Comparison of selenium and sulfur analogs in cancer prevention

Abstract

Several organoselenium compounds have been shown to have powerful anticarcinogenic activity. In view of certain similarities between selenium and sulfur biochemistry, we have evaluated the chemopreventive efficacy of three pairs of analogs using the 7,12-dimethylbenz[a]anthracene (DMBA)-induced mammary tumor model in rats. The compounds tested were selenocystamine/cysteamine, Semethylselenocysteine/S-methylcysteine, selenobetaine/sulfobetaine. In the first study, each agent was added to the basal AIN-76A diet and was given before and continued after DMBA treatment until the end. All three selenium compounds were active; a 50% inhibition was achieved at approximately 25 x 10(-6) mol/kg with Se-methylselenocysteine and selenobetaine and at approximately 40 x 10(-6) mol/kg with selenocystamine. In the sulfur series, only cysteamine and S-methylcysteine produced anticancer activity, and the levels required for comparable responses were 500- to 750-fold higher compared to the corresponding selenium analogs. Sulfobetaine was inactive even when present at near maximally tolerated levels. In the second study, Se-methylselenocysteine and S-methylcysteine were chosen for further examination during the initiation and post-initiation phases of mammary carcinogenesis. Se-Methylselenocysteine was effective when it was given either before or after DMBA administration. In contrast, S-methylcysteine was effective only after DMBA treatment. Thus, compared to the sulfur structural analogs, selenium compounds are much more active in cancer protection and may have a multi-modal mechanism in preventing cellular transformation as well as in delaying or inhibiting the expression of malignancy after carcinogen exposure.

Selenium and Vitamin E Improve the <i>In Vitro</i> Maturation, Fertilization and Culture to Blastocyst of Porcine Oocytes

“…These compounds might be better precursors for generating methylated Se intermediates. In general, Se undergoes reductive metabolism and forms methylated excretory products, whereas sulfur tends to form more oxidized excretory products [35]. The optimum concentration of Se and Vit-E used in the present study is similar to the concentration used by porcine embryos and sperm [12,36].…”

Physiological characteristics of selenite uptake by maize roots in response to different pH levels

“…It has also been demonstrated that certain Se-containing compounds (e.g., MeSeCys, GGMeSeCys, and SeMet) are effective chemoprotective agents, reducing the incidence of breast, liver, prostate, and colorectal cancers in model systems (Ip and Ganther, 1992;Vadgama et al, 2000;Whanger, 2002Whanger, , 2004. Plant foods are important sources of dietary Se, and low dietary intake of Se may increase the risk of cardiovascular disease, muscle disorders, and cancer (Salonen et al, 1982;Ip et al, 2000;Rajpathak et al, 2005).…”

Synthesis and antitumor properties of selenocoxib‐1 against rat prostate adenocarcinoma cells

“…6 Previous reports in literature have demonstrated that selenium compounds are superior antitumor agents to their corresponding sulfur compounds. 34,35 In particular, seleniumenriched garlic was superior to regular garlic, 36 Se-methylselenocysteine was better than S-methylcysteine, 37 and diallyl selenide was better than diallyl sulfide 38 in mammary cancer prevention. Isoselenocyanates have increased in vitro potency …”