Status of antioxidant enzyme: glutathione peroxidase and total polyphenol level in plasma of Tunisian patients suffering from colorectal and gastric cancer: interaction with clinical outcome.

In our case-control study, we measure the antioxidant status by dosing enzymes involved in oxidant stress in plasma of patients with colorectal and gastric cancer, and in the second step, we investigate the impact of chemotherapy before and after surgery on plasma antioxidant status and polyphenols in patients. Blood serum was collected from patients with stomach and colorectal cancer before conventional treatment, and glutathione peroxidase (GSHPX) enzyme activities and total polyphenols were determined by spectrophotometric methods. In our study, we found a significant decrease in glutathione peroxidase activity in plasma of patients compared with controls (P = 0.02), although we did not find a significant association between total polyphenols and 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) or ABTS in plasma of colorectal and stomach cancer compared with control; furthermore, we observed no significant difference in the average plasma polyphenols in patients treated with chemotherapy before and after surgery. We have shown the decrease in GSHPX activity in plasma of cases with colorectal and gastric cancer, and this decrease reflects that the oxidative stress is associated with tumor tract and related to oxidative metabolism; however, no association was found between total polyphenols and ABTS in our study.

Characterization of a novel biosurfactant produced by Staphylococcus sp. strain 1E with potential application on hydrocarbon bioremediation.

A biosurfactant-producing bacterium (Staphylococcus sp. strain 1E) was isolated from an Algerian crude oil contaminated soil. Biosurfactant production was tested with different carbon sources using the surface tension measurement and the oil displacement test. Olive oil produced the highest reduction in surface tension (25.9 dynes cm(-1)). Crude oil presented the best substrate for 1E biosurfactant emulsification activity. The biosurfactant produced by strain 1E reduced the growth medium surface tension below 30 dynes cm(-1). This reduction was also obtained in cell-free filtrates. Biosurfactant produced by strain 1E showed stability in a wide range of pH (from 2 to 12), temperature (from 4 to 55 °C) and salinity (from 0 to 300 g l(-1)) variations. The biosurfactant produced by strain 1E belonged to lipopeptide group and also constituted an antibacterial activity againt the pathogenic bacteria such as Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Bacillus subtilis. Phenanthrene solubility in water was enhanced by biosurfactant addition. Our results suggest that the 1E biosurfactant has interesting properties for its application in bioremediation of hydrocarbons contaminated sites.