Claudia Pérez

Synaptic failure and adenosine triphosphate imbalance induced by amyloid-β aggregates are prevented by blueberry-enriched polyphenols extract

The potential neuroprotective properties of fruits have been widely recognized. In this study, we evaluated the protective properties of a blueberry extract (BB‐4), rich in polyphenols, in a neurodegenerative model induced by amyloid‐β peptide (Aβ). Chronic treatment with Aβ drastically reduced synaptic transmission and the extent of secretory vesicles, which were recovered partially with BB‐4. Also, the extract recovered Ca2+ transients in hippocampal neurons preincubated with Aβ (0.5 and 5 μM) by about 25% ± 3% and 30% ± 2, respectively. In this work, we demonstrate a novel effect of the BB‐4 extract on Aβ‐induced ATP leakage, in which this extract was able to antagonize the acute ATP leakage but not chronic ATP depletion. On the other hand, BB‐4 prevented the uncoupling of mitochondrial function induced by FCCP by about 85%, but it was unable to modify the uncoupling induced by Aβ. The present results strongly indicate that BB‐4 plays a role in the process of Aβ aggregation by reducing the toxic species (i.e., 40 kDa). These findings suggest that a blueberry extract can protect neuronal tissue from Aβ toxicity mainly through its antiaggregation property, and its antioxidant properties and mitochondrial membrane potential capacities are secondary mechanisms important in chronic stages. Our work suggests that BB‐4 could be an important nutritional complement to neuronal health as well as a potential nutraceutical formulation useful as a dietary supplement in the elderly.

Synaptic Silencing and Plasma Membrane Dyshomeostasis Induced by Amyloid-β Peptide are Prevented by Aristotelia chilensis Enriched Extract

Alzheimers disease (AD) is characterized by the presence of different types of extracellular and neurotoxic aggregates of amyloid-β (Aβ). Recently, bioactive compounds extracted from natural sources showing neuroprotective properties have become of interest in brain neurodegeneration. We have purified, characterized, and evaluated the protective potential of one extract enriched in polyphenols obtained from Aristotelia chilensis (MQ), a Chilean berry fruit, in neuronal models of AD induced by soluble oligomers of Aβ1-40. For example, using primary hippocampal cultures from rats (E18), we observed neuroprotection when the neurons were co-incubated with Aβ (0.5 μM) plus MQ for 24 h (Aβ = 23 ± 2%; Aβ + MQ = 3 ± 1%; n = 3). In parallel, co-incubation of Aβ with MQ recovered the frequency of Ca2+ transient oscillations when compared to neurons treated with Aβ alone (Aβ = 72 ± 3%; Aβ + MQ = 86 ± 2%; n = 5), correlating with the changes observed in spontaneous synaptic activity. Additionally, MAP-2 immunostaining showed a preservation of the dendritic tree, suggesting that the toxic effect of Aβ is prevented in the presence of MQ. A new complex mechanism is proposed by which MQ induces neuroprotective effects including antioxidant properties, modulation of cell survival pathways, and/or direct interaction with the Aβ aggregates. Our results suggest that MQ induces changes in the aggregation kinetics of Aβ producing variations in the nucleation phase (Aβ: k1 = 2.7 ± 0.4 × 10-3 s-1 MQ: k1 = 8.3 ± 0.6 × 10-3 s-1) and altering Thioflavin T insertion in β-sheets. In conclusion, MQ induces a potent neuroprotection by direct interaction with the Aβ aggregates, generating far less toxic species and in this way protecting the neuronal network.

Influence of climate and land use in carbon biogeochemistry in lower reaches of rivers in central southern Chile: Implications for the carbonate system in river-influenced rocky shore environments

Freshwater discharge affects the biogeochemistry of river-influenced nearshore environments by contributing with carbon and nutrients. An increase in human activities in river basins may alter the natural riverine nutrients and carbon export to coastal ecosystems. Along a wide latitudinal range (32°55′S–40°10′S), this study explores the role of climate and land use in determining the nutrient and carbon concentrations in the river mouth and fluxes to adjacent coastal areas. Between winter 2011 and fall 2012, we collected monthly samples in five river mouths in central southern Chile and at rocky shore sites affected by river plumes. Basins were characterized by different land uses and meteorological conditions along this latitudinal range. Water samples were collected for pH measurements, nutrients, dissolved organic and inorganic carbon, particulate organic carbon, and isotopic signatures (δ13C). Our results show a north-south gradient in concentrations of nutrients and carbon. The highest concentrations were observed in the Maipo basin, which presents the highest percentage of urban-industrial activities. Nutrients and carbon contributions, in most cases, were lowest in the southern Valdivia basin, which has the least human intervention and a greater percentage of vegetation. The Biobio River had the highest nutrient and carbon fluxes, in most cases, due to its high river discharge. Our results show the influence of river plume effects on carbon and nitrogen concentrations in river-influenced rocky shore sites. Moreover, our study suggests that land use might influence some parameters of carbonate system in rivers and river-influenced rocky shore environments. River-influenced rocky shore environments may exhibit suppression in aragonite saturation state with implications for calcifiers inhabiting these marine environments.

Influences of riverine and upwelling waters on the coastal carbonate system off Central Chile and their ocean acidification implications

A combined data set, combining data from field campaigns and oceanographic cruises, was used to ascertain the influence of both river discharges and upwelling processes, covering spatial and temporal variation in dissolved inorganic carbon (DIC) and aragonite saturation state. This work was conducted in one of the most productive river-influenced upwelling areas in the South Pacific coasts (36°S). Additionally, further work was also conducted to ascertain the contribution of different DIC sources, influencing the dynamics of DIC along the land-ocean range. Six sampling campaigns were conducted across seven stations at the Biobio River basin, covering approximately 200 km. Three research cruises were undertaken simultaneously, covering the adjacent continental shelf, including 12 sampling stations for hydrographic measurements. Additionally, six stations were also sampled for chemical analyses, covering summer, winter, and spring conditions over 2010 and 2011. Our results evidenced that seaward extent of the river plume was more evident during the winter field campaign, when highest riverine DIC fluxes were observed. The carbonate system along the river-ocean continuum was very heterogeneous varying over spatial and temporal scales. High DIC and pCO2 were observed in river areas with larger anthropogenic effects. CO2 supersaturation at the river plume was observed during all campaigns due to the influence of low pH river waters in winter/spring and high-pCO2 upwelling waters in summer. δ13CDIC evidenced that main DIC sources along the river and river plume corresponded to the respiration of terrestrial organic matter. We have linked this natural process to the carbonate saturation on the adjacent river-influenced coastal area, suggesting that Ωaragonite undersaturation in surface/subsurface waters is largely modulated by the influence of both river discharge and coastal upwelling events in this productive coastal area. Conditions of low Ωaragonite might impact negatively physiological traits for marine organisms, such as bivalves, gastropods, and crustaceans. Therefore, local populations from river-influenced sites could be inherently more tolerant to ocean acidification than organisms living in regions with lower Ωaragonite variability.

Modulation of Neuronal Nicotinic Receptor by Quinolizidine Alkaloids Causes Neuroprotection on a Cellular Alzheimer Model

Alzheimers disease (AD) is a progressive and neurodegenerative disorder and one of the current therapies involves strengthening the cholinergic tone in central synapses. Neuroprotective properties for nicotine have been described in AD, through its actions on nicotinic receptors and the further activation of the PI3K/Akt/Bcl-2 survival pathway. We have tested a quinolizidine alkaloid extract (TM0112) obtained from Teline monspessulanna (L.) K. Koch seeds to evaluate its action on nicotinic acetylcholine receptor (nAChR) in a neuronal AD model. Our data show that PC-12 cells pretreated with amyloid-β (Aβ) peptide for 24 h in presence of TM0112 modified Aβ-reduction on cellular viability (Aβ = 80 ± 3%; +TM0112 = 113 ± 4%, n = 15). In addition, this effect was blocked with atropine, MLA, and α-BTX (+TM0112+atropine = 87 ± 4%; +TM0112+MLA = 86 ± 4%; +TM0112+α-BTX = 92 ± 3%). Furthermore, similar protective effects were observed in rat cortical neurons (Aβ = 63 ± 6%; +TM0112 = 114 ± 8%), but not in HEK293T cells (Aβ = 61.4 ± 6.1%; +TM0112 = 62.8 ± 5.2) that do not express α7 nAChR. Moreover, the frequency of synaptic activity in the neuronal network (Aβ = 51.6 ± 16.9%; +TM0112 = 210.8 ± 47.9%, n > 10), as well as the intracellular Ca2+ transients were recovered by TM0112 (Aβ = 61.4 ± 6.9%; +TM0112 = 112.0 ± 5.7%; n = 3) in rat hippocampal neurons. TM0112 increased P-Akt, up to 250% with respect to control, and elevated Bcl-2/Bax percentage (Aβ = 61.0 ± 8.2%; +TM0112 = 105.4 ± 19.5%, n = 4), suggesting a coupling between nAChR activation and an intracellular neuroprotective pathway. Our results suggest that TM0112 could be a new potential source for anti-AD drugs.

X-RAY CRYSTALLOGRAPHIC STRUCTURAL STUDY ON A CINNAMOLIDE-CLASS SESQUITERPENE LACTONE FROM DRIMYS WINTERIFORST. VAR. CHILENSIS

In order to ascertain the structure and secure the assignment of the stereochemistry of the title compound an X-ray analysis was performed, the absolute configuration was not determined by this analysis. 1 . Chemical studies has shown the presence of a variety of sesquiterpenes with drimano skeleton 2 and flavonoids. Some of these structures have shown significant antibacterial, antifungi, antitumor and insecticide properties 3, 4 . The extract of Drimys winteri leaves afforded Cinnamolide and Drimenin two lactones with drimano skeleton. Cinnamolide have not been previuosly reported for these specie. Recently it has been reported that the title compound was also isolated of Cinnamosma macrocarpa 5 . In order to ascertain the structure and secure the assignment of the stereochemistry of the title compound an X-ray analysis was performed, the absolute configuration was not determined by this analysis. The X-ray crystallographic analysis confirms the previously proposed molecular structure, including the molecular conformation. The molecular structure is shown in Fig.1 and selected geometric parameters are given in Table I. The structure consists of a drimane skeleton. The methyl group at C9a is seen to be β-oriented. The cyclohexene ring A and cyclohexane ring B exist in a half-chair and a chair conformation, respectively (Q T = 0.538(3) A, ϕ 2 = 227.4(4) °, q 2 = 0.428 (3) A for ring A; Q T = 0.556(4) A , ϕ 2 = 21 (4)o, q 2 = 0.060 (4) A for ring B) , and the lactone ring an envelope on C3a conformation 6 . The A and B rings are trans-fused. Bond lengths are within expected ranges 7

CHEMICAL DEFENSE RESPONSES IN Eucalyptus globulus (Labill) PLANTS

This study evaluated the expression of defense compounds by the secondary metabolism of Eucalyptus globulus plants subjected to attacks by the insect Ctenarytaina eucalypti (blue gum psyllid) and abiotic mechanical damage using gas chromatography with flame ionization detection (GC-FID) and mass detection (MS). The results show that both biological and mechanical attacks activated defense responses in the plants. We identified 34 compounds in the leaves of the treated plants. In the case of the plants damaged by C. eucalypti, four of the compounds differed from those of the control: three oxygenated monoterpenes (borneol, exo-2-hydroxy cineole and thymol) and one quinone (6-acethyl-flaviolin). In the case of the mechanical damage, five compounds differed from the control: three sesquiterpenes (alloaromadendrene, eremophilene, and caryophyllene-oxide), borneol, and 6-acethyl-flaviolin. According to the results, different compounds are biosynthesized when faced with biotic and abiotic inductions, indicating a certain level of specificity in the response of the plants to different types of damage.

Antiproliferative activity of yatein isolated from Austrocedrus chilensis against murine myeloma cells: Cytological studies and chemical investigations

Abstract Context: Fitzroya cupressoides (Molina) I. M. Johnst. and Austrocedrus chilensis (D. Don) Pic.Serm. & Bizzarri are two Chilean Cupressaceae that are naturally resistant to biodegradation. Secondary metabolites from these species display a variety of biological activities. Objective: To evaluate the antiproliferative activity of two lignans, a diterpene and a flavonol isolated from A. chilensis and F. cupressoides, to elucidate their cytological effects on P3X murine myeloma cells. Materials and methods: The antiproliferative activity of yatein, isotaxiresinol, ferruginol, and isorhamnetin was evaluated in vitro using the MTT assay. The effect of yatein at the cellular level, due to its high antiproliferative activity was evaluated. P3X cells treated for 24 h with 12.5 and 25 µg/mL of yatein were also examined at the cytological level using immunofluorescence and scanning and transmission electron microscopy. Results: Yatein, a lignan isolated from A. chilensis, potentially inhibited P3X murine myeloma cell proliferation, resulting in approximately 75% cell death in response to a 25 µg/mL treatment with the lignan. P3X cells lost membrane integrity at the nuclear and cytoplasmic levels, including organelles, in response to yatein treatment (12.5 µg/mL), and we observed changes in the cytoplasmic organization and distribution of microtubules. The other compounds tested had low activity. Discussion and conclusions: Yatein is a lignan precursor of podophyllotoxin, a key agent in anticancer drugs. Due to its structural similarities to podophyllotoxin, yatein could have similar cytoplasmic target(s), such as the microtubular apparatus. These findings suggest that yatein may be of potential pharmacological interest and warrants further investigation in human cell lines.

BIOLOGICAL ACTIVITY OF MACROMYCETES ISOLATED FROM CHILEAN SUBANTARCTIC ECOSYSTEMS

Twenty six compounds were identified by GC-MS analysis from culture broth of six Macromycetes growing in subantarctic forests in southern Chile: Mycena hialinotricha, Collybia butyracea, Inocybe geophylla, Entoloma nubigenum, Stropharia semiglobata and Psathyrella sp. Antifungal and antibacterial activity were evaluated through agar diffusion test. This assay showed bioactivity against Penicillium notatum, Fusarium oxysporum, Rhyzoctonia solani, Ceratocistys pilifera, Bacillus subtilis, Pseudomonas aeruginosa, Escherichia coli, Escherichia faecalis and Staphilococcus aureus.

6,6,9a-Trimethyl-5,5a,6,7,8,9,9a,9b-octa-hydro-naphtho[1,2-c]furan-1(3H)-one.

In the crystal structure of the title compound, C15H22O2, the cyclohexene and cyclohexane rings adopt half-boat and chair conformations, respectively, and the lactone ring is in an envelope conformation.