Table of Contents

Abstract: The phenolic profile and antioxidant activities of oolong tea extract wereinvestigated after tea was steeped in 90 or 100 ^oC water for 3 or 10 min. The extractionyield increased with increasing temperature and extended steeping time. However, highertemperature and longer time (100 ^oC water for 10 min) led to loss of phenolics. Theaqueous extract of oolong tea (AEOT) at 100 ^oC for 3 min exhibited the strongestantioxidant activity. The major polyphenolic components of the AEOT were identified as(-)-epigallocatechin (EGC), (-)-epigallocatechin gallate (EGCG) and (-)-epicatechin-3-gallate (ECG). The two major catechins (EGC and EGCG) in the tea infusion contributedsignificantly to the investigated antioxidant activities [i.e., the 2,2-diphenyl-2-picrylhydrazyl hydrate (DPPH) radical scavenging and superoxide radical scavengingactivities] with high correlation values in r = 0.9486 and 0.9327 for the EGC and r =0.9592 and 0.8718 for the EGCG, respectively.

Abstract: DNA topoisomerases (topos) and DNA polymerases (pols) are involved in manyaspects of DNA metabolism such as replication reactions. We found that long chainunsaturated fatty acids such as polyunsaturated fatty acids (PUFA) (i.e., eicosapentaenoicacid (EPA) and docosahexaenoic acid (DHA)) inhibited the activities of eukaryotic pols andtopos in vitro, and the inhibitory effect of conjugated fatty acids converted from EPA andDHA (cEPA and cDHA) on pols and topos was stronger than that of normal EPA and DHA.cEPA and cDHA did not affect the activities of plant and prokaryotic pols or other DNAmetabolic enzymes tested. cEPA was a stronger inhibitor than cDHA with IC50 values formammalian pols and human topos of 11.0 - 31.8 and 0.5 - 2.5 μM, respectively. cEPAinhibited the proliferation of two human leukemia cell lines, NALM-6, which is a p53-wildtype, and HL-60, which is a p53-null mutant, and the inhibitory effect was stronger than thatof normal EPA. In both cell lines, cEPA arrested in the G1 phase, and increased cyclin Eprotein levels, indicating that it blocks the primary step of in vivo DNA replication byinhibiting the activity of replicative pols rather than topos. DNA replication-relatedproteins, such as RPA70, ATR and phosphorylated-Chk1/2, were increased by cEPAtreatment in the cell lines, suggesting that cEPA led to DNA replication fork stressinhibiting the activities of pols and topos, and the ATR-dependent DNA damage response pathway could respond to the inhibitor of DNA replication. The compound induced cellapoptosis through both p53-dependent and p53-independent pathways in cell lines NALM-6and HL-60, respectively. These results suggested the therapeutic potential of conjugatedPUFA, such as cEPA, as a leading anti-cancer compound that inhibited pols and toposactivities.

Abstract: The synthesized cobalt(II) complex, CoPNBDENA and the binding of thiscomplex with sheep genomic DNA were investigated by UV–Visible absorption andviscosity techniques. Also the interaction of sheep genomic DNA with the complex wasstudied using the agarose gel electrophoresis method. The results indicated that thecomplex interacted with DNA. The nature of the binding seemed to be mainly anelectrostatic interaction between DNA and the cobalt(II) complex. Other binding modessuch as hydrogen bonds may also exist in this system. In this study, after the interaction ofDNA– CoPNBDENA, it was observed that the migration of the DNA band became slow asthe amount of cobalt(II) complex was increased. This clearly demonstrates that theCoPNBDENA complex neutralizes the negative charges of DNA.

Abstract: Although much has been discovered, discussed and written as to problems ofcontamination by various military unique compounds, particularly by the nitrogen basedenergetics (NOCs), remaining problems dictate further evaluation of actual and potentialrisk to the environment by these energetics and their derivatives and metabolites throughdetermination of their environmental impact—transport, fate and toxicity. This workcomprises an effort to understand structural relationships and degradation mechanisms ofcurrent and emerging explosives, including nitroaromatic; cyclic and cage cyclic nitramine;and a nitrocubane. This review of our computational chemistry and spectroscopic researchdescribes and compares competitive degradation mechanisms by free radical oxidative,reductive and alkali hydrolysis, relating them, when possible, to environmental risk.

Abstract: Several quantum-mechanics-based descriptors were derived for a diverse set of48 organic compounds using AM1, PM3, HF/6-31 G, and DFT-B3LYP/6-31 G (d) level ofthe theory. LC₅₀ values of acute toxicity of the compounds were correlated to the fatheadminnow and predicted using calculated descriptors by employing ComprehensiveDescriptors for Structural and Statistical Analysis (CODESSA) program. The heuristicmethod, implemented in the CODESSA program for selecting the ‘best’ regression model,was applied to a pre-selection of the most-representative descriptors by sequentiallyeliminating descriptors that did not satisfy a certain level of statistical criterion. First model,statistically, the most significant one has been drawn up with the help of DFT calculationsin which the squared correlation coefficient R² is 0.85, and the squared cross-validationcorrelation coefficient 2CV R is 0.79. Second model, which has been drawn up with the helpof HF calculations, has its statistical quality very close to the DFT-based one and in thismodel value of R² is 0.84 and that of R²_CV is 0.78. Third and fourth models have been drawnup with the help of AM1 and PM3 calculations, respectively. The values of R² and R²_CV in thethird case are correspondingly 0.79 and 0.66, whereas in the fourth case they are 0.78 and0.65 respectively. Results of this study clearly demonstrate that for the calculations of descriptors in modeling of acute toxicity of organic compounds to the fathead minnow, firstprincipal methods are much more useful than semi-empirical methods.Keywords: Comparative QSTR; fathead minnow; acute toxicity; DFT; HF;