Downregulation of microglial activation by achillolide A.

Chronic inflammation has been implicated in the pathogenesis of various neurodegenerative diseases. During the neuroinflammatory process, microglial cells release neurotoxic and proinflammatory mediators. In the present study, using activity-guided fractionation, we have purified an anti-inflammatory compound determined by spectroscopic methods to be a sesquiterpene lactone named achillolide A from Achillea fragrantissima (Forsk.) Sch. Bip. In primary cultures of lipopolysaccharide-activated microglial cells, achillolide A inhibited the lipopolysaccharide-induced levels of proinflammatory and toxic mediators including glutamate, nitric oxide, matrix metalloproteinase-9, cyclooxygenase-2, induced nitric oxide synthase, interleukin-1ß, and tumor necrosis factor-α. Achillolide A also exhibited an antioxidant capacity, as was shown in a cell free system as well as by its ability to reduce intracellular reactive oxygen species levels in microglial cells. Thus, achillolide A might have therapeutic potential for treatment of neurodegenerative diseases and deserves further studies.

3,5,4'-Trihydroxy-6,7,3'-trimethoxyflavone protects astrocytes against oxidative stress via interference with cell signaling and by reducing the levels of intracellular reactive oxygen species.

Oxidative stress is tightly involved in various neurodegenerative diseases such as Parkinson's and Alzheimer's diseases, and conditions such as ischemia. Astrocytes, the most abundant glial cells in the brain, protect neurons from reactive oxygen species (ROS) and provide them with trophic support. Therefore, any damage to astrocytes will affect neuronal survival. In a previous study we have demonstrated that an extract prepared from the plant Achillea fragrantissima (Af) prevented the oxidative stress-induced death of astrocytes and attenuated the intracellular accumulation of ROS in astrocytes under oxidative stress. In the present study, using activity guided fractionation, we have purified from this plant the active compound, determined to be a flavonoid named 3,5,4'-trihydroxy-6,7,3'-trimethoxyflavone (TTF). The effects of TTF in any biological system have not been studied previously, and this is the first study to characterize the anti-oxidant and protective effects of this compound in the context of neurodegenerative diseases. Using primary cultures of astrocytes we have found that TTF prevented the hydrogen peroxide (H2O2)-induced death of astrocytes, and attenuated the intracellular accumulation of ROS following treatment of these cells with H2O2 or the peroxyl radicals generating molecule 2,2'-Azobis(amidinopropane) (ABAP). TTF also interfered with cell signaling events and inhibited the phosphorylation of the signaling proteins stress-activated protein kinase/c-Jun N-terminal kinase (SAPK/JNK), extracellular signal regulated kinase (ERK 1/2) and mitogen activated protein kinase kinase (MEK1) and the phosphorylation of the transcription factor cyclic AMP response element-binding protein (CREB). The mechanism of the protective effect of TTF against H2O2-cytotoxicity could not be attributed to a direct H2O2 scavenging but rather to the scavenging of free radicals as was shown in cell free systems. Thus, TTF might be a therapeutic candidate for the prevention/treatment of neurodegenerative diseases where oxidative stress is part of the pathophysiology.

Protective and antioxidant effects of a chalconoid from Pulicaria incisa on brain astrocytes.

Oxidative stress is involved in the pathogenesis of neurodegenerative diseases such as Parkinson's and Alzheimer's diseases. Astrocytes, the most abundant glial cells in the brain, protect neurons from reactive oxygen species (ROS) and provide them with trophic support, such as glial-derived neurotrophic factor (GDNF). Thus, any damage to astrocytes will affect neuronal survival. In the present study, by activity-guided fractionation, we have purified from the desert plant Pulicaria incisa two protective compounds and determined their structures by spectroscopic methods. The compounds were found to be new chalcones-pulichalconoid B and pulichalconoid C. This is the first study to characterize the antioxidant and protective effects of these compounds in any biological system. Using primary cultures of astrocytes, we have found that pulichalconoid B attenuated the accumulation of ROS following treatment of these cells with hydrogen peroxide by 89% and prevented 89% of the H2O2-induced death of astrocytes. Pulichalconoid B exhibited an antioxidant effect both in vitro and in the cellular antioxidant assay in astrocytes and microglial cells. Pulichalconoid B also caused a fourfold increase in GDNF transcription in these cells. Thus, this chalcone deserves further studies in order to evaluate if beneficial therapeutic effect exists.

Anti-neuroinflammatory effects of the extract of Achillea fragrantissima.

BACKGROUND: The neuroinflammatory process plays a central role in the initiation and progression of neurodegenerative diseases such as Parkinson's and Alzheimer's diseases, and involves the activation of brain microglial cells. During the neuroinflammatory process, microglial cells release proinflammatory mediators such as cytokines, matrix metalloproteinases (MMP), Reactive oxygen species (ROS) and nitric oxide (NO). In the present study, extracts from 66 different desert plants were tested for their effect on lipopolysaccharide (LPS) - induced production of NO by primary microglial cells. The extract of Achillea fragrantissima (Af), which is a desert plant that has been used for many years in traditional medicine for the treatment of various diseases, was the most efficient extract, and was further studied for additional anti-neuroinflammatory effects in these cells. METHODS: In the present study, the ethanolic extract prepared from Af was tested for its anti-inflammatory effects on lipopolysaccharide (LPS)-activated primary cultures of brain microglial cells. The levels of the proinflammatory cytokines interleukin1ß (IL-1ß) and tumor necrosis factor-α (TNFα) secreted by the cells were determined by reverse transcriptase-PCR and Enzyme-linked immunosorbent assay (ELISA), respectively. NO levels secreted by the activate cells were measured using Griess reagent, ROS levels were measured by 2'7'-dichlorofluorescein diacetate (DCF-DA), MMP-9 activity was measured using gel zymography, and the protein levels of the proinflammatory enzymes cyclooxygenase-2 (COX-2) and induced nitric oxide synthase (iNOS) were measured by Western blot analysis. Cell viability was assessed using Lactate dehydrogenase (LDH) activity in the media conditioned by the cells or by the crystal violet cell staining. RESULTS: We have found that out of the 66 desert plants tested, the extract of Af was the most efficient extract and inhibited ~70% of the NO produced by the LPS-activated microglial cells, without affecting cell viability. In addition, this extract inhibited the LPS - elicited expression of the proinflammatory mediators IL-1ß, TNFα, MMP-9, COX-2 and iNOS in these cells. CONCLUSIONS: Thus, phytochemicals present in the Af extract could be beneficial in preventing/treating neurodegenerative diseases in which neuroinflammation is part of the pathophysiology.

Protective Effects of the Essential Oil of Salvia fruticosa and Its Constituents on Astrocytic Susceptibility to Hydrogen Peroxide-Induced Cell Death.

Oxidative stress has been implicated in pathologic processes associated with neurodegenerative diseases. Astrocytes, the most abundant glial cell type in the brain, protect neurons from reactive oxygen species (ROS), and any damage to them will affect neuronal survival. This study compares the ability of essential oils prepared from different herbs and spices to protect cultured primary brain astrocytes from H2O2-induced death. The results show that the essential oil of Salvia fruticosa (Sf) among the tested essential oils demonstrated remarkable protective activity. The protective effect of Sf could be attributed to alpha-humulene and alpha-pinene. Following incubation, alpha-humulene and trans-beta-caryophyllene could be found in the cytosol of astrocytes. It is proposed that Sf, by attenuating H2O2-induced cell death, might be used as a functional food or may be offered as a means of therapy in the treatment of neurodegenerative diseases.

Toxicity of propylene oxide at low pressure against life stages of four species of stored product insects.

The relative toxicity of propylene oxide (PPO) at a low pressure of 100 mm Hg to four species of stored product insect at 30 degrees C over a 4-h exposure period was investigated. PPO at 100 mm Hg was toxic to all four species tested: Tribolium castaneum (Herbst), Plodia interpunctella (Hübner), Ephestia cautella (Wlk.), and Oryzaephilus surinamensis (L.). There were differences in susceptibility between the life stages of the tested insect species. Mortality tests on all life stages of the insects resulted in LD99 values ranging from 4.7 to 26.1 mg/liter. The pupal stage of E. cautella, O. surinamensis, and T. castaneum was the most tolerant stage with LD99 values of 14.4, 26.1, and 25.7 mg/liter, respectively. For P. interpunctella, the egg stage was most tolerant, with a LD99 value of 15.3 mg/liter. Generally, PPO at 100 mm Hg was more toxic to P. interpunctella and E. cautella than to O. surinamensis and T. castaneum. A 99% mortality of all life stages of the tested species was achieved at a concentrations x time product of 104.4 mg h/liter. These findings indicate that a combination of PPO with low pressure can render the fumigant a potential alternative to methyl bromide for rapid disinfestation of commodities.