Catechin and epicatechin from Smilacis chinae rhizome protect cultured rat cortical neurons against amyloid beta protein (25-35)-induced neurotoxicity through inhibition of cytosolic calcium elevation

Unleashing nature's potential and limitations: Exploring molecular targeted pathways and safe alternatives for the treatment of multiple sclerosis (Review)

Driven by the limitations and obstacles of the available approaches and medications for multiple sclerosis (MS) that still cannot treat the disease, but only aid in accelerating the recovery from its attacks, the use of naturally occurring molecules as a potentially safe and effective treatment for MS is being explored in model organisms. MS is a devastating disease involving the brain and spinal cord, and its symptoms vary widely. Multiple molecular pathways are involved in the pathogenesis of the disease. The present review showcases the recent advancements in harnessing nature's resources to combat MS. By deciphering the molecular pathways involved in the pathogenesis of the disease, a wealth of potential therapeutic agents is uncovered that may revolutionize the treatment of MS. Thus, a new hope can be envisioned in the future, aiming at paving the way toward identifying novel safe alternatives to improve the lives of patients with MS.

A Comprehensive Review on Beneficial Effects of Catechins on Secondary Mitochondrial Diseases

Mitochondria are the main sites for oxidative phosphorylation and synthesis of adenosine triphosphate in cells, and are known as cellular power factories. The phrase "secondary mitochondrial diseases" essentially refers to any abnormal mitochondrial function other than primary mitochondrial diseases, i.e., the process caused by the genes encoding the electron transport chain (ETC) proteins directly or impacting the production of the machinery needed for ETC. Mitochondrial diseases can cause adenosine triphosphate (ATP) synthesis disorder, an increase in oxygen free radicals, and intracellular redox imbalance. It can also induce apoptosis and, eventually, multi-system damage, which leads to neurodegenerative disease. The catechin compounds rich in tea have attracted much attention due to their effective antioxidant activity. Catechins, especially acetylated catechins such as epicatechin gallate (ECG) and epigallocatechin gallate (EGCG), are able to protect mitochondria from reactive oxygen species. This review focuses on the role of catechins in regulating cell homeostasis, in which catechins act as a free radical scavenger and metal ion chelator, their protective mechanism on mitochondria, and the protective effect of catechins on mitochondrial deoxyribonucleic acid (DNA). This review highlights catechins and their effects on mitochondrial functional metabolic networks: regulating mitochondrial function and biogenesis, improving insulin resistance, regulating intracellular calcium homeostasis, and regulating epigenetic processes. Finally, the indirect beneficial effects of catechins on mitochondrial diseases are also illustrated by the warburg and the apoptosis effect. Some possible mechanisms are shown graphically. In addition, the bioavailability of catechins and peracetylated-catechins, free radical scavenging activity, mitochondrial activation ability of the high-molecular-weight polyphenol, and the mitochondrial activation factor were also discussed.

Potential of Sorghum Polyphenols to Prevent and Treat Alzheimer's Disease: A Review Article

Alzheimer's disease (AD) is characterized by the excessive deposition of extracellular amyloid-beta peptide (Aβ) and the build-up of intracellular neurofibrillary tangles containing hyperphosphorylated tau proteins. This leads to neuronal damage, cell death and consequently results in memory and learning impairments leading to dementia. Although the exact cause of AD is not yet clear, numerous studies indicate that oxidative stress, inflammation, and mitochondrial dysfunction significantly contribute to its onset and progression. There is no effective therapeutic approach to stop the progression of AD and its associated symptoms. Thus, early intervention, preferably, pre-clinically when the brain is not significantly affected, is a better option for effective treatment. Natural polyphenols (PP) target multiple AD-related pathways such as protecting the brain from Aβ and tau neurotoxicity, ameliorating oxidative damage and mitochondrial dysfunction. Among natural products, the cereal crop sorghum has some unique features. It is one of the major global grain crops but in the developed world, it is primarily used as feed for farm animals. A broad range of PP, including phenolic acids, flavonoids, and condensed tannins are present in sorghum grain including some classes such as proanthocyanidins that are rarely found in others plants. Pigmented varieties of sorghum have the highest polyphenolic content and antioxidant activity which potentially makes their consumption beneficial for human health through different pathways such as oxidative stress reduction and thus the prevention and treatment of neurodegenerative diseases. This review summarizes the potential of sorghum PP to beneficially affect the neuropathology of AD.

Anti-inflammatory properties of ethanolic extract from Vatairea macrocarpa leaves

ETHNOPHARMACOLOGICAL RELEVANCE

In Brazilian traditional folk medicine, the leaves and heartwood from Vatairea macrocarpa (Benth) Ducke (Angelim-of-Cerrado) (Fabaceae family) are used as remedy after cold maceration for the treatment of the condition popularly known as rheumatism, as well as for the general inflammatory aspects such as pains, injury and swelling. The rheumatological and rheumatic diseases affect 0.3-1.0% of the world population and all long-term treatment with conventional medications lead to adverse effects.

AIM OF THE STUDY

To investigate the chemical composition and the anti-inflammatory properties and of the ethanolic extract from V. macrocarpa leaves (EEVM) in experimental models.

MATERIAL AND METHODS

EEVM was chemically analyzed by spectrophotometry and the compounds characterization was performed by nuclear magnetic resonance and mass spectrometry. EEVM was evaluated in methylthiazolyldiphenyl-tetrazolium bromide (MTT) (3, 10, 30, and 90 μg/ml) and neutrophils phagocytic activity (1, 3, and 10 μg/ml) tests. For in vivo models, the EEVM (10, 30, 100, and 300 mg/kg) was orally administered (p.o.) for inflammatory evaluation in carrageenan-induced pleurisy in Swiss mice. The EEVM (30 and 100 mg/kg, p.o.) was tested against the Complete Freund Adjuvant (CFA)-induced paw persistent inflammation and Mycobacterium bovis (bacillus Calmette-Guerin - BCG)-induced pleurisy in C57bL6 mice.

RESULTS

The chemical composition of EEVM showed 157.06 mg (GAE)/g in relation to phenolic compounds, 82.13 mg (RUE)/g in relation to flavonoids and 48.99 mg (TAE)/g in relation to tannins. The flavonoid compounds identified were catechin, epicatechin and kaempferol-3-O-a-l-rhamnopyranoside. EEVM did not present cytotoxicity in MTT assay, however EEVM reduced phagocytic neutrophils activity at all tested concentration. EEVM significantly inhibited leukocytes migration/proteins exudation in carrageenan-induced pleurisy model. The daily administration of EEVM inhibited the inflammatory parameters in BCG and CFA models.

CONCLUSIONS

The present study showed anti-inflammatory features of EEVM (V. macrocarpa) as a natural agent against inflammatory diseases.

New sesquiterpene dilactone and β-carboline alkaloid and the α-glucosidase inhibitory activity of selected phytochemicals from Neolitsea cassia (L.) Kosterm

One new sesquiterpene dilactone, coccinine (1) and one new β-carboline alkaloid, daibucarboline F (2) together with 10 known compounds; linderane (3), linderalactone (4), pseudoneolinderane (5), linderanlide C (6), linderanine A (7), epicatechin (8), (-)-taxifolin (9), astilbin (10), L-quercitrin (11) and afzelin (12) were isolated from the stems and leaves of Neolitsea cassia (L.) Kosterm (Lauraceae). The structures of (1 and 2) were established by extensive spectroscopic methods and the known compounds were identified by comparisons with data reported in literature. The relative stereochemistry of compound (1) was assigned by X-ray diffraction analysis with Cu-Kα irradiation. Compounds (3-8) and (10) were evaluated for their α-glucosidase enzymatic inhibitory activity. Compounds (4-6), (8) and (10) exhibited inhibition towards α-glucosidase enzymatic activity with IC₅₀ values ranging from 12.10 to 96.77 μM. This is the first report on the isolation of phytochemicals from N. cassia and their bioactivities.

Natural stereoisomeric flavonoids exhibit different disruptive effects and the mechanism of action on Aβ42 protofibril

Our simulations reveal that two enantiomeric catechins display a better disruptive effect on Aβ42 protofibril than their stereoisomer epicatechin. Unexpectedly, we find that catechins adopt both collapsed and extended states, while epicatechin populates only an extended state. Their different protofibril-disruptive effects are mostly attributed to the steric effect caused by the conformational differences.

Glutathione- and apolipoprotein E-grafted liposomes to regulate mitogen-activated protein kinases and rescue neurons in Alzheimer's disease

Neurodegenerative disorders, such as Alzheimer's disease (AD), present biomedical challenges due to inability of pharmaceuticals to permeate the blood-brain barrier (BBB) and lack of therapeutic specificity in definite sites against multiple pathologies. Phosphatidylcholine (PC)-liposomes carrying curcumin (CURC), quercetin (QU), epigallocatechin gallate (EGCG) and rosmarinic acid (RA) with crosslinked glutathione (GSH) and apolipoprotein E (ApoE) were fabricated to recognize brain microvascular endothelial cells and amyloid beta (Aβ), and reduce tau protein hyperphosphorylation for AD management. Addition of stearic acid to liposomal bilayers ameliorated particle stability, promoted drug entrapment efficiency, and prolonged drug release duration. The triple targeting liposomes boosted the capability of CURC, QU, EGCG and RA for crossing the BBB with the assistance of grafted GSH and ApoE and docking Aβ around SK-N-MC cells using ApoE and PC. Moreover, GSH-ApoE-PC-liposomes benefited the 4 medicines in simultaneously transporting to Aβ_1-42-insulted neurons, in functioning against hyperphosphorylated mitogen-activated protein kinases, including p-c-Jun N-terminal protein kinase, p-extracellular signal-regulated protein kinase 1/2 and p-p38, in downregulating tau protein at S202, caspase-3 and interleukin-6, and in upregulating p-cyclic adenosine monophosphate response element-binding protein. GSH-ApoE-PC-liposomes can be promising colloidal carriers in delivering CURC, QU, EGCG and RA to degenerated neural tissue in a controlled manner, targeting pathological factors for neuroprotection, and raising preclinical effectualness for AD treatment.

Computer-assisted evaluation of plant-derived β-secretase inhibitors in Alzheimer’s disease

Background

Alzheimer’s disease (AD) is a progressive neurodegenerative age-related dementia that results in memory loss of elderly people. Many hypotheses have been formally articulated till now to decipher the pathogenesis of this disease. According to the compelling amyloidogenic hypothesis, β-secretase is a key regulatory enzyme in AD development and is therefore considered as one of the major targets for the development of drugs to treat AD. In this study, 40 plant-derived phytocompounds, proven to have β-secretase inhibitory activity in different laboratory experiments, were evaluated using computational approaches in order to identify the best possible β-secretase inhibitor(s).

Results

Amentoflavone (IFD score: − 7.842 Kcal/mol), Bilobetin (IFD score: − 7.417 Kcal/mol), and Ellagic acid (IFD score: − 6.923 Kcal/mol) showed highest β-secretase inhibitory activities with high binding affinity among all the selected phytocompounds and interacted with key amino acids, i.e., Asp32, Tyr71, and Asp228 in the catalytic site of β-secretase. Moreover, these three molecules exhibited promising results in different drug potential assessment experiments and displayed signs of correlation with significant pharmacological and biological activities.

Conclusion

Amentoflavone, Biolbetin, and Ellagic acid could be investigated further in developing β-secretase-dependent drug for the effective treatment of AD. However, additional in vivo and in vitro experiments might be required to strengthen the findings of this experiment.

Chinese Herbal Medicine Interventions in Neurological Disorder Therapeutics by Regulating Glutamate Signaling

Glutamate is the major excitatory neurotransmitter in the central nervous system, and its signaling is critical for excitatory synaptic transmission. The well-established glutamate system involves glutamate synthesis, presynaptic glutamate release, glutamate actions on the ionotropic glutamate receptors (NMDA, AMPA, and kainate receptors) and metabotropic glutamate receptors, and glutamate uptake by glutamate transporters. When the glutamate system becomes dysfunctional, it contributes to the pathogenesis of neurodegenerative and neuropsychiatric diseases such as Alzheimer's disease, Parkinson's disease, depression, epilepsy, and ischemic stroke. In this review, based on regulating glutamate signaling, we summarize the effects and underlying mechanisms of natural constituents from Chinese herbal medicines on neurological disorders. Natural constituents from Chinese herbal medicine can prevent the glutamate-mediated excitotoxicity via suppressing presynaptic glutamate release, decreasing ionotropic and metabotropic glutamate receptors expression in the excitatory synapse, and promoting astroglial glutamate transporter expression to increase glutamate clearance from the synaptic cleft. However, some natural constituents from Chinese herbal medicine have the ability to restore the collapse of excitatory synapses by promoting presynaptic glutamate release and increasing ionotropic and metabotropic glutamate receptors expression. These regulatory processes involve various signaling pathways, which lead to different mechanistic routes of protection against neurological disorders. Hence, our review addresses the underlying mechanisms of natural constituents from Chinese herbal medicines that regulate glutamate systems and serve as promising agents for the treatment of the above-mentioned neurological disorders.

Epigallocatechin-3-gallate Alleviates Cognitive Deficits in APP/PS1 Mice

Alzheimer's disease (AD) shows cognitive impairments in clinic, which is multifactorial with different etiopathogenic mechanisms such as Aβ deposition, neuroinflammation and neuronal dystrophy involved. Therefore, multi-targets drugs with neuroprotective, anti-amyloidogenic and anti-inflammatory properties will be effective in AD treatment. Epigallocatechin-3-gallate (EGCG) possesses a broad spectrum of pharmacological activities in the prevention and treatment of multiple neurodegenerative diseases. In the present study, we showed that oral administration of EGCG (50 mg/kg) for 4 months significantly attenuated the cognitive deficits in APP/PS1 transgenic mice, which served as AD model. Moreover, EGCG induced an improvement in dendritic integrity and expression levels of synaptic proteins in the brain of APP/PS1 mice. And EGCG exerted obvious anti-inflammatory effects, which was manifested by alleviating microglia activation, decreasing pro-inflammatory cytokine (IL-1β) and increasing anti-inflammatory cytokines (IL-10, IL-13). Furthermore, β-amyloid (Aβ) plaques were markedly reduced in the hippocampus of 6-month old APP/PS1 mice after EGCG treatment. In conclusion, these findings indicate that EGCG improves AD-like cognitive impairments through neuroprotective, anti-amyloidogenic and anti-inflammatory effects, thus is a promising therapeutic candidate for AD.

Supplementation with Curcuma longa Reverses Neurotoxic and Behavioral Damage in Models of Alzheimer's Disease: A Systematic Review

Background:

The formation of senile plaques and neurofibrillary tangles of the tau protein are the main pathological mechanism of Alzheimer’s disease (AD). Current therapies for AD offer discrete benefits to the clinical symptoms and do not prevent the continuing degeneration of neuronal cells. Therefore, novel therapeutic strategies have long been investigated, where curcumin (Curcuma longa) has shown some properties that can prevent the deleterious processes involved in neurodegenerative diseases.

Objective:

The aim of the present work is to review studies that addressed the effects of curcumin in experimental models (in vivo and in vitro) for AD.

Method:

This study is a systematic review conducted between January and June 2017, in which a consultation of scientific articles from indexed periodicals was carried out in Science Direct, United States National Library of Medicine (PubMed), Cochrane Library and Scielo databases, using the following descriptors: “Curcuma longa”, “Curcumin” and “Alzheimer’s disease”.

Results:

A total of 32 studies were analyzed, which indicated that curcumin supplementation reverses neurotoxic and behavioral damages in both in vivo and in vitro models of AD.

Conclusion:

The administration of curcumin in experimental models seems to be a promising approach in AD, even though it is suggested that additional studies must be conducted using distinct doses and through other routes of administration.

Aqueous Extract of Davallia mariesii Attenuates 6-Hydroxydopamine-Induced Oxidative Damage and Apoptosis in B35 Cells Through Inhibition of Caspase Cascade and Activation of PI3K/AKT/GSK-3β Pathway

The medicinal ferns of Polydiaceae and Davalliaceae species are called "Gusuibu" by Chinese physicians and used as antiaging dietary medicines. Our previous report revealed that Drynaria fortunei (Polydiaceae) protected against 6-hydroxydopamine (6-OHDA)-induced oxidative damage via the PI3K/AKT pathway in B35 neuroblastoma cells. The present study compares the antioxidant phytoconstituent contents and radical scavenging capacities of five Davalliaceae species. The further aim was to clarify the protective mechanism of Davallia mariesii (DM) against 6-OHDA-induced oxidative damage and apoptosis in B35 cells. The results show that Araiostegia perdurans (AP) and DM extracts have better radical scavenging capacities against 1,1-diphenyl-2-picryhydrazyl (DPPH) and reactive oxygen species (ROS) than other Davalliaceae species. However, only DM extract inhibited 6-OHDA autoxidation under cell-free systems and increased cell viability, compared to B35 cells solely exposed to 6-OHDA. DM extract decreased apoptosis and restored mitochondrial expression in 6-OHDA-treated B35 cells. Additional data indicated that DM extract decreased intracellular ROS and nitric oxide levels generated by 6-OHDA exposure. DM extract also restored glutathione (GSH) levels and the activities of glutathione peroxidase and reductase, and then decreased the elevated malondialdehyde (MDA) levels. Finally, DM extract regulated the protein expression of the caspase cascade and PI3K/AKT/GSK-3β pathways. These results suggest that the protective mechanism of DM extract against 6-OHDA-induced oxidative damage and apoptosis might be related to its radical scavenging capacity, maintaining the mitochondrial function to inhibit the Bcl-2/caspase cascade pathway and activating intracellular antioxidant defenses (GSH recycling, HO-1 and NQO-1) by modulating the activation of the PI3K/AKT/GSK-3β pathway.

Diabetes and Alzheimer's Disease: Can Tea Phytochemicals Play a Role in Prevention?

Dementia and diabetes mellitus are prevalent disorders in the elderly population. While recognized as two distinct diseases, diabetes has more recently recognized as a significant contributor to risk for developing dementia, and some studies make reference to type 3 diabetes, a condition resulting from insulin resistance in the brain. Alzheimer's disease, the most common form of dementia, and diabetes, interestingly, share underlying pathological processes, commonality in risk factors, and, importantly, pathways for intervention. Tea has been suggested to possess potent antioxidant properties. It is rich in phytochemicals including, flavonoids, tannins, caffeine, polyphenols, boheic acid, theophylline, theobromine, anthocyanins, gallic acid, and finally epigallocatechin-3-gallate, which is considered to be the most potent active ingredient. Flavonoid phytochemicals, known as catechins, within tea offer potential benefits for reducing the risk of diabetes and Alzheimer's disease by targeting common risk factors, including obesity, hyperlipidemia, hypertension, cardiovascular disease, and stroke. Studies also show that catechins may prevent the formation of amyloid-β plaques and enhance cognitive functions, and thus may be useful in treating patients who have Alzheimer's disease or dementia. Furthermore, other phytochemicals found within tea offer important antioxidant properties along with innate properties capable of modulating intracellular neuronal signal transduction pathways and mitochondrial function.

Plants-Derived Neuroprotective Agents: Cutting the Cycle of Cell Death through Multiple Mechanisms

Neuroprotection is the preservation of the structure and function of neurons from insults arising from cellular injuries induced by a variety of agents or neurodegenerative diseases (NDs). The various NDs including Alzheimer's, Parkinson's, and Huntington's diseases as well as amyotropic lateral sclerosis affect millions of people around the world with the main risk factor being advancing age. Each of these diseases affects specific neurons and/or regions in the brain and involves characteristic pathological and molecular features. Hence, several in vitro and in vivo study models specific to each disease have been employed to study NDs with the aim of understanding their underlying mechanisms and identifying new therapeutic strategies. Of the most prevalent drug development efforts employed in the past few decades, mechanisms implicated in the accumulation of protein-based deposits, oxidative stress, neuroinflammation, and certain neurotransmitter deficits such as acetylcholine and dopamine have been scrutinized in great detail. In this review, we presented classical examples of plant-derived neuroprotective agents by highlighting their structural class and specific mechanisms of action. Many of these natural products that have shown therapeutic efficacies appear to be working through the above-mentioned key multiple mechanisms of action.

The effect of epicatechin on oxidative stress and mitochondrial damage induced by homocycteine using isolated rat hippocampus mitochondria

Oxidative stress and mitochondrial dysfunction are the main suggested mechanisms for neurodegenerative diseases. In this study, we have evaluated the effects of epicatechin (EC) on mitochondrial damage induced by homocycteine (Hcy) using isolated rat hippocampus mitochondria in vivo. EC (50 mg/kg) was gavaged daily for a period of 10 days, starting 5 days prior to Hcy (0.5 μmol/μL) intra hippocampus injection in rats. Mitochondria were isolated from brain by different centrifuge techniques. Mitochondrial function was assayed by MTT test. Also, mitochondrial swelling and oxidative stress markers, such as reactive oxygen species (ROS), lipid peroxidation and glutathione (GSH), were assayed. Hcy induced mitochondrial dysfunction and swelling. Increase in ROS formation, lipid peroxidation, and decreased GSH were observed after Hcy treatment in isolated brain mitochondria. Furthermore, oral administration of EC significantly decreased the lipid peroxidation and ROS levels and also increased GSH levels. Also, EC treatment significantly improved mitochondrial function. As EC indicated protective effects against oxidative stress and mitochondrial damage induced by Hcy, it is suggested for further trials for prevention or treatments of neurodegenerative disorders such as Alzheimer disease.

Polyphenols Beyond Barriers: A Glimpse into the Brain

BACKGROUND

Ageing can be simply defined as the process of becoming older, which is genetically determined but also environmentally modulated. With the continuous increase of life expectancy, quality of life during ageing has become one of the biggest challenges of developed countries. The quest for a healthy ageing has led to the extensive study of plant polyphenols with the aim to prevent age-associated deterioration and diseases, including neurodegenerative diseases. The world of polyphenols has fascinated researchers over the past decades, and in vitro, cell-based, animal and human studies have attempted to unravel the mechanisms behind dietary polyphenols neuroprotection.

METHODS

In this review, we compiled some of the extensive and ever-growing research in the field, highlighting some of the most recent trends in the area.

RESULTS

The main findings regarding polypolyphenols neuroprotective potential performed using in vitro, cellular and animal studies, as well as human trials are covered in this review. Concepts like bioavailability, polyphenols biotransformation, transport of dietary polyphenols across barriers, including the blood-brain barrier, are here explored.

CONCLUSION

The diversity and holistic properties of polypolyphenol present them as an attractive alternative for the treatment of multifactorial diseases, where a multitude of cellular pathways are disrupted. The underlying mechanisms of polypolyphenols for nutrition or therapeutic applications must be further consolidated, however there is strong evidence of their beneficial impact on brain function during ageing. Nevertheless, only the tip of the iceberg of nutritional and pharmacological potential of dietary polyphenols is hitherto understood and further research needs to be done to fill the gaps in pursuing a healthy ageing.

Potential neuroprotective properties of epigallocatechin-3-gallate (EGCG)

Neurodegenerative diseases such as Alzheimer's disease (AD) and Parkinson's disease (PD) enforce an overwhelming social and economic burden on society. They are primarily characterized through the accumulation of modified proteins, which further trigger biological responses such as inflammation, oxidative stress, excitotoxicity and modulation of signalling pathways. In a hope for cure, these diseases have been studied extensively over the last decade to successfully develop symptom-oriented therapies. However, so far no definite cure has been found. Therefore, there is a need to identify a class of drug capable of reversing neural damage and preventing further neural death. This review therefore assesses the reliability of the neuroprotective benefits of epigallocatechin-gallate (EGCG) by shedding light on their biological, pharmacological, antioxidant and metal chelation properties, with emphasis on their ability to invoke a range of cellular mechanisms in the brain. It also discusses the possible use of nanotechnology to enhance the neuroprotective benefits of EGCG.

The Hot-Water Extract of Smilacis Chinae Rhizome Suppresses 2,4-Dinitrochlorobenzene and House Dust Mite-Induced Atopic Dermatitis-Like Skin Lesions in Mice

Smilacis Chinae Rhizome (SCR) has been used as an oriental folk medicine for various biological activities. However, its effect on atopic dermatitis (AD) remains undetermined to date. We assessed the effect of orally administered hot-water extract of SCR on AD-like skin lesions in mice and its underlying mechanisms. AD-like murine model was prepared by repeated alternate application of house dust mite (Dermatophagoides farinae) extract (DFE) and 2,4-dinitrochlorobenzene (DNCB) for 4 weeks, topically to the ears. Daily oral administration of SCR for 3 and 4 weeks significantly reduced inflammatory ear thickening, with the effect being enhanced at the earlier start and longer period of administration. This effect was accompanied by a significant decrease in both Th2 and Th1 serum antibodies (total IgE, DFE-specific IgE, and IgG2a). Histological analysis showed that SCR markedly decreased the epidermal/dermal ear thickening and the dermal infiltration of inflammatory cells. Furthermore, SCR suppressed DFE/DNCB-induced expression of IL-4, IL-13, IL-17, IL-18, TSLP, and IFN-γ genes in the ear tissue. Taken together, our observations demonstrate that chronic oral administration of SCR exerts beneficial effect in mouse AD model, suggesting that SCR has the therapeutic potential as an orally active treatment of AD by modulating both Th1 and Th2 responses.

Ilex latifolia Prevents Amyloid β Protein (25-35)-Induced Memory Impairment by Inhibiting Apoptosis and Tau Phosphorylation in Mice

Ilex latifolia Thunb. (Aquifoliaceae), a Chinese bitter tea called "kudingcha," has been widely consumed as a health beverage and found to possess antioxidant, antidiabetic, antihypertensive, anti-inflammatory, and anti-ischemic activities. The aim of the present study was to investigate the neuroprotective effects of an ethanol extract of I. latifolia against amyloid β protein (Aβ)-induced memory impairment in mice and neurotoxicity in cultured rat cortical neurons. Memory impairment in mice was induced by intracerebroventricular injection of 15 nmol Aβ (25-35) and measured by the passive avoidance test and Morris water maze test. Chronic administration of I. latifolia (25-100 mg/kg, p.o.) significantly prevented Aβ (25-35)-induced memory loss. I. latifolia also prevented the decrease of glutathione concentrations, increased lipid peroxidation, expression of phosphorylated tau (p-tau), and changes in apoptosis-associated proteins in the memory-impaired mouse brain. Exposure of cultured cortical neurons to 10 μM Aβ (25-35) for 36 h induced neuronal apoptotic death. The neuronal cell death, elevation of intracellular Ca(2+) concentration, generation of reactive oxygen species, and expression of proapoptotic proteins caused by Aβ (25-35) in the cultured neurons were inhibited by treatment with I. latifolia (1-50 μg/mL). These results suggest that I. latifolia may have a possible therapeutic role in managing cognitive impairment associated with Alzheimer's disease. The underlying mechanism might involve the antiapoptotic effects mediated by antioxidant activity and inhibition of p-tau formation.

Immunosuppressive phenolic compounds from Hydnora abyssinica A. Braun

BACKGROUND

Hydnora abyssinica (HA) A. Braun is an endemic Sudanese medicinal plant traditionally used as anti-inflammatory and against many infectious diseases. However, it proved to be very rich in phenols and tannins, so the present study was undertaken to investigate the immunomodulatory potential of the whole plant ethanolic extract and its isolated compounds.

METHODS

Lymphocyte proliferation, chemiluminescence and superoxide reduction assays were used for immunomodulatory evaluation. While, MTT (3-(4, 5-dimethylthazol-2-yl)-2, 5-diphenyl tetrazonium bromide) test was performed on 3 T3 cell line clone in order to evaluate the cytoxicity effect of the extracts and isolated compounds of phenolic derivatives which were carried out by chromotographic techniques.

RESULTS

Catechin, (1), tyrosol (2) and benzoic acid, 3, 4, dihydroxy-, ethyl ester (3) compounds were isolated from HA ethanolic extract which revealed potent immunosuppressive activity against reactive oxygen species from both polymorph nuclear cells (PMNs) (45-90 % inhibition) and mononuclear cells (MNCs) (30 -65 % inhibition), T lymphocyte proliferation assay (70-93 % inhibition) as well as potent inhibitory effect against superoxide production (42-71 % inhibition) at concentrations of 6.25-100 μg/mL. Catechin (1) was found the most potent immunosuppressive agent among all constituents examined.

CONCLUSION

These results can support the traditional uses of H. abyssinica extracts as anti-inflammatory and immunosuppressive and further investigations of the mode of action and other pharmacological studies are highly desirable.

The effects of bioactive compounds from plant foods on mitochondrial function: a focus on apoptotic mechanisms

Mitochondria are essential organelles for cellular integrity and functionality maintenance and their imparement is implicated in the development of a wide range of diseases, including metabolic, cardiovascular, degenerative and hyperproliferative pathologies. The identification of different compounds able to interact with mitochondria for therapeutic purposes is currently becoming of primary importance. Indeed, it is well known that foods, particularly those of vegetable origin, present several constituents with beneficial effects on health. This review summarizes and updates the most recent findings concerning the mechanisms through which different dietary compounds from plant foods affect mitochondria functionality in healthy and pathological in vitro and in vivo models, paying particular attention to the pathways involved in mitochondrial biogenesis and apoptosis.

Protective effects of plant seed extracts against amyloid β-induced neurotoxicity in cultured hippocampal neurons

AIM:

Alzheimer's disease (AD) is characterized by large deposits of amyloid β (Aβ) peptide. Aβ is known to increase reactive oxygen species (ROS) production in neurons, leading to cell death. In this study, we screened 15 plant seeds’ aqueous extracts (PSAE) for inhibitory effects on Aβ (25-35)-induced cell death using hippocampus neurons (HIPN).

MATERIALS AND METHODS:

Fifteen chosen plants were nine medical herbs (Japanese honeywort, luffa, rapeseed, Chinese colza, potherb mustard, Japanese radish, bitter melon, red shiso, corn, and kaiware radish) and six general commercial plants (common bean, komatsuna, Qing geng cai, bell pepper, kale, and lettuce). PSAE were measured for total phenolic content (TPC) with the Folin–Ciocalteu method, and the 2-diphenyl-1-picryl-hydrazyl (DPPH) radical scavenging effect of each seed extract was measured. To find a protectant against Aβ-induced oxidative stress, we screened 15 PSAE using a 2’, 7’-dichlorofluorescein diacetate assay. To further unravel the anti-inflammatory effects of PSAE on Aβ-induced inflammation, PSAE were added to HIPN. The neuroprotective effects of the PSAE were evaluated by Cell Counting Kit-8 assay, measuring the cell viability in Aβ-induced HIPN.

RESULTS:

TPC of 15 PSAE was in the range of 0.024-1.96 mg of chlorogenic acid equivalents/gram. The aqueous extracts showed antioxidant activities. Furthermore, intracellular ROS accumulation resulting from Aβ treatment was reduced when cells were treated with some PSAE. Kale, bitter melon, kaiware radish, red shiso, and corn inhibited tumor necrosis factor-alpha secretion by the Aβ-stimulated neurons and all samples except Japanese honeywort showed enhancement of cell survival.

CONCLUSION:

From these results, we suggest that some plant seed extracts offer protection against Aβ-mediated cell death.

NeuroAiD® (MLC601) and amyloid precursor protein processing

BACKGROUND

Amyloid precursor protein (APP) undergoes cleavage under physiological conditions, predominantly by α- and γ-secretases, to form the nonpathogenic sAPPα and p3 fragments. By contrast, amyloid-beta (Aβ) is produced via proteolytic cleavage by β- and γ-secretases. In Alzheimer's disease (AD), APP is preferentially processed via the amyloidogenic pathway, producing large amounts of Aβ that form the major constituent of senile plaques and tau-containing neurofibrillary tangles. Similarly, stroke patients have a higher level of Aβ around the area of infarct, suggesting that Aβ may mediate at least some of the secondary neurotoxicity observed in stroke patients.

METHODS

To investigate the effects of MLC601 (NeuroAiD(®)) on regulation of APP processing, the human neuroblastoma cell line SH-SY5Y was used for all experiments. Stocks of MLC601 were prepared at a final concentration of 50 mg/ml. Cells were treated with different concentrations of MLC601 before assessing changes in the levels of released lactate dehydrogenase (LDH), full-length APP and secreted sAPPα.

RESULTS

Concentrations of MLC601 between 1 and 1,000 µg/ml significantly lowered the levels of LDH released into the media when compared to control cells. In contrast, MLC601 concentrations at 5,000 and 10,000 µg/ml resulted in a significant increase in the LDH release. Treatment with 100, 500 and 1,000 μg/ml of MLC601 significantly increases the levels of sAPPα secreted by SH-SY5Y into the media. Treatment with 1,000 μg/ml of MLC601 significantly decreased the levels of full-length APP.

CONCLUSION

MLC601 is a possible modulator of APP processing and has implications as a putative therapeutic strategy for the treatment of poststroke dementia and AD.

Triterpenoids and flavonoids from Cecropia schreberiana Miq. (Urticaceae)

Phytochemical investigation of the leaves of Cecropia schreberiana Miq. (Urticaceae) led to the isolation of four triterpenoids (1-4), three flavone C-glycosides (5-7), two flavan-3-ols (8, 9), two flavanolignans (10, 11), and two proanthocyanidins (12, 13). All compounds were isolated from C. schreberiana for the first time. This is the first report demonstrating the presence of arjunolic acid (4), cinchonain Ia (10), and cinchonain Ib (11) in the Urticaceae family. The occurrence of flavanolignans within the family Urticaceae supports the likelihood that such compounds are more common within the class Magnoliopsida than previously thought.

Pharmacokinetics and blood-brain barrier penetration of (+)-catechin and (-)-epicatechin in rats by microdialysis sampling coupled to high-performance liquid chromatography with chemiluminescence detection

(+)-Catechin (C) and (-)-epicatechin (EC), as the basic monomer units of flavanols, can be widely found in natural products or medicinal herbs. Recent pharmacological studies have revealed that C and EC exhibit good neuroprotective effects. However, there is little information about pharmacokinetic profiles in the brain and in vivo BBB penetration of C and EC. In this paper, an ultrasensitive method using high-performance liquid chromatography (HPLC) with chemiluminescence (CL) detection was developed for the analysis of microdialysis samples. The detection limits for C and EC in Ringer's solution were 1.0 and 1.2 ng/mL, respectively. The intraday and interday accuracies for C and EC in Ringer's solution ranged from -3.0 to 4.4%, and the intraday and interday precisions were below 5.2%. The mean in vivo recoveries of C and EC in microdialysis probes were 33.7% and 26.5% in blood while 38.3% and 29.1% in brain. Pharmacokinetic parameters were estimated using the statistical moment method after iv administration (C and EC, 20 mg/kg of body weight) in rats. Brain-to-blood (AUC(brain)/AUC(blood)) distribution ratios were 0.0726 ± 0.0376 for C and 0.1065 ± 0.0531 for EC, indicating that C and EC could pass through the BBB, which is further evidence of their neuroprotective effects.

Alkenylresorcinols and cytotoxic activity of the constituents isolated from Labisia pumila

Phytochemical investigation on the leaves of Labisia pumila (Myrsinaceae), an important medicinal herb in Malaysia, has led to the isolation of 1-O-methyl-6-acetoxy-5-(pentadec-10Z-enyl)resorcinol (1), labisiaquinone A (2) and labisiaquinone B (3). Along with these, 16 known compounds including 1-O-methyl-6-acetoxy-5-pentadecylresorcinol (4), 5-(pentadec-10Z-enyl)resorcinol (5), 5-(pentadecyl)resorcinol (6), (-)-loliolide (7), stigmasterol (8), 4-hydroxyphenylethylamine (9), 3,4,5-trihydroxybenzoic acid (10), 3,4-dihydroxybenzoic acid (11), (+)-catechin (12), (-)-epicatechin (13), kaempferol-3-O-α-rhamnopyranosyl-7-O-β-glycopyranoside (14), kaempferol-4'-O-β-glycopyranoside (15), quercetin-3-O-α-rhamnopyranoside (16), kaempferol-3-O-α-rhamnopyranoside (17), (9Z,12Z)-octadeca-9,12-dienoic acid (18) and stigmasterol-3-O-β-glycopyranoside (19) were also isolated. The structures of these compounds were established on the basis of 1D and 2D NMR spectroscopy techniques (¹H, ¹³C, COSY, HSQC, NOESY and HMBC experiments), mass spectrometry and chemical derivatization. Among the constituents tested 1 and 4 exhibited strongest cytotoxic activity against the PC3, HCT116 and MCF-7 cell lines (IC₅₀ values ≤ 10 μM), and they showed selectivity towards the first two-cell lines relative to the last one.

Experimental inhibition of fibrillogenesis and neurotoxicity by amyloid-beta (Aβ) and other disease-related peptides/proteins by plant extracts and herbal compounds

Amyloid-β (Aβ) fibrillogenesis and associated cyto/neurotoxicity are major pathological events and hallmarks in diseases such as Alzheimer's disease (AD). The understanding of Aβ molecular pathogenesis is currently a pharmacological target for rational drug design and discovery based on reduction of Aβ generation, inhibition of Aβ fibrillogenesis and aggregation, enhancement of Aβ clearance and amelioration of associated cytotoxicity. Molecular mechanisms for other amyloidoses, such as transthyretin amyloidosis, AL-amyloidosis, as well as α-synuclein and prion protein are also pharmacological targets for current drug therapy, design and discovery. We report on natural herbal compounds and extracts that are capable binding to and inhibiting different targets associated with AD and other amyloid-associated diseases, providing a basis for future therapeutic strategies. Many herbal compounds, including curcumin, galantamine, quercetin and other polyphenols, are under active investigation and hold considerable potential for future prophylactic and therapeutic treatment against AD and other neurodegenerative diseases, as well as systemic amyloid diseases. A common emerging theme throughout many studies is the anti-oxidant and anti-inflammatory properties of the compounds or herbal extracts under investigation, within the context of the inhibition of cyto/neurotoxicity and anti-amyloid activity.

Estrogenic and anti-estrogenic compounds from the Thai medicinal plant, Smilax corbularia (Smilacaceae)

From the rhizomes of Smilax corbularia Kunth. (Smilacaceae), 11 compounds, (2R,3R)-2″-acetyl astilbin, (2R,3R)-3″-acetyl astilbin, (2R,3R)-4″-acetyl astilbin, (2R,3R)-3″-acetyl engeletin, (2R,3S)-4″-acetyl isoastilbin, 2-(4-hydroxyphenyl)-3,4,9,10-tetrahydro-3,5-dihydroxy-10-(3,4-dihydroxyphenyl)-(2R,3R,10R)-2H,8H-benzo [1,2-b:3,4-b'] dipyran-8-one, 2-(4-hydroxyphenyl)-3,4,9,10-tetrahydro-3,5-dihydroxy-10-(3,4-dihydroxyphenyl)-(2R,3R,10S)-2H, 8H-benzo [1,2-b:3,4-b'] dipyran-8-one, 3,4-dihydro-7-hydroxy-4-(3,4-dihydroxyphenyl)-5-[(1E)-2-(4-hydroxyphenyl) ethenyl]-2H-1-benzopyran-2-one, 3,4-dihydro-7-hydroxy-4-(3,4-dihydroxy-phenyl)-5-[(1E)-2-(3,4-dihydroxyphenyl) ethenyl]-2H-1-benzopyran-2-one, 3,4-dihydro-7-hydroxy-4-(4-hydroxy-3-methoxyphenyl)-5-[(1E)-2-(4-hydroxyphenyl) ethenyl]-2H-1-benzopyran-2-one, and 5,7,3',4'-tetrahydroxy-3-phenylcoumarin along with 34 known compounds were isolated and characterized as 19 flavonoids, 14 catechin derivatives, 6 stilbene derivatives, and 6 miscellaneous substances. All isolates had their estrogenic and anti-estrogenic activities determined using the estrogen-responsive human breast cancer cell lines MCF-7 and T47D. The major constituents were recognized as flavanonol rhamnosides by the suppressive effect on estradiol induced cell proliferation at a concentration of 1μM. Meanwhile, flavanonol rhamnoside acetates demonstrated estrogenic activity in both MCF-7 and T47D cells at a concentration of 100μM, and they enhanced the effects of co-treated E2 on T47D cell proliferation at concentrations of more than 0.1μM.

SSeCKS promote beta-amyloid-induced PC12 cells neurotoxicity by up-regulating tau phosphorylation in Alzheimer's disease

In Alzheimer's disease, beta-amyloid peptide (Abeta) could induce tau hyperphosphorylation which is the major cause of neuron apoptosis. However, the underlying mechanisms in the process remain unclear. In this study, Abeta-induced apoptosis and tau phosphorylation were investigated in differentiated PC12 cells. This Abeta-induced tau phosphorylation paralleled with the increase of expression and phosphorylation of Src-suppressed protein kinase C substrate (SSeCKS). By knocking down the expression of SSeCKS, Abeta-induced apoptosis and tau hyperphosphorylation in PC12 cells were partially rescued, and were increased further due to the overexpression of SSeCKS in PC12 cells. Also, the cell apoptosis and tau hyperphosphorylation were strongly decreased when the cells were pretreated with the protein kinase C inhibitor, Gö6983. In addition, Abeta-induced tau phosphorylation was also partially decreased due to the overexpression of SSeCKS in PC12cells. In summary, our data indicate that SSeCKS may play a critical role in Abeta-induced PC12 cells apoptosis through its phosphorylation.

Targeting NADPH oxidase and phospholipases A2 in Alzheimer's disease

Alzheimer's disease (AD) is marked by an increase in the production of extracellular beta amyloid plaques and intracellular neurofibrillary tangles associated with a decline in brain function. Increases in oxidative stress are regarded as an early sign of AD pathophysiology, although the source of reactive oxygen species (ROS) and the mechanism(s) whereby beta amyloid peptides (Abeta) impact oxidative stress have not been adequately investigated. Recent studies provide strong evidence for the involvement of NADPH oxidase and its downstream oxidative signaling pathways in the toxic effects elicited by Abeta. ROS produced by NADPH oxidase activate multiple signaling pathways leading to neuronal excitotoxicity and glial cell-mediated inflammation. This review describes recent studies demonstrating the neurotoxic effects of Abeta in conjunction with ROS produced by NADPH oxidase and the downstream pathways leading to activation of cytosolic phospholipase A(2) (PLA(2)) and secretory PLA(2). In addition, this review also describes recent studies using botanical antioxidants to protect against oxidative damage associated with AD. Investigating the metabolic and signaling pathways involving Abeta NADPH oxidase and PLA(2) can help understand the mechanisms underlying the neurodegenerative effects of oxidative stress in AD. This information should provide new therapeutic approaches for prevention of this debilitating disease.

Octyl Gallate Inhibits ATP-induced Intracellular Calcium Increase in PC12 Cells by Inhibiting Multiple Pathways

Phenolic compounds affect intracellular free Ca(2+) concentration ([Ca(2+)](i)) signaling. The study examined whether the simple phenolic compound octyl gallate affects ATP-induced Ca(2+) signaling in PC12 cells using fura-2-based digital Ca(2+) imaging and whole-cell patch clamping. Treatment with ATP (100 microM) for 90 s induced increases in [Ca(2+)](i) in PC12 cells. Pretreatment with octyl gallate (100 nM to 20 microM) for 10 min inhibited the ATP-induced [Ca(2+)](i) response in a concentration-dependent manner (IC(50)=2.84 microM). Treatment with octyl gallate (3 microM) for 10 min significantly inhibited the ATP-induced response following the removal of extracellular Ca(2+) with nominally Ca(2+)-free HEPES HBSS or depletion of intracellular Ca(2+) stores with thapsigargin (1 microM). Treatment for 10 min with the L-type Ca(2+) channel antagonist nimodipine (1 microM) significantly inhibited the ATP-induced [Ca(2+)](i) increase, and treatment with octyl gallate further inhibited the ATP-induced response. Treatment with octyl gallate significantly inhibited the [Ca(2+)](i) increase induced by 50 mM KCl. Pretreatment with protein kinase C inhibitors staurosporin (100 nM) and GF109203X (300 nM), or the tyrosine kinase inhibitor genistein (50 microM) did not significantly affect the inhibitory effects of octyl gallate on the ATP-induced response. Treatment with octyl gallate markedly inhibited the ATP-induced currents. Therefore, we conclude that octyl gallate inhibits ATP-induced [Ca(2+)](i) increase in PC12 cells by inhibiting both non-selective P2X receptor-mediated influx of Ca(2+) from extracellular space and P2Y receptor-induced release of Ca(2+) from intracellular stores in protein kinase-independent manner. In addition, octyl gallate inhibits the ATP-induced Ca(2+) responses by inhibiting the secondary activation of voltage-gated Ca(2+) channels.

Simultaneous manipulation of multiple brain targets by green tea catechins: a potential neuroprotective strategy for Alzheimer and Parkinson diseases

Current therapeutic approaches for Alzheimer and Parkinson disease (AD and PD, respectively) are merely symptomatic, intended for the treatment of symptoms, but offer only partial benefit, without any disease-modifying activity. Novel promising strategies suggest the use of antiinflammatory drugs, antioxidants, iron-complexing molecules, neurotrophic factor delivery, inhibitors of the amyloid precursor protein (APP)-processing secretases, gamma and beta (that generate the amyloid-beta peptides, Abeta), anti-Abeta aggregation molecules, the interference with lipid cholesterol metabolism and naturally occurring plant flavonoids to potentially reverse the course of the diseases. Human epidemiological and new animal data suggest that tea drinking may decrease the incidence of dementia, AD, and PD. In particular, its main catechin polyphenol constituent (-)-epigallocatechin-3-gallate (EGCG) has been shown to exert neuroprotective/neurorescue activities in a wide array of cellular and animal models of neurological disorders. In the current article, we review the literature on the impact of the multimodal activities of green tea polyphenols and their neuroprotective effect on AD and PD.

Targeting multiple neurodegenerative diseases etiologies with multimodal-acting green tea catechins

Green tea is currently considered a source of dietary constituents endowed with biological and pharmacological activities relevant to human health. Human epidemiological and new animal data suggest that the pharmacological benefits of tea drinking may help to protect the brain as we age. Indeed, tea consumption is inversely correlated with the incidence of dementia and Alzheimer's and Parkinson's diseases. In particular, its main catechin polyphenol constituent (-)-epigallocatechin-3-gallate has been shown to exert neuroprotective/neurorescue activities in a wide array of cellular and animal models of neurological disorders. The intense efforts dedicated in recent years to shed light on the molecular mechanisms participating in the brain protective action of green tea indicate that in addition to the known antioxidant activity of catechins, the modulation of signal transduction pathways, cell survival/death genes, and mitochondrial function all contribute significantly to the induction of neuron viability. Because of the multietiological character of neurodegenerative disease pathology, these natural compounds are receiving significant attention as therapeutic cytoprotective agents that simultaneously manipulate multiple desired targets in the central nervous system. This article elaborates on the multimodal activities of green tea polyphenols with emphasis on their recently described neurorescue/neuroregenerative and mitochondrial stabilization actions.

Amyloid beta peptide and NMDA induce ROS from NADPH oxidase and AA release from cytosolic phospholipase A2 in cortical neurons

Increase in oxidative stress has been postulated to play an important role in the pathogenesis of a number of neurodegenerative diseases including Alzheimer's disease. There is evidence for involvement of amyloid-beta peptide (Abeta) in mediating the oxidative damage to neurons. Despite yet unknown mechanism, Abeta appears to exert action on the ionotropic glutamate receptors, especially the N-methyl-D-aspartic acid (NMDA) receptor subtypes. In this study, we showed that NMDA and oligomeric Abeta(1-42) could induce reactive oxygen species (ROS) production from cortical neurons through activation of NADPH oxidase. ROS derived from NADPH oxidase led to activation of extracellular signal-regulated kinase 1/2, phosphorylation of cytosolic phospholipase A(2)alpha (cPLA(2)alpha), and arachidonic acid (AA) release. In addition, Abeta(1-42)-induced AA release was inhibited by d(-)-2-amino-5-phosphonopentanoic acid and memantine, two different NMDA receptor antagonists, suggesting action of Abeta through the NMDA receptor. Besides serving as a precursor for eicosanoids, AA is also regarded as a retrograde messenger and plays a role in modulating synaptic plasticity. Other phospholipase A(2) products such as lysophospholipids can perturb membrane phospholipids. These results suggest an oxidative-degradative mechanism for oligomeric Abeta(1-42) to induce ROS production and stimulate AA release through the NMDA receptors. This novel mechanism may contribute to the oxidative stress hypothesis and synaptic failure that underline the pathogenesis of Alzheimer's disease.