Sunanta Pongsamart

Studies on the immunomodulatory effect of polysaccharide gel extracted from Durio zibethinus in Penaeus monodon shrimp against Vibrio harveyi and WSSV.

Oral administration of polysaccharide gel (PG) in shrimp diets revealed immunostimulating potential and disease resistance in Penaeus monodon (black tiger shrimp). PG from the fruit-rind of Durio zibethinus has been characterized to be a pectic polysaccharide with immunomodulating and antibacterial activities. PG inhibited growth of the shrimp bacterial pathogen, Vibrio harveyi 1526, by agar diffusion and broth microdilution tests. Clear inhibition zones on agar plates were observed at the lowest PG concentration of 3.1 mg/ml, where minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values for PG were 6.3 and 12.5 mg/ml, respectively. Each group of juvenile shrimps, initial mean body weight 0.29 +/- 0.04 g, was housed in a closed-recirculating treated water system and was fed with PG-supplemented diets containing 1, 2 and 3% PG or shrimp basal diet in the control group for 8 and 12 weeks. PG-supplemented diets did not contribute to the overall growth of black tiger shrimp. The immune response was evaluated by analysis of prophenoloxidase activity and total hemocyte count in the shrimp fed PG-supplemented diets for 12 weeks. Prophenoloxidase activity in shrimp fed the 1, 2 and 3% PG-supplemented diet and total hemocyte count in shrimp fed the 1 and 2% PG-supplemented diet were higher (P < 0.05) than those of the control group. The percent survival was higher in groups fed the 1-3% PG-supplemented diets in challenge tests with either white spot syndrome virus (WSSV) or the bacterium V. harveyi 1526 than that of the control group. Relative percent survival (RPS) values in groups fed the 2% PG-supplemented diet showed the highest RPS value for disease resistance of 100% (at Day 6) and 36% (at Day 4) in treated shrimp against viral and bacterial infection, respectively. Mortality of PG-supplemented diets in treated shrimps against WSSV infection was also found to be much lower (P < 0.05) than that of the control group.

Hemoglobin constant spring: Hemoglobin synthesis in heterozygous and homozygous states

Abstract Thirteen adult and one newborn heterozygotes, and three homozygotes for hemoglobin Constant Spring were examined for globin chain synthesis. Reticulocytes from venous blood were incorporated with [3H]-leucine in an incubation mixture for 3 hours. Globin prepared from the radioactive, washed red cells was fractionated by CM-cellulose chromatography in 8 M urea and the total radioactivity of each globin chain was determined. The mean of α β ratio in the heterozygotes was 1.34 ± SD 0.08, which is significantly different from that of 1.07 ± SD 0.03 in eleven normal controls. The α β+γ ratio in the heterozygous neonate was also 1.39. The α β ratios in the three homozygotes were around 1.6. The α-Constant Spring chain appears to be over produced, but it may be unstable or labile, not fully available for conjugation with the non alpha chains.

Kaempferol-3-O-rutinoside from Afgekia mahidoliae promotes keratinocyte migration through FAK and Rac1 activation

The restoration of the epidermal epithelium through re-epithelialization is a critical process in wound healing. Directed keratinocyte migration to the wound is required, and the retardation of this process may result in a chronic, non-healing wound. The present study contributes to research aiming to identify promising compounds that promote wound healing using a human keratinocyte model. The effects of three kaempferol glycosides from an Afgekia mahidoliae leaf extract, kaempferol-3-O-arabinoside, kaempferol-3-O-glucoside, and kaempferol-3-O-rutinoside, on keratinocyte migration were determined. Interestingly, kaempferol-3-O-rutinoside exhibited a pronounced effect on wound closure in comparison to the parental kaempferol and other glycosides. The mechanism by which kaempferol-3-O-rutinoside enhances cell migration involves the induction of filopodia and lamellipodia formation, increased cellular levels of phosphorylated FAK (Tyr 397) and phosphorylated Akt (Ser 473), and up-regulation of active Rac1-GTP. The data obtained in this study may support the development of this compound for use in wound healing therapies.

Tamarind seed coat extract restores reactive oxygen species through attenuation of glutathione level and antioxidant enzyme expression in human skin fibroblasts in response to oxidative stress

OBJECTIVE To investigate the role and mechanism of tamarind seed coat extract (TSCE) on normal human skin fibroblast CCD-1064Sk cells under normal and oxidative stress conditions induced by hydrogen peroxide (H2O2). METHODS Tamarind seed coats were extracted with boiling water and then partitioned with ethyl acetate before the cell analysis. Effect of TSCE on intracellular reactive oxygen species (ROS), glutathione (GSH) level, antioxidant enzymes such as superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase activity including antioxidant protein expression was investigated. RESULTS TSCE significantly attenuated intracellular ROS in the absence and presence of H2O2 by increasing GSH level. In the absence of H2O2, TSCE significantly enhanced SOD and catalase activity but did not affected on GPx. Meanwhile, TSCE significantly increased the protein expression of SOD and GPx in H2O2-treated cells. CONCLUSIONS TSCE exhibited antioxidant activities by scavenging ROS, attenuating GSH level that could protect human skin fibroblast cells from oxidative stress. Our results highlight the antioxidant mechanism of tamarind seed coat through an antioxidant enzyme system, the extract potentially benefits for health food and cosmeceutical application of tamarind seed coat.

Characterization and inhibition of dihydrofolate synthetase from Neisseria gonorrhoeae

SummaryDihydrofolate synthetase (EC 6.3.2.12) from N. gonorrhoeae was isolated and enzyme characteristics were determined. The purified enzyme was found quite stable when stored at −60 °C. About 50% of the enzyme activity wag destroyed within 6 weeks when kept at 4 °C. Maximum velocity was observed at pH 9.3. The enzyme required a monovalent cation, K+ or NH4+ , and divalent cation, Mg2+ or Mn2+ for its function. ATP at 5 mM concentration gave maximum activity. Km values for dihydropteroate and L-glutamate at pH 9.3 were 3.5 × 10−5 M and 6.5 × 10−4 M, respectively. Patterns of product inhibition by dihydrofolate were found to be non-competitive with respect to dihydropteroate, having a Ki value of 5.1 ± 0.8 × 10−4 M, and competitive with respect to L-glutamate, having a Ki value of 6.2 × 10−4 M.