Selenite (H(2)SeO(3)) reacts with thiol compounds (RSH) under acidic conditions to form selenotrisulfides (RSSeSR, i.e. monoselenodithiols). The stoichiometry of the reaction is proposed as 4RSH+H(2)SeO(3)-->RSSeSR+RSSR+3H(2)O. Surprisingly, we found novel polynuclear selenium-containing compounds, i.e. polyselenodipenicillamines (PenSSe(2-4)SPen), in the reaction of D-penicillamine (PenSH) wit...

In the last ten years organocatalysis has emerged as an efficient and sustainable strategy for the asymmetric synthesis of chiral molecules. Optically active intermediates for novel interesting transformations are generated under mild and operationally simple conditions when selenium-containing compounds are used as reaction partners. The peculiar reactivity of organoselenium compounds has been...

Administration of selenium in humans has anticarcinogenic effects. However, the boundary between cancer-protecting and toxic levels of selenium is extremely narrow. The mechanisms of selenium toxicity need to be fully understood. In Saccharomyces cerevisiae, selenite in the millimolar range is well tolerated by cells. Here we show that the lethal dose of selenite is reduced to the micromolar ra...

The problem of selenium poisoning in farm animals has excited interest both from an academic and practical point of view. However, since the pioneering work of K. W. Franke and his coworkers, and the discovery of selenium in toxic grains by Robinson,’ relatively less attention has been paid to the mode of action of selenium compounds or means of detoxification. At an early date Hofmeister (1) r...

In a recent issue of the Journal, Taylor et al. (1) argued that selenium appears to play an important role not only in preventing various cancers but also in some degenerative diseases. Most of the data on the cancer prevention and cancer reduction effects of selenium are derived from epidemiologic studies (2). However, despite strong evidence for the importance of selenium in carcinogenesis, v...

The essential nature of selenium as well as its toxicity depend on the concentration and the chemical forms in which this element is present in environmental and biological samples. Dissolved inorganic selenium can be found in natural waters and soils as selenides, selenite and selenate. Organoselenium compounds that may be present in air, soils and plants are volatile methylselenides, trimethy...

background: critical macromolecules of cells such as dna are in exposure to damage of free radicals that induced from the interaction of ionizing radiation with biological systems. selenium and vitamin-e are natural compounds that have been shown to be a direct free radical scavenger. the aim of this study was to investigate the radioprotective effect of selenium and vitamin-e separately and sy...

Selenium and selenocompounds have attracted the attention and the efforts of scientists worldwide due to their promising potential applications in cancer prevention and/or treatment. Different organic selenocompounds, with diverse functional groups that contain selenium, have been reported to exhibit anticancer and/or chemopreventive activity. Among them, selenocyanates, selenoureas, selenoeste...

24 25 26 UN CO RR EC TE D PR Abstract. Selenium (Se) and arsenic are next-door neighbors on the periodic table and have similar chemical properties as metalloids. Arsenic antagonizes selenium toxicity in a number of organisms. Inorganic arsenic in drinking water is a human carcinogen while selenium compounds are anticarcinogenic in animals and humans. Our previous work showed that arsenite enha...

Selenium chemoprevention by apoptosis has been well studied, but it is not clear whether selenium can activate early barriers of tumorigenesis, namely senescence and DNA damage response. To test this hypothesis, we treated normal and cancerous cells with a gradient concentration of sodium selenite, methylseleninic acid and methylselenocysteine for 48 h, followed by a recovery of 1-7 days. Here ...