Youn Chul Kim

Anti-inflammatory mechanisms of resveratrol in activated HMC-1 cells: pivotal roles of NF-κB and MAPK.

Resveratrol is a phytoalexin polyphenolic compound found in various plants, including grapes, berries, and peanuts. Recently, studies have documented various health benefits of resveratrol including cardiovascular and cancer-chemopreventive properties. The aim of the present study was to demonstrate the effects of resveratrol on the expression of pro-inflammatory cytokines, as well as to elucidate its mechanism of action in the human mast cell line (HMC-1). Cells were stimulated with phorbol 12-myristate 13-acetate (PMA) plus A23187 in the presence or absence of resveratrol. To study the possible effects of resveratrol, ELISA, RT-PCR, real-time RT-PCR, Western blot analysis, fluorescence, and luciferase activity assays were used in this study. Resveratrol significantly inhibited the PMA plus A23187-induction of inflammatory cytokines such as tumour necrosis factor (TNF)-alpha, interleukin (IL)-6 and IL-8. Moreover, resveratrol attenuated cyclooxygenase (COX)-2 expression and intracellular Ca2+ levels. In activated HMC-1 cells, phosphorylation of extra-signal response kinase (ERK) 1/2 decreased after treatment with resveratrol. Resveratrol inhibited PMA plus A23187-induced nuclear factor (NF)-kappaB activation, IkappaB degradation, and luciferase activity. Resveratrol suppressed the expression of TNF-alpha, IL-6, IL-8 and COX-2 through a decrease in the intracellular levels of Ca2+ and ERK 1/2, as well as activation of NF-kappaB. These results indicated that resveratrol exerted a regulatory effect on inflammatory reactions mediated by mast cells.

Hepatoprotective constituents of the edible brown alga Ecklonia stolonifera on tacrine-induced cytotoxicity in Hep G2 cells

In this study, ethanolic extracts from 18 seaweed variants were assessed for hepatoprotective activity against tacrine-induced cytotoxicity in Hep G2 cells. Only one of these,Ecklonia stolonifera Okamura (Laminariaceae), a member of the brown algae, exhibited promising hepatoprotective activity. Bioassay-guided fractionation of the active ethyl acetate (EtOAc) soluble fraction obtained from the ethanolic extract ofE. stolonifera, resulted in the isolation of several phlorotannins [phloroglucinol (1), eckstolonol (2), eckol (3), phlorofucofuroeckol A (4), and dieckol (5)]. Compounds 2 and 4 were determined to protect Hep G2 cells against the cytotoxic effects of tacrine, with EC50 values of 62.0 and 79.2 μg/mL, respectively. Silybin, a well characterized hepatoprotective agent, was used as a positive control, and exhibited an EC50 value of 50.0 μg/mL. It has been suggested that the phlorotannins derived from marine brown algae might prove useful sources in the development of novel hepatoprotective agents.

Anti-Nociceptive and Anti-Inflammatory Effects of Angelicae Dahuricae Radix Through Inhibition of the Expression of Inducible Nitric Oxide Synthase and NO Production

The extract of Angelicae dahuricae radix has traditionally been used as an anti-noceptive remedy in China. In this study, the methanol extract of Angelicae dahuricae radix (MEAD) was evaluated to determine if it has anti-noceptive and anti-inflammatory action. The anti-nociceptive activities of MEAD were evaluated by determining the writhing response and sleeping time, as well as by a formalin test. In addition, the anti-inflammatory activities of MEAD were evaluated by a vascular permeability test as well as by measuring the carrageenan-induced paw edema and conducting a myeloperoxidase (MPO) assay. MEAD (600 and 1200 mg/kg) exhibited anti-inflammatory effects on acetic acid-induced vascular permeability, carrageenan-induced paw edema, and MPO activity. Moreover, the results of the formalin test, the acetic acid-induced writhing response and the pentobarbital-induced sleeping time indicated that MEAD had anti-nociceptive effects that occurred in a concentration-dependent manner. To determine the mechanism by which MEAD exerted its effects on the expression of inducible nitric oxide synthase (iNOS) and the production of nitric oxide (NO) by treated murine macrophage RAW 264.7 cells was evaluated. Similar to the in vivo activities, both the iNOS expression and NO production were significantly suppressed by MEAD in a dose-dependent manner. Furthermore, MEAD inhibited the activating phosphorylation of ERK1/2. These results provide a scientific basis that explains the mechanism by which Angelicae dahuricae radix relieves inflammatory pain.

Alaternin and emodin with hydroxyl radical inhibitory and/or scavenging activities and hepatoprotective activity on tacrine-induced cytotoxicity in HepG2 cells.

The antioxidative and hepatoprotective potentials of two anthraquinones, alaternin (2-hydroxy-emodin) and emodin, to scavenge and/or inhibit hydroxyl radicals generated by the Fenton reaction and to protect tacrine-induced cytotoxicity in human liver derived HepG2 cells were evaluated, respectively. The inhibitory activity on hydroxyl radical generated in a cell-free chemical system (FeSO4/H2O2) was investigated by a fluorescence spectrophotometer using a highly fluorescent probe, 2′,7′-dichlorofluorescein. The hydroxyl radical scavenging activity was determined by electron spin resonance spectroscopy using 5,5-dimethy-1-pyrroline-/V-oxide as hydroxyl radicals trapping agents. Tacrine-induced HepG2 cell toxicity was determined by a 3-[4,5-dimethylthiazole-2yl]-2,5-diphenyltertrazolium bromide assay. Although the scavenging activity of alaternin on hydroxyl radical was similar to that of emodin in dose-dependent patterns, the inhibitory activity exhibited by the former on hydroxyl radical generation was stronger than that of the latter, with IC50 values of 3.05 ± 0.26 μM and 13.29 ± 3.20 μM, respectively. In addition, the two anthraquinones, alaternin and emodin showed their hepatoprotective activities on tacrine-induced cytotoxicity, and the EC50 values were 4.02 μM and 2.37 μM, respectively. Silymarin, an antihepatotoxic agent used as a positive control exhibited the EC50 value of 2.00 μM. These results demonstrated that both alaternin and emodin had the simultaneous antioxidant and hepatoprotective activities.

The Cytoprotective Effect of Sulfuretin against tert-Butyl Hydroperoxide-Induced Hepatotoxicity through Nrf2/ARE and JNK/ERK MAPK-Mediated Heme Oxygenase-1 Expression

Sulfuretin is one of the major flavonoid components in Rhus verniciflua Stokes (Anacardiaceae) isolates. In this study, we investigated the protective effects of sulfuretin against tert-butyl hydroperoxide (t-BHP)-induced oxidative injury. The results indicated that the addition of sulfuretin before t-BHP treatment significantly inhibited cytotoxicity and reactive oxygen species (ROS) production in human liver-derived HepG2 cells. Sulfuretin up-regulated the activity of the antioxidant enzyme heme oxygenase (HO)-1 via nuclear factor E2-related factor 2 (Nrf2) translocation into the nucleus and increased the promoter activity of the antioxidant response element (ARE). Moreover, sulfuretin exposure enhanced the phosphorylation of c-Jun N-terminal kinase (JNK) and extracellular signal-regulated kinase 1/2 (ERK1/2), which are members of the mitogen-activated protein kinase (MAPK) family. Furthermore, cell treatment with a JNK inhibitor (SP600125) and ERK inhibitor (PD98059) reduced sulfuretin-induced HO-1 expression and decreased its protective effects. Taken together, these results suggest that the protective effect of sulfuretin against t-BHP-induced oxidative damage in human liver-derived HepG2 cells is attributable to its ability to scavenge ROS and up-regulate the activity of HO-1 through the Nrf2/ARE and JNK/ERK signaling pathways. Therefore, sulfuretin could be advantageous as a bioactive source for the prevention of oxidative injury.

Effects of Poncirus trifoliata on Type I Hypersensitivity Reaction

A study was carried out to examine the effect of an aqueous extract from immature fruit of Poncirus trifoliata L. (Rutaceae) (PTIFE) on the type I hypersensitivity reaction. Forty-eight hour PCA (passive cutaneous anaphylaxis) in rats was significantly inhibited by the oral administration of PTIFE (200 mg/kg). It also inhibited histamine release from rat peritoneal mast cells (RPMC) induced by mouse anti-dinitrophenyl (DNP)-IgE and dinitrophenyl-human serum albumin (DNP-HSA). These results suggest that PTIFE has anti-allergic action against the type I hypersensitivity reaction.

Vascular Protective Role of Vitexicarpin Isolated from Vitex rotundifolia in Human Umbilical Vein Endothelial Cells

Pro-inflammatory cytokines induce injury of endothelial cells caused by increases of adhesion molecules, leading to vascular inflammation and the development of atherosclerosis. Recent pharmacological studies have demonstrated that vitexicarpin, a flavonoid isolated from Vitex rotundifolia, has anti-inflammatory, antitumor, and analgesic properties. In this study, we investigated whether vitexicarpin (5–100xa0nM) prevented the TNF-α-induced vascular inflammation process in human umbilical vein endothelial cells (HUVEC). We found that pretreatment with vitexicarpin decreased TNF-α (10xa0ng/ml)-induced expression of cell adhesion molecules such as vascular cell adhesion molecule-1, intracellular adhesion molecule-1, and E-selectin as well as matrix metalloproteinase-2 and -9 expression. Preincubation with vitexicarpin also dose-dependently inhibited TNF-α-induced adhesion of HL-60 monocytic cells. Vitexicarpin significantly decreased TNF-α-induced intracellular reactive oxygen species (ROS) production. Furthermore, vitexicarpin suppressed NF-κB nuclear translocation and transcriptional activity in TNF-α-treated HUVEC. In conclusion, vitexicarpin significantly reduced vascular inflammation, through inhibition of ROS–NF-κB pathway in vascular endothelial cells.

Toll‐like receptor 4‐mediated immunoregulation by the aqueous extract of Mori Fructus

The aqueous extract of Mori Fructus (MF) exerts a change of phenotype and a cytoprotective effect in macrophages. The present study was carried out to investigate the immunomodulating activity of MF on the expression of nitric oxide (NO), tumor necrosis factor alpha (TNF‐α), co‐stimulatory molecules and also interferon‐gamma (IFN‐γ) in macrophages and splenocytes. Toll‐like receptor 4 (TLR4) is a promising molecular target for immune‐modulating drugs. It was hypothesized that one possible upstream signaling pathway leading to immunoregulation of MF may be mediated by TLRs. Multiple signaling molecules (NF‐κB, ERK1/2, p38 and JNK) of the TLR4 signaling pathway were also detected. It was found that MF increased NO production and TNF‐α secretion in RAW 264.7 and peritoneal macrophages, co‐stimulatory molecules expression in peritoneal macrophages and IFN‐γ expression in splenocytes. Further studies indicated that MF could significantly induce the phosphorylation of signal molecules of MAPKs and the degradation of IκBα which finally led to the activation and nuclear translocation of nuclear factor‐κB (NF‐κB) for the target gene expression. All those notions disclosed that the aqueous extract MF is a new TLR4 activator, which induces a Th1 immune response as a consequence of induction of cytokines secretion, especially TNF‐α and IFN‐γ. Copyright

Chemical constituents of Miliusa balansae leaves and inhibition of nitric oxide production in lipopolysaccharide-induced RAW 264.7 cells.

Methanolic extract of Miliusa balansae Finet et Gagnep exerts an anti-inflammatory effect via inhibition of nitric oxide (NO) production in lipopolysaccharide (LPS)-stimulated murine RAW 264.7 macrophage cells. Three new megastigmane glycosides, milbasides A-C (1-3), together with fifteen known compounds (4-18), were isolated from the active fraction. Their chemical structures were elucidated using extensive spectroscopic analyses, including 1D and 2D NMR, HR ESI MS, and CD analysis, as well as comparison with previously reported data. Compounds 1-3, 11 and 14 (20.0 μM) showed potent inhibitory activities with inhibition values of 98.5 ± 1.6%, 90.9 ± 7.8%, 84.8 ± 3.5%, 91.5 ± 8.7%, and 91.8 ± 2.7%, respectively. Our results suggest that megastigmane glycosides from M. balansae leaves may be used to treat inflammatory diseases.

Sauchinone from Saururus chinensis protects vascular inflammation by heme oxygenase-1 induction in human umbilical vein endothelial cells.

Sauchinone, a diastereomeric lignan isolated from the roots of Saururus chinensis (LOUR.) BAILL. (Saururaceae), is reported to exert a variety of biological activities such as hepatoprotective, anti-inflammatory actions and inhibitory effects on bone resorption. In this study, we investigated the effect of sauchinone in suppressing cell adhesion molecules such as vascular cell adhesion molecule-1 (VCAM-1) and intracellular adhesion molecule-1 (ICAM-1) expression in high glucose stimulated human umbilical vein endothelial cells (HUVEC). Sauchinone inhibited the phosphorylation and degradation of IκB-α, as well as the nuclear translocation of nuclear factor kappa B (NF-κB) p65 caused by the stimulation of high glucose. In addition, sauchinone induced heme oxygenase (HO)-1 expression through nuclear translocation of nuclear factor E2-related factor 2 in HUVEC. The effects of sauchinone on the high glucose-induced expression of VCAM-1 and ICAM-1 and nuclear translocation of NF-κB p65 were partially reversed by transfection of the cells with HO-1 siRNA. These findings suggest that sauchinone-induced HO-1 expression plays a key role in the vascular protective effects of sauchinone in HUVEC.