Jang-Gi Choi

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.

Luteolin Isolated from the Flowers of Lonicera japonica Suppresses Inflammatory Mediator Release by Blocking NF-κB and MAPKs Activation Pathways in HMC-1 Cells

Luteolin (3′,4′,5,7-tetrahydroxylflavone) is a plant flavonoid and pharmacologically active agent that has been isolated from several plant species. In the present study, the effect of luteolin from the flowers of Lonicera japonica on phorbol 12-myristate 13-acetate (PMA) plus A23187-induced mast cell activation was examined. Luteolin significantly inhibited the induction of inflammatory cytokines such as tumor necrosis factor (TNF)-α, interleukin (IL)-8, IL-6 and granulocyte-macrophage colony-stimulating factor (GM-CSF) by PMA plus A23187. Moreover, luteolin attenuated cyclooxygenase (COX)-2 expression and intracellular Ca2+ levels. In activated HMC-1 cells, the phosphorylation of extra-signal response kinase (ERK 1/2) and c-jun N-terminal Kinase (JNK 1/2), but not p38 mitogen-activated protein kinase (p38 MAPK) were decreased by treatment of the cells with luteolin. Luteolin inhibited PMA plus A23187-induced nuclear factor (NF)-κB activation, IκB degradation, and luciferase activity. Furthermore, luteolin suppressed the expression of TNF-α, IL-8, IL-6, GM-CSF, and COX-2 through a decrease in the intracellular Ca2+ levels, and also showed a suppression of the ERK 1/2, JNK 1/2, and NF-κB activation. These results indicated that luteolin from the flowers of Lonicera japonica exerted a regulatory effect on mast cell-mediated inflammatory diseases, such as RA, allergy disease and IBD.

Antibacterial Activity of Methyl Gallate Isolated from Galla Rhois or Carvacrol Combined with Nalidixic Acid Against Nalidixic Acid Resistant Bacteria

Methyl gallate is a major component of Galla Rhois, as carvacrol is of oregano essential oils. Both have shown good antibacterial activity against intestinal bacteria. This study investigated the antibacterial activities of nalidixic acid in combination with methyl gallate and carvacrol against nalidixic acid resistant bacteria. The combined effect of nalidixic acid with methyl gallate and carvacrol was evaluated using the checkerboard method to obtain a fractional inhibitory concentration index. The results showed that the combinations of nalidixic acid + methyl gallate/carvacrol improved nalidixic acid resistant pathogenic bacteria inhibition with synergy or partial synergy activity. Thus, a strong bactericidal effect of the drug combinations was observed. In vitro data thus suggested that nalidixic acid combined with methyl gallate and carvacrol may be microbiologically beneficial, rather than antagonists.

In Vitro and In Vivo Antibacterial Activity of Punica granatum Peel Ethanol Extract against Salmonella.

Punica granatum is commonly used in Korea as a traditional medicine for the treatment of pathogenic bacteria. In this study, we investigated the in vitro and in vivo antimicrobial activity of P. granatum peel EtOH extract (PGPE) against 16 strains of Salmonella. The minimal inhibitory concentrations of PGPE were in the range of 62.5–1000 x03BCg mL−1. In addition, the in vivo antibacterial activity of the PGPE extract was examined in a S. typhimurium infection mouse model. Mice were initially infected with S. typhimurium and then with PGPE. The extract was found to have significant effects on mortality and the numbers of viable S. typhimurium recovered from feces. Although clinical signs and histological damage were rarely observed in the treated mice, the untreated controls showed signs of lethargy and histological damage in the liver and spleen. Taken together, the results of this study indicate that PGPE has the potential to provide an effective treatment for salmonellosis.

Synergistic effects of the combination of galangin with gentamicin against methicillin-resistant Staphylococcus aureus

The antimicrobial killing activity toward methicillin-resistant Staphylococcus aureus (MRSA) has been a serious emerging global issue. New effective antimicrobials and/or new approaches to settle this issue are urgently needed. The oriental herb, Alpinia officinarum, has been used in Korea for several hundreds of years to treat various infectious diseases. As it is well known, one of the active constituents of Alpinia officinarum is galangin. Against the 17 strains, the minimum inhibitory concentrations (MICs) of galangin (GAL) were in the range of 62.5∼125 μg/ml, and the MICs of gentamicin (GEN) ranged from 1.9 μg/ml to 2,000 μg/ml. The fractional inhibitory concentrations (FICs) of GAL, in combination with GEN, against 3 test strains were 0.4, 3.9, and 250 μg/ml, and were all 15.62 μg/ml in GEN. The FIC index showed marked synergism in the value range of 0.19 to 0.25. By determining time-kill curves, also confirmed the low synergism of the GAL and GEN combination against 4 h, 8 h, 12 h, and 24 h cultured MRSA. The time-kill study results indicated a low synergistic effect against 3 test strains. Thus, the mixture of GAL and GEN could lead to the development of new combination antibiotics against MRSA infection.

Antibacterial activity of Ecklonia cava against methicillin-resistant Staphylococcus aureus and Salmonella spp.

Ecklonia cava is a brown alga (Laminariales, Phaeophyta) growing on the subtidal rocky shores of Korea. It has antioxidant, antidiarrhea, and anticoagulant effects. In this study, the antimicrobial activity of E. cava EtOH extract and its fractions (n-hexane, CH2Cl2, EtOAc, n-BuOH, and H2O) were investigated against methicillin-resistant Staphylococcus aureus and Salmonella spp. The E. cava EtOAc fraction showed good antibacterial activity against all bacteria. Eckol isolated from E. cava EtOAc fraction showed antimicrobial activity against all the tested strains. The minimum inhibitory concentration of eckol against S. aureus strains ranged from 125 to 250 microg/mL and 125 to 250 microg/mL for Salmonella strains. The fraction inhibitory concentration index of eckol in combination with ampicillin ranged from 0.31 to 0.5, indicating remarkable synergism against S. aureus. However, against Salmonella gallinarum ATCC 9184 and Salmonella typhimurium, it ranges from 0.75 to 1.0. The combinations of eckol + ampicillin exhibited improved inhibition of S. aureus and Salmonella with synergy or additive effect. We suggest that eckol ingredients of the E. cava against S. aureus and Salmonella have antibacterial activity.

Inhibition of LPS-Induced iNOS, COX-2 and Inflammatory Mediator Expression by Paeonol through the MAPKs Inactivation in RAW 264.7 Cells

We evaluated the in vivo anti-inflammatory and analgesic activities of orally administered paeonol in mice, and also investigated the anti-inflammatory activity of paeonol in a cell line. Paeonol significantly reduced the edema induced by arachidonic acid in rats. The analgesic effects were assayed using 2 different models, i.e., by acetic acid-induced writhing response and by formalin induced licking and biting time. Moreover, we examined the effects of paeonol on the release of inflammatory mediators such as NO, PGE(2) and IL-6. Our results demonstrated that paeonol inhibited LPS induced expression of NO, PGE(2) and IL-6. Paeonol prevented LPS induced iNOS, COX-2 and ERK activation. Therefore, paeonol appears to have potential as a treatment for inflammatory disease and analgesic.

Anti-Inflammatory Effect of Resveratrol by Inhibition of IL-8 Production in LPS-Induced THP-1 Cells

Resveratrol is a polyphenol compound and prominent anti-inflammatory agent found in plants, including the fruits of Morus alba. However, the therapeutic mechanisms of resveratrol remain largely unclear. To gain insight into the biological effects of resveratrol, we examined its influence on LPS-induced IL-8 production in the human monocytic cell line, THP-1. In inflammatory diseases, IL-8 plays a central role in the initiation and maintenance of inflammatory response. In the present study, IL-8 production was measured by ELISA and RT-PCR, while MAPK activation, IkappaBalpha degradation, nuclear factor (NF)-kappaB activation and cyclooxygenase (COX)-2 expression were determined by Western blot analysis. Resveratrol inhibited LPS-induced IL-8 production in a dose-dependent manner. Furthermore, resveratrol inhibited extracellular signal-regulated kinase (ERK) and p38 MAPK phosphorylation, IkappaBalpha degradation, NF-kappaB activation and cyclooxygenase (COX)-2 expression, which suggest that resveratrol inhibits IL-8 secretion by blocking MAPK phosphorylation and NF-kappaB activation. Taken together, these findings may help elucidate the mechanism by which resveratrol modulates THP-1 cell activation under inflammatory conditions.

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.

Synergistic effect of emodin in combination with ampicillin or oxacillin against methicillin-resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) is a substantial contributor to morbidity and mortality. In search of a natural products capable of inhibiting this multidrug resistant bacteria, we have investigated the antimicrobial activity of emodin (EM) isolated from Rheum palmatum L. (Polygonaceae) against 17 different strains of the bacterium. New antimicrobial activity was found using the paper disc diffusion method, agar dilution as well as checkerboard method. Against the 17 strains, the disc diffusion test was in the range of 18–30 mm, and the minimum inhibitory concentrations (MICs) of EM were in the range of 1.5–25 μg/mL. From those results we performed the checkerboard test to determine the synergism of EM in combination with ampicillin (AM) or oxacillin (OX) against all strains. The combined activity of EM and two antimicrobial agents (AM, OX) against all strains resulted in a fractional inhibitory concentrations index (FICI) ranging from 0.37–0.5 and from 0.37–0.75, respectively. The effect of EM with AM and OX was found to be synergistic or partially synergistic. We found that EM reduced the MICs of AM and OX. EM and in combination with AM or OX could lead to the development of new combination antibiotics against MRSA infection.