Attenuation of neuroinflammatory responses and behavioral deficits by Ligusticum officinale (Makino) Kitag in stimulated microglia and MPTP-induced mouse model of Parkinson's disease

Phytomolecules from conventional to nano form: Next-generation approach for Parkinson's disease

The incidence of neurodegenerative diseases is increasing exponentially worldwide. Parkinson's disease (PD) is a neurodegenerative disease caused by factors like oxidative stress, gene mutation, mitochondrial dysfunction, neurotoxins, activation of microglial inflammatory mediators, deposition of Lewy's bodies, and α- synuclein proteins in the neurons leading to neuroinflammation and neurodegeneration in the substantia nigra. Hence the development of efficacious neuro-therapy is in demand which can prevent neurodegeneration and protect the nigrostriatal pathway. One of the approaches for managing PD is reducing oxidative stress due to aging and other co-morbid diseased conditions. The phytomolecules are reported as safe and efficacious antioxidants as they contain different secondary metabolites. However, the limitations of low solubility restricted permeability through the blood-brain barrier, and low bioavailability limits their clinical evaluation and application. This review discusses the therapeutic efficacy of phytomolecules in PD and different nanotechnological approaches to improve their brain permeability.

Environmental pollutants induce NLRP3 inflammasome activation and pyroptosis: Roles and mechanisms in various diseases

Environmental pollution is changing with economic development. Most environmental pollutants are characterized by stable chemical properties, strong migration, potential toxicity, and multiple exposure routes. Harmful substances are discharged excessively, and large quantities of unknown new compounds are emerging, being transmitted and amplifying in the food chain. The increasingly severe problems of environmental pollution have forced people to re-examine the relationship between environmental pollution and health. Pyroptosis and activation of the NLRP3 inflammasome are critical in maintaining the immune balance and regulating the inflammatory process. Numerous diseases caused by environmental pollutants are closely related to NLRP3 inflammasome activation and pyroptosis. We intend to systematically explain the steps and important events that are common in life but easily overlooked by which environmental pollutants activate the NLRP3 inflammasome and pyroptosis pathways. This comprehensive review also discusses the interaction network between environmental pollutants, the NLRP3 inflammasome, pyroptosis, and diseases. Thus, research progress on the impact of decreasing oxidative stress levels to inhibit the NLRP3 inflammasome and pyroptosis, thereby repairing homeostasis and reshaping health, is systematically examined. This review aims to deepen the understanding of the impact of environmental pollutants on life and health and provide a theoretical basis and potential programs for the development of corresponding treatment strategies.

A Review on Potential Footprints of Ferulic Acid for Treatment of Neurological Disorders

Ferulic acid is being screened in preclinical settings to combat various neurological disorders. It is a naturally occurring dietary flavonoid commonly found in grains, fruits, and vegetables such as rice, wheat, oats, tomatoes, sweet corn etc., which exhibits protective effects against a number of neurological diseases such as epilepsy, depression, ischemia-reperfusion injury, Alzheimer's disease, and Parkinson's disease. Ferulic acid prevents and treats different neurological diseases pertaining to its potent anti-oxidative and anti-inflammatory effects, beside modulating unique neuro-signaling pathways. It stays in the bloodstream for longer periods than other dietary polyphenols and antioxidants and easily crosses blood brain barrier. The use of novel drug delivery systems such as solid-lipid nanoparticles (SLNs) or its salt forms (sodium ferulate, ethyl ferulate, and isopentyl ferulate) further enhance its bioavailability and cerebral penetration. Based on reported studies, ferulic acid appears to be a promising molecule for treatment of neurological disorders; however, more preclinical (in vitro and in vivo) mechanism-based studies should be planned and conceived followed by its testing in clinical settings.

Neuroinflammation Mechanisms and Phytotherapeutic Intervention: A Systematic Review

Neuroinflammation is indicated in the pathogenesis of several acute and chronic neurological disorders. Acute lesions in the brain parenchyma induce intense and highly complex neuroinflammatory reactions with similar mechanisms among various disease prototypes. Microglial cells in the CNS sense tissue damage and initiate inflammatory responses. The cellular and humoral constituents of the neuroinflammatory reaction to brain injury contribute significantly to secondary brain damage and neurodegeneration. Inflammatory cascades such as proinflammatory cytokines from invading leukocytes and direct cell-mediated cytotoxicity between lymphocytes and neurons are known to cause "collateral damage" in models of acute brain injury. In addition to degeneration and neuronal cell loss, there are secondary inflammatory mechanisms that modulate neuronal activity and affect neuroinflammation which can even be detected at the behavioral level. Hence, several of health conditions result from these pathogenetic conditions which are underlined by progressive neuronal function loss due to chronic inflammation and oxidative stress. In the first part of this Review, we discuss critical neuroinflammatory mediators and their pathways in detail. In the second part, we review the phytochemicals which are considered as potential therapeutic molecules for treating neurodegenerative diseases with an inflammatory component.

Effects of Exercise and Ferulic Acid on Alpha Synuclein and Neuroprotective Heat Shock Protein 70 in An Experimental Model of Parkinsonism Disease

BACKGROUND & OBJECTIVE

This study investigated the effects of ferulic acid (FR), muscle exercise (Ex) and combination of them on rotenone (Rot)-induced Parkinson disease (PD) in mice as well as their underlying mechanisms.

METHOD

56 male C57BL/6 mice were allocated into 8 equal groups, 1) Normal control (CTL), 2) FR (mice received FR at 20 mg/kg/day), 3) Ex (mice received swimming Ex) and 4) Ex + FR (mice received FR and Ex), 5) Rot (mice received Rot 3 mg/Kg i.p. for 70 days), 6) ROT+ FR (mice received Rot + FR at 20 mg/kg/day), 7) ROT+ Ex (mice received Rot + swimming Ex) and 8) ROT+ Ex + FR (mice received Rot + FR and Ex). ROT group showed significant impairment in motor performance and significant reduction in tyrosine hydroxylase (TH) density and Hsp70 expression (p< 0.05) with Lewy bodies (alpha synuclein) aggregates in corpus striatum. Also, ROT+FR, ROT+EX and ROT + Ex+ FR groups showed significant improvement in behavioral and biochemical changes, however the effect of FR alone was more potent than Ex alone (p< 0.05) and addition of Ex to FR caused no more significant improvement than FR alone.

CONCLUSION

We concluded that, FR and Ex improved the motor performance in rotenone-induced PD rodent model which might be due to increased Hsp70 expression and TH density in corpus striatum and combination of both did not offer more protection than FR alone.

Low-Molecular Weight Metabolites from Polyphenols as Effectors for Attenuating Neuroinflammation

Age-associated pathophysiological changes such as neurodegenerative diseases are multifactorial conditions with increasing incidence and no existing cure. The possibility of altering the progression and development of these multifactorial diseases through diet is an attractive approach with increasing supporting data. Epidemiological and clinical studies have highlighted the health potential of diets rich in fruits and vegetables. Such food sources are rich in (poly)phenols, natural compounds increasingly associated with health benefits, having the potential to prevent or retard the development of various diseases. However, absorption and the blood concentration of (poly)phenols is very low when compared with their corresponding (poly)phenolic metabolites. Therefore, these serum-bioavailable metabolites are much more promising candidates to overcome cellular barriers and reach target tissues, such as the brain. Bearing this in mind, it will be reviewed that the molecular mechanisms underlying (poly)phenolic metabolites effects, range from 0.1 to <50 μM and their role on neuroinflammation, a central hallmark in neurodegenerative diseases.

Jiawei Foshou San Induces Apoptosis in Ectopic Endometrium Based on Systems Pharmacology, Molecular Docking, and Experimental Evidence

Foshou San is a typical gynaecological formula with wild usage in traditional Chinese medicine. Jiawei Foshou San (JFS) is a novel ingredient prescription from Foshou San with antiendometriosis effect in unclear mechanisms. To uncover the potential application and proapoptotic mechanisms of JFS, JFS ingredient-drug target-disease networks, GO enrichment, and pathway analysis were established for potential application prediction. Molecular docking and validation in vivo were investigated by the proapoptotic mechanisms of JFS. In this study, 99 common targets were related to 108 diseases. 484 biological processes, 44 cell components, 59 molecular functions, and 37 pathways were significantly identified in GO enrichment and pathway analysis. In molecular docking, ligustrazine showed binding activity with Bcl-2, Bax, caspase-9, caspase-3, and PARP. In vivo, JFS elevated the shrink rate of ectopic endometrium, by suppressing E2 and PROG. An in-depth study showed that apoptosis was activated through diminishing Bcl-2, rising Bax and Bad, and expressing more caspase-3 and caspase-9 using JFS. JFS promoted the protein level of cleaved-PARP. In brief, JFS might be applied for various diseases through multiple targets and pathways, especially endometriosis by Bcl-2 pathway. These findings reveal the potential application for further evaluation and uncover the proapoptotic mechanism of JFS.

Anti-inflammatory Activity of Ursolic Acid in MPTP-Induced Parkinsonian Mouse Model

Neuroinflammation plays an important role in the progression of Parkinson's disease (PD) and hence may represent a target for treatment. The drugs used currently for PD only provide symptomatic relief and have adverse effects in addition to their inability in preventing degeneration of neurons. Flavonoids show potent antioxidant and anti-inflammatory activities which is very valuable for the health of human beings. Thus, in the present study, we have tried to explore the anti-inflammatory activity of orally given ursolic acid (UA) (25 mg/kg bwt), a pentacyclic triterpenoid in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-intoxicated mouse model. Significant severe oxidative stress and biochemical alterations have been seen in Parkinsonian mice after MPTP intoxication. Whereas, UA administration has significantly rescued the harmful consequence of MPTP intoxication. Ionized calcium-binding adaptor molecule 1 (Iba1), tumor necrosis factor-alpha (TNF-α), and nuclear transcription factor-κB (NF-κB) were seen to be altered in the substantia nigra pars compacta (SNpc) of MPTP-intoxicated mice through immunohistochemical studies. The changes in the expression level of these parameters primarily suggest increased inflammatory responses in MPTP-intoxicated mice as compared with the control. However, UA have significantly reduced these inflammatory parameters (Iba1 and TNF-α) along with transcription factor NF-κB, which regulates these inflammatory parameters and thus have inhibited MPTP-induced neuroinflammation. The immunoreactivity of tyrosine hydroxylase (TH) was considerably increased by UA treatment in the SNpc of Parkinsonian mice. The neuroinflammation and neurodegeneration along with impairments in biochemical and behavioral parameters were found to be reversed on treatment with UA. Thus, UA has shown potent anti-inflammatory activity by preventing the degeneration of dopaminergic neurons from MPTP-induced Parkinsonian mice.

Ferulic acid ameliorates pentylenetetrazol-induced seizures by reducing neuron cell death

To investigate the neuroprotective effect of ferulic acid (FA) in a pentylenetetrazol (PTZ)-induced seizures model in rat, the motor response, spatial learning ability and memory capability of the rats were assessed. Both the antioxidation and anti-apoptosis pathways were also investigated. In this study, male Wistar rats were randomly divided into 3 groups (n = 12 in each group). For 28 days, the rats were administered saline alone (i.p. normal saline, NS group), PTZ (40 mg/kg, i.p., PTZ group) once daily to induce seizures, or FA (i.p. 60 mg/kg) 20 min before being given PTZ (40 mg/kg, i.p., FA + PTZ group) to assess the neuroprotective effect of FA. The motor response of the rats was analysed with the Racine scale. The spatial learning and memory capacity of the rats were assessed by the Morris water maze test. The superoxide dismutase (SOD) activity and malondialdehyde (MDA) content were measured, and both in situ staining with the DNA-binding bisbenzimide Hoechst 33258 and TUNEL assays were used to assess apoptosis. Western blotting was used to further analyse the expression of Apaf-1, caspase-9, caspase-3, Bcl-2, Bid, Bax, cleaved caspase-3 and cytochrome c. The results showed that compared to the those of the PTZ group, FA pre-treatment significantly (p <  0.01) reduced the Racine scores starting at day 4, prolonged the latency of the onset of seizure at day 28, reduced the escape latency period starting at day 2, increased the frequency of crossing the platform location, increased the SOD activity, reduced the MDA content and apoptosis percentage, and upregulated the Bcl-2 levels whilst downregulating the Bax, cytochrome c, Apaf-1, caspase-9, caspase-3, cleaved caspase-3 and Bid expression levels. This study demonstrated that pre-treatment with FA exerts strong neuroprotective effects by reducing the motor response and by improving spatial learning ability and memory capacity. The neuroprotective effect may be a result of a reduction in neuron cell death that occurs via the antioxidative and anti-apoptotic pathways.

Ulmosides A: Flavonoid 6-C-glycosides from Ulmus wallichiana attenuates lipopolysacchride induced oxidative stress, apoptosis and neuronal death

Extract of Ulmus wallichiana is being used as traditional medicine used for the treatment of fractured bones however the effect of its individual flavonols is not known. The present study was conducted to investigate the effect of its novel flavonol, (2S, 3S)-(+)-30, 40, 5, 7-tetrahydroxydihydroflavonol-6-C-b-d-glucopyranoside named as Ulmoside A (UA), on lipopolysaccharides (LPS) treated neurons. LPS treatment to neuronal cells caused significant cytotoxicity, reactive oxygen species generation, depletion in glutathione and mitochondrial impairment which were significantly inhibited with UA treatment. LPS treatment also caused significant translocation of cytochrome-c, decreased level of Bcl2, increased level of Bax and cleaved caspase-3 in neuronal cells reflecting the involvement of intrinsic apoptotic pathway in neuronal death which was attenuated with UA treatment. Since LPS is a well known pro-inflammatory agent it also offered the significant increase in proinflammatory cytokines (tumor necrosis factors-α & interleukin 1-beta) however, UA treatment did not exhibit significant inhibition against LPS induced inflammatory response. LPS also caused the augmented level of inducible nitric oxide synthase (iNOS) which was also not inhibited with co treatment of UA. We have also observed the significant DNA fragmentation and augmented level of cleaved Poly (ADP-Ribose) polymerase 1 after LPS treatment which was significantly reverted with UA treatment. Findings suggested that UA acts through mitochondria and exhibited its anti-oxidative and anti-apoptotic activities in neuronal cells while no significant anti-inflammatory activity and effect on iNOS were observed.

Aqueous Extract of Dendropanax morbiferus Leaves Effectively Alleviated Neuroinflammation and Behavioral Impediments in MPTP-Induced Parkinson's Mouse Model

Parkinson's disease (PD) is a commonly reported age-related neurodegenerative disorder. Microglial-mediated neuroinflammation is one of the cardinal hallmarks of various neurodegenerative disorders, including PD progression. Inadequate therapeutic strategies and substantial adverse effects of well-established drug candidates demand new therapeutic leads to treat PD. Dendropanax morbifera (DM) is an endemic plant species of South Korea, and it has been used extensively as traditional medicine to treat numerous clinical complications. In this study, we conducted an initial profiling of the few major phytoconstituents of aqueous DM leaf extracts (DML) and quantified the same using high-performance liquid chromatography tandem mass spectrometry with electrospray ionization (HPLC-ESI-MS/MS). We subsequently evaluated the antineuroinflammatory activity and ameliorative potential of DML in both in vitro and in vivo experimental PD models. The prophylactic treatment of DML effectually improved the behavioral deficits, curbed the microglial-mediated neuroinflammation, and protected dopaminergic (DA) neuronal loss by restoring tyrosine hydroxylase (TH) levels in brain tissue of the MPTP-induced PD mouse model. We conducted chromatographic profiling and identified chlorogenic acid (CA) as a major constituent (19.5 mg/g of BuOH fraction), which has been well documented as an antioxidant and anti-inflammatory agent. This was found to be in harmony with our in vitro results, where DML suppressed the level of inflammatory mediators and allied the signaling pathway in LPS-stimulated microglial cells. The results of our study indicate that DML and its bioactive constituents can be developed as potential therapeutic candidates against progressive PD complications.

Mucuna pruriens Protects against MPTP Intoxicated Neuroinflammation in Parkinson's Disease through NF-κB/pAKT Signaling Pathways

Till date, drugs that have been used to manage Parkinson’s disease (PD) have only shown symptomatic relief with several adverse effects besides their inability to prevent neurodegeneration. Neuroinflammation plays an important role in the advancement of PD and can be targeted for its effective treatment. Researchers have suggested that herbal plants exhibiting the anti-inflammatory and anti-oxidant properties are therefore beneficial to human health. Conventionally, Mucuna pruriens (Mp) seeds are used for maintaining male virility in India. Reportedly, Mp is used as a rejuvenator drug having neuroprotective property. Our study aimed to investigate effects of aqueous extract of Mp (100 mg/kgbwt) on neuroinflammation, orally administered to mice intoxicated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) as well as the molecular mechanism involved in the progression of PD. In this study, we have observed significant behavioral abnormalities beside decreased antioxidant defense in MPTP intoxicated mice. We have also observed significant increase in inflammatory parameters like Glial Fibrillary Acidic Protein, Inducible Nitric Oxide Synthase, Intercellular Cell Adhesion Molecule, and Tumor Necrosis Factor alpha in substantia nigra pars compacta (SNpc) of parkinsonian mice, while Mp treatment has notably reduced these inflammatory parameters. Mp also inhibited the MPTP induced activation of NF-κB and promoted pAkt1 activity which further prevented the apoptosis of the dopaminergic neurons. Moreover, Mp exhibited significant antioxidant defense by inhibiting the lipid peroxidation and nitrite level, and by improving catalase activity and enhancing GSH level in nigrostriatal region of mouse brain. Mp also recovered the behavioral abnormalities in MPTP treated mice. Additionally, Mp treatment considerably increased the immunoreactivity of Tyrosine Hydroxylase and Dopamine Transporter in SNpc of parkinsonian mice. Our high performance liquid chromatography analysis of the Mp seed extract have shown L-DOPA, gallic acid, phytic acid, quercetin, and catechin equivalents as the major components which might cause neuroprotection in PD mice. Our result suggested that Mp extract treatment containing L-DOPA and a mixture of rich novel phytochemicals significantly alleviates the MPTP induced neurotoxicity by NF-κB and pAkt pathway. The findings observed thereby indicate that Mp extract have suggestively ameliorated MPTP induced neuroinflammation, restored the biochemical and behavioral abnormalities in PD mouse and thus provided a scientific basis for its traditional claim.

Brain infusion of α-synuclein oligomers induces motor and non-motor Parkinson's disease-like symptoms in mice

Parkinson's disease (PD) is characterized by motor dysfunction, which is preceded by a number of non-motor symptoms including olfactory deficits. Aggregation of α-synuclein (α-syn) gives rise to Lewy bodies in dopaminergic neurons and is thought to play a central role in PD pathology. However, whether amyloid fibrils or soluble oligomers of α-syn are the main neurotoxic species in PD remains controversial. Here, we performed a single intracerebroventricular (i.c.v.) infusion of α-syn oligomers (α-SYOs) in mice and evaluated motor and non-motor symptoms. Familiar bedding and vanillin essence discrimination tasks showed that α-SYOs impaired olfactory performance of mice, and decreased TH and dopamine levels in the olfactory bulb early after infusion. The olfactory deficit persisted until 45days post-infusion (dpi). α- SYO-infused mice behaved normally in the object recognition and forced swim tests, but showed increased anxiety-like behavior in the open field and elevated plus maze tests 20 dpi. Finally, administration of α-SYOs induced late motor impairment in the pole test and rotarod paradigms, along with reduced TH and dopamine content in the caudate putamen, 45 dpi. Reduced number of TH-positive cells was also seen in the substantia nigra of α-SYO-injected mice compared to control. In conclusion, i.c.v. infusion of α-SYOs recapitulated some of PD-associated non-motor symptoms, such as increased anxiety and olfactory dysfunction, but failed to recapitulate memory impairment and depressive-like behavior typical of the disease. Moreover, α-SYOs i.c.v. administration induced motor deficits and loss of TH and dopamine levels, key features of PD. Results point to α-syn oligomers as the proximal neurotoxins responsible for early non-motor and motor deficits in PD and suggest that the i.c.v. infusion model characterized here may comprise a useful tool for identification of PD novel therapeutic targets and drug screening.

Pathogenic Upregulation of Glial Lipocalin-2 in the Parkinsonian Dopaminergic System

Lipocalin-2 (LCN2) is a member of the highly heterogeneous secretory protein family of lipocalins and increases in its levels can contribute to neurodegeneration in the adult brain. However, there are no reports on the role of LCN2 in Parkinson's disease (PD). Here, we report for the first time that LCN2 expression is increased in the substantia nigra (SN) of patients with PD. In mouse brains, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) treatment for a neurotoxin model of PD significantly upregulated LCN2 expression, mainly in reactive astrocytes in both the SN and striatum. The increased LCN2 levels contributed to neurotoxicity and neuroinflammation, resulting in disruption of the nigrostriatal dopaminergic (DA) projection and abnormal locomotor behaviors, which were ameliorated in LCN2-deficient mice. Similar to the effects of MPTP treatment, LCN2-induced neurotoxicity was also observed in the 6-hydroxydopamine (6-OHDA)-treated animal model of PD. Moreover, treatment with the iron donor ferric citrate (FC) and the iron chelator deferoxamine mesylate (DFO) increased and decreased, respectively, the LCN2-induced neurotoxicity in vivo In addition to the in vivo results, 1-methyl-4-phenylpyridinium (MPP(+))-induced neurotoxicity in cocultures of mesencephalic neurons and astrocytes was reduced by LCN2 gene deficiency in the astrocytes and conditioned media derived from MPP(+)-treated SH-SY5Y neuronal enhanced glial expression of LCN2 in vitro Therefore, our results demonstrate that astrocytic LCN2 upregulation in the lesioned DA system may play a role as a potential pathogenic factor in PD and suggest that inhibition of LCN2 expression or activity may be useful in protecting the nigrostriatal DA system in the adult brain.

SIGNIFICANCE STATEMENT

Lipocalin-2 (LCN2), a member of the highly heterogeneous secretory protein family of lipocalins, may contribute to neuroinflammation and neurotoxicity in the brain. However, LCN2 expression and its role in Parkinson's disease (PD) are largely unknown. Here, we report that LCN2 is upregulated in the substantia nigra of patients with PD and neurotoxin-treated animal models of PD. Our results suggest that LCN2 upregulation might be a potential pathogenic mechanism of PD, which would result in disruption of the nigrostriatal dopaminergic system through neurotoxic iron accumulation and neuroinflammation. Therefore, inhibition of LCN2 expression or activity may be useful in protecting the nigrostriatal dopaminergic projection in PD.

Activation of Sonic hedgehog signal by Purmorphamine, in a mouse model of Parkinson's disease, protects dopaminergic neurons and attenuates inflammatory response by mediating PI3K/AKt signaling pathway

In Parkinson's disease (PD), microglial activation-mediated neuroinflammation is associated with dopaminergic neurons degeneration in the substantia nigra pars compacta. Previous studies that have investigated this neurodegenerative disease have reported that the Sonic hedgehog (SHH) signaling pathway, through inhibiting the inflammatory processes, exerts a beneficial neuroprotective effect. However, the mechanisms underlying the anti-inflammatory and neuroprotective effects of this signaling pathway remain poorly understood. The present study aimed to further investigate these mechanisms in vitro and in vivo. At first, BV2 microglial cells treated with lipopolysaccharide (LPS) were used to induce an inflammatory response. It was observed that the activation of SHH signaling by Purmorphamine attenuated the LPS-induced inflammatory response, increased the expression of transforming growth factor-β1 through the phosphatidylinositol 3-kinase (PI3K)/AKT serine/threonine kinase (Akt) intracellular signaling pathway and inhibited nuclear receptor subfamily 4 group A member 2, independently of the PI3K/Akt signaling pathway. Furthermore, the blockade of the PI3K/Akt signaling pathway by intranasal administration of LY294002, significantly reduced the SHH-associated neuroprotective effects on dopaminergic neurons, improved motor functions, and increased the microglial activation and inflammatory response in a mouse model of PD induced using 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine. In conclusion, the data of the present study reported that anti-inflammatory and neuroprotective effects can be obtained in BV2 microglial cells and in a mouse model of PD by successive activation of the SHH and PI3K/Akt signaling pathways.

The mechanism of neuroprotective action of natural compounds

Disturbance of cerebral redox homeostasis is the primary cause of human neurodegenerative disorders, such as Parkinson's disease or Alzheimer's disease. Well known experimental research demonstrates that oxidative stress is a main cause of cell death. A high concentration of reactive oxygen and nitrogen species leads to damage of a lot of proteins, lipids and also DNA. Synthetic compounds used for the treatment in the neurodegenerative diseases failed to meet the hopes they had raised and often exhibit a number of side effects. Therefore, in recent years interest in natural compounds derived from plants appears to be on the rise. This review describes a few natural compounds (1MeTIQ, resveratrol, curcumin, vitamin C and Gingko biloba) which revealed neuroprotective potential both in experimental studies and clinical trials. 1MeTIQ has a privileged position because, as opposed to the remaining compounds, it is an endogenous amine synthesized in human and animal brain. Based on evidence from research, it seems that a common protective mechanism for all the above-mentioned natural compounds relies on their ability to inhibit or even scavenge the excess of free radicals generated in oxidative and neurotoxin-induced processes in nerve cells of the brain. However, it was demonstrated that further different molecular processes connected with neurotoxicity (e.g. the inhibition of mitochondrial complex I, activation of caspase-3, apoptosis) follow later and are initiated by the reactive oxygen species. What is more, these natural compounds are able to inhibit further stages of apoptosis triggered by neurotoxins in the brain.

Recent trends in the development of nanophytobioactive compounds and delivery systems for their possible role in reducing oxidative stress in Parkinson's disease models

Oxidative stress plays a very critical role in neurodegenerative diseases, such as Parkinson's disease (PD), which is the second most common neurodegenerative disease among elderly people worldwide. Increasing evidence has suggested that phytobioactive compounds show enhanced benefits in cell and animal models of PD. Curcumin, resveratrol, ginsenosides, quercetin, and catechin are phyto-derived bioactive compounds with important roles in the prevention and treatment of PD. However, in vivo studies suggest that their concentrations are very low to cross blood-brain barrier thereby it limits bioavailability, stability, and dissolution at target sites in the brain. To overcome these problems, nanophytomedicine with the controlled size of 1-100 nm is used to maximize efficiency in the treatment of PD. Nanosizing of phytobioactive compounds enhances the permeability into the brain with maximized efficiency and stability. Several nanodelivery techniques, including solid lipid nanoparticles, nanostructured lipid carriers, nanoliposomes, and nanoniosomes can be used for controlled delivery of nanobioactive compounds to brain. Nanocompounds, such as ginsenosides (19.9 nm) synthesized using a nanoemulsion technique, showed enhanced bioavailability in the rat brain. Here, we discuss the most recent trends and applications in PD, including 1) the role of phytobioactive compounds in reducing oxidative stress and their bioavailability; 2) the role of nanotechnology in reducing oxidative stress during PD; 3) nanodelivery systems; and 4) various nanophytobioactive compounds and their role in PD.

Neuroprotective potential of ferulic acid in the rotenone model of Parkinson's disease

Parkinson's disease (PD) is a chronic, progressive, and the second most common form of neurodegenerative disorders. In order to explore novel agents for the treatment of PD, in the current study, we have evaluated the neuroprotective efficacy of ferulic acid (FA) using rotenone (ROT)-induced rat model of PD. ROT was administered 2.5 mg/kg body weight to male Wistar rats for 4 weeks to induce the PD. Since PD is progressive and chronic in nature, the paradigm for evaluating FA was based on chronic administration for 4 weeks at the dose of 50 mg/kg, 30 minutes prior to ROT administration. ROT administration caused significant reduction in endogenous antioxidants such as superoxide dismutase, catalase, and glutathione. ROT challenge-induced lipid peroxidation evidenced by increased malondialdehyde following perturbation of antioxidant defense. Apart from oxidative stress, ROT also activated proinflammatory cytokines and enhanced inflammatory mediators such as cyclooxygenase-2 and inducible nitric oxide synthase. The immunofluorescence analysis revealed a significant increase in the number of activated microglia and astrocytes accompanied by a significant loss of dopamine (DA) neurons in the substantia nigra pars compacta area upon ROT injection. However, treatment with FA rescued DA neurons in substantia nigra pars compacta area and nerve terminals in the striatum from the ROT insult. FA treatment also restored antioxidant enzymes, prevented depletion of glutathione, and inhibited lipid peroxidation. Following treatment with FA, the inflammatory mediators such as cyclooxygenase-2 and inducible nitric oxide synthase and proinflammatory cytokines were also reduced. Further, the results were supported by a remarkable reduction of Iba-1 and GFAP hyperactivity clearly suggests attenuation of microglial and astrocytic activation. Results of our study suggest that FA has promising neuroprotective effect against degenerative changes in PD, and the protective effects are mediated through its antioxidant and anti-inflammatory properties.

Endothelium-Independent Vasorelaxant Effect of Ligusticum jeholense Root and Rhizoma on Rat Thoracic Aorta

Ligusticum jeholense has been used as the traditional medicine ‘Go-Bon’ (Chinese name, Gao-ben) in China and Korea. Considering the increased use of medicinal herbs to treat hypertension, in this study, we aimed to investigate the mechanisms of the vasorelaxation effect caused by L. jeholense. We tested the methanol (MeOH) extract of L. jeholense root and rhizoma for vasorelaxant effects; while using an isolated organ-chamber technique, L. jeholense extract (LJE) induced relaxation in the rat aortic rings by stimulating vascular endothelial and smooth muscle cells. LJE showed concentration-dependent relaxant effects on endothelium-intact and endothelium-denuded aortic rings pre-contracted with both phenylephrine (PE) and potassium chloride (KCl) in Krebs-Henseleit (KH) buffer. The vasorelaxant effect of LJE was partly attenuated by pre-treatment with glibenclamide or 4-aminopyridine (4-AP) as K⁺ channel blockers. Moreover, LJE showed concentration-dependent inhibition of vasoconstriction by Ca²⁺ supplementation in the aortic rings that were pre-contracted with PE or KCl in Ca²⁺-free KH buffer. In addition, a combination of LJE and nifedipine, pre-incubated further, decreased PE-induced contractions. The results suggested that LJE-induced vasorelaxation were related to blocking K⁺ channels and inhibiting entry of extracellular Ca²⁺ via receptor-operative Ca²⁺ channels (ROCCs) or voltage-dependent Ca²⁺ channels (VDCCs).