A Diet Containing Rutin Ameliorates Brain Intracellular Redox Homeostasis in a Mouse Model of Alzheimer's Disease

Quercetin has been studied extensively for its anti-Alzheimer's disease (AD) and anti-aging effects. Our previous studies have found that quercetin and in its glycoside form, rutin, can modulate the proteasome function in neuroblastoma cells. We aimed to explore the effects of quercetin and rutin on intracellular redox homeostasis of the brain (reduced glutathione/oxidized glutathione, GSH/GSSG), its correlation with β-site APP cleaving enzyme 1 (BACE1) activity, and amyloid precursor protein (APP) expression in transgenic TgAPP mice (bearing human Swedish mutation APP transgene, APPswe). On the basis that BACE1 protein and APP processing are regulated by the ubiquitin-proteasome pathway and that supplementation with GSH protects neurons from proteasome inhibition, we investigated whether a diet containing quercetin or rutin (30 mg/kg/day, 4 weeks) diminishes several early signs of AD. Genotyping analyses of animals were carried out by PCR. In order to determine intracellular redox homeostasis, spectrofluorometric methods were adopted to quantify GSH and GSSG levels using o-phthalaldehyde and the GSH/GSSG ratio was ascertained. Levels of TBARS were determined as a marker of lipid peroxidation. Enzyme activities of SOD, CAT, GR, and GPx were determined in the cortex and hippocampus. ΒACE1 activity was measured by a secretase-specific substrate conjugated to two reporter molecules (EDANS and DABCYL). Gene expression of the main antioxidant enzymes: APP, BACE1, a Disintegrin and metalloproteinase domain-containing protein 10 (ADAM10), caspase-3, caspase-6, and inflammatory cytokines were determined by RT-PCR. First, overexpression of APPswe in TgAPP mice decreased GSH/GSSG ratio, increased malonaldehyde (MDA) levels, and, overall, decreased the main antioxidant enzyme activities in comparison to wild-type (WT) mice. Treatment of TgAPP mice with quercetin or rutin increased GSH/GSSG, diminished MDA levels, and favored the enzyme antioxidant capacity, particularly with rutin. Secondly, both APP expression and BACE1 activity were diminished with quercetin or rutin in TgAPP mice. Regarding ADAM10, it tended to increase in TgAPP mice with rutin treatment. As for caspase-3 expression, TgAPP displayed an increase which was the opposite with rutin. Finally, the increase in expression of the inflammatory markers IL-1β and IFN-γ in TgAPP mice was lowered by both quercetin and rutin. Collectively, these findings suggest that, of the two flavonoids, rutin may be included in a day-to-day diet as a form of adjuvant therapy in AD.

A Neuroprotective Bovine Colostrum Attenuates Apoptosis in Dexamethasone-Treated MC3T3-E1 Osteoblastic Cells

Glucocorticoid-induced osteoporosis (GIO) is one of the most common secondary forms of osteoporosis. GIO is partially due to the apoptosis of osteoblasts and osteocytes. In addition, high doses of dexamethasone (DEX), a synthetic glucocorticoid receptor agonist, induces neurodegeneration by initiating inflammatory processes leading to neural apoptosis. Here, a neuroprotective bovine colostrum against glucocorticoid-induced neuronal damage was investigated for its anti-apoptotic activity in glucocorticoid-treated MC3T3-E1 osteoblastic cells. A model of apoptotic osteoblastic cells was developed by exposing MC3T3-E1 cells to DEX (0-700 μM). Colostrum co-treated with DEX was executed at 0.1-5.0 mg/mL. Cell viability was measured for all treatment schedules. Caspase-3 activation was assessed to determine both osteoblast apoptosis under DEX exposure and its potential prevention by colostrum co-treatment. Glutathione reduced (GSH) was measured to determine whether DEX-mediated oxidative stress-driven apoptosis is alleviated by colostrum co-treatment. Western blot was performed to determine the levels of p-ERK1/2, Bcl-XL, Bax, and Hsp70 proteins upon DEX or DEX plus colostrum exposure. Colostrum prevented the decrease in cell viability and the increase in caspase-3 activation and oxidative stress caused by DEX exposure. Cells, upon colostrum co-treated with DEX, exhibited higher levels of p-ERK1/2 and lower levels of Bcl-XL, Bax, and Hsp70. Our data support the notion that colostrum may be able to reduce DEX-induced apoptosis possibly via the activation of the ERK pathway and modulation of the Hsp70 system. We provided preliminary evidence on how bovine colostrum, as a complex and multi-component dairy product, in addition to its neuroprotective action, may affect osteoblastic cell survival undergoing apoptosis.

Peripheral IL-6 Levels but not Sarcopenia Are Predictive of 1-Year Mortality After Hip Fracture in Older Patients

BACKGROUND

Sarcopenic patients may have an increased risk of poor outcomes after a hip fracture. The objective of this study was to determine whether sarcopenia and a set of biomarkers were potential predictors of 1-year-mortality in older patients after a hip fracture.

METHODS

About 150 patients at least 80 years old were hospitalized for the surgical treatment of a hip fracture. The primary outcome measure was the death in the first year after the hip fracture. Sarcopenia was defined at baseline by having both low muscle mass (bioimpedance analysis) and handgrip and using the updated European Working Group on Sarcopenia in Older People (EWGSOP2) definition of probable sarcopenia. Janssen's (J) and Masanés (M) cutoff points were used to define low muscle mass.

RESULTS

Mortality 1 year after the hip fracture was 11.5%. In univariate analyses, baseline sarcopenia was not associated with mortality, using neither of the muscle mass cutoff points: 5.9% in sarcopenic (J) versus 12.4% in non-sarcopenic participants (p = .694) and 16% in sarcopenic (M) versus 9.6% in non-sarcopenic participants (p = .285). Probable sarcopenia (EWGSOP2) was not associated with mortality. Peripheral levels of IL-6 at baseline were significantly higher in the group of participants who died in the year after the hip fracture (17.14 ± 16.74 vs 11.42 ± 7.99 pg/mL, p = .026). TNF-α peripheral levels had a nonsignificant trend to be higher in participants who died. No other biomarker was associated with mortality.

CONCLUSIONS

Sarcopenia at baseline was not a predictor of 1-year mortality in older patients after a hip fracture. IL-6 was associated with a higher risk of mortality in these patients, regardless of sarcopenia status.

Biomarkers of sarcopenia in very old patients with hip fracture

BACKGROUND

Hip fracture is both a cause and a consequence of sarcopenia. Older persons with sarcopenia have an increased risk of falling, and the prevalence of sarcopenia may be increased in those who suffer a hip fracture. The aim of this study was to explore potential biomarkers (neuromuscular and peripheral pro-inflammatory and oxidative stress markers) that may be associated with sarcopenia in very old persons with hip fracture.

METHODS

We recruited 150 consecutive patients ≥80 years old admitted to an orthogeriatric unit for an osteoporotic hip fracture. Muscle mass was assessed pre-operatively using bioelectrical impedance analysis; Janssen's (J) and Masanés' (M) reference cut-off points were used to define low muscle mass. Muscle strength was assessed with handgrip strength (Jamar's dynamometer). Sarcopenia was defined by having both low muscle mass and strength and using the European Working Group on Sarcopenia in Older People 2 definition of probable sarcopenia (low grip strength). Peripheral markers-pro-inflammatory and oxidative stress parameters-were determined either in the plasma or in the erythrocyte fraction obtained from peripheral whole blood of every patient pre-operatively.

RESULTS

Mean age was 87.6 ± 4.9 years, and 78.7% were women. The prevalence of sarcopenia was 11.5% with Janssen's, 34.9% with Masanés' cut-offs, and 93.3% with the European Working Group on Sarcopenia in Older People 2 definition of probable sarcopenia. Among the four pro-inflammatory cytokines tested in plasma, only tumour necrosis factor-α was different (lower) in sarcopenic than in non-sarcopenic participants using both muscle mass cut-offs (J 7.9 ± 6.2 vs. 8.3 ± 5.8, M 6.8 ± 4.7 vs. 9.1 ± 6.2). Erythrocyte glutathione system showed a non-significant tendency to lower glutathione levels and glutathione/oxidized glutathione ratios in sarcopenic participants compared with non-sarcopenic subjects. Catalase activity was also lower in sarcopenic participants (J 2904 ± 1429 vs. 3329 ± 1483, M 3037 ± 1430 vs. 3431 ± 1498). No significant differences were found between groups in chymotrypsin-like activity of the 20S proteasome, superoxide dismutase, glutathione peroxidase and butyrylcholinesterase activity, C-terminal agrin fragment, interferon-γ, or interleukin-1β.

CONCLUSIONS

The prevalence of sarcopenia in patients with hip fracture varies according to the definition and the muscle mass reference cut-off points used. We did not find differences in most neuromuscular, pro-inflammatory, or oxidative stress markers, except for lower peripheral tumour necrosis factor-α levels and catalase activity in sarcopenic participants, which may be markers of an early inflammatory reaction that is hampered in sarcopenic patients.

[Prevalence of sarcopenia and characteristics of sarcopenic subjects in patients over 80 years with hip fracture]

INTRODUCTION

Aim: to estimate the prevalence of sarcopenia in very old patients admitted to an Orthogeriatric Unit for the treatment of a hip fracture (HF), and to compare characteristics of patients with and without sarcopenia. Methods: one hundred and fifty consecutive patients ≥ 80 years old admitted with HF were included. Sarcopenia was diagnosed with low muscle mass (bioimpedance, using two different cut-off points, Janssen and Masanés) and low grip strength (Jamar's dynamometer). Socio-demographic, nutritional variables (MNA-SF, body mass index [BMI], phase angle), cognitive (Pfeiffer, Reisberg's GDS) and functional variables (Barthel index, FAC) were registered, as well as the number of recent falls and medications on admission. Results: mean age: 87.6 ± 4.9 years (78.7% women). Prevalence of sarcopenia: 11.5% (Janssen's cut-offs) and 34.9% (Masanés cut-offs). Of the 77.5% who had independent ambulation before the fracture, 40% reported three or more recent falls. Before admission, 38% had dementia and 80.4% had mild to moderate dependence to BADL before admission; 14.2% were independent for all BADL. MNA was suggestive of malnutrition in 12.6%, and 85.2% were on four or more prescribed drugs. Sarcopenic (Masanés) had a lower BMI than non-sarcopenic participants (18.6 vs 24.3, p = 0.003), but no other significant differences were found between both groups. Phase angle was also unrelated to sarcopenia status. Conclusions: up to one third of very old patients with HF had sarcopenia on admission. Prevalence varied widely depending on the cut-off points selected to define low muscle mass. Sarcopenic patients in this setting were mostly similar to non-sarcopenic patients, except for a lower BMI.

Lichens of Parmelioid Clade as Promising Multitarget Neuroprotective Agents

Neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease are multifactorial disorders which are increasing in incidence and prevalence over the world without existing effective therapies. The search for new multitarget compounds is the latter therapeutic strategy to address these pathological conditions. Lichens have an important and unknown therapeutic value attributed to their unique secondary metabolites. The aim of this study is to evaluate for the first time the in vitro neuroprotective activities and molecular mechanisms underlying methanol extracts of lichens of the parmelioid clade and to characterize major bioactive secondary metabolites responsible for their pharmacological actions. Of the 15 parmelioid lichen species, our results showed that Parmotrema perlatum and Hypotrachyna formosana methanol extracts exhibited high antioxidant activity as evidenced in ORAC, DPPH, and FRAP assays. Then, SH-SY5Y cells were pretreated with methanol extracts (24 h) followed by Fenton reagent exposure (2 h). Pretreatments with these two more antioxidant methanol lichen extracts increased cell viability, reduced intracellular ROS, prevented oxidative stress biomarkers accumulation, and upregulated antioxidant enzyme (CAT, SOD, GR, and GPx) activity compared to Fenton reagent cells. The neuroprotective activity was much higher for H. formosana than for P. perlatum, even equal to or higher than Trolox (reference compound). Moreover, H. formosana extracts inhibited both AChE and BuChE activities in a concentration dependent manner, and P. perlatum only showed concentration dependent activity against AChE. Finally, chemical composition analysis using TLC and HPLC methods revealed that physodic acid, lividic acid, and lichexanthone are major secondary metabolites in H. formosana and stictic acid and constictic acid are in P. perlatum. These results demonstrated that P. perlatum and, specially, H. formosana are promising multitargeted neuroprotective agents due to their antioxidant and AChE and BuChE inhibition activities.

Neurohormetic responses of quercetin and rutin in a cell line over-expressing the amyloid precursor protein (APPswe cells)

BACKGROUND

Plant secondary metabolites may induce adaptive cellular stress-responses in a variety of cells including neurons at the sub-toxic doses ingested by humans. Such 'neurohormesis' phenomenon, activated by flavonoids such as quercetin or rutin, may involve cell responses driven by modulation of signaling pathways which are responsible for its neuroprotective effects.

PURPOSE

We attempt to explore the molecular mechanisms involved in the neurohormetic responses to quercetin and rutin exposure, in a SH-SY5Y cell line which stably overexpresses the amyloid precursor protein (APP) Swedish mutation, based on a biphasic concentration-response relationship for cell viability.

METHODS

We examined the impact of both natural compounds, at concentrations in its hormetic range on the following cell parameters: chymotrypsin-like activity of the proteasome system; PARP-1 protein levels and expression and caspase activation; APP processing; and the main endogenous antioxidant enzymes.

RESULTS

Proteasome activities following quercetin or rutin treatment were significantly augmented in comparison with non-treated cells. Activity of caspase-3 was significantly attenuated by treatment with quercetin or rutin. Modest increased levels of PARP-1 protein and mRNA transcripts were observed in relation to the mild increase of proteasome activity. Significant reductions of the full-length APP and sAPP protein and APP mRNA levels were related to significant enhancements of α-secretase ADAM-10 protein and mRNA transcripts and significant increases of BACE processing in cells exposed to rutin. Furthermore, quercetin or rutin treatment displayed an overall increase of the four antioxidant enzymes.

CONCLUSIONS

The upregulation of the proteasome activity observed upon quercetin or rutin treatment could be afforded by a mild increased of PARP-1. Consequently, targeting the proteasome by quercetin or rutin to enhance its activity in a mild manner could avoid caspase activation. Moreover, it is likely that APP processing of cells upon rutin treatment is mostly driven by the non-amyloidogenic pathway leading to a putative reduction of βA production. Overall induction of endogenous antioxidant enzymes under quercetin or rutin treatments of APPswe cells might modulate its proteasome activity. We might conclude that quercetin and rutin might exert a neurohormetic cell response affecting various signaling pathways and molecular networks associated with modulation of proteasome function.

Discovery of alkenylboronic acids as neuroprotective agents affecting multiple biological targets involved in Alzheimer's disease

Alkenylboronic acids have shown important biological activities that contribute to neuroprotection. We have determined their influence on the β-amyloid (βA) aggregation process, β-secretase and acethylcholinesterase activities on cell-free systems, on the redox and lipid peroxidation status, and on the vulnerability to apoptotic death in an APPswe neuroblastoma cell line, before and after hydrogen peroxide treatment. We have discovered that 2-arylvinylboronic acids and some of their esters possess a set of properties which makes them highly useful as neuroprotective agents affecting multiple biological targets involved in AD. These properties are not paralleled by the related 2-arylboronic acids.

SNP-mediated neuroprotection under glucose deprivation is enhanced by Hypericum perforatum

Hypericum perforatum is a medicinal herb possessing ability for protecting neurons from oxidative stress. Since nitric oxide (NO) may be protective against oxidative stress-induced cell death as occurs in glucose deprivation (GD)-induced neurotoxicity, whether a standardized extract of H. perforatum (HP) increases the NO-mediated neuroprotective effect in GD-PC12 cells was investigated. Induced death in PC12 cells by GD exposure for 18 h was partially prevented by cell incubation with sodium nitroprusside (SNP), a NO-donor. SNP increased survival and nitrite production in GD-cells in a concentration-dependent manner. Co-incubation of cells with 10 μM SNP plus 50-100 μg/ml HP under GD insult significantly prevented GD-induced cell death to a higher extent than SNP alone as shown by an augmentation of cell survival and intracellular bcl-2 levels and a decrease of lipid peroxidation, caspase-3 activation and PARP cleavage. Cytoprotection by the NO-donor was almost abolished by the use of a NO scavenger and potentiated by the presence of superoxide dismutase. SNP and/or HP neuroprotection on GD-cells was significantly reversed by rotenone treatment. These results suggest that: (1) SNP could protect PC12 cells from GD-induced cytotoxicity through NO generation and (2) the enhancement of the SNP-mediated neuroprotective effect on GD-cells by HP might arise in part through scavenging of reactive oxygen species (ROS) and inhibition of mitochondrial dysfunction associated with the hypoglycemic episode. This current finding might highlight the development of therapeutic strategies aimed at manipulating NO-donors in combination with herb supplements containing ROS scavenger compounds for prophylaxis from brain ischemia.

Synthesis and evaluation of arylquinones as BACE1 inhibitors, β-amyloid peptide aggregation inhibitors, and destabilizers of preformed β-amyloid fibrils

BACE1 activity, inhibition of Aβ aggregation, and disaggregation of preformed Aβ fibrils constitute the three major targets in the development of small-molecule lipophilic new drugs for the treatment of Alzheimer's disease (AD). Quinones are widely distributed among natural products and possess relevant and varied biological activities including antitumor and antibiotic, inhibition of HIV-1 reverse transcriptase, antidiabetic, or COX-inhibition, among others. We report herein the interaction of several arylquinones and their derivatives with the amyloidogenic pathway of the amyloid precursor protein processing. Our studies put forward that these compounds are promising candidates in the development of new drugs which are effective simultaneously towards the three major targets of AD.

Neuroprotection by Spirulina platensis protean extract and phycocyanin against iron-induced toxicity in SH-SY5Y neuroblastoma cells

We investigated the effect of Spirulina platensis protean extract and the biliprotein phycocyanin isolated from this microalga, on the activities of the antioxidant enzymes SOD, CAT, GPx, and GR, lipid peroxidation inhibitory activity and glutathione levels after the iron induced oxidative stress in SH-SY5Y neuroblastoma cells. Iron is one of the most important agents that produce oxidative stress and decline of neuronal functions. S. platensis protean extract and phycocyanin exert the antioxidant activity by protecting the activity of the cellular antioxidant enzymes total GPx, GPx-Se and GR and by increasing reduced glutathione in cells against oxidative stress induced by iron. These results suggested that S. platensis protean extract is a powerful antioxidant through a mechanism related to antioxidant activity, capable of interfering with radical-mediated cell death. S. platensis may be useful in diseases known to be aggravated by reactive oxygen species and in the development of novel treatments for neurodegenerative disorders as long as iron has been implicated in the neuropathology of several neurodegenerative disorders such as Alzheimer's or Parkinson diseases.