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Dr. Sebastiano Venturi via Tre Genghe n. 2;  47864 PENNABILLI (RN) ;  (Italy) Tel : (+39) 0541 928205. E-mail : venturi.sebastiano@gmail.com C.V. Updated March 12, 2011

SELENIUM AND IODIDE: ANCIENT ANTIOXIDANTS OF CELLULAR MEMBRANE LIPIDS?
  7th International  Symposium on Selenium in Biology and Medicine. Venezia (Italy) Oct.1-5, 2000 Abstract Book,  P-88  :134

Massimo Cocchi and ¹Sebastiano Venturi.

Scottish Agricultural College

¹Servizio d’Igiene USL n.1- Novafeltria (PS), Italy

Over three billion years ago, blue-green algae (Cyanobacteria) ancestors of eukaryotic algae which contain high amount of iodine and selenium, were the first living cells to produce oxygen in the terrestrial atmosphere. So, algal membrane lipids and polyunsaturated fatty acids (PUFAs) required a protective antioxidant action in which iodide and selenium might have had this specific role. In fact, iodides and selenium are greatly available in seawater, where algal phytoplankton, the basis of marine food-chain, which is rich in PUFAs, acts as a biological accumulator of both of these trace elements (1). PUFAs and in particular Arachidonic Acid (AA, omega-6) and Docosahexaenoic Acid (DHA, omega-3) are essential for animal development and for cell membrane structure and function. DHA itself stimulates in cells the activites of catalase, glutatione-peroxidase and GSH.

Recently, we have hypothesised that iodide might have an ancestral antioxidant function in all iodide-concentrating cells from primitive algae to more recent vertebrates (2). There is an interesting chemical gradient of electronegativity, according to Pauling-scale units, among Oxygen (3.44), Iodide (2.66), Selenium (2.55), which may explain their role in electron tranfert into oxygen of H2O2 via peroxidase enzymes. In the cells iodide acts as an electron donor in the presence of H2O2 and peroxidase, and the remaining iodine atom readily iodinates the tyrosine or the histidine or some specific PUFA, and so, it neutralizes its oxidant power. Iodine can add to double bonds of PUFAs, making them less reactive to free oxygen radicals. These iodolidips (iodo-lactone, iodo-AA, iodo-DHA) have structural and probably metabolic functions in vegetable and animal cells.

In our current research we are studying iodide, selenium and PUFAs in different conditions during chick embryo development (3).

References

1 Cann SA et al. 2000. Hypothesis: iodine, selenium and the development of breast cancer. Cancer

Causes Control; 11(2):121-7

2 Venturi S et al. 2000. Role of iodine in evolution and carcinogenesis of thyroid, breast and stomach. Advances in Clinical Pathology; 4, 1:11-17

3. Cocchi M and Venturi S. 2000. Iodide, antioxidant function and omega-6 and omega-3 fatty acids. Progress in Nutrition; 2, 1:15-19

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