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5-Hydroxymethylfurfural (HMF) was produced from monosaccharide (fructose and glucose), polysaccharide (inulin) and the Jerusalem artichoke juice by a simple one-pot reaction including hydrolysis and dehydration using solid acid under mild condition. Hydrated niobium pentoxide (Nb(2)O(5)·nH(2)O(2)) after pretreatment showed high catalytic activities for dehydration of mono- and polysaccharide to HMF at 433 K in water-2-butanol (2:3 v/v) biphasic system, giving high HMF yield of 89% and 54% from fructose and inulin, respectively. The HMF yield was up to 74% and 65% when inulin and Jerusalem artichoke juice were hydrolyzed by exoinulinase. The solid acid made the process environment-friendly and energy-efficient to convert carbohydrates into bio-fuels and platform chemicals.

Sepsis and its derivative syndromes are major causes of morbidity and mortality in the intensive care unit. Recently, lots of studies have shown that the progression of sepsis is attributed to redox imbalance and overproduction of proinflammatory cytokines. In previous studies, we have reported the anti-oxidative and anti-inflammatory effects of chitosan oligosaccharides in vitro. In the light of these findings, we applied the model of sepsis to mice by LPS injection to investigate whether chitosan oligosaccharides have a protective effect on LPS-induced sepsis. We found that treatment by chitosan oligosaccharides not only attenuated organ dysfunction but also improved survival rate after LPS injection. To further understand how it works, we examined several proinflammatory markers including neutrophil infiltration in organs and TNF-α and IL-1β in serum, and found that these cytokines were significantly reduced by chitosan oligosaccharide treatment. In addition to this, anti-oxidants including glutathione (GSH) and catalase (CAT) levels were depleted and malondialdehyde (MDA) levels were increased in LPS-induced sepsis, while chitosan oligosaccharides smoothed out the redox imbalance. Furthermore, we also assessed c-Jun NH(2)-terminal kinase and p38 mitogen-activated protein kinase signal activation by LPS-stimulation, and found both of them were attenuated by chitosan oligosaccharide treatment. Collectively, our data demonstrated that chitosan oligosaccharides can protect mice from the LPS challenge by virtue of anti-inflammatory effects as well as anti-oxidation properties, which might offer beneficial effects for patients with sepsis.

Lipopolysaccharide, a potent activator of the immune system, elicits the production of pro-inflammatory mediators in immunocytes. Toll-like receptor 4 (TLR4) and myeloid differentiation factor (MD) 2 receptor complex is required for recognition and signaling of LPS. Previous study suggested water soluble chitosan decreased secretion of pro-inflammatory cytokines TNF-α and IL-6. However, no studies have provided direct target and molecular mechanism of anti-inflammatory effect of chitosan oligosaccharide on LPS-stimulated cells. In this study, we found that chitosan oligosaccharides significantly inhibited binding of LPS to TLR4/MD-2 receptor complex, thus attenuated activation of mitogen-activated protein kinases (MAPKs) and decreased nuclear translocation of nuclear factor-κB (NF-κB). Finally, chitosan oligosaccharides reduced the production of pro-inflammatory mediator, such as IL-1β and nitric oxide (NO) in LPS-stimulated RAW 264.7 cells. Therefore, chitosan oligosaccharides are potential inhibitive effector of LPS.

Chitosan oligosaccharides (COS) have been reported to have anticancer activity, immuno-enhancing effect and antimicrobial activity. However, other biological activities are unknown. Herein, we investigated the protective effects of COS against hydrogen peroxide (H(2)O(2))-induced oxidative damage on human umbilical vein endothelial cells (HUVEC, ECV304 cells). After 24h pre-incubation with COS (25-200 microg/ml), the viability loss in ECV304 cells induced by H(2)O(2) (300 microM) for 12h was markedly restored in a concentration-dependent manner as measured by MTT assay. This effect was accompanied by a marked decrease in intracellular reactive oxygen species (ROS) by measuring intensity of DCFH fluorescence. COS also exerted preventive effects on suppressing the production of lipid peroxidation such as malondialdehyde (MDA), restoring activities of endogenous antioxidants including superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), along with the capacity of increasing levels of nitric oxide (NO) and nitric oxide synthase (NOS), as were determined by commercial regent kits. In addition, pre-incubation of COS with ECV304 cells for 24h resulted in the reduction of apoptosis and the induction of cell cycle arrest in G(1)/S+M phase as assayed quantitatively by Annexin V-fluorescein isothiocyanate (FITC) apoptosis detection kit using flow cytometry. Taken together, our findings suggest that COS can effectively protect HUVECs against oxidative stress by H(2)O(2), which might be of importance in the treatment of cardiovascular diseases.

chitooligosaccharides (cos) have been shown to regulate various cellular and biological functions. however, the effect of cos on apoptosis of hepatocellular carcinoma cells remains unclear. in this study, the activity and mechanism of cos against human hepatocellular carcinoma cells (smmc-7721 cells) were investigated in vitro. the experiments showed that cos notably induced the apoptosis of smmc-7721 cells and increased the cleavage of poly(adp-ribose) polymerase. it presented a dose-dependent manner, and the apoptotic rate amounted to about 38% after treatment with 0.8 mg/ml cos for 72 h. the mrna and protein levels of bax were up-regulated by cos. these results demonstrated that cos induced apoptosis of smmc-7721 cells. the possible mechanism is that cos up-regulate pro-apoptotic protein bax, and trigger the cells a start-up of the apoptosis program. (c) 2007 elsevier ltd. all rights reserved.

Animal blood is potentially an untapped source of drugs and value-added food production. More than 400 million pigs are slaughtered each year but porcine blood is usually discarded in China. In this paper, globin derived from porcine hemoglobin was digested by pepsin, then the hydrolysate was separated on Sephadex LH-20 gel filtration column and five major fractions (I, II, III, IV and V) were obtained. Biological functions of the hydrolysate and five fractions were assayed. The hydrolysate and fractions IV and V had good angiotensin-I-converting enzyme inhibitory activity, with IC50 values of 1.19, 0.67, 0.10 mg/ml, respectively. Fractions I, II, III, IV showed no significant α-glucosidase inhibitory activity, but fraction V showed appreciably stronger activity than acarbose at the same concentration. Thus, the study has shown that porcine blood can be utilized to generate high value-added products, ACE inhibitory peptides and α-glucosidase inhibitory peptides.

An inhibitor was found in the culture fluid of Pseudomonas aeruginosa PAO1, which could inhibit the activity of the Pseudomonas autoinducer (PAI). The maximal inhibitory activity occurred in stationary phase culture sup ernatant. The PAI inhibitor did not influence the cell growth and the PAI production by P. aeruginosa PAO1 when the PAI inhibitor was added into culture medium. The induced expression of lacZ in the reporter strain Agrobacterium tumefaciens NT1 was suppressed by this PAI inhibitor, whereas inhibition could be relieved by increasing the auto inducer concentration. The quorum sensing of P. aeruginosa was inhibited presumably by inhibiting the inducing activity of Pseudomonas autoinducer but not by inhibiting the production of Pseudomonas autoinducer. It was demonstrated that the structure of the PAI inhibitor was different from that of acyl-homoserine lactones.Key words: quorum sensing, autoinducer, PAI inhibitor, Pseudomonas aeruginosa, N-acylhomoserine lactone.

The development of human cancers is a multistep complex process by which cancer cells acquire the ability to overcome the restraints imposed by the surrounding normal tissue microenvironment (7). This process is believed to be driven by the intrinsic genomic instability of cancer cells to express genes that confer selective advantages under the adverse growth conditions associated with a rapidly expanding tumor mass, such as hypoxia and a poor supply of nutrients. After reaching a critical mass, cancer cells have to find ways to promote angiogenesis in order to progress and expand during late stages of tumorigenesis (4, 5). To this end, a number of genes, such as the vascular endothelial growth factor (VEGF), have been demonstrated to play critical roles in the development of tumor vasculature (4, 5, 10). However, much more remains to be learned about the molecular nature of still unidentified players and their modes of action in promoting tumor angiogenesis. Recently, large-scale efforts have been made to determine gene expression pattern differences between various types of human cancers and their corresponding normal tissues by using the serial analysis of gene expression (SAGE) and gene array analyses (14, 33-35, 37). Indeed, significant differences in gene expression patterns have been revealed by these studies. In breast cancer, for example, such investigations have led to the application of gene array analysis in the diagnosis, prognosis, and design of rational treatment of patients according to the molecular signatures of the individual tumors (21, 22, 32, 35). In the meantime, although the alterations of oncogenes and tumor suppressor genes have shown a close association with the progression of human cancers based on their defined functions, less is known about the specific contributions of a large number of genes whose expression patterns are also significantly changed during the tumorigenic process. Particularly interesting is the observation that mesenchyme-specific genes, normally associated with osteoblasts, are highly expressed by various types of human cancers (17, 31). However, the expression of mesenchyme-specific genes has not been functionally linked to the development of specific tumor phenotypes. To address this question, we sought to determine the potential contributions of such candidate genes to specific phenotypic changes associated with the progression of late-stage tumorigenesis and identified a mesenchyme-specific gene product, periostin, as a novel angiogenic factor whose overexpression by human breast cancers leads to the significant enhancement of angiogenesis. The angiogenic activity of periostin correlated with the increased expression of the VEGF receptor Flk-1/KDR by endothelial cells through an integrin αvβ3-focal adhesion kinase (FAK)-mediated signaling pathway. These findings indicate that epithelial cell-derived tumors may gain the capabilities to generate more blood vessels, invade, and metastasize during late stages of tumorigenesis by the acquired expression of genes whose functions are normally associated only with mesenchymal cells.

Molecular mechanisms associated with tumor metastasis remain poorly understood. Here we report that acquired expression of periostin by colon cancer cells greatly promoted metastatic development of colon tumors. Periostin is overexpressed in more than 80% of human colon cancers examined with highest expression in metastatic tumors. Periostin expression dramatically enhanced metastatic growth of colon cancer by both preventing stress-induced apoptosis in the cancer cells and augmenting endothelial cell survival to promote angiogenesis. At the molecular level, periostin activated the Akt/PKB signaling pathway through the α v β 3 integrins to increase cellular survival. These data demonstrated that the survival-promoting function is crucial for periostin to promote tumor metastasis of colon cancer.

Chitosan oligosaccharides (COS) have been reported to exert anti-fungal activities, antitumour activities and immuno-enhancing effects. However, the potential roles of COS in the treatment of vascular inflammations remain unknown. In the present study, we examined the effects of COS on interleukin-6 (IL-6) production in human umbilical vein endothelial cells (HUVECs) induced by lipopolysaccharide (LPS). Induction of HUVECs with LPS (100 ng/ml) increased the mRNA expression and protein secretion of IL-6 (versus the vehicle-treated group, p < 0.01), which were significantly reverted by the pre-treatment with COS (50-200 microg/ml) for 24 hr before LPS exposure (versus the LPS-treated group, p < 0.05 or 0.01). Signal transduction studies showed that the pre-treatment of HUVECs with COS (50-200 microg/ml) for 24 hr markedly inhibited the LPS-induced over-expression of phosphorylated p38 mitogen-activated protein kinase (MAPK), phosphorylated ERK1/2 and nuclear factor kappaB (NF-kappaB). Moreover, the LPS-induced NF-kappaB activation was suppressed by the specific ERK1/2 inhibitor PD98059 (30 microM) (versus the LPS-treated group, p < 0.01), but not by the specific p38 MAPK inhibitor SB203580 (25 microM). Additionally, both MAPK inhibitors markedly suppressed LPS-induced IL-6 mRNA expression in HUVECs (versus the LPS-treated group, p < 0.01). In conclusion, our results suggest that COS inhibit LPS-induced up-regulation of IL-6 in HUVECs, and this can be regulated by at least two parallel signalling pathways: one via p38 MAPK pathway independent of NF-kappaB activation and one via ERK1/2 pathway dependent on NF-kappaB activation.

Enfuvirtide (ENF), the first human immunodeficiency virus type 1 (HIV-1) fusion inhibitor approved for clinical use, acts by binding to gp41 heptad repeat 1 (HR1) and preventing its interaction with the viral HR2 region. Treatment-emergent resistance to ENF has been mapped to residues within HR1, and these mutations decrease its susceptibility to ENF and may reduce viral fitness and pathogenesis, although the mechanism for these effects is not clear. N43D, a common ENF resistance mutation, was found in in vitro assays to cause a 5-50-fold in antiviral activity. We introduced this mutation into peptide models and determined the impact of this mutation by circular dichroism and X-ray crystallography. We find that the mutation results in a decrease in the thermal stability of the six-helix bundle and causes a significant change in the HR1-HR2 interface, including a loss of HR2 helicity. These data form a mechanistic basis for the decrease in ENF sensitivity and six-helix bundle stability. The E137K polymorphism, generally present at baseline in patients who develop N43D, partially compensates for the loss of stability, and we show that these residues likely form an ion pair. These data form a framework for understanding the impact of resistance mutations on viral fitness and pathogenesis and provide a pathway for the development of novel fusion inhibitor peptides.

A new solid acid, based on tantalum hydroxide, was used to catalyze saccharide dehydration into 5-hydroxymethylfurfural (HMF) with high catalytic activity and excellent stability in a water-2-butanol biphasic system. Furthermore, good results were also obtained from Jerusalem artichoke juice with the catalyst under the same conditions.