The wide media coverage given recently to a study correlating higher
selenium levels with a reduced risk of advanced
prostate cancer is but the latest addition to a growing body of epidemiological findings which link dietary
selenium deficiency to diseases as diverse as
cancer, heart disease,
arthritis and
AIDS. Indeed,
selenium has a long history of association with human health and disease. Moreover, direct evidence is now emerging for specific beneficial effects of dietary
selenium supplementation. Thus, the pharmacology, biology and biochemistry of
selenium metabolism have become subjects of intense current interest. At the molecular level,
selenium (as
selenocysteine) is an essential component of the active sites of the
enzymes glutathione peroxidase,
iodothyronine 5'-deiodinase and mammalian
thioredoxin reductase, and is also present in several other mammalian
selenoproteins. Both
glutathione peroxidase and
thioredoxin reductase catalyse reactions essential to the protection of cellular components against oxidative and
free radical damage. As a consequence of the growing recognition of the important
biological role of
selenium, a number of novel
pharmaceutical agents, either
selenium-based or which target specific aspects of
selenium metabolism, are under development. Among these are orally active
selenium-based
antihypertensive agents, anticancer,
antiviral, immunosuppressive and
antimicrobial agents, and
organoselenium compounds which reduce oxidative tissue damage and oedema. It can be anticipated that as our understanding of the basic biology and biochemistry of
selenium increases, future efforts will uncover even more sophisticated approaches for the rational development of new
selenium-based
pharmaceutical agents.