Synthesis of 1,4-Dialkoxynaphthalene-Based Imidazolium Salts and Their Cytotoxicity in Cancer Cell Lines.

In this study, we designed and synthesized novel 1,4-dialkoxynaphthalene-2-alkyl imidazolium salt (IMS) derivatives containing both 1,4-dialkoxynaphthalene and imidazole, which are well known as pharmacophores. The cytotoxicities of these newly synthesized IMS derivatives were investigated in order to explore the possibility of using them to develop anticancer drugs. It was found that some of the new IMS derivatives showed good cytotoxic activities. In addition, an initial, qualitative structure-activity relationship is presented on the basis of observations of activity changes corresponding to structural changes.

Fine particulate matter (PM2.5) inhibits ciliogenesis by increasing SPRR3 expression via c-Jun activation in RPE cells and skin keratinocytes.

Exposure to fine particulate matter (PM) with diameter <2.5 µm (PM2.5) causes epithelium injury and endothelial dysfunction. Primary cilia are sensory organelles that transmit extracellular signals into intracellular biochemical responses and have roles in physiology. To date, there have been no studies investigating whether PM2.5 affects primary cilia in skin. We addressed this in the present study using normal human epidermal keratinocytes (NHEKs) and retinal pigment epithelium (RPE) cells. We found that formation of primary cilium is increased in differentiated NHEKs. However, treatment with PM2.5 blocked increased ciliogenesis in NHEKs and RPE cells. Furthermore, PM2.5 transcriptionally upregulated small proline rich protein 3 (SPRR3) expression by activating c-Jun, and ectopic expression of SPRR3 inhibits suppressed the ciliogenesis. Accordingly, treatment with c-Jun activator (anisomycin) induced SPRR3 expression, whereas the inhibitor (SP600125) recovered the ciliated cells and cilium length in PM2.5-treated cells. Moreover, c-Jun inhibitor suppressed upregulation of SPRR3 in PM2.5-treated cells. Taken together, our finding suggested that PM2.5 inhibits ciliogenesis by increasing SPRR3 expression via c-Jun activation in RPE cells and keratinocytes.

Salmonella­induced miR­155 enhances necroptotic death in macrophage cells via targeting RIP1/3.

Salmonella enterica serovar Typhimurium (hereafter referred to as Salmonella), a virulent pathogen, is known to induce host­cell death. Using reverse transcription­quantitative polymerase chain reaction, a 28­fold increase of microRNA (miR)­155 expression in RAW 264.7 macrophages was observed following infection with Salmonella for 24 h. This miR­155 upregulation increased macrophage cell death by up to 40% in 48 h following infection. Western blot analysis revealed that receptor interacting protein 1 (RIP1) and 3 (RIP3) were increased at 18 h following miR­155 transfection to macrophages, similar to Salmonella infection. In addition, inhibition of RIP1 by pre­incubating macrophages with necrostatin­1, a RIP1 specific inhibitor, increased the viability of Salmonella­infected cells and miR­155­transfected cells by up to 20%. The cleavage of poly (adenosine diphosphate­ribose) polymerase­1 (PARP­1) was also enhanced by miR­155 induction upon Salmonella infection. Therefore, it was suggested that RIP1/3­induced necroptosis and PARP­1­mediated necrosis caused by miR­155 induction may represent distinct routes of programmed necrotic cell death of Salmonella­infected macrophages.

Cynandione A inhibits lipopolysaccharide-induced cell adhesion via suppression of the protein expression of VCAM­1 in human endothelial cells.

Cynandione A (CA) is one of the most active compounds in the roots of Cynanchum wilfordii, the extracts of which have been used extensively in East Asia to treat various diseases including anti­ischemic stroke. In the present study, the anti­adherent activity of CA in lipopolysaccharide (LPS)­stimulated human umbilical vascular endothelial cells (HUVECs) was investigated. CA markedly reduced the expression of vascular adhesion molecule­1 (VCAM­1) by LPS in HUVECs. The results also demonstrated that CA significantly reduced the expression of pro­inflammatory and chemoattractant cytokines, including interleukin (IL)­1ß, IL­6, IL­8, monocyte chemoattractant protein­1 and tumor necrosis factor­α, in LPS­activated human endothelial cells. CA inhibited the phosphorylation of mitogen­activated protein kinases, including the extracellular signal­regulated kinase 1/2 and p38 kinases. It was found that CA decreased the IKK/IκB­α phosphorylation of inhibitor of nuclear factor (NF)­κB kinase/inhibitor of NF­κB­α, suppressed translocation of the NF­κB p65 subunit into the nucleus and inhibited the transcriptional activity of NF­κB. CA also decreased human monocyte cell adhesion to endothelial cells in LPS­stimulated conditions. These results demonstrated that CA inhibited the protein expression of VCAM­1 and pro­inflammatory cytokines by suppressing the transcriptional activity of NF­κB. The results also suggested that CA may be important in the development of anti­inflammatory drugs by inhibiting the expression of cell adhesion molecules.

The Methoxyflavonoid Isosakuranetin Suppresses UV-B-Induced Matrix Metalloproteinase-1 Expression and Collagen Degradation Relevant for Skin Photoaging.

Solar ultraviolet (UV) radiation is a main extrinsic factor for skin aging. Chronic exposure of the skin to UV radiation causes the induction of matrix metalloproteinases (MMPs), such as MMP-1, and consequently results in alterations of the extracellular matrix (ECM) and skin photoaging. Flavonoids are considered as potent anti-photoaging agents due to their UV-absorbing and antioxidant properties and inhibitory activity against UV-mediated MMP induction. To identify anti-photoaging agents, in the present study we examined the preventative effect of methoxyflavonoids, such as sakuranetin, isosakuranetin, homoeriodictyol, genkwanin, chrysoeriol and syringetin, on UV-B-induced skin photo-damage. Of the examined methoxyflavonoids, pretreatment with isosakuranetin strongly suppressed the UV-B-mediated induction of MMP-1 in human keratinocytes in a concentration-dependent manner. Isosakuranetin inhibited UV-B-induced phosphorylation of mitogen-activated protein kinase (MAPK) signaling components, ERK1/2, JNK1/2 and p38 proteins. This result suggests that the ERK1/2 kinase pathways likely contribute to the inhibitory effects of isosakuranetin on UV-induced MMP-1 production in human keratinocytes. Isosakuranetin also prevented UV-B-induced degradation of type-1 collagen in human dermal fibroblast cells. Taken together, our findings suggest that isosakuranetin has the potential for development as a protective agent for skin photoaging through the inhibition of UV-induced MMP-1 production and collagen degradation.

Inhibitory effect of 5,6-dihydroergosteol-glucoside on atopic dermatitis-like skin lesions via suppression of NF-κB and STAT activation.

BACKGROUND: Atopic dermatitis (AD) is a Th2-type disease. Keratinocytes, a major type in the skin, produce Th2 chemokines such as thymus and activation-regulated chemokine (TARC)/CCL17 and macrophage-derived chemokine (MDC)/CCL22, which play pivotal roles in the development of Th2-dominant inflammatory skin diseases. Recently, it was reported that 5,6-dihydroergosterol-glucoside (DHE-Glc) was synthesized and exhibited strong anti-inflammatory activity. OBJECTIVE: We aimed to investigate the effects of DHE-Glc, a synthetic molecule derived from ergosterol, on AD-like skin lesions induced by 2,4-dinitrochlorobenzene (DNCB) in mice and to elucidate the effects of DHE-Glc on TNF-α/IFN-γ-induced production of CCL17 and CCL22 in human keratinocytes (HaCaTs) and DNCB induced skin inflammation mice model. METHOD: Mice were sensitized and challenged on the skin of their backs with DNCB. At 30-60 days after sensitization, mice were treated with cutaneous administration of DHE-Glc by skin smear. HaCaT cells were used to evaluate the effects of DHE-Glc on production of CCL17 and CCL22 and investigate mechanisms of action by RT-PCR, ELISA, Western blot, and reporter assays. RESULT: Topical administration of DHE-Glc attenuated AD-like skin inflammatory symptoms. DHE-Glc decreased infiltration of epidermal eosinophils and mast cells, and reduced levels of IgE, histamine, and mRNA expression and protein levels of CCL17/CCL22 in the plasma of DNCB-treated animals. In addition, DHE-Glc suppressed TNF-α/IFN-γ-induced expression of the Th2 chemokines CCL17 and CCL22 by inhibiting NF-κB and STAT activation in TNF-α/IFN-γ-induced HaCaT cells. CONCLUSION: DHE-Glc improved AD-like skin inflammatory symptoms on the backs of DNCB-induced mice, partly by suppressing production of Th2 chemokines, CCL17 and CCL22 in inflamed skin. Therefore, DHE-Glc is a potential therapeutic agent for skin inflammatory diseases such as AD.

Inhibition of autophagy suppresses sertraline-mediated primary ciliogenesis in retinal pigment epithelium cells.

Primary cilia are conserved cellular organelles that regulate diverse signaling pathways. Autophagy is a complex process of cellular degradation and recycling of cytoplasmic proteins and organelles, and plays an important role in cellular homeostasis. Despite its potential importance, the role of autophagy in ciliogenesis is largely unknown. In this study, we identified sertraline as a regulator of autophagy and ciliogenesis. Sertraline, a known antidepressant, induced the growth of cilia and blocked the disassembly of cilia in htRPE cells. Following treatment of sertraline, there was an increase in the number of cells with autophagic puncta and LC3 protein conversion. In addition, both a decrease of ATG5 expression and the treatment of an autophagy inhibitor resulted in the suppression of the sertraline-induced activation of autophagy in htRPE cells. Interestingly, we found that genetic and chemical inhibition of autophagy attenuated the growth of primary cilia in htRPE cells. Taken together, our results suggest that the inhibition of autophagy suppresses sertraline-induced ciliogenesis.

Tetramethylpyrazine, a natural alkaloid, attenuates pro-inflammatory mediators induced by amyloid ß and interferon-γ in rat brain microglia.

Neuroinflammation has been consistently reported as a pathological hallmark of Alzheimer׳s disease and other neurodegenerative diseases. Microglial cells are activated by diverse pathological stimuli and play key roles in development of neuroinflammation. Amyloid ß peptide (Aß), the major constituent of amyloid plaques in Alzheimer׳s brain, is known to activate cultured microglial cells to produce increased amounts of proinflammatory and neurotoxic factors. Tetramethylpyrazine (TMP) is the main bioactive alkaloid isolated from Ligusticum chuanxiong. TMP has multiple pharmacological activities, including anti-oxidant, anti-inflammatory, and anti-cancer effects. Neuroprotective potential of TMP has been demonstrated in animal models of neuropathologies. However, the efficacy of this compound for controlling Aß-related neuropathology has not been explored yet. We examined the efficacy of TMP in the repression of inflammatory response in cultured microglial cells stimulated with Aß25-35 in the presence of interferon (IFN)-γ. TMP significantly inhibited the Aß25-35 and IFN-γ-stimulated productions of nitric oxide, tumor necrosis factor (TNF)-α, interleukin (IL)-1ß, monocyte chemoattractant protein-1, and intracellular reactive oxygen species from primary microglial cells. TMP also effectively reduced Aß25-35 and IFN-γ-elicited NF-κB activation. In organotypic hippocampal slice cultures (OHSCs), TMP significantly blocked Aß25-35-induced reactive oxygen species generation and phosphorylation of Akt. Furthermore, TMP also inhibited Aß1-42-induced TNF-α and IL-1ß production in primary microglial cells and neuronal death in OHSCs. These results suggest that TMP provide a possible therapeutic approach for alleviating the inflammatory progression of Alzheimer׳s disease.

Effects of ginsenoside Rb1 on the stress-induced changes of BDNF and HSP70 expression in rat hippocampus.

Ginsenoside Rb1 (GRb1) has been determined to exert diverse neuromodulatory effects including antistress effects in the brain. The hippocampus is a key brain structure for memory, learning, and cognition and is especially vulnerable to neurotoxic effects associated with stress. The aim of this study was to further explore neuroprotective potential of GRb1 on stress-mediated changes in hippocampal gene expression. Recent studies recognize agents that inducing brain-derived neurotrophic factor (BDNF) and heat shock protein (HSP) 70 as important neuroprotective approaches. Thus, we specifically determined the effects of GRb1 on mRNA expression of BDNF and HSP70, in a model of immobilization stress. In agreement with these reports, acute immobilization stress led to a decrease and an increase in the mRNA levels of the BDNF and HSP70, respectively, in the hippocampus. When pretreated orally, GRb1 significantly inhibited the stress-mediated decline of BDNF level whereas it further increased the stress-mediated elevation of HSP70 level. Our results strongly suggest GRb1 effective in controlling stress-related hippocampal dysfunction. Our finding also contributes further understanding of medicinal usefulness of GRb1 targeting hippocampal network alteration which is commonly observed in aging and neurodegenerative disorders.

Down-regulation of mortalin exacerbates Aß-mediated mitochondrial fragmentation and dysfunction.

Mitochondrial dynamics greatly influence the biogenesis and morphology of mitochondria. Mitochondria are particularly important in neurons, which have a high demand for energy. Therefore, mitochondrial dysfunction is strongly associated with neurodegenerative diseases. Until now various post-translational modifications for mitochondrial dynamic proteins and several regulatory proteins have explained complex mitochondrial dynamics. However, the precise mechanism that coordinates these complex processes remains unclear. To further understand the regulatory machinery of mitochondrial dynamics, we screened a mitochondrial siRNA library and identified mortalin as a potential regulatory protein. Both genetic and chemical inhibition of mortalin strongly induced mitochondrial fragmentation and synergistically increased Aß-mediated cytotoxicity as well as mitochondrial dysfunction. Importantly we determined that the expression of mortalin in Alzheimer disease (AD) patients and in the triple transgenic-AD mouse model was considerably decreased. In contrast, overexpression of mortalin significantly suppressed Aß-mediated mitochondrial fragmentation and cell death. Taken together, our results suggest that down-regulation of mortalin may potentiate Aß-mediated mitochondrial fragmentation and dysfunction in AD.

ARP101 inhibits α-MSH-stimulated melanogenesis by regulation of autophagy in melanocytes.

Autophagy is a cooperative process between autophagosomes and lysosomes that degrades cellular organelles. Although autophagy regulates the turnover of cellular components, its role in melanogenesis is not clearly established. Previously, we reported that ARP101 induces autophagy in various cancer cells. Here, we show that ARP101 inhibits melanogenesis by regulation of autophagy. ARP101 inhibited α-MSH-stimulated melanin synthesis and suppressed the expression of tyrosinase and TRP1 in immortalized mouse melanocytes. ARP101 also induced autophagy in melanocytes. Knockdown of ATG5 reduced both anti-melanogenic activity and autophagy mediated by ARP101 in α-MSH treated melanocytes. Electron microscopy analysis further revealed that autophagosomes engulf melanin or melanosome in α-MSH and ARP101-treated cells. Collectively, our results suggest that ARP101 inhibits α-MSH-stimulated melanogenesis through the activation of autophagy in melanocytes.

Paeoniflorin, a monoterpene glycoside, attenuates lipopolysaccharide-induced neuronal injury and brain microglial inflammatory response.

Chronic activation of microglial cells endangers neuronal survival through the release of various proinflammatory and neurotoxic factors. Paeoniflorin (PF), a water-soluble monoterpene glycoside found in the root of Paeonia lactiflora Pall, has a wide range of pharmacological functions, such as anti-oxidant, anti-inflammatory, and anti-cancer effects. Neuroprotective potential of PF has also been demonstrated in animal models of neuropathologies. Here, we have examined the efficacy of PF in the repression of inflammation-induced neurotoxicity and microglial inflammatory response. In organotypic hippocampal slice cultures, PF significantly blocked lipopolysaccharide (LPS)-induced hippocampal cell death and productions of nitric oxide (NO) and interleukin (IL)-1ß. PF also inhibited the LPS-stimulated productions of NO, tumor necrosis factor-α, and IL-1ß from primary microglial cells. These results suggest that PF possesses neuroprotective activity by reducing the production of proinflammatory factors from activated microglial cells.

Prevention of inflammation-mediated neurotoxicity by butylidenephthalide and its role in microglial activation.

Microglial cells are the prime effectors in immune and inflammatory responses of the central nervous system (CNS). During pathological conditions, the activation of these cells helps restore CNS homeostasis. However, chronic microglial activation endangers neuronal survival through the release of various proinflammatory molecules and neurotoxins. Thus, negative regulators of microglial activation have been considered as potential therapeutic candidates to target neurodegeneration, such as that in Alzheimer's and Parkinson's diseases. The rhizome of Ligusticum chuanxiong Hort. (Ligusticum wallichii Franch) has been widely used for the treatment of vascular diseases in traditional oriental medicine. Butylidenephthalide (BP), a major bioactive component from L. chuanxiong, has been reported to have a variety of pharmacological activities, including vasorelaxant, anti-anginal, anti-platelet and anti-cancer effects. The aim of this study was to examine whether BP represses microglial activation. In rat brain microglia, BP significantly inhibited the lipopolysaccharide (LPS)-induced production of nitric oxide (NO), tumour necrosis factor-α and interleukin-1ß. In organotypic hippocampal slice cultures, BP clearly blocked the effect of LPS on hippocampal cell death and inhibited LPS-induced NO production in culture medium. These results newly suggest that BP provide neuroprotection by reducing the release of various proinflammatory molecules from activated microglia.

Hirsutine, an indole alkaloid of Uncaria rhynchophylla, inhibits inflammation-mediated neurotoxicity and microglial activation.

Chronic microglial activation endangers neuronal survival through the release of various pro-inflammatory and neurotoxic factors. As such, negative regulators of microglial activation have been considered as potential therapeutic candidates to reduce the risk of neurodegeneration associated with inflammation. Uncaria rhynchophylla (U. rhynchophylla) is a traditional oriental herb that has been used for treatment of disorders of the cardiovascular and central nervous systems. Hirsutine (HS), one of the major indole alkaloids of U. rhynchophylla, has demonstrated neuroprotective potential. The aim of the present study was to examine the efficacy of HS in the repression of inflammation-induced neurotoxicity and microglial cell activation. In organotypic hippocampal slice cultures, HS blocked lipopolysaccharide (LPS)-related hippocampal cell death and production of nitric oxide (NO), prostaglandin (PG) E2 and interleukin-1ß. HS was demonstrated to effectively inhibit LPS-induced NO release from cultured rat brain microglia. The compound reduced the LPS-stimulated production of PGE2 and intracellular reactive oxygen species. HS significantly decreased LPS-induced phosphorylation of the mitogen-activated protein kinases and Akt signaling proteins. In conclusion, HS reduces the production of various neurotoxic factors in activated microglial cells and possesses neuroprotective activity in a model of inflammation-induced neurotoxicity.

Suppression of autophagy exacerbates Mefloquine-mediated cell death.

Mefloquine is an effective treatment drug for malaria. However, it can cause several adverse side effects, and the precise mechanism associated with the adverse neurological effects of Mefloquine is not clearly understood. In this study, we investigated the effect of Mefloquine on autophagy in neuroblastoma cells. Mefloquine treatment highly induced the formation of autophagosomes and the conversion of LC3I into LC3II. Moreover, Mefloquine-induced autophagy was efficiently suppressed by an autophagy inhibitor and by down regulation of ATG6. The autophagy was also completely blocked in ATG5 deficient mouse embryonic fibroblast cells. Moreover, suppression of autophagy significantly intensified Mefloquine-mediated cytotoxicity in SH-SY5Y cells. Our findings suggest that suppression of autophagy may exacerbate Mefloquine toxicity in neuroblastoma cells.

Neuroprotective effects of INM-176 against lipopolysaccharide-induced neuronal injury.

Neuroinflammation plays a critical role in the etiology of chronic neurodegenerative diseases such as Alzheimer's disease. INM-176 is a standardized ethanolic extract of Angelica gigas, which has been traditionally used as a tonic to treat anemia. In the present study, we investigated whether INM-176 exhibits neuroprotective activities against lipopolysaccharide (LPS)-induced neuronal damage in vitro and in vivo. In primary microglial cells, INM-176 significantly inhibited LPS-induced nitric oxide release and expression of tumor necrosis factor-α and interleukin-1ß. The expression levels of inducible nitric oxide synthase and cylcooxygenase-2 in BV2 microglial cells were markedly upregulated by LPS, but this increased expression was counteracted by INM-176. LPS-mediated neuronal damage in an organotypic hippocampal slice culture was also attenuated by the administration of INM-176. In addition, LPS (1 µg/2 µl, i.c.v.)-induced cognitive dysfunction in mice, as determined by passive avoidance and Y-maze tasks, was significantly attenuated by the administration of INM-176. Furthermore, the activation of microglia or astrocytes by LPS in the hippocampal regions of mice was suppressed by INM-176. These results suggest that the neuroprotective and cognition ameliorating effects of INM-176 against LPS-induced damage are mediated, in part, by its anti-inflammatory activities.

Ginsenoside rb1 modulates level of monoamine neurotransmitters in mice frontal cortex and cerebellum in response to immobilization stress.

Cerebral monoamines play important roles as neurotransmitters that are associated with various stressful stimuli. Some components such as ginsenosides (triterpenoidal glycosides derived from the Ginseng Radix) may interact with monoamine systems. The aim of this study was to determine whether ginsenoside Rb1 can modulate levels of the monoamines such as dihydroxyphenylalanine (DOPA), dopamine (DA), norepinephrine (NE), epinephrine (EP), 3,4-dihydroxyphenylacetic acid (DOPAC), 5-hydorxytryptamine (5-HT), 5-hydroxindole-3-acetic acid (5-HIAA), and 5-hydroxytryptophan (5-HTP) in mice frontal cortex and cerebellum in response to immobilization stress. Mice were treated with ginsenoside Rb1 (10 mg/kg, oral) before a single 30 min immobilization stress. Acute immobilization stress resulted in elevation of monoamine levels in frontal cortex and cerebellum. Pretreatment with ginsenoside Rb1 attenuated the stress-induced changes in the levels of monoamines in each region. The present findings showed the anti-stress potential of ginsenoside Rb1 in relation to regulation effects on the cerebral monoaminergic systems. Therefore, the ginsenoside Rb1 may be a useful candidate for treating several brain symptoms related with stress.

Gami-Chunghyuldan ameliorates memory impairment and neurodegeneration induced by intrahippocampal Aß 1-42 oligomer injection.

Soluble oligomeric forms of amyloid beta (AßO) are regarded as a main cause of synaptic and cognitive dysfunction in Alzheimer's disease (AD) and have been a primary target in the development of drug treatments for AD. The present study utilized a mouse model of AD induced by intrahippocampal injection of AßO (10 µM) to investigate the effects of Gami-Chunghyuldan (GCD), a standardized multi-herbal medicinal formula, on the presentation of memory deficits and neurohistological pathogenesis. GCD (10 and 50mg/kg/day, 5 days, p.o.) improved AßO-induced memory impairment as well as reduced neuronal cell death, astrogliosis, and microgliosis in the hippocampus. In addition, GCD prevented AßO-triggered synaptic disruption and cholinergic fiber loss. These results suggest that GCD may be useful in the prevention and treatment of AD.

Indirubin-3'-oxime inhibits inflammatory activation of rat brain microglia.

Microglial cells play critical roles in the immune and inflammatory responses of the brain. Under pathological conditions, the activation of microglia helps to restore brain homeostasis. However, chronic microglial activation endangers neuronal survival through the release of various proinflammatory and neurotoxic factors. As such, regulators of microglial activation have been considered as potential therapeutic candidates to reduce the risk of neurodegeneration associated with neurodegenerative diseases, including Alzheimer's and, Parkinson's diseases. Indirubin-3'-oxime, a potent inhibitor of cyclin-dependent kinases and glycogen synthase kinase-3ß, has been shown to have neuroprotective potential. The specific aim of this study was to examine the efficacy of indirubin-3'-oxime in the repression of microglial activation. Indirubin-3'-oxime was shown to effectively inhibit lipopolysaccharide (LPS)-induced nitric oxide release from cultured rat brain microglia. This compound reduced the LPS-stimulated productions of tumor necrosis factor-α, interleukin-1ß, prostaglandin E(2), and intracellular reactive oxygen species and also effectively reduced LPS-elicited NF-κB activation. In organotypic hippocampal slice cultures, indirubin-3'-oxime blocked LPS-related hippocampal cell death. These results suggest that indirubin-3'-oxime provides neuroprotection by reducing the productions of various neurotoxic molecules in activated microglia.

Anti-inflammatory effects of crocin and crocetin in rat brain microglial cells.

Microglial cells play critical roles in the immune and inflammatory responses of the central nervous system (CNS). Under pathological conditions, the activation of microglia helps in restoring CNS homeostasis. However, chronic microglial activation endangers neuronal survival through the release of various proinflammatory and neurotoxic factors. Thus, negative regulators of microglial activation have been considered as potential therapeutic candidates to target neurodegeneration, such as that observed in Alzheimer's and Parkinson's diseases. Crocin and crocetin, found in the fruits of gardenia and in the stigmas of saffron, have been considered for the treatment of various disorders in traditional oriental medicine. Crocin and crocetin have been reported to have diverse pharmacological functions, such as anti-hyperlipidemic, anti-atherosclerotic, and anti-cancer effects. Specifically, the neuroprotective potential of crocetin derivatives has previously been demonstrated. The specific aim of this study was to examine whether crocin or crocetin represses microglial activation. Crocin and crocetin were shown to be effective in the inhibition of LPS-induced nitric oxide (NO) release from cultured rat brain microglial cells. These compounds reduced the LPS-stimulated productions of tumor necrosis factor-α, interleukin-1ß, and intracellular reactive oxygen species. The compounds also effectively reduced LPS-elicited NF-κB activation. In addition, crocin reduced NO release from microglia stimulated with interferon-γ and amyloid-ß. In organotypic hippocampal slice cultures, both crocin and crocetin blocked the effect of LPS on hippocampal cell death. These results suggest that crocin and crocetin provide neuroprotection by reducing the production of various neurotoxic molecules from activated microglia.