Cytoprotective effects of lindenenyl acetate isolated from Lindera strychnifolia on mouse hippocampal HT22 cells

Chemistry and bioactivity of lindenane sesquiterpenoids and their oligomers

Covering: 1925 to July 2023Among the sesquiterpenoids with rich structural diversity and potential bioactivities, lindenane sesquiterpenoids (LSs) possess a characteristic cis, trans-3,5,6-carbocyclic skeleton and mainly exist as monomers and diverse oligomers in plants from the Lindera genus and Chloranthaceae family. Since the first identification of lindeneol from Lindera strychnifolia in 1925, 354 natural LSs and their oligomers with anti-inflammatory, antitumor, and anti-infective activities have been discovered. Structurally, two-thirds of LSs exist as oligomers with interesting skeletons through diverse polymeric patterns, especially Diels-Alder [4 + 2] cycloaddition. Fascinated by their diverse bioactivities and intriguing polycyclic architectures, synthetic chemists have engaged in the total synthesis of natural LSs in recent decades. In this review, the research achievements related to LSs from 1925 to July of 2023 are systematically and comprehensively summarized, focusing on the classification of their structures, chemical synthesis, and bioactivities, which will be helpful for further research on LSs and their oligomers.

Linderae Radix Ameliorates Cognitive Dysfunction by Inhibiting Neuroinflammation and Synaptic Damage in Alzheimer's Disease Models

Neuroinflammation and synaptic damage are important etiologies associated with the progression of Alzheimer's disease (AD). Linderae Radix (LR) has antioxidant and anti-inflammatory properties. This study investigated whether LR attenuates microglia activation-mediated neuroinflammation and synaptic degeneration and improves AD pathological phenotypes induced by amyloid beta oligomers (AβO) or lipopolysaccharide (LPS) toxicity. For in vitro studies, we treated LR to AβO-stimulated HT22 cells or LR LPS-stimulated BV2 cells. For in vivo studies, we administered LR to mice and AβO was injected by stereotaxic to induce cognitive impairment, neuroinflammation, and synaptic loss. We found that LR increased the cell viability reduced by AβO. Moreover, LR inhibited pro-inflammatory mediators such as nitric oxide (NO), inducible NO synthase (iNOS), and cyclooxygenase-2 (COX-2), and downregulated p38 mitogen-activated protein kinase (MAPK) signaling in BV2 cells. Behavioral assessments demonstrated that LR administration significantly improved cognitive decline induced by AβO-injection. Furthermore, we found that microglia activation increased, and the expression of synaptic proteins decreased in the hippocampus of the AβO-injected group, which was alleviated in the LR-treated group. These findings suggest that LR may be a potential candidate for protection against neuroinflammation and synaptic loss, and may prevent or delay AD progression.

A review on the chemical constituents and pharmacological efficacies of Lindera aggregata (Sims) Kosterm

Lindera aggregata (Sims) Kosterm. (L. aggregata), which belongs to the genus Lindera in the family Lauraceae, is widely distributed in Asia and the temperate, tropical regions of North America. Its roots and leaves have been used for thousands of years as traditional Chinese medicine and/or functional food. To further explore its underlying nutritional value, this review provided a comprehensive insight into chemical constituents and pharmacological effects on L. aggregata. The phytochemical investigation of different parts of L. aggregata led to the identification of up to 349 components belonging to sesquiterpenoids, alkaloids, flavonoids, essential oils, and other compounds. Among them, sesquiterpenoids, flavonoids, and alkaloids are assessed as representative active ingredients of L. aggregata. A wide variety of pharmacological effects of L. aggregata, such as anti-hyperlipidemic, anti-tumor, anti-inflammatory, analgesic, and anti-oxidant, have been proved in vitro and in vivo. In summary, this review aims to provide a scientific basis and reference for further research and utilization of L. aggregata and lay the foundation for developing functional foods with potential active ingredients for the prevention and management of related diseases.

Quantitation of Diclofenac, Tolbutamide, and Warfarin as Typical CYP2C9 Substrates in Rat Plasma by UPLC-MS/MS and Its Application to Evaluate Linderane-Mediated Herb-Drug Interactions

Linderane (LDR), the main active and distinctive component of L. aggregate, is a mechanism-based inactivator of CYP2C9 in vitro, indicating the occurrence of herb-drug interactions. However, little is known about the changes of the pharmacokinetic properties of the common clinical drugs as CYP2C9 substrates after coadministration with LDR. In this study, a selective and rapid ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS-MS) method for the determination of diclofenac, tolbutamide, and warfarin as CYP2C9 substrates in rat plasma has been developed. Chlorzoxazone was employed as an internal standard (IS), and protein precipitation was used for sample preparation. Chromatographic separation was achieved on a UPLC BEH-C₁₈ (2.1 × 50 mm, 1.7 µm) with 0.1% (v:v) formic acid in water (A) and acetonitrile (B) as the mobile phase with gradient elution. The total run time was only 3.8 min. MS analysis was performed under multiple reaction monitoring (MRM) with electron spray ionization (ESI) operated in the negative mode. The bioanalytical method was validated, and the selectivity, carryover effects, linearity, precision, accuracy, matrix effect, extraction recovery, and stability were acceptable. The validated method was then successfully applied for evaluating the potential pharmacokinetic interactions when LDR was used along with diclofenac, tolbutamide, and warfarin, respectively. Results showed that the C _max of diclofenac in the treated group was 1287.82 ± 454.16 μg/L, which was about 5-fold of that in the control group (P < 0.01). The C _max of tolbutamide in the treated group was 60.70 ± 10.70 mg/L, which was significantly decreased by about 25% when compared with the control group (P < 0.01). The V _d of warfarin in the treated group was obviously increased, which was about 1.4-fold of that in the control group (P < 0.01).

Bioassay-Guided Isolation of Two Eudesmane Sesquiterpenes from Lindera strychnifolia Using Centrifugal Partition Chromatography

In this study, a centrifugal partition chromatography (CPC) separation was applied to identify antioxidant-responsive element (ARE) induction molecules from the crude extract of Lindera strychnifolia roots. CPC was operated with a two-phase solvent system composed of n-hexane-methanol-water (10:8.5:1.5, v/v/v) in dual mode (descending to ascending), which provided a high recovery rate (>95.5%) with high resolution. Then, ARE induction activity of obtained CPC fractions was examined in ARE-transfected HepG2 cells according to the weight ratios of the obtained fractions. The fraction exhibiting ARE-inducing activity was further purified by preparative HPLC that led to isolation of two eudesmane type sesquiterpenes as active compounds. The chemical structures were elucidated as linderolide U (1) and a new sesquiterpene named as linderolide V (2) by spectroscopic data. Further bioactivity test demonstrated that compounds 1 and 2 enhanced ARE activity by 22.4-fold and 7.6-fold, respectively, at 100 μM concentration while 5 μM of sulforaphane induced ARE activity 24.8-fold compared to the control.

Therapeutic Potential of Lindera obtusiloba: Focus on Antioxidative and Pharmacological Properties

Lindera obtusiloba (LO) BLUME from the genus Lindera (Lauraceae) is a medicinal herb traditionally used in Southeast Asian countries. Indigenously, extracts of different parts of the plant have been used to improve blood circulation and treat allergy, inflammation, rheumatism, and liver diseases. LO is a rich source of therapeutically beneficial antioxidative phytochemicals, such as flavonoids, butenolides, lignans and neolignans. Moreover, recent studies have unravelled the pharmacological properties of several newly found active constituents of LO, such as anti-inflammatory antioxidants (+)-syringaresinol, linderin A, anti-atherosclerotic antioxidant (+)-episesamin, anti-melanogenic antioxidants quercitrin and afzelin, cytotoxic 2-(1-methoxy-11-dodecenyl)-penta-2,4-dien-4-olide, (2Z,3S,4S)-2-(11-dodecenylidene)-3-hydroxy-4-methyl butanolide, anti-allergic koaburaside, (6-hydroxyphenyl)-1-O-beta-d-glucopyranoside and 2,6-dimethoxy-4-hydroxyphenyl-1-O-beta-d-glucopyranoside and the antiplatelet-activity compound Secolincomolide A. These findings demonstrate that LO can be a potential source of antioxidants and other prospective therapeutically active constituents that can lead to the development of oxidative stress-mediated diseases, such as cardiovascular disorders, neurodegenerative disorders, allergies, inflammation, hepatotoxicity, and cancer. Here, the antioxidant properties of different species of Lindera genus are discussed briefly. The traditional use, phytochemistry, antioxidative and pharmacological properties of LO are also considered to help researchers screen potential lead compounds and design and develop future therapeutic agents to treat oxidative stress-mediated disorders.

Linderolide U, a new sesquiterpene from Lindera aggregata root

A new sesquiterpene, namely linderolide U (1), was isolated from the root of Lindera aggregata (Sims) Kosterm along with five known sesquiterpenes (2-6). The structures of the obtained compounds were identified by spectroscopic methods, specifically nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS). The acquired data were compared with those previously reported in the literature. The anticancer effects of the isolated natural products were studied using the HCT116 human colon cancer cell line. Compound 5 was found to significantly suppress cell proliferation, which was associated with induction of apoptosis and cell cycle arrest (G2/M and S phase). The findings of the present study suggest derivative 5 as a potential agent for the treatment of colon cancer.

The antidepressant-like effect of guanosine is dependent on GSK-3β inhibition and activation of MAPK/ERK and Nrf2/heme oxygenase-1 signaling pathways

Although guanosine is an endogenous nucleoside that displays antidepressant-like properties in several animal models, the mechanism underlying its antidepressant-like effects is not well characterized. The present study aimed at investigating the involvement of ERK/GSK-3β and Nrf2/HO-1 signaling pathways in the antidepressant-like effect of guanosine in the mouse tail suspension test (TST). The immobility time in the TST was taken as an indicative of antidepressant-like responses and the locomotor activity was assessed in the open-field test. Biochemical analyses were performed by Western blotting in the hippocampus and prefrontal cortex (PFC). The combined treatment with sub-effective doses of guanosine (0.01 mg/kg, p.o.) and lithium chloride (a non-selective GSK-3β inhibitor, 10 mg/kg, p.o.) or AR-A014418 (selective GSK-3β inhibitor, 0.01 μg/site, i.c.v.) produced a synergistic antidepressant-like effect in the TST. The antidepressant-like effect of guanosine (0.05 mg/kg, p.o.) was completely prevented by the treatment with MEK1/2 inhibitors U0126 (5 μg/site, i.c.v.), PD98059 (5 μg/site, i.c.v.), or zinc protoporphyrin IX (ZnPP) (HO-1 inhibitor, 10 μg/site, i.c.v). Guanosine administration (0.05 mg/kg, p.o.) increased the immunocontent of β-catenin in the nuclear fraction and Nrf2 in the cytosolic fraction in the hippocampus and PFC. The immunocontent of HO-1 was also increased in the hippocampus and PFC. Altogether, the results provide evidence that the antidepressant-like effect of guanosine in the TST involves the inhibition of GSK-3β, as well as activation of MAPK/ERK and Nrf2/HO-1 signaling pathways, highlighting the relevance of these molecular targets for antidepressant responses.

Multiple pathways for natural product treatment of Parkinson's disease: A mini review

BACKGROUND

It is established that natural medicines for Parkinson's disease (PD) provide an antioxidant activity in preventing dopaminergic neurons from degeneration. However, the underlying and related molecular details remain poorly understood.

METHODS AND AIM

We review published in vitro and rodent studies of natural products in PD models with the aim to identify common molecular pathways contributing to the treatment efficacy. Commonly regulated genes were identified through the systemic literature search and further analyzed from a network perspective.

FINDINGS

Approximately thirty different types of natural products have been investigated for their ability to regulate protein density and gene activity in various experimental systems. Most were found to attenuate neurotoxin-induced regulations. Three common PD pathways are involved. The most studied pathway was neuronal development/anti-apoptosis consisting of Bax/Bcl-2, caspases 3/9, and MAPK signaling. Another well studied was anti-inflammation comprising iNOS, nNOS, Nrf2/ARE, cytokines, TNFα, COX2 and MAPK signaling. The third pathway referred to dopamine transmission modulation with upregulated VMAT2, DAT, NURR1 and GDNF levels. To date, HIPK2, a conserved serine/threonine kinase and transcriptional target of Nrf2 in an anti-apoptosis signaling pathway, is the first protein identified as the direct binding target of a natural product (ZMHC).

IMPLICATIONS

Natural products may utilize multiple and intercellular pathways at various steps to prevent DA neurons from degeneration. Molecular delineation of the mechanisms of actions is revealing new, perhaps combinational therapeutic approaches to stop the progression of DA degeneration.

Neuroprotective Effects of Taraxacum officinale Wigg. Extract on Glutamate-Induced Oxidative Stress in HT22 Cells via HO-1/Nrf2 Pathways

Oxidative stress-mediated neuron damage is considered an important contributor to the pathogenesis and development of neurodegenerative diseases. Taraxacum officinale has been reported to possess antioxidant activities. However, whether it can protect neurons against oxidative damage and the underlying molecular mechanisms have not been fully determined. In the present study, we examined the neuroprotective effects of ethanol extracts of this plant (ETOW) on glutamate-induced oxidative stress in HT22 cells. Both cell viability and reactive oxygen species (ROS) assays showed that ETOW effectively attenuated glutamate-induced cytotoxicity and ROS generation. Furthermore, our results revealed that ETOW increased the expression of heme oxygenase-1 (HO-1) and promoted the nuclear translocation of nuclear factor erythroid 2-related factor-2 (Nrf2). The inhibitory effects of ETOW on glutamate-stimulated cell toxicity and ROS production were partially reversed by tin protoporphyrin (SnPP), an HO activity inhibitor. Taken together, these results demonstrate that ETOW can protect HT22 cells against glutamate-induced oxidative damage by inducing the Nrf2/HO-1 pathways. Our study supports the idea that Taraxacum officinale Wigg. is a promising agent for preventing neurodegenerative diseases.

Heme Oxygenase-1-Inducing Activity of 4-Methoxydalbergione and 4'-Hydroxy-4-methoxydalbergione from Dalbergia odorifera and Their Anti-inflammatory and Cytoprotective Effects in Murine Hippocampal and BV2 Microglial Cell Line and Primary Rat Microglial Cells

Dalbergia odorifera T. Chen (Leguminosae) grows in Central and South America, Africa, Madagascar, and Southern Asia. D. odorifera possesses many useful pharmacological properties, such as antioxidative and anti-inflammatory activities in various cell types. 4-Methoxydalbergione (MTD) and 4'-hydroxy-4-methoxydalbergione (HMTD) were isolated from the EtOH extract of D. odorifera by several chromatography methods. The chemical structures were elucidated by nuclear magnetic resonance (NMR) and mass spectrum (MS). Anti-inflammatory and cytoprotective effects were examined using BV2 microglial cells and murine hippocampus. MTD and HMTD were demonstrated to induce heme oxygenase (HO)-1 protein levels through the nuclear translocation of nuclear factor E2-related factor 2 (Nrf2) in BV2 microglial cells, while only MTD upregulated HO-1 in HT22 cells. MTD and HMTD induced HO-1 expression through JNK MAPK pathway in BV2 cells, whereas only MTD activated the ERK and p38 pathways in HT22 cells. MTD was also shown to activated MTD and HMTD suppressed lipopolysaccharide-stimulated nitric oxide (NO) and prostaglandin E2 production by inhibiting inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2) expression in a dose-dependent manner. Furthermore, MTD and HMTD attenuated pro-inflammatory cytokine productions. These anti-inflammatory effects were found to be mediated through the nuclear factor-kappa B (NF-κB) pathway. MTD exhibited neuroprotective effects on glutamate-induced neurotoxicity by promoting HO-1 in HT22 cells. The anti-inflammatory and cytoprotective effects of MTD and HMTD were partially reversed by an HO inhibitor tin protoporphyrin IX. In addition, MTD and HMTD inhibited pro-inflammatory cytokines and NF-κB pathway in primary rat microglia. These findings suggest that MTD and HMTD have therapeutic potential against neurodegenerative diseases accompanied by microglial activation and/or oxidative cellular injury.

Phytochemicals as future drugs for Parkinson’s disease: a comprehensive review

Parkinson’s disease (PD) is the second most common chronic neurodegenerative disease that affects motor skills and cognitive performance. The conventional therapeutic approaches for the management of PD are just able to alleviate symptoms. Exploring for achieving novel substances with therapeutic benefits in PD patients is the focus of a wide range of current investigations. The aim of the present study is to comprehensively review phytochemicals with protective or therapeutic activities in PD and focus on their neuropsychopharmacological mechanisms. Various subgroups of polyphenols (flavonoids, phenolic acids, stilbenes, and lignanes) and terpenes are the most abundant groups of phytochemicals with well-established antiparkinsonian effects. Other phytochemical categories, such as alkaloids, cinnamates, carbohydrates, amino acids, and fatty acid amides, also have some representatives with positive effects in PD. Phytochemicals perform their antiparkinsonian effect through several mechanisms of action, including suppressing apoptosis (via the reduction of Bax/Bcl-2, caspase-3, -8, and -9, and α-synuclein accumulation), decreasing dopaminergic neuronal loss and dopamine depletion, reducing the expression of proinflammatory cytokines (such as prostaglandin E2, interleukin-6, interleukin-1β, and nuclear factor-κB), and modulating nuclear and cellular inflammatory signaling, elevation of neurotrophic factors, and improvement of antioxidant status. Plant-derived natural products can be considered as future pharmaceutical drugs or adjuvant treatment with conventional therapeutic approaches to improve their efficacy and alleviate their psychological adverse effects in the management of PD. Well-designed clinical trials are mandatory to evaluate the protective and healing benefits of phytochemicals as promising future drugs in the management of neurodegenerative diseases.

Anti-Inflammatory and Cytoprotective Effects of TMC-256C1 from Marine-Derived Fungus Aspergillus sp. SF-6354 via up-Regulation of Heme Oxygenase-1 in Murine Hippocampal and Microglial Cell Lines

In the course of searching for bioactive secondary metabolites from marine fungi, TMC-256C1 was isolated from an ethyl acetate extract of the marine-derived fungus Aspergillus sp. SF6354. TMC-256C1 displayed anti-neuroinflammatory effect in BV2 microglial cells induced by lipopolysaccharides (LPS) as well as neuroprotective effect against glutamate-stimulated neurotoxicity in mouse hippocampal HT22 cells. TMC-256C1 was shown to develop a cellular resistance to oxidative damage caused by glutamate-induced cytotoxicity and reactive oxygen species (ROS) generation in HT22 cells, and suppress the inflammation process in LPS-stimulated BV2 cells. Furthermore, the neuroprotective and anti-neuroinflammatory activities of TMC-256C1 were associated with upregulated expression of heme oxygenase (HO)-1 and nuclear translocation of nuclear factor-E2-related factor 2 (Nrf2) in HT22 and BV2 cells. We also found that TMC-256C1 activated p38 mitogen-activated protein kinases (MAPK) and phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathways in HT22 and BV2 cells. These results demonstrated that TMC-256C1 activates HO-1 protein expression, probably by increasing nuclear Nrf2 levels via the activation of the p38 MAPK and PI3K/Akt pathways.

MEF2D Mediates the Neuroprotective Effect of Methylene Blue Against Glutamate-Induced Oxidative Damage in HT22 Hippocampal Cells

Methylene blue (MB) can ameliorate behavioral, neurochemical, and neuropathological impairments in animal models of acute and chronic neurodegenerative disorders, but the underlying mechanism remains unclear. Myocyte enhancer factor 2 (MEF2D) is known to promote neuronal survival in several models, and several survival and death signals converge on MEF2D and regulate its activity. Here, we investigated the role of MEF2D in the neuroprotective effect of MB against glutamate-induced toxicity in HT22 neuronal cells. Our results showed that MB, event at less than 100 nM, improved the viability of HT22 cells exposed to 2 mM glutamate. MB attenuated the mitochondrial impairment and quenches the reactive oxygen species (ROS) induced by glutamate. Surprisingly, MB at 50-200 nM did not affect the Nrf2/HO-1 pathway, an important endogenous anti-oxidative system. Further study showed that MB increased the transcription and translation of MEF2D. In addition, MB upregulated the expression of mitochondrial NADH dehydrogenase 6 (ND6) in a MEF2D-dependent manner. Knockdown of MEF2D abolished both MB-medicated increase of ND6 and MB-induced neuroprotection against glutamate-induced toxicity. Moreover, we showed that MB promoted Akt function activity, suppressed GSK-3β activity, and increased MEF2D level in hippocampus of mice and HT22 cells. These findings for the first time demonstrate that MB protects HT22 neuronal cells against glutamate-induced cell death partially via the regulation of MEF2D-associated survival pathway.

Overview of Nrf2 as Therapeutic Target in Epilepsy

Oxidative stress is a biochemical state of imbalance in the production of reactive oxygen and nitrogen species and antioxidant defenses. It is involved in the physiopathology of degenerative and chronic neuronal disorders, such as epilepsy. Experimental evidence in humans and animals support the involvement of oxidative stress before and after seizures. In the past few years, research has increasingly focused on the molecular pathways of this process, such as that involving transcription factor nuclear factor E2-related factor 2 (Nrf2), which plays a central role in the regulation of antioxidant response elements (ARE) and modulates cellular redox status. The aim of this review is to present experimental evidence on the role of Nrf2 in this neurological disorder and to further determine the therapeutic impact of Nrf2 in epilepsy.

Involvement of heme oxygenase-1 in neuroprotection by sanguinarine against glutamate-triggered apoptosis in HT22 neuronal cells

Sanguinarine is a natural compound isolated from the roots of Macleaya cordata and M. microcarpa, has been reported to possess several biological activities such as anti-inflammatory and anti-oxidant effects. In the present study, we demonstrated that sanguinarine markedly induces the expression of HO-1 which leads to a neuroprotective response in mouse hippocampus-derived neuronal HT22 cells from apoptotic cell death induced by glutamate. Sanguinarine significantly attenuated the loss of mitochondrial function and membrane integrity associated with glutamate-induced neurotoxicity. Sanguinarine protected against glutamate-induced neurotoxicity through inhibition of HT22 cell apoptosis. JC-1 staining, which is a well-established measure of mitochondrial damage, was decreased after treatment with sanguinarine in glutamate-challenged HT22cells. In addition, sanguinarine diminished the intracellular accumulation of ROS and Ca(2+). Sanguinarine also induced HO-1, NQO-1 expression via activation of Nrf2. Additionally, we found that si RNA mediated knock-down of Nrf2 or HO-1 significantly inhibited sanguinarine-induced neuroprotective response. These findings revealed the therapeutic potential of sanguinarine in preventing the neurodegenerative diseases.

Effect of tacrine-3-caffeic acid, a novel multifunctional anti-Alzheimer's dimer, against oxidative-stress-induced cell death in HT22 hippocampal neurons: involvement of Nrf2/HO-1 pathway

AIMS

Oxidative stress (OS) plays an important role in the pathogenesis of neurodegenerative diseases, including Alzheimer's disease (AD). This study was designed to uncover the cellular and biochemical mechanisms underlying the neuroprotective effects of tacrine-3-caffeic acid (T3CA), a novel promising multifunctional anti-Alzheimer's dimer, against OS-induced neuronal death.

METHODS AND RESULTS

T3CA protected HT22 cells against high-concentration-glutamate-induced cell death in time- and concentration-dependent manners and potently attenuated glutamate-induced intracellular reactive oxygen species (ROS) production as well as mitochondrial membrane-potential (ΔΨ) disruption. Besides, T3CA significantly induced nuclear factor erythroid 2-related factor 2 (Nrf2) nuclear translocation and increased its transcriptional activity, which were demonstrated by Western blotting, immunofluorescence, and antioxidant response element (ARE)-luciferase reporter gene assay. Further studies showed that T3CA potently up-regulated heme oxygenase-1 (HO-1), an endogenous antioxidative enzyme and a downstream effector of Nrf2, at both mRNA and protein levels. The neuroprotective effects of T3CA were partially reversed by brusatol, which reduced protein level of Nrf2, or by inhibiting HO-1 with siRNA or ZnPP-IX, a specific inhibitor of HO-1.

CONCLUSIONS

Taken together, these results clearly demonstrate that T3CA protects neurons against OS-induced cell death partially through Nrf2/ARE/HO-1 signaling pathway, which further supports that T3CA might be a promising novel therapeutic agent for OS-associated diseases.

Garlic sprouting is associated with increased antioxidant activity and concomitant changes in the metabolite profile

Although garlic (Allium sativum) has been extensively studied for its health benefits, sprouted garlic has received little attention. We hypothesized that sprouting garlic would stimulate the production of various phytochemicals that improve health. Ethanolic extracts from garlic sprouted for different periods had variable antioxidant activities when assessed with in vitro assays, including the 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity assay and the oxygen radical absorbance capacity assay. Extracts from garlic sprouted for 5 days had the highest antioxidant activity, whereas extracts from raw garlic had relatively low antioxidant activity. Furthermore, sprouting changed the metabolite profile of garlic: the metabolite profile of garlic sprouted for 5-6 days was distinct from the metabolite profile of garlic sprouted for 0-4 days, which is consistent with the finding that garlic sprouted for 5 days had the highest antioxidant activity. Therefore, sprouting may be a useful way to improve the antioxidant potential of garlic.

Acanthopanax senticosus exerts neuroprotective effects through HO-1 signaling in hippocampal and microglial cells

Extracts of Acanthopanax senticosus, a traditional herb commonly found in Northeastern Asia, are used for treating neurodegenerative disorders such as ischemia and depression. However, the mechanisms of its neuroinflammatory and cytoprotective effects have not been investigated. We examined the mechanism of A. senticosus activity in anti-neuroinflammatory and neuroprotective processes. HO-1 is an inducible enzyme present in most cell lines. ASE increased HO-1 expression, which reduced LPS-induced nitric oxide/ROS production in BV2 cells. Moreover, the induction of HO-1 expression protected cells against glutamate-induced neuronal cell death. Activation of the p38-CREB pathway and translocation of Nrf2 are strongly involved in ASE-induced HO-1 expression. Our results showed that ASE-induced HO-1 expression through the p38-CREB pathway plays an important role in the generation of anti-neuroinflammatory and neuroprotective responses. ASE also increases the translocation of Nrf2 to regulate HO-1 expression. Furthermore, our results indicate that ASE serves as a potential therapeutic agent for neuronal disorders.

A cannabigerol quinone alleviates neuroinflammation in a chronic model of multiple sclerosis

Phytocannabinoids like ∆(9)-tetrahydrocannabinol (THC) and cannabidiol (CBD) show a beneficial effect on neuroinflammatory and neurodegenerative processes through cell membrane cannabinoid receptor (CBr)-dependent and -independent mechanisms. Natural and synthetic cannabinoids also target the nuclear receptor peroxisome proliferator-activated receptor-gamma (PPARγ), an attractive molecular target for the treatment of neuroinflammation. As part of a study on the SAR of phytocannabinoids, we have investigated the effect of the oxidation modification in the resorcinol moiety of cannabigerol (CBG) on CB(1), CB(2) and PPARγ binding affinities, identifying cannabigerol quinone (VCE-003) as a potent anti-inflammatory agent. VCE-003 protected neuronal cells from excitotoxicity, activated PPARγ transcriptional activity and inhibited the release of pro-inflammatory mediators in LPS-stimulated microglial cells. Theiler's murine encephalomyelitis virus (TMEV) model of multiple sclerosis (MS) was used to investigate the anti-inflammatory activity of this compound in vivo. Motor function performance was evaluated and the neuroinflammatory response and gene expression pattern in brain and spinal cord were studied by immunostaining and qRT-PCR. We found that VCE-003 ameliorated the symptoms associated to TMEV infection, decreased microglia reactivity and modulated the expression of genes involved in MS pathophysiology. These data lead us to consider VCE-003 to have high potential for drug development against MS and perhaps other neuroinflammatory diseases.

Dangkwisoo-san, an herbal medicinal formula, ameliorates acute lung inflammation via activation of Nrf2 and suppression of NF-κB

ETHNOPHARMACOLOGICAL RELEVANCE

Dangkwisoo-san (DS), an herbal medicinal formula, has long been used in Korea for the treatment of inflammatory complications caused by physical trauma. Although the therapeutic effect of DS is likely associated with anti-inflammatory activity, the precise underlying mechanisms are largely unknown. Here we sought to elucidate the possible mechanisms of anti-inflammatory activity of DS.

MATERIALS AND METHODS

The water extract of DS was orally fed to C57BL/6 mice for 14 days prior to LPS intranasal instillation for lung inflammation. The effects of DS on lung inflammation were determined by differential cell counting, lung histology, and semi-quantitative RT-PCR of lung sections. The effects of DS on the activities of Nrf2 and NF-κB were assessed by western blotting, semi-quantitative RT-PCR, and luciferase reporter assays in RAW 264.7, an NF-κB reporter cell line, and HEK 293 transfected with an NF-κB reporter construct.

RESULTS

Mice that were treated with a water extract of DS showed significant attenuation of lung inflammation induced by intranasal lipopolysaccharide (LPS) compared to control mice treated with vehicle. In vitro experiments show that DS activated Nrf2, an anti-oxidant transcription factor that protects from various inflammatory diseases, and induced Nrf2-regulated genes including GCLC, NQO-1 and HO-1. In addition, DS suppressed NF-κB activity and reduced the production of pro-inflammatory cytokines. Transfection experiment indicates that inhibition of NF-κB likely occurred upstream of IKK complex. Furthermore, DS enhanced the expression of HO-1 and suppressed that of IL-1β and TNF-α in inflamed mouse lungs.

CONCLUSIONS

These results suggest that the therapeutic effects of DS are related with suppression of inflammation, which is, at least in part, mediated by activation of anti-inflammatory factor Nrf2 and inhibition of pro-inflammatory factor NF-κB.

Anti-inflammatory effects of lindenenyl acetate via heme oxygenase-1 and AMPK in human periodontal ligament cells

The molecular basis for the anti-inflammatory effects of lindenenyl acetate (LA) was investigated in the lipopolysaccharide (LPS)-stimulated human periodontal ligament (HPDL) cell model. LA concentration-dependently inhibited LPS-induced inducible nitric oxide synthase (iNOS) derived nitric oxide (NO) and cyclooxygenase-2 (COX-2) derived prostaglandin E2 (PGE(2)) production in HPDL cells. LA also attenuated the production of LPS-induced tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6 and IL-12. LA stimulated heme oxygenase-1 (HO-1) protein expression and enzyme activity of HPDL cells in a dose-dependent manner. Pretreatment with the HO-1 inhibitor, tin protoporphyrin (SnPP), attenuated the inhibitory activities of LA on LPS-induced inflammatory NO, PGE(2), IL-1β, TNF-α, IL-6 and IL-12 production. LA induced translocation of Nrf-2. Furthermore, an inhibitor of JNK MAPK abolished LA-induced HO-1 expression. LA exposure up-regulated the levels of phosphorylated adenosine monophosphate-activated protein kinase (AMPK) and its upstream kinase activators, including LKB1 and Ca2+/calmodulin-dependent protein kinase kinase-II. Furthermore, compound C, a specific AMPK inhibitor, partially blocked the LA-induced anti-inflammatory effect. Taken together, these results indicate that LA has anti-inflammatory activity in HPDL cells that might be mediated by the HO-1, AMPK, JNK MAPK, and Nrf-2 pathways. Thus, LA may serve as a potential therapeutic agent in periodontal disease.

Asperlin from the marine-derived fungus Aspergillus sp. SF-5044 exerts anti-inflammatory effects through heme oxygenase-1 expression in murine macrophages

Asperlin is a fungal metabolite isolated from Aspergillus sp. SF-5044. In the present study, we isolated asperlin from the marine-derived fungus Aspergillus sp. SF-5044 and demonstrated that it inhibited inducible nitric oxide synthase (iNOS) expression, reduced iNOS-derived NO, suppressed cyclooxygenase (COX)-2 expression, and reduced COX-derived prostaglandin (PG) E₂ production in lipopolysaccharide (LPS)-stimulated RAW264.7 and murine peritoneal macrophages. Similarly, asperlin reduced the production of tumor necrosis factor (TNF)-α and interleukin (IL)-1β. In addition, asperlin inhibited the phosphorylation and degradation of IκB-α, as well as the nuclear translocation of p65 caused by the stimulation of LPS in RAW264.7 macrophages. Furthermore, asperlin induced heme oxygenase (HO)-1 expression through nuclear translocation of nuclear factor E2-related factor 2 and increased HO activity in RAW264.7 macrophages. The effects of asperlin on the LPS-induced expression of iNOS and COX-2 and production of NO, PGE₂, TNF-α, and IL-1β were partially reversed by a HO-1 inhibitor, tin protoporphyrin. These findings suggest that asperlin-induced HO-1 expression plays a role in the anti-inflammatory effects of asperlin in macrophages.

Fumaric acid esters exert neuroprotective effects in neuroinflammation via activation of the Nrf2 antioxidant pathway

Inflammation and oxidative stress are thought to promote tissue damage in multiple sclerosis. Thus, novel therapeutics enhancing cellular resistance to free radicals could prove useful for multiple sclerosis treatment. BG00012 is an oral formulation of dimethylfumarate. In a phase II multiple sclerosis trial, BG00012 demonstrated beneficial effects on relapse rate and magnetic resonance imaging markers indicative of inflammation as well as axonal destruction. First we have studied effects of dimethylfumarate on the disease course, central nervous system, tissue integrity and the molecular mechanism of action in an animal model of chronic multiple sclerosis: myelin oligodendrocyte glycoprotein induced experimental autoimmune encephalomyelitis in C57BL/6 mice. In the chronic phase of experimental autoimmune encephalomyelitis, preventive or therapeutic application of dimethylfumarate ameliorated the disease course and improved preservation of myelin, axons and neurons. In vitro, the application of fumarates increased murine neuronal survival and protected human or rodent astrocytes against oxidative stress. Application of dimethylfumarate led to stabilization of the transcription factor nuclear factor (erythroid-derived 2)-related factor 2, activation of nuclear factor (erythroid-derived 2)-related factor 2-dependent transcriptional activity and accumulation of NADP(H) quinoline oxidoreductase-1 as a prototypical target gene. Furthermore, the immediate metabolite of dimethylfumarate, monomethylfumarate, leads to direct modification of the inhibitor of nuclear factor (erythroid-derived 2)-related factor 2, Kelch-like ECH-associated protein 1, at cysteine residue 151. In turn, increased levels of nuclear factor (erythroid-derived 2)-related factor 2 and reduced protein nitrosylation were detected in the central nervous sytem of dimethylfumarate-treated mice. Nuclear factor (erythroid-derived 2)-related factor 2 was also upregulated in the spinal cord of autopsy specimens from untreated patients with multiple sclerosis. In dimethylfumarate-treated mice suffering from experimental autoimmune encephalomyelitis, increased immunoreactivity for nuclear factor (erythroid-derived 2)-related factor 2 was detected by confocal microscopy in neurons of the motor cortex and the brainstem as well as in oligodendrocytes and astrocytes. In mice deficient for nuclear factor (erythroid-derived 2)-related factor 2 on the same genetic background, the dimethylfumarate mediated beneficial effects on clinical course, axon preservation and astrocyte activation were almost completely abolished thus proving the functional relevance of this transcription factor for the neuroprotective mechanism of action. We conclude that the ability of dimethylfumarate to activate nuclear factor (erythroid-derived 2)-related factor 2 may offer a novel cytoprotective modality that further augments the natural antioxidant responses in multiple sclerosis tissue and is not yet targeted by other multiple sclerosis therapies.