Shuhong Ye

Effects of selected ionic liquids on lipid production by the oleaginous yeast Rhodosporidium toruloides

Lignocellulosic biomass pretreatment with ionic liquids (ILs) has been emerged as a new technology, but the effects of residual ILs on the downstream biotransformation remain largely unknown. Here, three typical ILs were tested for their effects on lipid production by the oleaginous yeast Rhodosporidium toruloides AS 2.1389. When cultures were maintained at pH 6.0 in the presence of 30mM ILs, [Emim]Cl, [Emim][DEP], or [Emim][OAc], minor inhibition effects were observed. When cultures were performed in the presence of 60mM ILs or without pH control, inhibition was largely dependent on ILs. Detailed analysis indicated that the anion of [Emim][OAc] was assimilated, leading to a rapid alkaline-pH shift and enhanced inhibition on cell growth and lipid production. Our results demonstrated that R. toruloides is a robust lipid producer tolerating ILs at low concentrations, and that care should be taken in bioprocess control and data analysis when ILs are involved.

Biosynthesis of selenium rich exopolysaccharide (Se-EPS) by Pseudomonas PT-8 and characterization of its antioxidant activities.

Biosynthesis of organo-selenium is achieved by submerged fermentation of selenium-tolerant Pseudomonas PT-8. The end product of metabolic process is selenium-bearing exopolysaccharide (Se-EPS), which contains a higher content of uronic acid than the exopolysaccharide (EPS) by the strain without selenium in the culture medium. Selenium content in Se-EPS reached a maximum yield of 256.7 mg/kg when using an optimized culture condition. Crude Se-EPS was purified into two fractions-a pH neutral Se-EPS-1 and an acidic Se-EPS-2. Structure and chemical composition of Se-EPS-2 were investigated by chromatographic analyses. Results showed that Se-EPS-2 was a homogenous polysaccharide with molecular weight of 7.3 kDa, consisting of monosaccharides, rhamnose, arabinose, xylose, mannose, glucose and galactose with a molar ratio of 19.58:19.28:5.97:18.99:23.70:12.48, respectively. Compared to the EPS, the content of rhamnose in Se-EPS increased and molecular weight decreased. The Se-EPS had strong scavenging actions on DPPH•, •OH and •O2(-), which is much higher than the EPS.

Compound K Induces Apoptosis of Bladder Cancer T24 Cells Via Reactive Oxygen Species-Mediated p38 MAPK Pathway

Compound K (CK; 20-O-D-glucopyranosyl-20(S)-protopanaxadiol), a major metabolite of ginsenoside, has been shown to possess several biological activities such as potent antitumor properties. However, the effect of CK on the apoptosis of bladder cancer cells and its underlying mechanisms remain poorly understood. Therefore, we examined the effect of CK on the apoptosis of bladder cancer T 24 cells. Cell counts showed that treatment of T24 cells with CK decreased the cell number in a dose- and time-dependent manner. Flow cytometric analysis revealed that CK could significantly induce apoptosis of T24 cells in vitro. Further, cellular glutathione reduction, accumulation of reactive oxygen species (ROS) were also observed in CK-treated T24 cells. Western blot demonstrated the release of cytochrome c, activation of procaspases-3, procaspases-9, and the change of Bax/Bcl-2 proteins ratio. We also found that the phosphorylation of p38MAPK was increased by CK, while treatment with SB203580 inhibited CK-induced cell apoptosis in T24 cells. The blockage of ROS generation by N-acetylcysteine effectively prevented the apoptosis induction in T24 cells with CK treatment, accompanied by the decrease of activation of p38MAPK. These results suggested that CK induced the apoptosis of bladder cancer T24 cells, which is partially due to ROS generation and p38MAPK activation.

Induction of apoptosis by c9, t11-CLA in human endometrial cancer RL 95-2 cells via ERα-mediated pathway

Numerous studies have shown that conjugated linoleic acid (CLA) can inhibit cancer cells growth and induce apoptosis in vitro and in vivo. The aim of the present study was to investigate the effects of CLA, including cis9, trans11-conjugated linoleic acid (c9, t11-CLA) and trans10, cis12-conjugated linoleic acid (t10, c12-CLA), on apoptosis of human endometrial cancer RL 95-2 cells and its related mechanisms. The MTT analysis was used to evaluate the effect of CLA isomers on the viability of endometrial cancer RL 95-2 cells. We then estimated the apoptosis by Morphological observation and Annexin V-FITC/PI staining and flow cytometry. We also used Western blot analysis to assess the expression of caspase-3, Bax, Bcl-2 proteins and the activation of Akt/p-Akt and ERα/p-ERα. Propylpyrazole-triol (PPT), a selective ERα agonist was used to confirm the induction of apoptosis by c9, t11 CLA may relate to ERα-mediated pathway. In CLA-treated RL 95-2 cells, we found that c9, t11-CLA inhibited viability and trigged apoptosis, as judged from nuclear morphology and flow cytometric analysis. The expression of caspase-3 and the ratio of Bax/Bcl-2 were significant increased, but no obvious change was observed about Akt and p-Akt in c9, t11-CLA-treated cells. However, the expression of total ERα level in RL 95-2 cells-treated with c9, t11-CLA was unchanged, while in the concentration of 80 mM, c9, t11-CLA down-regulated the protein expression level of p-ERα. Then PPT has the antagonistic action on growth inhibitory effect in RL 95-2 cells incubated with c9, t11-CLA. This study demonstrated that c9, t11- CLA could induce apoptosis in RL 95-2 cells, and may involve in ERα-mediated pathway. These results indicated that c9, t11- CLA could induce apoptosis of endometrial cancer cells and may be potential agents for the treatment of endometrial cancer.

Beta-eleostearic acid induce apoptosis in T24 human bladder cancer cells through reactive oxygen species (ROS)-mediated pathway

Beta-eleostearic acid (β-ESA, 9E11E13E-18:3), a linolenic acid isomer with a conjugated triene system, is a natural and biologically active compound. Herein, we investigated effects of β-eleostearic acid on T24 human bladder cancer cells. In this study, results showed that β-eleostearic acid had strong cytotoxicity to induce cell apoptosis, which was mediated by reactive oxygen species (ROS) in T24 cells. The cell viability assay results showed that incubation with β-eleostearic acid concentrations of 10-80μmol/L caused a dose- and time-dependent decrease of T24 cell viability, and the IC(50) value was 21.2μmol/L at 24h and 13.1μmol/L at 48h. Annexin V/PI double staining was used to assess apoptosis with flow cytometry. Treatment with β-eleostearic acid caused massive ROS accumulation and GSH decrease, which lead to activation of caspase-3 and down-regulation of Bcl-2 indicating induction of apoptosis. Subsequently, N-acetyl-l-cysteine (NAC) and PEG-catalase effectively blocked the ROS elevated effect of β-eleostearic acid, which suggested that β-eleostearic acid-induced apoptosis involved ROS generated. Additionally, we found that treating T24 cells with β-eleostearic acid induced activation of PPARγ. A PPARγ-activated protein kinase inhibitor was able to partially abrogate the effects of β-eleostearic acid. These results suggested that β-eleostearic acid can induce T24 cells apoptosis via a ROS-mediated pathway which may be involved PPARγ activation.

Effects of carbohydrate sources on biosorption properties of the novel exopolysaccharides produced by Arthrobacter ps-5.

The crude exopolysaccharides (EPSs) were obtained from Arthrobacter ps-5 fermentation using various carbohydrate sources followed by centrifugation, ethanol precipitation, and the isolated EPSs were further deproteinized and lyophilized. Carbohydrates from various sources resulted in different yield of EPSs from the fermentation and different molecular weight of EPSs. A maximum yield of 0.27 mg/g was achieved by using the culture medium supplemented with sucrose. The EPS produced by glucose-supplemented medium had the maximum content of acidic polysaccharides, subsequently presented the highest biosorption capacity for Cu(2+) and Pb(2+) at 257.9 mg/g and 331.8 mg/g, respectively. The ratio of acidic to neutral polysaccharides presented in EPSs was a key factor to explicate the biosorption mechanism, the higher the ratio, the stronger the biosorption capacity.

Induction of apoptosis and inhibition of invasion in choriocarcinoma JEG-3 cells by α-calendic acid and β-calendic acid.

Alfa-calendic acid and β-calendic acid, geometric and positional isomers of linolenic acid were previously shown to possess potent anticancer properties. In this study, we found that α-calendic acid and β-calendic acid could induce apoptosis and suppress invasion of human choriocarcinoma JEG-3 cells in vitro. Treatment with α-calendic acid and β-calendic acid significantly increased oxidative stress in human choriocarcinoma JEG-3 cells detected by the level of reactive oxygen species (ROS), lipid peroxidation production malondialdehyde (MDA), glutathione (GSH) and the effects of antioxidants NAC and α-tocopherol. Furthermore, oxidative stress activated the phosphorylation of p38MAPK. SB203580, a selective p38MAPK inhibitor, blocked the apoptosis induced by α-calendic acid and β-calendic acid by upregulating Bcl-2/Bax ratio and inhibition of the activation of Caspase-3 and Caspase-9. SB20350 also partially abrogated the cell invasion effects of α-calendic acid and β-calendic acid. These results suggested that α-calendic acid and β-calendic acid induced apoptosis and inhibited invasion in JEG-3 cells by activation of oxidative stress pathways and subsequent activation of P38MAPK.