β-Secretase (BACE1) inhibitors from Sanguisorbae Radix

A comprehensive review of Cornus officinalis: health benefits, phytochemistry, and pharmacological effects for functional drug and food development

Introduction

Cornus officinalis sieb. et zucc, a deciduous tree or shrub, is renowned for its "Cornus flesh" fruit, which is widely acknowledged for its medicinal value when matured and dried. Leveraging C. officinalis as a foundational ingredient opens avenues for the development of environmentally friendly health foods, ranging from beverages and jams to preserves and canned products. Packed with diverse bioactive compounds, this species manifests a spectrum of pharmacological effects, including anti-inflammatory, antioxidant, antidiabetic, immunomodulatory, neuroprotective, and cardiovascular protective properties.

Methods

This study employs CiteSpace visual analysis software and a bibliometric analysis platform, drawing upon the Web of Science (WOS) database for literature spanning the last decade. Through a comprehensive analysis of available literature from WOS and Google Scholar, we present a thorough summary of the health benefits, phytochemistry, active compounds, and pharmacological effects of C. officinalis. Particular emphasis is placed on its potential in developing functional drugs and foods.

Results and Discussion

While this review enhances our understanding of C. officinalis as a prospective therapeutic agent, its clinical applicability underscores the need for further research and clinical studies to validate findings and establish safe and effective clinical applications.

Neuroprotective Effect of β-secretase Inhibitory Peptide from Pacific Hake (Merluccius productus) Fish Protein Hydrolysate

BACKGROUND

Various methodologies have been employed for the therapeutic interpolation of the progressive brain disorder Alzheimer's disease. Thus, β-secretase inhibition is significant to prevent disease progression in the early stages.

OBJECTIVE

This study seeks to purify and characterize a novel β-secretase inhibitory peptide from Pacific hake enzymatic hydrolysate.

METHODS

A potent β-secretase inhibitory peptide was isolated by sequential purifications using Sephadex G-25 column chromatography and octadecylsilane (ODS) C18 reversed-phase HPLC. A total of seven peptides were synthesized using the isolated peptide sequences. SH-SY5Y cells stably transfected with the human ''Swedish'' amyloid precursor protein (APP) mutation APP695 (SH-SY5YAPP695swe) were used as an in-vitro model system to investigate the effect of Leu-Asn peptide on APP processing.

RESULTS

The β-secretase inhibitory activity (IC50) of the purified peptide (Ser-Leu-Ala-Phe-Val-Asp- Asp-Val-Leu-Asn) from fish protein hydrolysate was 18.65 μM and dipeptide Leu-Asn was the most potent β-secretase inhibitor (IC50 value = 8.82 µM). When comparing all the seven peptides, the inhibition pattern of Leu-Asn dipeptide was found to be competitive by Lineweaver-Burk plot and Dixon plot (Ki value = 4.24 µM). The 24 h treatment with Leu-Asn peptide in SH-SY5Y cells resulted in reducing the β-amyloid (Aβ) production in a dose-dependent manner.

CONCLUSION

Therefore, the results of this study suggest that β-secretase inhibitory peptides derived from marine organisms could be potential candidates to develop nutraceuticals or pharmaceuticals as antidementia agents.

Plants traditionally used in age-related brain disorders (dementia): an ethanopharmacological survey

CONTEXT

Epidemiological studies have shown that despite mortality due to communicable diseases, poverty and human conflicts, the incidence of dementia increases in the developing world in tandem with the ageing population. Although some FDA approved drugs are available for the treatment of dementia, the outcomes are often unsatisfactory. In traditional practices of medicine, numerous plants have been used to treat cognitive disorders, including neurodegenerative diseases such as Alzheimer's disease (AD) and other memory-related disorders. In western medicine most of the drugs used for the treatment of neurodegenerative disorders are derived from plant sources.

OBJECTIVE

This article reviews plants and their active constituents that have been used for their reputed cognitive-enhancing and antidementia effects.

METHODS

A literature survey in Science Direct, Pubmed, and Google Scholar was performed to gather information regarding drug discovery from plants sources for the treatment of congnitive disorders and dementia.

RESULTS

More than forty herbal remedies were identified with cholinesterase inhibitory, anti-inflammatory, or antioxidant activities. Bioactive compounds include alkaloids, flavonoids, steroids, saponins, terpenoids, and essential oils. About eleven herbal plants with multipotent activity against AD are discussed.

CONCLUSION

Literature surveys show that most of the research has been conducted on herbal remedies effect on cholinesterase inhibitory and antioxidant activities. Studies regarding the effect of herbal drugs on β-secretase inhibitory activity and antiaggregation property are lacking. This review provides leads for identifying potential new drugs from plant sources for the treatment of neurodegenerative disorders.

Inhibitory activity of Filipendula ulmaria constituents on recombinant human histidine decarboxylase

Histidine decarboxylase (HDC) catalyses the formation of histamine, a bioactive amine. Agents that control HDC activity are beneficial for treating histamine-mediated symptoms, such as allergies and stomach ulceration. We searched for inhibitors of HDC from the ethyl acetate extract of the petal of Filipendula ulmaria, also called meadowsweet. Rugosin D, rugosin A, rugosin A methyl ester (a novel compound), and tellimagrandin II were the main components; these 4 ellagitannins exhibited a non-competitive type of inhibition, with K(i) values of approximately 0.35-1 μM. These K(i) values are nearly equal to that of histidine methyl ester (K(i)=0.46 μM), an existing substrate analogue inhibitor. Our results show that food products contain potent HDC inhibitors and that these active food constituents might be useful for designing clinically available HDC inhibitors.

Inhibitory effect of tannins from galls of Carpinus tschonoskii on the degranulation of RBL-2H3 Cells

In this study, the anti-allergy potency of thirteen tannins isolated from the galls on buds of Carpinus tschonoskii (including two tannin derivatives) was investigated. RBL-2H3 (rat basophilic leukemia) cells were incubated with these compounds, and the release of β-hexosaminidase and cytotoxicity were measured. Of the thirteen tannins, tetragalloylglucose (2), pentagalloylglucose (3), casuarictin (4), and casuarinin (9) were the most potent inhibitors, and all the tannins showed no cytotoxic effect after 24 h of incubation. The results obtained suggest that tannins from C. tschonoskii are capable of inhibiting allergic reactions and may be useful for the treatment or prevention of type I allergic diseases.

Galloyl glucoses from the seeds of Cornus officinalis with inhibitory activity against protein glycation, aldose reductase, and cataractogenesis ex vivo

In an ongoing project directed toward the discovery of novel treatments for diabetic complications from traditional herbal medicines, six galloyl glucoses, 1,2,3-tri-O-galloyl-β-D-glucose (1), 1,2,6-tri-O-galloyl-β-D-glucose (2), 1,2,3,6-tetra-O-galloyl-β-D-glucose (3), 1,2,4,6-tetra-O-galloyl-β-D-glucose (4), 1,2,3,4,6-penta-O-galloyl-β-D-glucose (5), and tellimagrandin II (6), and two phenolic acids, gallic acid 4-O-β-D-glucoside (7) and gallic acid 4-O-β-D-(6'-O-galloyl)-glucoside (8), were isolated from an EtOAc-soluble fraction of the seeds of Cornus officinalis (Cornaceae). The structures of the compounds were identified using physical and spectroscopic methods, as well as by comparison of their data with values reported in the literature. All the isolates were evaluated in vitro for inhibitory activity against the formation of advanced glycation end-products (AGEs) and rat lens aldose reductase (RLAR). Compounds 1-6 were subjected to further bioassay to examine their inhibitory effects on AGE cross-linking. The opacity of lenses was significantly prevented when treated with 3 in an ex vivo experiment.

BACE1 inhibitory activity of fungal endophytic extracts from Malaysian medicinal plants

BACKGROUND

BACE1 was found to be the major β-secretase in neurons and its appearance and activity were found to be elevated in the brains of AD patients. Fungal endophytic extracts for BACE1 inhibitory activity and cytotoxicity against PC-12 (a rat pheochromocytoma with neuronal properties) and WRL68 (a non-tumorigenic human hepatic) were investigated.

METHODS

Endophytes were isolated from plants collected from Kuala Pilah, Negeri Sembilan and the National Park, Pahang and the extracts were tested for BACE1 inhibition. For investigation of biological activity, the pure endophytic cultures were cultivated for 14 days on PDA plates at 28°C and underwent semipolar extraction with ethyl acetate.

RESULTS

Of 212 endophytic extracts (1000 μg/ml), 29 exhibited more than 90% inhibition of BACE1 in the preliminary screening. Four extracts from isolates HAB16R13, HAB16R14, HAB16R18 and HAB8R24 identified as Cytospora rhizophorae were the most active with IC(50(BACE1)) values of less than 3.0 μg/ml. The most active extract HAB16R13 was shown to non-competitively inhibit BACE1 with K(i) value of 10.0 μg/ml. HAB16R13 was considered non-potent against PC-12 and WRL68 (IC(50(CT))) of 60.0 and 40.0 μg/ml, respectively).

CONCLUSIONS

This first report on endophytic fungal extract with good BACE1 inhibitory activity demonstrates that more extensive study is required to uncover the potential of endophytes.

Natural products as a source of Alzheimer's drug leads

This review focuses on recent developments in the use of natural products as therapeutics for Alzheimer's disease. The compounds span a diverse array of structural classes and are organized according to their mechanism of action, with the focus primarily on the major hypotheses. Overall, the review discusses more than 180 compounds and summarizes 400 references.

Anti-cancer gallotannin penta-O-galloyl-beta-D-glucose is a nanomolar inhibitor of select mammalian DNA polymerases

Penta-1,2,3,4,6-O-galloyl-beta-D-glucose (PGG) has been shown by us and others to inhibit the in vivo growth of human prostate cancer (PCa) xenografts in athymic nude mice and mouse lung cancer allograft in syngenic mice without evident adverse effect on their body weight. We observed a rapid inhibition of DNA synthesis in S-phase cells in PGG-exposed cancer cells and in PGG-treated isolated nuclei. The purpose of the present study was to test the hypothesis that PGG inhibits DNA replicative synthesis through a direct inhibition of one or more DNA polymerases (pols). Using purified pols, we show that PGG exhibited a selective inhibition against the activities of B-family replicative pols (alpha, delta and epsilon) and Y-family (eta, iota and kappa) of bypass synthesis pols, and the inhibitory effect of PGG on pol alpha was the strongest with IC(50) value of 13 nM. PGG also inhibited pol beta, but the potency was an order of magnitude less than against pol alpha. PGG inhibition of pol alpha and kappa activity was non-competitive with respect to the DNA template-primer and the dNTP substrate; whereas it inhibited pol beta competitively. Docking simulation on pol beta, which is the only mammalian pol with solved crystal structure, suggests several favorable interactions with the catalytic pocket/binding site for the incoming dNTP. These results support PGG as a novel inhibitor of select families of mammalian pols by distinct mechanisms, and suggest that the potent pol inhibition may contribute to its anti-cancer efficacy.

Neuroprotective effect of Sanguisorbae radix against oxidative stress-induced brain damage: in vitro and in vivo

Sanguisorbae radix (SR), the root of Sanguisorba officinalis L. (Rosaceae), has been traditionally used for its anti-inflammatory, anti-infectious and analgesic activities in Korea. Previous work has shown that SR prevents neuronal cell damage induced by Abeta (25--35) in cultured rat cortical neurons. The present study was carried out to further investigate the neuroprotective effect of SR on oxidative stress-induced toxicity in primary culture of rat cortical neurons, and on ischemia-induced brain damage in rats. SR, over a concentration range of 10--50 microg/ml, inhibited H2O2 (100 microM)-induced neuronal death, which was significantly inhibited by MK-801 (5 microM), an N-methyl-D-aspartate (NMDA) receptor antagonist, and verapamil (20 microM), an L-type Ca2+ channel blocker. Pretreatment of SR (10-50 microg/ml), MK-801 (5 microM), and verapamil (20 microM) inhibited H2O2-induced elevation of intracellular Ca2+ concentration ([Ca2+]i) measured by a fluorescent dye, Fluo-4 AM. SR (10-50 microg/ml) inhibited H2O2-induced glutamate release into medium measured by HPLC, and generation of reactive oxygen species (ROS) measured by 2',7'-dichlorodihydrofluorescein diacetate (H2DCFDA). In vivo, SR prevented cerebral ischemic injury induced by 2-h middle cerebral artery occlusion (MCAO) and 24-h reperfusion. The ischemic infarct and edema were significantly reduced in rats that received SR (10, 30 mg/kg, orally), with a corresponding improvement in neurological function. Catechin isolated from SR inhibited H2O2-induced neuronal death in cultures. Taken together, these results suggest that SR inhibits H2O2-induced neuronal death by interfering with the increase of [Ca2+]i, and inhibiting glutamate release and generation of ROS, and that the neuroprotective effect of SR against focal cerebral ischemic injury is due to its anti-oxidative effects. Thus SR might have therapeutic roles in neurodegenerative diseases such as stroke.

Screening and Optimal Extraction of a New Antidementia β-Secretase Inhibitor-Containing Mushroom

To produce a potent antidementia β-secretase inhibitor from a mushroom, the β-secretase inhibitory activities of various mushroom extracts were determined. Methanol extracts of Lentinula edodes exhibited the highest inhibitory activity (40.1%). The inhibitor was maximally extracted when a fruiting body of L. edodes was treated with 50% methanol at 40℃ for 24 h.

Beta-secretase (BACE1) inhibitors from Perilla frutescens var. acuta

In the course of screening for anti-dementia agents from natural products, two beta-secretase (BACE1) inhibitors were isolated from the methanolic extract of Perilla frutescens var. acuta and identified as luteolin (1) and rosmarinic acid (2) with IC50 values of 5.0 x 10(-7) M and 2.1 x 10(-5) M, respectively. They inhibited BACE1 in a non-competitive manner with a substrate in Dixon plots, suggesting that they might bind to either beta-secretase subsite or to another regulatory site. Kivalues of 1 and 2 were 6.2 x 10(-5) M and 3.9 x 10(-5) M, respectively. They were less inhibitory against other enzymes such as alpha-secretase (TACE), acetylcholine esterase (AchE), chymotrypsin, and elastase, indicating that they were relatively specific inhibitors of BACE1.

Molecular mechanisms for Alzheimer's disease: implications for neuroimaging and therapeutics

Alzheimer's disease is a progressive neurodegenerative disorder characterised by the gradual onset of dementia. The pathological hallmarks of the disease are beta-amyloid (Abeta) plaques, neurofibrillary tangles, synaptic loss and reactive gliosis. The current therapeutic effort is directed towards developing drugs that reduce Abeta burden or toxicity by inhibiting secretase cleavage, Abeta aggregation, Abeta toxicity, Abeta metal interactions or by promoting Abeta clearance. A number of clinical trials are currently in progress based on these different therapeutic strategies and they should indicate which, if any, of these approaches will be efficacious. Current diagnosis of Alzheimer's disease is made by clinical, neuropsychologic and neuroimaging assessments. Routine structural neuroimaging evaluation with computed tomography and magnetic resonance imaging is based on non-specific features such as atrophy, a late feature in the progression of the disease, hence the crucial importance of developing new approaches for early and specific recognition at the prodromal stages of Alzheimer's disease. Functional neuroimaging techniques such as functional magnetic resonance imaging, magnetic resonance spectroscopy, positron emission tomography and single photon emission computed tomography, possibly in conjunction with other related Abeta biomarkers in plasma and CSF, could prove to be valuable in the differential diagnosis of Alzheimer's disease, as well as in assessing prognosis. With the advent of new therapeutic strategies there is increasing interest in the development of magnetic resonance imaging contrast agents and positron emission tomography and single photon emission computed tomography radioligands that will permit the assessment of Abeta burden in vivo.