Kil-Nam Kim

Evaluation of anti-inflammatory effect of fucoxanthin isolated from brown algae in lipopolysaccharide-stimulated RAW 264.7 macrophages.

In this study, potential anti-inflammatory effect of fucoxanthin isolated from brown algae was assessed via inhibitory effect of nitric oxide (NO) production in lipopolysaccharide (LPS) induced RAW 264.7 macrophage cells. The Myagropsis myagroides was selected for further experiments due to its profound NO inhibitory effect, and was partitioned with different organic solvents. Highest NO inhibitory effect was detected in the chloroform fraction, and the active compound was identified as fucoxanthin, a kind of carotenoid available in brown algae evidenced high correlation with the inhibitory effect of NO production (r(2)=0.9511). Though, fucoxanthin significantly inhibited the NO production, it slightly reduced the prostaglandin E(2) (PGE(2)) production. The inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX-2) protein expressions were inhibited by fucoxanthin. Further, RT-PCR analysis indicated that the iNOS and COX-2 mRNA expressions were suppressed by fucoxanthin. Moreover, the release of tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), and interleukin-6 (IL-6), and the mRNA expression levels of those cytokines were reduced by the addition of fucoxanthin in a dose-dependent manner. Hence, these results suggest that the use of fucoxanthin may be a useful therapeutic approach for the various inflammatory diseases.

Fucoxanthin inhibits the inflammatory response by suppressing the activation of NF-κB and MAPKs in lipopolysaccharide-induced RAW 264.7 macrophages

It has been previously determined that pro-inflammatory mediators including nitric oxide (NO), prostaglandin E₂ (PGE₂), tumor necrosis factor (TNF)-α, and interleukin (IL)-1β and IL-6 contribute to the courses of a variety of inflammatory diseases. In this study, we evaluated the anti-inflammatory effects of fucoxanthin (FX), a natural biologically active substance isolated from Ishige okamurae, by determining its inhibitory effects on pro-inflammatory mediators in lipopolysaccharide (LPS)-stimulated murine macrophage RAW 264.7 cells. FX induced dose-dependent reductions in the levels of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) proteins and concomitant reductions in the production of NO and PGE₂. Additionally, FX was shown to suppress the production of inflammatory cytokines including IL-1β, TNF-α, and IL-6. Furthermore, FX inhibited the cytoplasmic degradation of inhibitors of B (IκB)-α and the nuclear translocation of p50 and p65 proteins, resulting in lower levels of nuclear factor (NF)-κB transactivation. Additionally, FX was shown to induce a dose-dependent inhibition of the phosphorylation of mitogen-activated protein kinases (MAPKs; JNK, ERK and p38). Collectively, the results of this study demonstrate that FX reduces the levels of pro-inflammatory mediators including NO, PGE₂, IL-1β, TNF-α, and IL-6 via the inhibition of NF-κB activation and the suppression of MAPK phosphorylation in RAW 264.7 cells. These findings reveal, in part, the molecular basis underlying the anti-inflammatory properties of FX.

Fucoxanthin induces apoptosis in human leukemia HL-60 cells through a ROS-mediated Bcl-xL pathway.

Fucoxanthin, a natural biologically active substance isolated from Ishige okamurae, evidences antitumor activity in human leukemia cell HL-60 cells via the induction of apoptosis. However, the mechanism underlying fucoxanthin-induced apoptosis in HL-60 cells remains unclear. In this study, we focused on the effect of fucoxanthin induction on the accumulation of reactive oxygen species (ROS), and on the triggering of Bcl-xL signaling pathway in HL-60 cells. We determined that ROS are generated during fucoxanthin-induced cytotoxicity and apoptosis in HL-60 cells, and that N-acetylcysteine (NAC), a ROS scavenger, suppressed fucoxanthin-induced cytotoxicity and apoptosis. Moreover, fucoxanthin-induced the cleavage of caspases -3 and -7, and poly-ADP-ribose polymerase (PARP) and a decrease of Bcl-xL levels, whereas NAC pre-treatment significantly inhibited caspase-3, -7, and PARP cleavage and the reduction in Bcl-xL levels. In this study, it was demonstrated for the first time that fucoxanthin generated ROS and that the accumulation of ROS performed a crucial role in the fucoxanthin-induced Bcl-xL signaling pathway.

Inhibition of tumor growth in vitro and in vivo by fucoxanthin against melanoma B16F10 cells.

The present study was designed to evaluate the molecular mechanisms of fucoxanthin against melanoma cell lines (B16F10 cells). Fucoxanthin reduced the proliferation of B16F10 cells in a dose-dependent manner accompanied by the induction of cell cycle arrest during the G(0)/G(1) phase and apoptosis. Fucoxanthin-induced G(0)/G(1) arrest was associated with a marked decrease in the protein expressions of phosphorylated-Rb (retinoblastoma protein), cyclin D (1 and 2) and cyclin-dependent kinase (CDK) 4 and up-regulation of the protein levels of p15(INK4B) and p27(Kip1). Fucoxanthin-induced apoptosis was accompanied with the down-regulation of the protein levels of Bcl-xL, an inhibitor of apoptosis proteins (IAPs), resulting in a sequential activation of caspase-9, caspase-3, and PARP. Furthermore, the anti-tumor effect of fucoxanthin was assessed in vivo in Balb/c mice. Intraperitoneal administration of fucoxanthin significantly inhibited the growth of tumor mass in B16F10 cells implanted mice.

Anti-inflammatory effect of essential oil and its constituents from fingered citron (Citrus medica L. var. sarcodactylis) through blocking JNK, ERK and NF-κB signaling pathways in LPS-activated RAW 264.7 cells

We investigated the composition of essential oil from fingered citron (Citrus medica L. var. sarcodactylis) (FCEO) peels by GC-MS and its anti-inflammatory effects on lipopolysaccharide (LPS) - stimulated mouse macrophage (RAW 264.7) cells. Fifteen compounds, representing 98.97% of the essential oil, were tentatively identified; the main constituents were limonene (52.44%) and γ-terpinene (28.41%). FCEO significantly inhibited nitric oxide (NO) and prostaglandin E2 (PGE2) by suppressing the protein expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX)-2, respectively. Additionally, FCEO suppressed the production of tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, and IL-6. FCEO attenuated LPS-induced nuclear factor-κB (NF-κB) activation via inhibition of inhibitor κB-α phosphorylation. Furthermore, FCEO blocked activation of c-Jun N-terminal kinase (JNK) and extracellular signal-regulated kinase (ERK) but not that of p38 mitogen-activated protein kinase. These results indicate that FCEO inhibits LPS-stimulated inflammation by blocking the NF-κB, JNK, and ERK pathways in macrophages, and demonstrate that FCEO possesses anti-inflammatory properties.

Molecular docking studies of a phlorotannin, dieckol isolated from Ecklonia cava with tyrosinase inhibitory activity

In this study, the phlorotannin dieckol, which was isolated from the brown alga Ecklonia cava, was examined for its inhibitory effects on melanin synthesis. Tyrosinase inhibitors are important agents for cosmetic products. We therefore examined the inhibitory effects of dieckol on mushroom tyrosinase and melanin synthesis, and analyzed its binding modes using the crystal structure of Bacillus megaterium tyrosinase (PDB ID: 3NM8). Dieckol inhibited mushroom tyrosinase with an IC(50) of 20μM and was more effective as a cellular tyrosinase having melanin reducing activities than the commercial inhibitor, arbutin, in B16F10 melanoma cells, and without apparent cytotoxicity. It was found that dieckol behaved as a non-competitive inhibitor with l-tyrosine substrates. For further insight, we predicted the 3D structure of tyrosinase and used a docking algorithm to simulate binding between tyrosinase and dieckol. These molecular modeling studies were successful (calculated binding energy value: -126.12kcal/mol), and indicated that dieckol interacts with His208, Met215, and Gly46. These results suggest that dieckol has great potential to be further developed as a pharmaceutical or cosmetic agent for use in dermatological disorders associated with melanin.

Chromene induces apoptosis via caspase-3 activation in human leukemia HL-60 cells

In this study, the potent anti-tumor effects of brown algae on human leukemia HL-60 cells were investigated. The Sargassum siliquastrum extract among the 14 species of brown algae exhibited profound growth inhibitory effect on HL-60 cells in the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, therefore, S. siliquastrum was selected for use in further experiments. The highest inhibitory activity of S. siliquastrum on HL-60 cells was detected in the chloroform fraction, and the active compound was identified as a kind of chromene, sargachromanol E (SE). SE treatment showed significant growth inhibitory effects on HL-60 cells in a dose-dependent manner by inducing apoptosis, as evidenced by the formation of apoptotic bodies, fragmented DNA ladder, and the accumulation of DNA in the sub-G(1) phase of cell cycle. SE induced apoptosis was accompanied by downregulation of Bcl-xL, upregulation of Bax, activation of caspase-3, and cleavage of poly (ADP-ribose) polymerase (PARP). Moreover, z-DEVD-fmk, a caspase-3 inhibitor, significantly inhibited cell cytotoxicity, apoptotic characteristics such as apoptotic bodies, sub-G(1) DNA content, and cleavage of PARP induced by SE. These results suggest that SE exerts its growth inhibitory effects on HL-60 cells through caspase-3-mediated induction of apoptosis. Therefore, SE offers promising chemotherapeuric potential to prevent cancers such as human leukemia.

Quercitrin protects against ultraviolet B-induced cell death in vitro and in an in vivo zebrafish model

Chronic exposure of skin to ultraviolet (UV) B radiation induces oxidative stress, which in turn, plays a crucial role in the induction of skin aging. The search for strategies to reverse skin aging is being constantly pursued. Here, the cytoprotective effect of quercitrin (QR) on UVB-induced cell injury in HaCaT human keratinocytes and in the zebrafish was investigated. Intracellular reactive oxygen species (ROS) generated by the exposure of HaCaT cells to UVB radiation were significantly decreased after treatment with QR, and significantly so with QR at 50 μM. As a result, QR reduced UVB-induced cell death and apoptosis in HaCaT cells. QR similarly reduced UVB-induced ROS generation and cell death in live zebrafish.

Anti-inflammatory effects of trans-1,3-diphenyl-2,3-epoxypropane-1-one mediated by suppression of inflammatory mediators in LPS-stimulated RAW 264.7 macrophages

To assess the potential therapeutic properties of trans-1,3-diphenyl-2,3-epoxypropane-1-one (DPEP), its anti-inflammatory effects were investigated in lipopolysaccharide (LPS)-stimulated mouse macrophage (RAW 264.7) cells. DPEP induced dose-dependent reduction of the protein levels of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) and concomitant reduction in the production of NO and prostaglandin E(2) (PGE(2)). Additionally, DPEP suppressed the production of inflammatory cytokines, including tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, and IL-6. We investigated the mechanism by which DPEP inhibits NO and PGE(2) by examining the level of nuclear factor-κB (NF-κB) activation within the mitogen-activated protein kinase (MAPK) pathway, which is an inflammation-induced signaling pathway in RAW 264.7 cells. DPEP inhibited LPS-induced phosphorylation of ERK, JNK, and p38. Furthermore, DPEP inhibited the LPS-induced phosphorylation of inhibitor κB (IκB)-α and NF-κB p50. Taken together, the results of this study demonstrate that DPEP inhibits LPS-stimulated inflammation by blocking the NF-κB and MAPK pathways in macrophages.

Hepatoprotective effects of dieckol-rich phlorotannins from Ecklonia cava, a brown seaweed, against ethanol induced liver damage in BALB/c mice

Alcoholic liver disease, which is one of the most serious liver disorders, has been known to cause by ethanol intake. In the present study, in vivo hepatoprotective effects of dieckol-rich phlorotannins (DRP) from Ecklonia cava, a brown seaweed, on ethanol induced hepatic damage in BALB/c mice liver were investigated. After administration of 5 and 25mg/kg mouse of DRP and 4 g/kg mice ethanol, the body weights and survival rates were increased as compared to the control, which is ethanol-treated group without DRP. The glutamic oxaloacetic transaminase and glutamic pyruvic transaminase levels in the serum were lower than those of the control. DRP exhibited a reduction of the total cholesterol. The lower levels of SOD enzyme and a reduction of the formation of malondialdehyde were occurred in mice fed with 5 and 25mg/kg mouse of DRP. Finally the effect on improvement of fatty liver induced by ethanol was observed by taking out the liver immediately after dissecting the mouse. However, no significant difference was observed on hepatic histopathological changes. In conclusion, this study indicated that DRP could protect liver injury induced by ethanol in vivo. It suggested that DRP possesses the beneficial effect to human against ethanol-induced liver injury.