Mechanism-based inactivation of dopamine beta-monooxygenase in adrenal chromaffin cells

Selenium-based drug design: rationale and therapeutic potential

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.

Evaluation of cardiovascular parameters of a selenium-based antihypertensive using pulsed Doppler ultrasound

The pharmacology of selenium is of much interest because selenium deficiency has been linked to cardiovascular diseases, cancer, and arthritis, and selenoenzymes are critical cellular antioxidants. We have previously reported that phenyl-2-aminoethylselenide (PAESe) and its derivatives represent a novel class of selenium-based antihypertensive agents that exhibit unique biochemical and pharmacologic properties. We now report on experiments designed to probe the hemodynamic mechanism of action of these compounds in spontaneously hypertensive rats (SHR). A noninvasive pulsed Doppler ultrasound probe was used to measure peak blood flow velocity in the aortic arch from the right second intercostal space. PAESe was found to increase peak aortic blood flow velocity (+44%), heart rate (+16%), and blood flow acceleration (+105%), while decreasing left ventricular ejection time (LVET) (-37%) concomitant with a decrease in mean arterial pressure (-54%). These results were compared with the known vasodilator hydralazine, which had similar effects on mean arterial pressure (MAP) and peak velocity but caused an increase in LVET (+42%) and a decrease in heart rate (-18%). Taken together, our results suggest that PAESe decreases blood pressure via a decrease in peripheral resistance, which overcomes the initial increase in heart rate and acceleration to give a net decrease in MAP.