Torularhodin as a Potent Scavenger against Peroxyl Radicals Isolated from a Soil Yeast, Rhodotorula glutinis

• Published in: Journal of Clinical Biochemistry and Nutrition Vol. 30; pp. 1 - 10
• Main Authors: SAKAKI, Hideyuki, NAKANISHI, Tatsuya, KOMEMUSHI, Sadao, NAMIKAWA, Koshi, MIKI, Wataru
• Format: Journal Article
• Language: English
• Published: Tokyo SOCIETY FOR FREE RADICAL RESEARCH JAPAN 2001; Institute of Applied Biochemistry; Japan Science and Technology Agency
• Subjects: Biological and medical sciences; Fundamental and applied biological sciences. Psychology; Growth, nutrition, metabolism, transports, enzymes. Molecular biology; lipid peroxidation; Microbiology; Mycology; peroxyl radicals; Rhodotorula glutinis; torularhodin; Yeast; Rhodotorula glutinis; Lipids; Biosynthesis; Antioxidant; lipid peroxidation; Biological activity; Free radical; Fungi; Soils; Microbial origin; torularhodin; peroxyl radicals; Fungi Imperfecti; Carotenoid; Thallophyta; Peroxidation
• ISSN: 0912-0009; 1880-5086
• DOI: 10.3164/jcbn.30.1

A soil yeast Rhodotorula glutinis increased torularhodin, that is one of the final products of carotenoid biosynthesis, when loading oxygen stress. In addition, a mutant of this yeast, which produces torularhodin more than β-carotene, gained resistance to oxygen stress. In this study, changes in carotenoids biosynthesis due to addition of 2, 2'-azobis(2-amidinopropane)-dihydrochloride (AAPH) as a peroxyl radicals generator were examined, and scavenging peroxyl radicals by torularhodin was also compared with that by β-carotene. When 0.01mM AAPH was added to the culture medium, the amount of carotenoids in yeast was increased. With increase in load by AAPH addition, torularhodin was consumed faster than β-carotene. After torularhodin decreased to the same concentration as AAPH free condition, β-carotene began to decrease. These results suggest that torularhodin was important in defense against oxidation loading by peroxyl radicals in R. glutinis. Scavenging of peroxyl radicals by torularhodin was evaluated using electron spin resonance. In the reaction of cumene hydroperoxide and 5, 10, 15, 20-tetraphenyl-21H, 23H-prophine iron (III) [TPP-Fe(III)], torularhodin exhibited concentration-dependent inhibition and its activity reached to 60% at 2.5mM. On the other hand, α-tocopherol exhibited strong activity at low concentrations with a maximum at 0.25mM, but its activity decreased above this concentration. Scavenging activity by torularhodin was greater than that of α-tocopherol at 2.5mM. In the pyrolysis of 2, 2′-azobisisobutyronnitrile (AIBN), both torularhodin and α-tocopherol exhibited concentration-dependent inhibition, but the scavenging activity of α-tocopherol was stronger. In addition, torularhodin inhibited lipid peroxide formation of rat brain homogenate in a concentration-dependent manner, and its inhibitory effect was stronger than that of α-tocopherol at concentration of 1μM and above. Torularhodin thus appears to be an effective scavenger of peroxyl radicals and to have strong antiperoxidative activity. The strong inhibition of lipid peroxidation by torularhodin at low concentration suggests that torularhodin has other activities in addition to peroxyl radical scavenging. R. glutinis tenders to increase the production of torularhodin by load oxygen stress, but this was because of its strong peroxyl radicals scavenging.