An antioxidant protein in Curcuma comosa Roxb. Rhizomes

Curcuma comosa Roxb. is an indigenous Thai herb which is usually used as a food ingredient but it is also used in traditional folk medicine for the treatment of uterine inflammation. The crude protein extract from the rhizomes of this plant was found to possess free radical scavenging capacity, as detected by the DPPH assay. This antioxidant activity was purified by DEAE anion exchange chromatography to a fraction (called IE-1) that was comprised of a single main protein band of ∼18 kDa (UB-DEAE), as determined by SDS–PAGE resolution with Coomassie blue staining, and had a specific activity of 193.8 U/mg. In-gel trypsin digestion of the SDS–PAGE resolved UB-DEAE band followed by liquid chromatography–tandem mass spectrometry produced three reliably sequenced peptides, which all were found to very likely be fragments of a superoxide dismutase homologue (SOD, EC 1.15.1.1), an antioxidant enzyme that has been found in several plants. In support of this notion, the IE-1 fraction was found to yield positive results with the riboflavin–nitroblue tetrazolium (NBT) assay, a standard test for SOD-like activity. Together, these data then support the existence of an SOD homologue antioxidant protein in the rhizomes of C. comosa as a contributing agent to the total observed antioxidant activity.     

Cytotoxicity in the frog (Fejervarya limnocharis) after acute cadmium exposure in vivo

Chromosome aberrations (CA) in frogs (Fejervarya limnocharis) exposed to 5, 10 and 20 mg/L of cadmium chloride (CdCl₂) for 24, 48 and 72 h were invetegated. Treated frogs were compared to a control group. Cadmium (Cd) was not detected in the water or control frogs. The highest Cd concentrations in water and frog samples were found at 20 mg/L exposed for 72 h. The water samples indicated that exposure to 10 mg/L of Cd for 24 h was significantly different from the control (p < 0.05). Cd concentrations in frogs differed significantly between the control and experimental groups (p < 0.05). The cytotoxicity assessment revealed ten types of CA in the frogs, including single chromatid gap (SCG), isochromatid gap, single chromatid break, isochromatid break, iso-arm fragmentation, single chromatid decomposition, centric fragmentation, centromere gap, deletion and fragmentation. The most common CA in the study was SCG. The statistical analysis indicated significant differences in the percentage of cells with CA for exposures of 20 mg/L (24 h), 10 and 20 mg/L (48 h) and 5, 10 and 20 mg/L (72 h) compared to the control (p < 0.05). The results of this study show that high Cd concentrations and long duration exposure can cause CA in frogs.     

Preliminary Study of Conformation and Drug Release Mechanism of Doxorubicin-Conjugated Glycol Chitosan, via cis-Aconityl Linkage, by Molecular Modeling

An investigation of the structure and drug release mechanism of a drug delivery system is proposed on the basis of semi-empirical and ab initio computations in vacuum stage. Cis-aconityl linkage is used to improve the interaction between an anti-cancer agent, doxorubicin, and a glycol chitosan biopolymer. It has been found that the doxorubicin-conjugated glycol chitosan carrier has more stability. The stability is increased when the lengths of the polyethylene glycol (PEG) chains in the glycol chitosan biopolymer are increased. Cis-aconityl can release doxorubicin under appropriate environmental conditions. Relative energies of this mechanism in an acid condition, as determined by B3LYP/6-31G//PM3, are 122.41, 119.27, 160.18 and 222.22 kcal/mol, and by the B3LYP/6-31G//HF/6-31G method are 54.23, 109.28, 219.98 and 980.49 kcal/mol, with mono-, di-, tri-, and quanta-ethylene glycol, respectively. In a normal condition, the relative energies are above 300 kcal/mol for all reactions. Therefore, cis-aconityl will release doxorubicin in an acid solution but not in a normal condition. The glycol chitosan polymer can be degraded in an acid solution as well. Long PEG chains influence the release mechanism of doxorubicin. The proposed length of the PEG chain is di-ethylene glycol. These simulation results agree well with various reported experimental data.     

Efficiency of Hydroxycinnamic Phenolic Acids to Inhibit the Production of Ochratoxin A by Aspergillus westerdijkiae and Penicillium verrucosum

Ochratoxin A (OTA) is one of the worldwide most important mycotoxins in terms of health and agroeconomic consequences. With the aim to promote the use of phytochemicals as alternatives to synthetic fungicides, the effect of hydroxycinnamic acids on the fungal growth and OTA yield by two major OTA-producing species was investigated. After a first step dedicated to the definition of most suitable culture conditions, the impact of 0.5 mM ferulic (FER), p-coumaric (COUM), caffeic and chlorogenic acids was evaluated on Aspergillus westerdijkiae and Penicillium verrucosum. Whereas no fungal growth reduction was observed regardless of the phenolic acid and fungal isolate, our results demonstrated the capacity of FER and COUM to inhibit OTA production. The most efficient compound was FER that led to a 70% reduction of OTA yielded by P. verrucosum and, although not statistically significant, a 35% inhibition of OTA produced by A. westerdijkiae. To further investigate the bioactivity of FER and COUM, their metabolic fate was characterized in fungal broths. The capacity of P. verrucosum to metabolize FER and COUM through a C₂-clivage type degradation was demonstrated. Overall, our data support the potential use of FER to prevent OTA contamination and reduce the use of synthetic pesticides.     

System performance of a three-phase PV-grid-connected system installed in Thailand: Data monitored analysis

PV-grid-connected systems are worldwide installed because it allows consumer to reduce energy consumption from the electricity grid and to feed the surplus energy back into the grid. The system needs no battery so therefore the system price is very cheap comparing to other PV systems. PV-grid-connected systems are used in buildings that already hooked up to the electrical grid.Finding efficiency of the PV-grid-connected system can be done by using a standard instrument which needs to disconnect the PV arrays from the grid before measurement. The measurement is also difficult and we lose energy during the measurement.This paper will present the system performance of a PV-grid-connected system installed in Thailand by using a monitoring system. The monitored data are installed by acquisition software into a computer. Analysis of monitored data will be done to find out the system performance without disconnecting the PV arrays from the system. The monitored data include solar radiation, PV voltage, PV current, and PV power which has been recorded from a 5 kWp system installed of amorphous silicon PV at Rajamangala University of Technology Suvarnabhumi, Nonthaburi, Thailand. The system performance of the system by using the data monitored is compared to the standard instrument measurement. The paper will give all details about system components, monitoring system, and monitored data. The result of data analysis will be fully given.     

Occurrence and effect of casting skin in compacted graphite iron

Most iron castings retain their as cast surfaces because of their geometric complexity and to minimise the machining costs. However, the mechanical properties that are documented in standards (i.e. ASTM) are tested on fully machined test bars. Therefore, the effect of the as cast surface and subsurface features (commonly referred as ‘casting skin’) on mechanical properties should be evaluated. Preliminary works have shown the negative effect of the casting skin on mechanical properties of grey and ductile irons. This paper reviews the recent works on the casting skin effect on tensile and fatigue properties in compacted graphite and ductile irons. It was found that the tensile and fatigue strength were reduced by 9 and 40% respectively because of the presence of the casting skin. In addition, the correlations between processing parameters (e.g. nodularity and section thickness) and the casting skin features were presented. The experimental results suggest that the Mg depletion because of metal–mould and metal–air interactions was the main reason for the formation of the casting skin.