Β-secretase Inhibitory Activity Research Articles

Therapeutic Potential and Pharmacological Activities of Bioflavonoid ‘Ochnaflavone’ in Medicine: Diverse Scaffolds and Promise Leads for Drug Discovery

Background: Biflavonoids are natural phytocompounds that received enormous at-tention in various remedies due to their diverse biological activities. Biflavonoids have anti-inflammatory, anti-leishmanial, anti-plasmodial, anti-viral and β-secretase inhibitory activity in medicine. Ochnaflavone is a biflavone class natural phytochemical isolated from plants belong-ing to the Ochnaceae family. Methods:: Scientific information on ochnaflavone was collected and analyzed in the present investigation to investigate the biological activities of ochnaflavone. The present paper de-scribes the pharmacological activities and bioanalytical aspects of ochnaflavone based on the available scientific research on ochnaflavone in research work, books and other literature data-bases. Scientific data on ochnaflavone were collected from various scientific databases (Google, Science Direct, Scopus and PubMed) in this paper in order to investigate the health-beneficial potential of ochnaflavone in medicine. Further, the pharmacological activity of ochnaflavone was also collected in a detailed manner and discussed here in order to know the health-beneficial aspects of ochnaflavone. Results:: The therapeutic importance of ochnaflavone has been summarized in the present paper through available literature data on ochnaflavone in the scientific fields. Ochnaflavone was found to be an active phytochemical of Campylospermum excavatum, Cespedesia spathulata, Godoya antioquiensis, Lonicera japonica, Lonicerae Japonicae, Ochna afzelii, Ochna bed-domei, Ochna beddomi, Ochna integerrima, Ochna kibbiensis, Ochna pretoriensis, Ochna squarrosa Linn., Selaginella trichoclada and Triclisia gilletii. Scientific data revealed the bio-logical importance of ochnaflavone for its effectiveness on inflammation, SARS-CoV-2, fungal arthritis, enzymes, mutagenic effect, lymphocyte proliferation, and inhibition of arachidonate release. However, its antimycobacterial activity, cytotoxic effect, anti-HIV-1 activity, and anti-oxidant potential were also presented in this work. Further, analytical data on ochnaflavone has also been described. Conclusion: The present paper describes the therapeutic role of ochnaflavone in human disor-ders with their analytical aspects.

Phenolic content of Thai Bao mango peel and its in-vitro antioxidant, anti-cholinesterase, and antidiabetic activities

Plant phenolics have been known for various biological activities. This study aims to extract and examine the presence of phenolics in Bao mango (Mangifera indica L. var.) peel ethanolic extract (MPE). Further, antioxidant, anti-diabetic (α-amylase, and α-glucosidase inhibitory activity), and anti- Alzheimer’s disease (AD) (acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and β-secretase (BACE-1) inhibitory activity) efficacy of MPE were determined. The results indicated that mangiferin (8755.89 mg/ 100 g extract) was the major phenolic compound in MPE. An antioxidant mechanism revealed that MPE had a higher radical scavenging ability (4266.70 µmol TE/g extract) compared to reducing power (FRAP) or oxygen radical absorption capacity (ORAC). Further in-vitro enzyme inhibitory assay against diabetic and AD involved enzymes showed that MPE had stronger inhibitory action against an enzyme involved in diabetes compared to their standard drug (Acarbose) (P < 0.05). While a lower IC50 value was observed against AD-involved enzymes compared to their standard drug (donepezil) (P < 0.05). The results show that Thai Bao mango peel byproduct can be a potential source of nutraceuticals to lower diabetes and improve cognitive health.

Synthesis and Biological Study of 4-Aminopyridine-Peptide Derivatives Designed for the Treatment of Neurodegenerative Disorders.

Alzheimer's disease (AD) and Multiple sclerosis (MS) lead to neurodegenerative processes negatively affecting millions of people worldwide. Their treatment is still difficult and practically incomplete. One of the most commonly used drugs against these neurodegenerative diseases is 4-aminopyridine. However, its use is confined by the high toxicity. The aim of this work is to obtain new peptide derivatives of 4-aminopyridine with decreased toxicity compared to 4-aminopyridine. Synthesis was conducted in solution using a consecutive condensation approach. The new derivatives were characterized by melting points, NMR, and Mass spectra. Important ADME (absorption, distribution, metabolism, and excretion) properties have been studied in silico using ACD/Percepta v.2020.2.0 software. Acute toxicity was determined in mice according to a Standard protocol. All new derivatives were tested in vitro for cytotoxic activity in a panel of human (HEP-G2, BV-173) and murine (NEURO 2A) tumor cell lines via a standard MTT-based colorimetric method. β-secretase inhibitory activity was determined by applying the fluorescent method. New derivatives of 4-aminopyridine containing analogues of the β-secretase inhibitory peptide (Boc-Val-Asn-Leu-Ala-OH) were obtained. The in vivo toxicity of the tested compounds was found to be as high as 1500 mg/kg. Cell toxicity screening against tumor cell lines of different origins showed negligible growth-inhibitory effects of all investigated 4-aminopyridine analogues. Synthesis of new peptide derivatives of 4-aminopyridine is reported. Acute toxicity studies revealed a ca. 150 times lower toxicity of the new compounds as compared to 4-aminopyridine that may be ascribed to their peptide fragment.

Synthesis and biological study of new galanthamine-peptide derivatives designed for prevention and treatment of Alzheimer's disease.

The Alzheimer's disease leads to neurodegenerative processes and affecting negatively million people worldwide. The treatment of the disease is still difficult and incomplete in practice. Galanthamine is one of the most commonly used drugs against the illness. The main aim of this work is design and synthesis of new derivatives of galanthamine comprising peptide moiety as well as study of their β-secretase inhibitory activity and the anti-aggregating effect. All new derivatives of galanthamine containing analogues of Leu-Val-Phe-Phe (Aβ17-Aβ20) were synthesized in solution using fragment and consecutive condensation approaches. The new derivatives were characterized by melting points, NMR, and HPLC/MS. They were tested in vitro for β-secretase inhibition activity by means of fluorescent method and were investigated in vitro for anti-aggregation activity on sheep platelet-rich plasma. Although the new compounds do not contain a structural element responsible for the β-secretase inhibition, five of them show high or good β-secretase inhibitory activity between 19.98 and 51.19% with IC50 between 1.95 and 5.26nM. Four of the new molecules were able to inhibit platelet aggregation between 55.0 and 90.0% with IC50 between 0.69 and 1.36µM. Four of the compounds were able to inhibit platelet aggregation and two of them have high anti-aggregating effects.

Possibility for Prevention of Type 2 Diabetes Mellitus and Dementia Using Three Kinds of Brown Rice Blends after High-Pressure Treatment.

As it has been reported that type 2 diabetes mellitus increases the risk of Alzheimer’s disease, we investigated how to prevent type 2 diabetes and dementia using biofunctional boiled rice. We adopted unpolished super-hard rice (SHBR) for diabetes and wax-free unpolished black rice (WFBBR) for dementia and blended those with ordinary non-polished rice (KBR) (blending ratio 4:4:2), adding 2.5% waxy black rice bran (WBB) and 0.3% rice oil after high-pressure treatment (HPT) (WFBSK) to improve its palatability. This boiled rice is rich in dietary fiber, anthocyanin, free ferulic acid and β-secretase inhibitory activity. A randomized, parallel-group comparison study was conducted for 12 weeks with 24 subjects, using Cognitrax to evaluate their cognitive function primarily. Furthermore, as the secondary purpose, we performed a single-dose test for postprandial blood glucose and insulin secretion at the end of the human intervention test. After 12 weeks, consumers of the WFBSK rice exhibited significant improvement in language memory by cognitive test battery compared with those who consumed the control white rice (p < 0.05). Moreover, subjects who consumed the WFBSK rice had lower insulin secretion levels than those who consumed the control polished rice (p < 0.05).

Characterization and purification of β−secretase inhibitory peptides fraction from sea cucumber (Holothuria spinifera) enzymatic hydrolysates

Alzheimer’s disease (AD) is widely known as a progressive neurodegenerative disorder, mainly found in the elderly population. Progressive neurodegeneration in AD can lead to cognitive functional and behavioral alterations, thus affecting public health. Based on the amyloid cascade hypothesis, enzymatic cleavage of amyloid precursor protein (APP) by β-secretase and the formation of amyloid-beta (Aβ) peptides lead to neuron cell degradation. In this study, we focused on this hypothesis and investigated bioactivities of dried Holothuria spinifera enzymatic hydrolysates. Dried H. spinifera contained 79.77 % protein with glycine being the most abundant amino acid (178.89 g/kg). Trypsin hydrolysate of H. spinifera exhibited the highest β-secretase inhibitory activity with an IC50 value of 81.94 μg/mL. RP-HPLC produced an active fraction (HPLC-F3) containing four bioactive peptides (YPIEHGIVTNWDDM*EK, IEELEEEIEAER, EYVEETTGDEYVSLK, YPIEHGIVTNWDDMEK). The predominant peptide presented in HPLC-F3 was IEELEEEIEAER. Effects of HPLC-F3 against SH-SY5Y neuroblastoma cells were tested. HPLC-F3 reduced cellular levels of β-secretase enzyme, Aβ, and soluble amyloid precursor protein beta (sAPPβ) proteins. HPLC-F3 also protected SH-SY5Y cells from oxidative stress by decreasing phosphorylation of c-Jun N-terminal kinases and p38 mitogen-activated protein kinases. Results of this study suggest that H. spinifera is a potential source for functional foods and biomedicine industries.

Inhibitory mechanism of O-methylated quercetins, highly potent β-secretase inhibitors isolated from Caragana balchaschensis (Kom.) Pojark

Ethnopharmacological relevanceCaragana has a standing history of implementation in Traditional Chinese Medicine (TCM). Most species of this genus have been explored for multi-functional purposes, such as promoting blood circulation and curing neuralgia, fatigue, migraine, arthritis, and vascular hypertension (Meng et al., 2009). Among them, the well-known species C. sinica showed the most promising potential to increase the expression of ADAM10 among 313 tested medicinal plants, which is one of the promising approach for the treatment of Alzheimer's disease (AD). (Schuck et al., 2015). Aim of this studyThe aim of this work is to explore β-secretase inhibitory activity of compounds isolated from the aerial part of endemic Caragana balchaschensis (Kom.) Pojark. We provided a full characterization of their inhibitory mechanisms, binding affinities, and binding modes. Materials and methodsThe isolation of quercetin derivatives was accomplished by various chromatographical approaches and their structures were annotated by spectroscopic analysis. The detailed kinetic behavior of β-secretase inhibitors was determined by estimation of kinetic parameters (Km, Vmax, KI, and KIS). Binding affinities (KSV) and binding modes of inhibitors were elucidated by fluorescence quenching and molecular docking studies, respectively. ResultsO-methylated quercetins (2-7) were significantly effective in β-secretase inhibition with IC50 ranging from 1.2 to 6.5 μM. The most active one (6) was 20-fold effective than the mother skeleton, quercetin. The O-methyl motif was a critical factor in β-secretase inhibition: tri-O-methylated (1.2 μM) > di-O-methylated (3.5 μM) > mono-O-methylated (6.5 μM) > quercetin (25.2 μM). In the kinetic study, all quercetins (1–7) showed a noncompetitive inhibition, but glucoside ones (8 and 9) were mixed type I inhibitors. The binding affinities (KSV) were agreed with inhibitory potencies. The O-methylated quercetins were annotated as the most natural abundant metabolites in the aerial part by LC-ESI-TOF/MS. Binding modes of inhibitors to enzyme were elucidated by molecular docking experiments. ConclusionThis study disclosed that most of the major phenolic metabolites of the aerial part of C. balchaschensis are O-methylated quercetins, which have a significant inhibitory effect on β-secretase, which is a critical factor for AD.

Synthesis and biological evaluation of 2-arylbenzofuran derivatives as potential anti-Alzheimer’s disease agents

Alzheimer's disease (AD) is a type of progressive dementia caused by degeneration of the nervous system. A single target drug usually does not work well. Therefore, multi-target drugs are designed and developed so that one drug can specifically bind to multiple targets to ensure clinical effectiveness and reduce toxicity. We synthesised a series of 2-arylbenzofuran derivatives and evaluated their in vitro activities. 2-Arylbenzofuran compounds have good dual cholinesterase inhibitory activity and β-secretase inhibitory activity. The IC50 value of compound 20 against acetylcholinesterase inhibition (0.086 ± 0.01 µmol·L−1) is similar to donepezil (0.085 ± 0.01 µmol·L−1) and is better than baicalein (0.404 ± 0.04 µmol·L−1). And most of the compounds have good BACE1 inhibitory activity, of which 3 compounds (8, 19 and 20) show better activity than baicalein (0.087 ± 0.03 µmol·L−1). According to experimental results, 2-arylbenzofuran compounds provide an idea for drug design to develop prevention and treatment for AD.

A peptide fraction of Olive Flounder (Paralichthys olivaceus) Skin Hydrolysate Inhibits Amyloid-β Generation in SH-SY5Y Cells via Suppression of BACE1 Expression

The prevalence of degenerative neuro-diseases such as Alzheimer’s disease has increased with an increase in the life expectancy especially as seen in developed countries. According to the Amyloid Hypothesis, β-secretase leads to the onset of Alzheimer's disease though the generation of amyloid-β by proteolysis of amyloid precursor protein. Amyloid-β aggregates to form oligomers that build up to form plaques. Olive flounder (Paralichthys olivaceus) is high in protein content, with a higher protein content in skin (27.65%) compared to muscle (19.65%) according to proximate analysis results. Enzyme hydrolysates were prepared from skin and muscle using several enzymes. The neutrase skin hydrolysate showed the highest β-secretase inhibitory activity IC50 0.61 mg/mL. Purification steps were performed using ion exchange chromatography on QMA and CM-cellulose columns and SPE C18 column to produce an active fraction QMA-F1 with an IC50 value of 32.80 µg/mL. QMA-F1 was non-cytotoxic to SH-SY5Y cells, reduced BACE1 overexpression and attenuated amyloidogenesis. This suggests that the active β-secretase inhibitory peptides from olive flounder skin hydrolysates can be utilized as an ingredient in development of new pharmaceutical and nutraceutical therapeutic agents for Alzheimer’s Disease.

One Pot Synthesis of Micromolar BACE-1 Inhibitors Based on the Dihydropyrimidinone Scaffold and Their Thia and Imino Analogues.

A library of dihydropyrimidinones was synthesized via a “one-pot” three component Biginelli reaction using different aldehydes in combination with β-dicarbonyl compounds and urea. Selected 2-thiooxo and 2-imino analogs were also obtained with the Biginelli reaction from thiourea and guanidine hydrochloride, respectively. The products were screened in vitro for their β-secretase inhibitory activity. The majority of the compounds resulted to be active, with IC50 in the range 100 nM–50 μM.

Resveratrol oligomers from Paeonia suffruticosa protect mice against cognitive dysfunction by regulating cholinergic, antioxidant and anti-inflammatory pathways

Ethnopharmacological relevancePaeonia suffruticosa Andr. has been widely used in traditional Chinese medicine as an anti-tumour, anti-oxidant, anti-inflammatory and neuroprotective agent. Resveratrol oligomers are the main components of the seed coat extracts of Paeonia suffruticosa (PSCE) and have DPPH free radical scavenging and β-secretase inhibitory activity. However, studies of its effect on ameliorating cognitive deficits are limited, and analyses of the underlying mechanisms are insufficient. Aim of studyThis study aimed to investigate the cholinesterase inhibitory activities of resveratrol oligomers from P. suffruticosa in vitro and their effects on diminishing the oxygen-glucose deprivation/reoxygenation (OGD/R) -induced cytotoxicity in PC12 cells and scopolamine-induced cognitive deficits in mice. Moreover, the underlying mechanisms were further explored. Materials and methodsIn vitro, the inhibitory effects of PSCE and its 10 stilbenes on acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) were evaluated using the Ellman's assay, and its protective effects on normal and OGD/R-injured PC12 cells were evaluated using the MTT assay. For the in vivo assay, C57BL/6 mice were orally administered with PSCE at doses of 150 and 600 mg/kg for 28 days, and injected with scopolamine (1.5 mg/kg) to induce cognitive deficits. The memory behaviours were evaluated using the novel object recognition, Morris water maze and inhibitory avoidance test. Levels of various biochemical markers were also examined, including AChE, choline acetyltransferase (ChAT), acetylcholine (ACh), superoxide dismutase (SOD), catalase (CAT), glutathione (GSH) in the mouse brain and interleukin-1β (IL-1β), interleukin-6 (IL-6), tumour necrosis factor-α (TNF-α), interleukin-4 (IL-4) in serum. ResultsPSCE and its 10 stilbenes display good inhibition of AChE and BuChE activities and significantly increase the viability of normal and OGD/R-injured PC12 cells. PSCE improves the cognitive performance of scopolamine-treated mice in behavioural tests. Meanwhile, PSCE increases AChE, ChAT, SOD, and CAT activities and ACh, GSH, IL-4 levels, and decreases IL-1β, IL-6, TNF-α levels in the model animals. ConclusionsResveratrol oligomers from P. suffruticosa show neuroprotective effect in vitro and in vivo by regulating cholinergic, antioxidant and anti-inflammatory pathways, may have promising application in the treatment of Alzheimer’s disease.

Design, synthesis, and evaluation of novel cinnamic acid-tryptamine hybrid for inhibition of acetylcholinesterase and butyrylcholinesterase.

Acetylcholine deficiencies in hippocampus and cortex, aggregation of β-amyloid, and β-secretase over activity have been introduced as main reasons in pathogenesis of Alzheimer's disease. Colorimetric Ellman's method was used for determination of IC50 value in AChE and BChE inhibitory activity. The kinetic studies, neuroprotective and β-secretase inhibitory activities, evaluation of inhibitory potency on β-amyloid (Aβ) aggregations induced by AChE, and docking study were performed for prediction of the mechanism of action. A new series of cinnamic acids-tryptamine hybrid was designed, synthesized, and evaluated as dual cholinesterase inhibitors. These compounds demonstrated in-vitro inhibitory activities against acetyl cholinesterase (AChE) and butyryl cholinesterase (BChE). Among of these synthesized compounds, (E)-N-(2-(1H-indol-3-yl)ethyl)-3-(3,4-dimethoxyphenyl)acrylamide (5q) demonstrated the most potent AChE inhibitory activity (IC50 = 11.51μM) and (E)-N-(2-(1H-indol-3-yl)ethyl)-3-(2-chlorophenyl)acrylamide (5b) were the best anti-BChE (IC50 = 1.95μM) compounds. In addition, the molecular modeling and kinetic studies depicted 5q and 5b were mixed type inhibitor and bound with both the peripheral anionic site (PAS) and catalytic sites (CAS) of AChE and BChE. Moreover, compound 5q showed mild neuroprotective in PC12 cell line and weak β-secretase inhibitory activities. This compound also inhibited aggregation of β-amyloid (Aβ) in self-induced peptide aggregation test at concentration of 10μM. It is worth noting that both the kinetic study and the molecular modeling of 5q and 5b depicted that these compounds simultaneously interacted with both the catalytic active site and the peripheral anionic site of AChE and BChE. These findings match with those resulted data from the enzyme inhibition assay. Graphical abstract A new series of cinnamic-derived acids-tryptamine hybrid derivatives were designed, synthesized and evaluated as butyrylcholinesterase (BChE) and acetylcholinesterase (AChE) inhibitors and neuroprotective agents. Compound 5b and 5q, as the more potent compounds, interacted with both the peripheral site and the choline binding site having mixed type inhibition. Results suggested that derivatives have a therapeutic potential for the treatment of AD.

Memory-enhancing effects of Ishige foliacea extract: In vitro and in vivo study.

Ishige foliacea is used as a functional food in East-Asian countries. We evaluated the memory-enhancing effect of an ethanol extract of I. foliacea (EEI) using in vitro and in vivo models. In vitro acetylcholinesterase and β-secretase inhibitory activities, antioxidant properties, and neuroprotective effects against human neuronal cell death by H2 O2 and β-amyloid (Aβ) were investigated. We explored the memory-enhancing effect and its underlying mechanism in a mouse model of scopolamine (SCO)-induced memory deficits. EEI showed free radical scavenging and acetylcholinesterase and β-secretase inhibition activities. Additionally, EEI significantly decreased neuronal cell death induced by H2 O2 or Aβ in human neuroblastoma SH-SY5Y cells. In behavior tests, SCO-induced memory deficits was improved by EEI administration. EEI increased the protein expression of brain-derived neurotrophic factor (BDNF) and tropomyosin receptor kinase B (TrkB) and phosphorylated extracellular signal-regulated kinase, which are related to synaptic plasticity in the hippocampus. EEI may ameliorate memory deficits and prevent neurodegenerative disorders. PRACTICAL APPLICATIONS: As the population ages, dementia, a neurodegenerative disease, is becoming an important problem. Various Alzheimer's drugs have been developed based on the disease mechanism, but alternative treatments are required because of the low bioavailability and hepatotoxicity of current medications. Ishige foliacea is a type of brown algae containing various bioactive substances. Phlorotannins, known as brown algae polyphenols, have been studied for their various functionalities such as, anticancer, anti-obesity, antioxidant, and sleep improvement effects, and have attracted attention as raw materials for developing new natural products. We found that the EEI mitigates SCO-induced damage by protecting neurons from oxidative stress-induced cell damage, controlling synthesis mechanisms of the causative agents of AD, and activating BDNF-TrkB-ERK signaling to promote memory function in the hippocampus. The results of this study can serve as a foundation for further research. Additionally, I. foliacea may be useful for treating and improving AD.

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

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

Chemical characterization, antioxidant properties, cholinesterase inhibitory and anti-amyloidogenic activities of sulfated polysaccharides from some seaweeds

Sulfated polysaccharides were extracted from Ecklonia maxima (PKPM), Gelidium pristoides (PMNP) and Ulva rigida (PURL) and characterized using scanning electron microscope with energy dispersing x-ray (SEM-EDX), Fourier transform infrared spectroscopy (FTIR) and Gas Chromatography-coupled with mass spectrometry (GC-MS). The radical scavenging activity, metal chelating effects, enzyme inhibitory potentials and anti-amyloidogenic activities of the sulfated polysaccharide samples were also evaluated. The elemental analysis and FTIR results confirmed the presence of sulfate groups in the polysaccharides. Furthermore, GC-MS analysis revealed the presence of glucose, galactose, fucose, arabinose and xylose as the main monosaccharides present in the samples. PKPM, PMNP and PURL exhibited radical scavenging activities against DPPH, ABTS and OH radicals and were able to chelate Fe2+. The sulfated polysaccharides also showed inhibitory effects on acetylcholinesterase, butyrylcholinesterase and β-secretase activities. PKPM showed higher cholinesterase and β-secretase inhibitory activities than PURL and PMNP. Thioflavin-T assay revealed that incubation of β-amyloid (Aβ1-42) peptide without the polysaccharides showed high fluorescence intensity compared to Aβ1-42 treated with PMNP, PKPM and PURL which showed drastic reduction in fluorescence intensity. Electron micrographs also revealed continuous aggregation of amyloid fibrils in the control (Aβ1-42 alone). However, Sulfated polysaccharides samples incubated with Aβ1-42 showed disappearance of Aβ1-42 fibrils which connotes disaggregation and inhibition of aggregation of the fibrils. These results suggest that the sulfated polysaccharide samples exhibit antioxidant and neuroprotective potentials which could be explored as nutraceuticals for the management of AD.

Characterization of a New Anti-dementia β-secretase Inhibitory Peptide from Arctoscopus japonicus

Amyloid plaque is a product of aggregation of β-amyloid peptide (Aβ) and is an important factor in the pathogenesis of Alzheimer’s Disease (AD). Aβ is a major component of amyloid plaque and vascular deposits in the AD brain. The enzyme β- secretase is required for the production of Aβ; thus, prevention of the formation of Aβ through the inhibition of β-secretase is a major focus in the study of the treatment of AD. In this study, we investigated β-secretase inhibitory activity of an Arctoscopus japonicus peptide. An Alcalase hydrolysate had the highest β-secretase inhibitory activity. A β-secretase inhibitory activity peptide was separated using ion exchange column chromatography (carboxy-methyl: CM, quaternary methyl ammonium: QMA) and reverse phase high performance liquid chromatography (RP-HPLC) on a C18 column. The IC50 value of the purified peptide was 248.2±1.73 μg/mL. The β-secretase inhibitory peptide was identified as a six amino acid residue of Gly-Pro-Val-Gly-Ala- Pro (MW: 497.27 Da). In cell viability experiments, the final purified fraction, the carboxy-methyl ion exchange column fraction (CM-F1) showed no significant cytotoxic effect in SH-SY5Y cells at concentrations below 100 μg/mL in 24 h. The results of this study suggest that peptides separated from Arctoscopus japonicus may be beneficial as β-secretase inhibitor compounds in functional foods.

Synthesis, molecular modeling and BACE-1 inhibitory study of tetrahydrobenzo[b] pyran derivatives

β-Secretase (BACE1) has been broadly documented as one of the possible therapeutic targets for the treatment of Alzheimer’s disease. In this paper, we report the synthesis and the for β-secretase (BACE-1) inhibitory activity of new series of tetrahydrobenzo [b] pyran derivatives. One-pot synthesis of tetrahydrobenzo [b] pyrans was carried out by condensing aromatic aldehyde, malononitrile and 1,3-cyclohexanedione using ionic liquid 1-butyl-3-methyl imidazolium chloride ([bmIm]Cl−) in aqueous alcohol media. The addition of alcohol and water in the ratio of 1:2 keeps all the reactants in solution which facilitates the reaction and makes the product formation very easy. The synthesized compounds were subjected to BACE1 inhibition assay and six compounds, 4d, 4e, 4f, 4h, 4i, and 4p have shown significant IC50 values at micromolar level. Among these six active compounds, 4e was a potential inhibitor with its IC50 value in nanomolar range. All the synthesized compounds were docked onto the active site of β-Secretase enzyme.

Sulfonamido-derivatives of unsubstituted carbazoles as BACE1 inhibitors

A novel series of variously substituted N-[3-(9H-carbazol-9-yl)-2-hydroxypropyl]-arylsulfonamides has been synthesized and assayed for β-Secretase (BACE1) inhibitory activity. BACE1 is a widely recognized drug target for the prevention and treatment of Alzheimer's Disease (AD). The introduction of benzyl substituents on the nitrogen atom of the arylsulfonamide moiety has so far led to the best results, with three derivatives showing IC50 values ranging from 1.6 to 1.9 μM. Therefore, a significant improvement over the previously reported series of N-carboxamides (displaying IC50’s ≥ 2.5 μM) has been achieved, thus suggesting an active role of the sulfonamido-portion in the inhibition process. Preliminary molecular modeling studies have been carried out to rationalize the observed structure-activity relationships.

Effects of super-hard rice bread blended with black rice bran on amyloid β peptide production and abrupt increase in postprandial blood glucose levels in mice

Alzheimer's disease and type 2 diabetes are very serious diseases with the latter having been suggested to cause the former. We prepared super-hard rice bread blended with black rice bran (SRBBB), which contained a high amount of resistant starch that showed strong inhibitory activities against β-secretase and acetylcholinesterase even after heating. Black rice bran showed greater β-secretase inhibitory activity (3.6-fold) than Koshihikari rice. The bran contained more oleic acid and anthocyanin, meaning that it is potentially a biofunctional food with a high antioxidant capacity. Furthermore, aged mice, which were fed a SRBBB diet for four weeks, showed lower amyloid β 40 peptide in the blood than mice fed a commercial diet (p<0.01). Additionally, their initial blood glucose levels (BGLs) after 12 weeks of being fed SRBBB were significantly lower than those in the control group. Taken together, our results indicate SRBBB shows promise for inhibiting not only amyloid β production, but also abrupt increases in postprandial BGLs.

Inhibitory Activities of Sesame Seed Extract and its Constituents against β-Secretase

The need for a preventive agent against dementia led us to screen natural plant resources. Among the herbs and spices tested, sesame seed prepared from Sesamum indicum seeds showed potent β-secretase inhibitory activity. The active principles were determined to be sesamin and sesamolin, typical lignans in S. indicum. The IC(50) values of sesamin and sesamolin were 257 and 140 μM, respectively. These compounds were investigated in a preliminary absorption experiment. After oral administration, these compounds were detected in an intact form in the brain and serum. These results suggest that consumption of sesame seeds may prevent dementia by sesamin and sesamolin, the constituents in sesame seeds.