Biol. Pharm. Bull. 28(1) 47—52 (2005)

cal antioxidant that occurs naturally in a wide variety of living organisms. ASX has shown some pharmacological activities, including anti-oxidative, anti-tumor and anti-cancer, anti-inflammatory, anti-diabetic and immunomodulatory activities. It was reported to exhibit strong free radical scavenging activity and to protect cells against lipid peroxidation and the oxidative damage of low-density lipoproteins (LDL)-cholesterol and of the cell membrane. The role of the oxidation of unsaturated lipids in LDL and its complex sequelae in the pathogenesis of a number of cardiovascular diseases (CVD) has been widely investigated. Epidemiological and clinical data have indicated that dietary antioxidants, such as carotenoids, might protect against CVD and help to prevent several human diseases such as prostate cancer and inflammatory disorders. In this study, we first investigated the effects of ASX on hypertension in rats in vivo. A dietary product of astaxanthin (ASX-O) was used in this experiment. The present study was also designed to investigate mechanisms of action and effects of ASX-O on vascular reactivity in rat aortic preparations. We evaluated the effects of ASX-O on the aorta in relation to the endothelium and nitric oxide (NO). Moreover, the effects of ASX-O administration on behavior were studied in mice. To the best of our knowledge, this is the first report on the antihypertensive and neuroprotective effects of ASX in experimental animals; however a mixture composition for lowering BP consisting of a group of carotenoids has previously been cited.