In this study, 7,8-dihydroxy-3-(4-methylphenyl) coumarin (DHMPC), a new coumarin derivative, was tested for the first time to determine whether it had any antioxidant and lipid lowering effects. Hypercholesterolemia was induced by feeding rats with a high cholesterol diet for 17 days. The lipid lowering and antioxidant effects of DHMPC were compared with those of hesperidin (CAS 520-26-3) and rutin (CAS 153-18-4), which have been pharmacologically determined as potential lipid lowering and antioxidant agents. DHMPC significantly decreased total cholesterol levels but not as efficient as hesperidin. When the ratios of high density lipoprotein-cholesterol (HDL-cholesterol) to total cholesterol were evaluated, the most significant changes were observed in DHMPC and rutin treatments. The results of serum triglyceride levels indicate that DHMPC and hesperidin did not significantly decrease triglyceride level when compared to rutin group but prevented it to rise. Serum malondialdehyde (MDA) levels increased as expected in high cholesterol diet groups but no significant decrease was observed for serum MDA levels in all treated groups. In contrast to serum MDA levels, liver homogenates MDA levels decreased in all treated groups but a considerable decrease was not observed for DHMPC treated group. Liver homogenates glutathione (GSH) levels drastically decreased in hyperlipidemic group and increased in all treated groups. As a conclusion DHMPC displayed both antioxidant and lipid lowering effects and can be a candidate drug for further studies.

Poly(vinyl alcohol)/poly(acrylic acid) (PVA/PAA) nanofibers with the fiber diameter of 100–150 nanometers were fabricated by electrospinning. PVA/PAA nanofibers were crosslinked by heat‐induced esterification and resulting nanofiber mats insoluble in water. α‐Amylase was covalently immobilized onto the PVA/PAA nanofiber surfaces via the activation of amine groups in the presence of 1,1′‐carbonyldiimidazole. The immobilized α‐amylase has more resistance to temperature inactivation than that of the free form and showed maximum activity at 50°C. pH‐dependent activities of the free and immobilized enzymes were also investigated, and it was found that the pH of maximum activity for the free enzyme was 6.5, while for the optimal pH of the immobilized enzyme was 6.0. Reuse studies demonstrated that the immobilized enzyme could reuse 15 times while retaining 81.7% of its activity. Free enzyme lost its activity completely within 15 days. Immobilized enzyme lost only 17.1% of its activity in 30 days. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Halophilic archaea offer a potential source for production of polyhydroxyalkanoates (PHAs). Hence, the experiments were carried out with five extremely halophilic archaeal isolates to determine the highest PHA-producing strain. PHA production of each isolates was separately examined in cheap carbon sources such as corn starch, sucrose, whey, apple, melon and tomato wastes. Corn starch was found to be a fairly effective substrate for PHA production. Among the strains studied here, the strain with the highest capability for PHA biosynthesis was found to be 1KYS1. Phylogenetic analysis based on 16S rRNA gene sequence comparison showed that 1KYS1 closely related to species of the genus Natrinema. The closest phylogenetic similarity was with the strain of Natrinema pallidum JCM 8980 (99 %). PHA content of 1KYS1 was about 53.14 % of the cell dry weight when starch was used as a carbon source. The formation of large and uniform PHA granules was confirmed by transmission electron microscopy and the biopolymer was identified as poly(3-hydroxybutyrate-co-hydroxyvalerate) (PHBV). PHBV produced by 1KYS1 was blended with low molar mass polyethylene glycol (PEG 300) to prepare biocompatible films for drug delivery. Rifampicin was used as a model drug and its release from PHBV films was investigated at pH 7.4, 37 °C. It was found that PHBV films obtained from 1KYS1 were very effective for drug delivery. In conclusion, PHBV of 1KYS1 may have a potential usage in drug delivery applications.

Chemically synthesized polyaniline (PANI) was used as polymeric support for xylanase immobilization. The polymer was first activated with glutaraldehyde and then xylanase was successfully immobilized. Xylanase bound polymer was characterized using FTIR. The optimum pH of the immobilized enzyme was at pH 5, which was shifted 1.0 pH unit to the acidic region when compared to the free enzyme. Thermal stability of the xylanase was improved with the immobilization. The characteristic properties of the immobilized and native enzyme, such as kinetic activity, reusability and storage stability were also studied at optimum pH and temperature. Immobilized enzyme exhibited better reusability and storage stability than the free one. Vmax values for the free and immobilized enzymes were calculated as 1.44 and 0.44 mg/mL/min, respectively. The Km values for the immobilized xylanase were found to be lower.

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