In addition to a wide range of adverse effects on human health, toxic metals such as cadmium, arsenic and nickel can also promote carcinogenesis. The toxicological properties of these metals are partly related to generation of reactive oxygen species (ROS) that can induce DNA damage and trigger redox-dependent transcription factors. The precise mechanisms that induce oxidative stress are not fu...

Chemoprevention is considered a new strategy in fighting diverse types of cancer. To influence cancer development and progression, signaling pathways, for example, enzymes like cyclooxygenase-2, transcription factors like NF-kB, and several metabolic processes leading to activation or deactivation of carcinogenic agents, are envisaged as promising approaches. Cytochrome P450 (CYP) enzymes activ...

The present study reports a novel supramolecular photochemical reaction that focuses on the direct electronic interactions between a host reaction substrate and guest metal salts. The reaction pathways in the photochemical reactions of quinone derivatives bearing a methoxy group and a long oligoether sidearm QEn (n = 0 and 3) with tetramethylethylene (TME) are changed upon noncovalent complexat...

The reactions of glutathione (GSH) with polychlorinated biphenyl (PCB) quinones having different degrees of chlorination on the quinone ring were examined. EPR spectroscopy and MS revealed 2 types of reactions yielding different products: (i) a nonenzymatic, nucleophilic displacement of chlorine on the quinone ring yielding a glutathiylated conjugated quinone and (ii) Michael addition of GSH to...

In termites, as in many social insects, some individuals specialize in colony defense, developing diverse weaponry. As workers of the termite Neocapritermes taracua (Termitidae: Termitinae) age, their efficiency to perform general tasks decreases, while they accumulate defensive secretions and increase their readiness to fight. This defensive mechanism involves self-sacrifice through body ruptu...

Melanins are a group of complex pigments of biological origin, widely spread in all species from fungi to man. Among diverse types of melanins, the human melanins, eumelanins, are brown or black nitrogen-containing pigments, mostly known for their photoprotective properties in human skin. We have undertaken theoretical studies aimed to understand absorption spectra of eumelanins and their chemi...

Metal ions are known to lie in close proximity with these species in biological systems, thus resulting in immediate interaction. The two coupled, metal and organic redox centers have been found to participate in several biological processes such as, the oxidative maintenance of biological amine levels, (Klinman, 1996) tissue (collagen and elastin) formation, (Klinman, 1996) photosynthesis (Cal...