is highlighted due to its interesting biological profile in σ1R, AChE, 5-LOX, MAO-A and MAO-B. In phenotypic assays, it protects a neuronal cell line against mitochondrial oxidative stress and promotes maturation of neural stem cells into a neuronal phenotype, which could contribute to the reparation of neuronal tissues. Molecular modelling studies of 18 in AChE, 5-LOX and σ1R revealed the main interactions with these proteins, which will be further exploited in the optimization of new, more efficient DFHs.

Evaluation of the Antioxidant and Neuroprotectant Activities of New Asymmetrical 1,3-Diketones

A series of fourteen new asymmetrical 1,3-diketone derivatives have been synthesized and evaluated in the ABTS, FRAP and DPPH assays as a new chemotype with antioxidant and drug-like properties. All the compounds displayed low cytotoxicity in comparison to curcumin against the human neuroblastoma SH-SY5Y cell line. Among them, (3Z,5E)-6-(2,5-difluoro-4-hydroxy-phenyl)-1,1,1-trifluoro-4-hydroxyhexa-3,5-dien-2-one (6b) and (3Z,5E)-6-(2,3-difluoro-4-hydroxy-phenyl)-1,1,1-trifluoro-4-hydroxyhexa-3,5-dien-2-one (7b) with excellent solubility and chemical stability in biorelevant media, have also shown a similar Fe+2 chelation behavior to that of curcumin. Additionally, both derivatives 6b and 7b have afforded good neuroprotection activity against H₂O₂ induced oxidative stress in the same neuronal cell line, with a significant reduction of intracellular ROS levels, in parallel with a good recovery of the Mitochondrial Membrane Potential (ΔΨm). Compounds 6b and 7b with a promising antioxidant and drug-like profile, with low cytotoxic and good neuroprotectant activity, constitute a new interesting chemical class with high potential as new therapeutic agents against neurodegenerative diseases.

Anti-Parkinson Potential of Silymarin: Mechanistic Insight and Therapeutic Standing

Parkinson’s disease (PD) involves aggregation of α-synuclein and progressive loss of dopaminergic neurons. Pathogenesis of PD may also be related to one’s genetic background. PD is most common among geriatric population and approximately 1–2% of population suffers over age 65 years. Currently no successful therapies are in practice for the management of PD and available therapies tend to decrease the symptoms of PD only. Furthermore, these are associated with diverse range of adverse effects profile. The neuroprotective effects of polyphenols are widely studied and documented. Among phytochemicals, silymarin is one of the most widely used flavonoids because of its extensive therapeutic properties and has been indicated in pathological conditions of prostate, CNS, lungs, skin, liver, and pancreas. Silymarin is a mixture of flavonolignans (silybin, isosilybin, and silychristin), small amount of flavonoids (taxifolin), fatty acids, and other polyphenolic compounds extracted from the dried fruit of Silybum marianum and is clinically used for hepatoprotective effects since ancient times. Neuroprotective effects of silymarin have been studied in various models of neurological disorders such as Alzheimer’s disease, PD, and cerebral ischemia. The aim of the present study is to provide a comprehensive review of the recent literature exploring the effects of silymarin administration on the progression of PD. Reducing oxidative stress, inflammatory cytokines, altering cellular apoptosis machinery, and estrogen receptor machinery are mechanisms that are responsible for neuroprotection by silymarin, as discussed in this review. Additionally, because of poor aqueous solubility, the bioavailability of silymarin is low and only 23–47% of silymarin reaches systemic circulation after oral administration. Our primary focus is on the chemical basis of the pharmacology of silymarin in the treatment of PD and its mechanisms and possible therapeutic/clinical status while addressing the bioavailability limitation.

Sophora flavescens Aiton Decreases MPP+-Induced Mitochondrial Dysfunction in SH-SY5Y Cells

Sophora flavescens Aiton (SF) has been used to treat various diseases including fever and inflammation in China, South Korea and Japan. Several recent reports have shown that SF has anti-inflammatory and anti-apoptotic effects, indicating that it is a promising candidate for treatment of Parkinson's disease (PD). We evaluated the protective effect of SF against neurotoxin 1-methyl-4-phenylpyridinium ion (MPP⁺)-induced mitochondrial dysfunction in SH-SY5Y human neuroblastoma cells, an in vitro PD model. SH-SY5Y cells were incubated with SF for 24 h, after which they were treated with MPP⁺. MPP⁺-induced cytotoxicity and apoptosis were confirmed by 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay and terminal deoxynucleotidyl transferase-mediated biotinylated UTP nick end labeling assay. MitoSOX red mitochondrial superoxide indicator, tetramethylrhodamine methyl ester perchlorate and Parkin, PTEN-induced putative kinase 1 (PINK1), and DJ-1 immunofluorescent staining were conducted to confirm the mitochondrial function. In addition, western blot was performed to evaluate apoptosis factors (Bcl-2, Bax, caspase-3 and cytochrome c) and mitochondrial function-related factors (Parkin, PINK1 and DJ-1). SF suppressed MPP⁺-induced cytotoxicity, apoptosis and collapse of mitochondrial membrane potential by inhibiting the increase of reactive oxidative species (ROS) and DNA fragmentation, and controlling Bcl-2, Bax, caspase-3 and cytochrome c expression. Moreover, it attenuated Parkin, PINK1 and DJ-1 expression from MPP⁺-induced decrease. SF effectively suppressed MPP⁺-induced cytotoxicity, apoptosis and mitochondrial dysfunction by regulating generation of ROS, disruption of mitochondrial membrane potential, mitochondria-dependent apoptosis and loss or mutation of mitochondria-related PD markers including Parkin, PINK1 and DJ-1.

Observation of acetyl phosphate formation in mammalian mitochondria using real-time in-organelle NMR metabolomics

Recent studies point out the link between altered mitochondrial metabolism and cancer, and detailed understanding of mitochondrial metabolism requires real-time detection of its metabolites. Employing heteronuclear 2D NMR spectroscopy and ¹³C₃-pyruvate, we propose in-organelle metabolomics that allows for the monitoring of mitochondrial metabolic changes in real time. The approach identified acetyl phosphate from human mitochondria, whose production has been largely neglected in eukaryotic metabolism since its first description about 70 years ago in bacteria. The kinetic profile of acetyl phosphate formation was biphasic, and its transient nature suggested its role as a metabolic intermediate. The method also allowed for the estimation of pyruvate dehydrogenase (PDH) enzyme activity through monitoring of the acetyl-CoA formation, independent of competing cytosolic metabolism. The results confirmed the positive regulation of mitochondrial PDH activity by p53, a well-known tumor suppressor. Our approach can easily be applied to other organelle-specific metabolic studies.

Alpha Lipoamide Ameliorates Motor Deficits and Mitochondrial Dynamics in the Parkinson's Disease Model Induced by 6-Hydroxydopamine

The precise mechanisms underlying neuronal injury in Parkinson's disease (PD) are not yet fully elucidated; however, evidence from the in vitro and in vivo PD models suggest that mitochondrial dysfunction may play a major role in PD pathogenesis. Alpha lipoamide, a neutral amide derivative of the lipoic acid, is a better cofactor for mitochondrial dehydrogenase with a stronger protective effect on mitochondria than lipoic acid. Identification of these protective effects of alpha lipoamide on mitochondria, together with the evidence that mitochondrial dysfunction plays a critical role in PD, we speculate that alpha lipoamide may exert a protective effect in PD by regulating the mitochondrial function. The present study investigated the neuroprotective effects of alpha lipoamide in an animal model of PD induced by 6-hydroxydopamine (6-OHDA). The results demonstrated that alpha lipoamide could significantly antagonize the 6-OHDA-induced behavioral damages; restore ATP levels in the midbrain; and also improve the fragmentation, vacuolization, and morphology of the mitochondria. The results of Western blot indicated that alpha lipoamide significantly restored the number of dopaminergic neurons in midbrain and substantially recovered the balance between mitochondrial fission, fusion, and transport. In conclusion, the results demonstrated that alpha lipoamide might exert a significant neuroprotective effect in the animal model of PD by regulation of the dynamic properties of mitochondria.

Dl-3n-butylphthalide reduces epileptiform activity through GluA2-lacking calcium-permeable AMPARs in epilepsy models

Epilepsy is the most prevalent chronic neurological disorder, and its pathological mechanism indicates that an imbalance between excitatory and inhibitory neurotransmission leads to neuronal hyperexcitability. Previous studies have suggested that dl-3n-butylphthalide (NBP) regulates the excitatory neurotransmitter glutamate in the brains of epileptic mice, however, the mechanisms are unknown. We investigated behavioral and electrophysiological factors in rats using NBP. In an in vivo pentylenetetrazole (PTZ)-induced epileptic seizure animal model, NBP decreased the generalized tonic-clonic seizure (GTCS) severity. In an acute hippocampal slice 4-aminopyridine (4-AP) epilepsy model in vitro, NBP decreased the epileptiform activity and miniature excitatory postsynaptic current (mEPSC) amplitude; there was no change in the miniature inhibitory postsynaptic current (mIPSC) amplitude or frequency. This effect suggested changes in excitatory synaptic transmission, which was altered through postsynaptic GluA2-lacking calcium-permeable AMPA receptors (CP-AMPARs). These findings showed that NBP suppressed epileptiform activity in these epilepsy models and provided the first detailed electrophysiological analysis of the impact of NBP in epilepsy models, which may be employed in future experimental or clinical therapies for patients with epilepsy.

Serum Growth Differentiation Factor 15 in Parkinson Disease

BACKGROUND

Growth differentiation factor 15 (GDF15) has been shown to be protective for dopaminergic neurons in animal and ex vivo experiments. However, little is known about its effect on the human body.

OBJECTIVE

This study investigated associations between serum GDF15 levels and clinical parameters in patients with Parkinson disease (PD).

METHODS

Idiopathic PD patients (n = 104) and age-matched controls (n = 88) were enrolled. Serum GDF15 levels were measured by human enzyme-linked immunosorbent assay. Univariate and multivariate analyses investigated correlations between GDF15 and clinical characteristics, including disease severity by the Unified PD Rating Scale (UPDRS)-III. The diagnostic value of GDF15 was evaluated by receiver-operating characteristic curve (ROC) analysis.

RESULTS

The serum GDF15 levels of the PD patients were significantly higher than those of the healthy controls. In PD patients, serum GDF15 levels in men were significantly higher than in women. GDF15 levels correlated with age, gender, disease duration, and UPDRS-III score. After adjusting for confounding factors, multiple linear regression analysis showed that the serum GDF15 level (β = 0.015, p = 0.001) was an independent risk factor for UPDRS-III score. In ROC analysis, GDF15 achieved an area under the curve of 0.86 for the identification of PD, with a sensitivity of 71.15% and a specificity of 87.50%.

CONCLUSION

GDF15 may be a potential biomarker for the diagnosis and monitoring of motor severity in PD.

The use of high-throughput screening techniques to evaluate mitochondrial toxicity

Toxicologists and chemical regulators depend on accurate and effective methods to evaluate and predict the toxicity of thousands of current and future compounds. Robust high-throughput screening (HTS) experiments have the potential to efficiently test large numbers of chemical compounds for effects on biological pathways. HTS assays can be utilized to examine chemical toxicity across multiple mechanisms of action, experimental models, concentrations, and lengths of exposure. Many agricultural, industrial, and pharmaceutical chemicals classified as harmful to human and environmental health exert their effects through the mechanism of mitochondrial toxicity. Mitochondrial toxicants are compounds that cause a decrease in the number of mitochondria within a cell, and/or decrease the ability of mitochondria to perform normal functions including producing adenosine triphosphate (ATP) and maintaining cellular homeostasis. Mitochondrial dysfunction can lead to apoptosis, necrosis, altered metabolism, muscle weakness, neurodegeneration, decreased organ function, and eventually disease or death of the whole organism. The development of HTS techniques to identify mitochondrial toxicants will provide extensive databases with essential connections between mechanistic mitochondrial toxicity and chemical structure. Computational and bioinformatics approaches can be used to evaluate compound databases for specific chemical structures associated with toxicity, with the goal of developing quantitative structure-activity relationship (QSAR) models and mitochondrial toxicophores. Ultimately these predictive models will facilitate the identification of mitochondrial liabilities in consumer products, industrial compounds, pharmaceuticals and environmental hazards.