Naphthalene degradation by Fe2+/Oxone/UV - Applying an unconventional kinetics model and studying the reaction mechanism.

This study shows the degradation of naphthalene (Nap) in aqueous solution using Oxone process mediated by Fe2+ with UV-A irradiation (FOU). To elucidate the role of different parameters, Fe2+/Oxone (FO), Fe2+/UV (FU), Oxone/UV (OU) and direct photolysis processes were studied, separately. The degradation efficiency under different dosage of Fe2+, Oxone, initial probe compound concentration and solution pH were evaluated. It is concluded that FOU process has significantly better degradation capacity and efficiency. More than 90% of 0.125 mM Nap was removed in 20 min, under the optimal conditions of FOU ([Fe2+]0 = 0.250 mM, [Oxone]0 = 0.250 mM, wavelength = 350 nm and pH = 2.8). A mathematical model is proposed to describe the two-stage reaction kinetics involving Oxone. To alleviate the problems of radical surge at the initial stage and a radical deficit at later stage, a stepwise addition of oxidants was conducted and achieved a higher removal performance. Besides, the decay pathways of Nap under FOU process were proposed by using LC-ESI/MS analysis. The TOC content was found to be increased initially and decreased after 2 h reaction. It is clarified that the TOC increment was contributed by the partially degraded intermediates rather than the persistent Nap, since the latter was not completely combustible in the TOC analyzer, demonstrating that the FOU process is effective in degrading Nap into more degradable products such naphthoic acids and aldehydes.

Effect of polysaccharides from Angelica sinensis on gastric ulcer healing.

Our previous study showed that a crude extract from Angelica sinensis (ASCE), which mainly consisted of polysaccharides, significantly promoted migration and proliferation of normal gastric epithelial cells. These results strongly suggest that ASCE has a direct wound healing effect on gastric mucosa. However, there is no report concerning the effect of ASCE on gastric ulcer healing in animal models. In this study, we found that ASCE promoted ulcer healing. The area of the ulcer was reduced. This was accompanied with a significant increase in mucus synthesis when compared with the control. Angiogenesis was inhibited by the treatment of ASCE. Cell proliferation, ODC and EGFR protein expression was not affected in this process. Thus, the mechanism of how ASCE accelerates ulcer healing in addition to its effect on mucus synthesis remains to be investigated.

Protective effect of polysaccharides-enriched fraction from Angelica sinensis on hepatic injury.

A polysaccharides-enriched fraction from the root of Angelica sinensis, which is known for its antiulcer action on the gastrointestinal tract, was isolated and studied for its hepato-protective effect in rodents. Intra-gastric administration of Angelica sinensis polysaccharides-enriched fraction (AP) at the doses of 50 or 75 mg/kg dose-dependently prevented liver toxicity induced by acetaminophen in mice but did not affect the serum acetaminophen concentration. It normalized the rises of serum alanine transferase (ALT) and hepatic nitric oxide synthase (NOS) activities and the decrease of glutathione level in the liver. It also reduced the hepatic malondialdehyde (MDA) concentration. The protective effect was less evident in the carbon tetrachloride (CCl4)-treated animals including mice and rats. In the rat the elevated serum ALT level was unaffected though the MDA level was similarly reduced by the higher dose of AP. In these animals, CCl4 increased the hepatic glutathione level instead while the NOS activity remained unchanged. These findings suggest that the pathogenic mechanisms of both acetaminophen and CCl4 are different. AP is more effective in the protection against liver damage induced by acetaminophen, which is associated with the glutathione depletion and nitric oxide synthase activation in the liver.

Study of the gastrointestinal protective effects of polysaccharides from Angelica sinensis in rats.

We studied the protective effects of polysaccharides isolated from the root of Angelica sinensis (Oliv.) (Danggui) on gastrointestinal damage induced by ethanol or indomethacin in rats. Oral administration of ethanol provoked a marked hemorrhagic damage in the glandular mucosa, which was accompanied with a significant increase of myeloperoxidase (MPO) activity, a marker enzyme for inflammation and neutrophil infiltration. An extract from Angelica, which mainly consisted of polysaccharides (95%) (AP), dose-dependently prevented gastric mucosal damage. This ulcer protective effect could last at least 12 h after administration. Prostaglandin E2 produced a similar anti-lesion effect. AP and prostaglandin E2 also reduced mucosal MPO activity. Indomethacin-induced gastrointestinal damage, another neutrophil-dependent lesion model in the gastrointestinal tract, was also prevented by AP pretreatment. The present findings suggest that polysaccharides from Angelica possess an anti-inflammatory action, perhaps through the inhibitory action on neutrophil infiltration in the gastrointestinal mucosa. AP could potentially be useful to prevent any neutrophil-dependent mucosal injury in the gastrointestinal tract.