现代营养学之自由基疾病.pptxVIP

会计学 1 现代营养学之自由基疾病 2 Main Content What Are Free Radicals Generation of Free Radicals in vitro Types of Free Radicals Damage of ROS to Biological Molecules Free Radicals and Diseases Defense against ROS Antioxidants 3 1 What Are Free Radicals Any molecule, atom, ion, group, containing one or more unpaired electrons (不成对电子) in the outmost shell (最外层) 4 5 Characteristics of Free Radicals High reactivity Tend to grab or lose a electron, forming a stable state. short lifespan (low concentration) At 37℃, free radicals have short half life (with exceptions): 1O2, O2·- , RO· 10-6s ·OH 10-9s R · 10-8s ROO · 10-2s NO · 6~50s 过氧化叔丁基 9500year 6 2 Generation of Free Radicals in vitro 2.1 Heating (Thermolysis热解) Frying (200℃) Oil molecules break into free radicals when the temperature is above 50℃ fried food →free radical; cooking → lung cancer Toasting Toasted bread and steamed bread caramelized sugar (焦糖) 7 2.2 Electromagnetic radiation (UV, X-ray, γ-ray) tyrosine (酪氨酸) in milk melanin (黑色素) and carotene (胡萝卜素 ) in the skin porphyrin (卟啉) in the blood generate free radical under radiation. 8 9 2.3 Redox reaction Fenton reaction 10 2.4 Chemical reaction of free radical Grab H A· + RH → AH + R· Electron transfer X·－ + Y → X + Y· － Addition reaction X· + RCH＝CHR → XRCH－CHR· 11 3 Types of Free Radicals 3.1 Reactive oxygen species (ROS) 活性氧 electron transport chain produce O2·－ O2 + e → O2·－ (超氧阴离子自由基) O2·－ + 2H+ + e → H2O2 H2O2 + H+ + e → H2O + HO· (羟自由基) HO· + H+ + e → H2O O2·－ weak oxidant H2O2 strong oxidant HO· very strong oxidant 12 3.2 Reactive nitrogen species (RNS) 活性氮 ·NO Important messenger in signal transduction ·NO + O·2－ → ONOO·－ 过氧亚硝基阴离子 ·NO + O2 → NO2· 13 3.3 React