Poster Session:
5th International Functional Food Symposium, Hong Kong, Mar 10 & 11, 2011
EVOLUTION of DIETARY ANTIOXIDANTS Sebastiano Venturi and *Mattia Venturi, Servizio di Igiene, ASL n. 1, Pennabilli (RN) Italy,
*Department of Oral Sciences, University of Bologna, Italy.
SUMMARY We proposed that: The evolution of oxygen-producing cells was probably one of the most significant events in the history of life. Oxygen is a potent oxidant whose accumulation in terrestrial atmosphere resulted from the development of photosynthesis over three billion years ago, in blue-green algae (Cyanobacteria), which were the most primitive oxygenic photosynthetic organisms. Brown algae (seaweeds) accumulate inorganic iodine to more than 30,000 times the concentration of this element in seawater, up to levels as high as 1-4 % of dry weight. Protective endogenous antioxidant enzymes and exogenous dietary antioxidants helped to prevent oxidative damage (1-2). In particular, mineral inorganic antioxidants present in the primitive sea, as some reduced compounds of metalloproteins of Rubidium, Vanadium, Zinc, Iron, Copper, Molybdenum, Selenium and Iodine, which play an important role in electron transfer and in redox chemical reactions.
2 I- I2 + 2 e- (electrons) = - 0.54 Volt 2 I- + Peroxidase + H2O2 + 2 Tyrosine 2 Iodo-Tyrosine + H2O + 2 eand 2 e- + H2O2 + 2 H+ (of physiological water-solution) 2 H2O
iodide acts as a primitive electrondonor, through peroxidase, and has an ancestral antioxidant function in all iodide-concentrating cells from primitive marine algae to more recent terrestrial vertebrates.
2 I- + Peroxidase + H2O2 + Tyrosine, Histidine, Lipids, Carbons Iodo-Compounds + H2O + 2 e(antioxidants)
Iodo-Compounds: Iodo-Tyrosine, Iodo- Histidine, Iodo- Lipids,IodoCarbons
Antioxidant biochemical mechanism of iodides: the most ancient and the most powerful natural antioxidant mechanism of defence from poisonous reactive oxygen species. (Venturi S., 1985; Küpper F. et al., 2008; Packer L., 2008)
Most of these substances act in the cells as essential trace-elements in redox and antioxidant metalloenzymes. When about 500 million years ago plants and animals began to transfer from the sea to rivers and land, environmental deficiency of marine inorganic antioxidants and iodine, was a challenge to the evolution of terrestrial life (1). Terrestrial plants slowly optimized the production of “novel” endogenous organic antioxidants such as ascorbic acid, polyphenols, flavonoids, tocopherols etc. A few of these appeared more recently, in the last 200-50 million years ago, in fruits and flowers of angiosperm plants. In fact Angiosperms (the dominant type of plant today) and most of their antioxidant pigments evolved during the late Jurassic period. Plants employ antioxidants to defend their structures against reactive oxygen species (ROS) produced during photosynthesis (3), and formed a part of the human healthy diet. Chordates, the primitive vertebrates, began to use also the “novel” thyroidal follicles, as reservoir for iodine, and to use the thyroxine in order to transport antioxidant iodide. Iodide is one of the most abundant electron-rich essential element in the diet of marine and terrestrial organisms. Iodide, which acts as a primitive electrondonor through peroxidase enzymes, has an ancestral antioxidant function in all iodideconcentrating cells from primitive marine algae to more recent terrestrial vertebrates (2-3). Recently, we hypothesized that in the wide range of antioxidants, there might be an “evolutionary hierarchy”, where the most ancient might be more essential than the recent antioxidants in the developing stages of animal and human organisms (3).
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In the XIV Biennial Meeting of the Society for Free Radical Research International (18-22 October, 2008 – Beijing, China)
Professor Lester Packer (USA), the world's foremost antioxidant research scientist, gave a general introductory talk on the field of Oxidants and Antioxidants in Biology :
“ The 2nd half of the 20th century increasingly identified climatic conditions, environmental oxidative stressors, micronutrients, antioxidants, and lifestyle as important in oxygen biology.”
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Interestingly, the most powerful natural antioxidant is inorganic free iodine ions that acts in the unique environment of the apoplast of brown algae. If iodine were inside the cell its powerful antioxidant activity would totally prevent redox signaling hence through evolution iodine transport mechanisms necessarily were developed.”
REFERENCES 1)- Venturi S. et al. (2000). Environmental iodine deficiency: A challenge to the evolution of terrestrial life? Thyroid, 10, 727–9. 2)- Küpper F.C. et al. (2008). Iodide accumulation provides kelp with an inorganic antioxidant impacting atmospheric chemistry. Proc Natl Acad Sci USA. 13, 105(19), 6954–8. 3)- Venturi S. and Venturi, M. (2007). Evolution of Dietary Antioxidant Defences. European EpiMarker,11(3), 1–12.
Iodine in Evolution Over three billion years ago, blue-green algae were the first living Prokaryota to produce oxygen, halocarbons (such as CH3I) in the atmosphere, and also PUFAs in lipid membranes. About 500-600 million years ago, when also the primitive brain evolved in marine animals, thyroid cells originated from primitive gut in vertebrates, migrated and specialized in uptake and storage of iodocompounds in a novel follicular “thyroidal” structure, as a reservoir for iodine. 400-300 Mya some vertebrates evolved in amphibians and reptiles and transferred to I-deficient land. In vertebrates, thyroid hormones became active in the metamorphosis and thermogenesis for a better adaptation to terrestrial environment.
Sequence of 123-iodide total-body scintiscans of a woman after intravenous injection of 123iodide (half-life: 13 hours); (from left) respectively at 30 minutes, and at 6, 20 and 48 hours. The highest and rapid concentration of radio-iodide (in white) is evident in gastric mucosa of the stomach, salivary glands and oral mucosa. In gastric mucosa of the stomach, 131-iodide (half-life: 8 days) persists in scintiscans for more than 72 hours. In the thyroid, iodide-concentration is more progressive, as in a reservoir [from 1% (after 30 minutes) to 5.8 % (after 48 hours) of the total injected dose]. A high excretion of radio-iodide is observed in the urine.