Zong-Tsi Chen

Regulation of heme oxygenase-1 expression and MAPK pathways in response to kaempferol and rhamnocitrin in PC12 cells.

Oxidative stress has been considered as a major cause of cellular injuries in a variety of clinical abnormalities, especially neural diseases. Our aim of research is to investigate the protective effects and mechanisms of kaempferol and rhamnocitrin (kaempferol-7-methyl ether) on oxidative damage in rat pheochromocytoma PC12 cells induced by a limited supply of serum and hydrogen peroxide (H2O2). The current result demonstrated that kaempferol protected PC12 cells from serum deprivation-induced apoptosis. Pretreatment of cells with kaempferol also diminished intracellular generation of reactive oxygen species (ROS) in response to H2O2 and strongly elevated cell viability. RT-Q-PCR and Western blotting revealed that kaempferol and rhamnocitrin significantly induced heme oxygenase (HO)-1 gene expression. Addition of zinc protoporphyrin (Znpp), a HO-1 competitive inhibitor, significantly attenuated their protective effects in H2O2-treated cells, indicating the vital role of HO-1 in cell resistance to oxidative injury. While investigating the signaling pathways responsible for HO-1 induction, we observed that kaempferol induced sustained extracellular signal-regulated protein kinase 1/2 (ERK1/2) in PC12 cells grown in low serum medium; while rhamnocitrin only stimulated transient ERK cascade. Addition of U0126, a highly selective inhibitor of MEK1/2, which is upstream of ERK1/2, had no effect on kaempferol- or rhamnocitrin-induced HO-1 mRNA expression, indicating no direct cross-talk between these two pathways. Furthermore, both kaempferol and rhamnocitrin were able to persistently attenuate p38 phosphorylation. Taking together, the above findings suggest that kaempferol and rhamnocitrin can augment cellular antioxidant defense capacity, at least in part, through regulation of HO-1 expression and MAPK signal transduction.

Protective effects of sweet orange (Citrus sinensis) peel and their bioactive compounds on oxidative stress

Protective effects of sweet orange (Citrus sinensis) peel and their bioactive compounds on oxidative stress were investigated. According to HPLC-DAD and HPLC-MS/MS analysis, hesperidin (HD), hesperetin (HT), nobiletin (NT), and tangeretin (TT) were present in water extracts of sweet orange peel (WESP). The cytotoxic effect in 0.2mM t-BHP-induced HepG2 cells was inhibited by WESP and their bioactive compounds. The protective effect of WESP and their bioactive compounds in 0.2mM t-BHP-induced HepG2 cells may be associated with positive regulation of GSH levels and antioxidant enzymes, decrease in ROS formation and TBARS generation, increase in the mitochondria membrane potential and Bcl-2/Bax ratio, as well as decrease in caspase-3 activation. Overall, WESP displayed a significant cytoprotective effect against oxidative stress, which may be most likely because of the phenolics-related bioactive compounds in WESP, leading to maintenance of the normal redox status of cells.

Cytotoxic effect of Eucalyptus citriodora resin on human hepatoma HepG2 cells.

The aim of this study was to evaluate the antiproliferative effect of Eucalyptus citriodora resin (ECR) on human hepatoma HepG2 cells. The results from MTT assay and LDH leakage analysis showed that water extracts of ECR (WEECR) in the dose range of 0-500 μg/ml displayed stronger cytotoxic effects on HepG2 cells than other organic solvent extracts of ECR. By flow cytometry analysis, WEECR slowed down the cell cycle at the G0/G1 phase after 24 h of incubation. Moreover, WEECR treatment induced an apoptotic response in HepG2 cells. WEECR-induced apoptosis was in association with the attenuation of mitochondrial transmembrane potentials (ΔΨ(m)), increased Bax/Bcl-2 ratio and activation of caspase-3. In addition, WEECR contained high concentration of phenolics and flavonoids, which may be responsible for the potent cytotoxicity of WEECR on HepG2 cells. Taken together, WEECR may be a potent antihepatoma agent due to apoptosis in HepG2 cells.

Antiproliferative Activity and Apoptosis Induction of Eucalyptus Citriodora Resin and Its Major Bioactive Compound in Melanoma B16F10 Cells

Antiproliferative activity and apoptosis induction of ethyl acetate of Eucalyptus citriodora resin (EAEER), and its major bioactive compound in melanoma B16F10 cells were investigated. 6-[1-(p-Hydroxy-phenyl)ethyl]-7-O-methyl aromadendrin (HEMA), a flavanol derivative, was isolated from EAEER and identified on the basis of its mass and NMR spectra. The results from MTT assay showed high antiproliferative effects of EAEER and HEMA on B16F10 cells. Moreover, EAEER- and HEMA-induced cell apoptosis was association with the decrease in the mitochondrial transmembrane potentials (Δψ(m)), increase in Bax/Bcl-2 ratio, and activation of caspase-3. Cells treated with EAEER and HEMA generated intracellular reactive oxygen species (ROS) and nitric oxide (NO), indicating that ROS and RNS play important roles in the induction of apoptosis in B16F10 cells. Taken together, EAEER and its major bioactive compound, HEMA, inhibited the proliferation of B16F10 cells via apoptosis and may be a potential antimelanoma agent.

Cytotoxic Triterpenoids from the Root Bark of Helicteres angustifolia

Three new triterpenoids, 3β‐acetoxy‐27‐[(E)‐cinnamoyloxy]lup‐20(29)‐en‐28‐oic acid methyl ester (1), 3β‐acetoxy‐27‐[(4‐hydroxybenzoyl)oxy]lup‐20(29)‐en‐28‐oic acid (2), and 3β‐acetoxy‐27‐[(4‐hydroxybenzoyl)oxy]olean‐12‐en‐28‐oic acid methyl ester (3), together with nine known triterpenoids, 4–12, were isolated from the root bark of Helicteres angustifolia. The structures of these compounds were established on the basis of spectroscopic methods including 2D‐NMR experiments. All twelve compounds were tested for their cytotoxic activities against human colorectal cancer (COLO 205), human hepatoma (Hep G2), and human gastric cancer (AGS) cell lines in vitro. Among them, compounds 2, 3, 3β‐O‐[(E)‐coumaroyl]betulinic acid (6), and pyracrenic acid (7) showed significant cytotoxic activities against human cancer cells COLO 205 and AGS.

Effect of lactic acid bacteria isolated from fermented mustard on immunopotentiating activity

ABSTRACT Objective To investigate the effect of lactic acid bacteria isolated from fermented mustard on immunopotentiating activity Methods One hundred and fifty nine strains of lactic acid bacteria isolated from traditional Taiwan fermented mustard were evaluated for their immunopotentiating activity on a murine macrophage cell line RAW 264.7. Results Of the strains, pronounced increases in the levels of nitric oxide (NO), tumor necrosis factor-α and interleukin-6 were observed in strains B0040, B0110 and B0145. Among them, strain B0145 had the highest NO and tumor necrosis factor-α generation in RAW 264.7 cells; strains B0040 and B0110 were also superior to that of Lactobacillus casei. These results demonstrated that NO and cytokines were effectively induced when the bacterial stimulants were treated with macrophages. In addition, strains B0040 and B0110 were identified as Lactobacillus plantarum , and B0145 as Weissella cibaria using 16S rDNA analysis. Conclusions The results implicated selected strains may be regarded as a biological response modifier and had a broad application prospects in exploiting new functional food or as a feed additive.

A new flavonol from the kino of Eucalyptus citriodora

Abstract A new flavonol, 6-[1-(p-hydroxyphenyl)ethyl]rhamnocitrin (3) together with two known compounds, kaempferol (4) and 7-O-methyl aromadendrin (5) were isolated from the kino of Eucalyptus citriodora and their structures were elucidated on the basis of spectroscopic methods including 2D NMR spectra. Rhamnocitrin (1), 6-[1-(p-hydroxyphenyl)ethyl]-7-O-methyl aromadendrin (2), previously isolated from this plant and compounds 3−5 were tested for inhibitory activity against 15-lipoxygenase. All compounds exhibited moderate to strong inhibitory activities, of which compounds 2, 3 and 5 showed stronger inhibitory activity (IC50 19.7 ± 0.5, 29.3 ± 0.9 and 31.4 ± 1.0 μM, respectively) than the positive control quercetin (IC50 37.5 ± 0.8 μM).