Improvement of brain energy metabolism and cholinergic functions contributes to the beneficial effects of silibinin against streptozotocin induced memory impairment

Recently, silibinin, a clinically used hepatoprotectant, has been reported to prevent amyloid beta induced memory impairment by reducing oxidative stress and inflammation in mice brain. However, the exact mechanism of neuroprotective effect of silibinin has not been properly studied especially in context of brain energy metabolism and cholinergic functions, the essential factors that undergo impairment in Alzheimer's disease. Therefore, the present study investigated the effect of silibinin on impairment in memory, brain energy metabolism and cholinergic function following intracerebral (IC) streptozotocin (STZ) administration in mice. STZ (0.5 mg/kg), administered twice at an interval of 48 h, caused significant memory impairment tested by Morris water maze. Further, STZ significantly decreased ATP and increased synaptosomal calcium level in mice brain. Increased oxidative and nitrosative stress was also observed in IC STZ injected mice brain. STZ IC induced memory impairment is associated with increased activity and mRNA expression of acetylcholinesterase (AChE) and decreased α-7 nicotinic acetylcholine receptor (α-7-nAChR) mRNA expression in mice brain. Pretreatment with silibinin (100 and 200 mg/kg, po) attenuated STZ induced memory impairment by reducing oxidative and nitrosative stress and synaptosomal calcium ion level. Further, silibinin dose dependently restored ATP level indicating improvement in brain energy metabolism. The activity and mRNA expression of AChE was restored by silibinin. Moreover, α-7-nAChR mRNA expression was significantly increased by silibinin in STZ treated mice brain. The present study clearly demonstrates that beneficial effects of silibinin in STZ induced memory impairment in mice is due to improvement in brain energy metabolism and cholinergic function.     

Nanocarriers for topical administration of resveratrol: A comparative study

The trans-resveratrol (t-res), a non-flavonoid polyphenol extracted from different plants, has recently earned interest for application on the skin for different applications. In this work, the potential of nanocarriers, namely transfersomes and ethanol-containing vesicles, to deliver t-res into/through the skin was investigated. Thus, transfersomes with different surfactants, namely polysorbate 80 (Tw80), sodium cholate (SC) and sodium deossicholate (SDC) and ethanol-containing vesicles with different lipid composition, namely soy phosphatidylcholine (SPC) and cholesterol (chol), encapsulating t-res were prepared and characterized. The nanocarriers had a mean diameter ranging between 83 and 116 nm with a high t-res encapsulation efficiency (≥70%). Moreover, cytotoxicity as well as the inhibition of production of reactive oxygen species (ROS) and lipid peroxidation, following incubation of H₂O₂-stimulated human keratinocyte (HaCaT) with t-res, as free or encapsulated into the nanocarriers, were investigated. Only blank nanocarriers containing Tw80 or ethanol were cytotoxic and led to increase of ROS, but this effect was not observed when using nanocarriers encapsulating t-res. Finally, permeation studies on porcine skin carried out on Franz diffusion cells, showed that only ethanol-containing vesicles based SPC were able to promote t-res permeation through the skin.     

Standardized extract of Dicksonia sellowiana Presl. Hook (Dicksoniaceae) decreases oxidative damage in cultured endothelial cells and in rats

Aims

Aging and a variety of pathologies, including cancer, diabetes, cardiovascular and inflammatory diseases have been associated with reactive oxygen species (ROS), such as superoxide anion (O₂⁻), hydroxyl radical (OH) and hydrogen peroxide (H₂O₂) generation. Plant polyphenols bear radical scavenging/antioxidant activity. A phytomedicinal preparation obtained from aerial parts of Dicksonia sellowiana (Dicksoniaceae), a native plant from Central and South America, has been widely used in Brazil against asthma and presents beneficial effects in several other diseases, including cardiovascular disturbance. In this work, we investigated whether Dicksonia sellowiana, which is also known to contain high levels of polyphenols, presents antioxidant activity.

Methods

The antioxidant activity of the hydroalcoholic extract obtained from Dicksonia sellowiana leaves (HEDS) was investigated by in vitro and in vivo tests.

Results

HEDS (0.1-100 μg/mL) exhibited a strong scavenging activity against all reactive species tested (DPPH, O₂⁻,OH and H₂O₂; IC₅₀ = 6.83 ± 2.05, 11.6 ± 5.4, 2.03 ± 0.4, and 4.8 ± 0.4 μg/mL, respectively). HEDS strongly protected endothelial cells against H₂O₂-induced oxidative stress by mechanisms other than increasing catalase activity. In addition, HEDS protected cell membrane from oxidative damage. HEDS, (20 and 40 mg/kg) inhibited lipid peroxidation in vivo (29.8% and 24.5%, respectively).

Conclusions

According to our results, we can speculate that the traditional uses of Dicksonia sellowiana for cardiovascular diseases, asthma and skin diseases could be, at least in part, related to the potent antioxidant and endothelial protective activities of the plant.     

Protection by ascorbic acid from denaturation and release of cytochrome c, alteration of mitochondrial membrane potential and activation of multiple caspases induced by H(2)O(2), in human leukemia cells

We investigated peroxide and superoxide accumulation, cytochrome c nature and release from mitochondria, as well as caspase activation during exposure of HL-60 cells to H(2)O(2) and the protective effect of ascorbic acid. Exposure of the cells to 100 microM H(2)O(2) resulted in intracellular accumulation of peroxides, denaturation of cytochrome c that was identified in the mitochondria and cytosol, release of native cytochrome c to the cytosol and fall in mitochondrial membrane potential (DeltaPsi(m)). Loading of cells with ascorbic acid before exposure to H(2)O(2) resulted in a dose-dependent protective effect against: intracellular accumulation of peroxides, DeltaPsi(m) alteration, cytochrome c denaturation and release. The accumulation of peroxides induced processings and activations of procaspase-8, -9 and -3. Double staining with antiserum which recognizes the p18 subunit of cleaved caspase-3 and with Hoechst had shown that a high percentage of cells exposed to 100 microM H(2)O(2) stained positively with the antibody and showed features of apoptosis. Ascorbic acid loading prevented caspase activation induced by H(2)O(2). We conclude that ascorbic acid protects against activation of apoptotic cascades in HL-60 cells exposed to H(2)O(2) and against apoptosis.     

Nanoparticle interactions with zinc and iron: implications for toxicology and inflammation

BACKGROUND: Particulate air pollution (PM(10)) consists of a mixture of components, including nanoparticles and metals. Studies from our laboratory have demonstrated that transition metals can potentiate the ability of nanoparticles to induce lung inflammation and that the zinc content of PM(10) was largely responsible for their potential to induce inflammation. These results are also relevant to zinc-containing engineered nanoparticles. OBJECTIVES: To investigate the potential of ZnCl(2) and FeCl(3) to interact with nanoparticle carbon black in cell-free and biological systems to generate ROS, express pro-inflammatory mediators and cytotoxic ability. METHODS: ROS production was examined using DCFH-DA. J774 cells were treated for 4 h with 14 nm CB and/or ZnCl(2) before measuring TNF-alpha by ELISA. Cytoskeletal changes were investigated using confocal microscopy. Flow cytometry was used to examine apoptotic/necrotic cells and phagocytic ability. RESULTS: In a cell-free system the particles generated significant ROS, whereas ZnCl(2) did not. Treatment of cells with 100 microM ZnCl(2), but not FeCl(3), increased TNF-alpha. Treatment with 14 nm CB alone induced TNF-alpha, which was synergistically enhanced by ZnCl(2). No interactions were observed in cells treated with 14 nm CB and FeCl(3). Cytoskeletal changes were observed with increasing concentrations of ZnCl(2). These results were confirmed by flow cytometry indicating that ZnCl(2) induced markers of apoptosis and necrosis. The phagocytic ability of cells was also significantly decreased. Nanoparticle carbon black alone did not induce changes in apoptosis/necrosis or the phagocytosis activity of the cells. CONCLUSION: Despite an inability to induce ROS production, ZnCl(2) stimulated TNF-alpha production which was synergistically enhanced by 14 nm carbon black. The ability of zinc to induce morphological changes and cell death was not altered by nanoparticle treatment.