Study On The Pharmacological Activity Of Deinoxanthin From Deinococcus Radiodurans

Deinococcus radiodurans is famous for its extraordinary tolerance toγ-ray, UV-radiation,oxidizing agents and desiccation, and is one of the most radiation-resistant organisms on the earth.D. radiodurans can produce carotenoids. Carotenoids are recognized as playing an important role in the prevention of human diseases and maintaining good health. The main mechanisms by which they afford their beneficial effects including cell growth regulation, modulating gene expression immune response and acting as modulators of drug metabolizing enzymes.Also the antioxidant properties of carotenoids do a lot in these processes. Deinoxanthin, an unique carotenoid, is the major carotenoid synthesized by D. radiodurans. It has significantly stronger scavenging ability on H2O2 and singlet oxygen than other carotenes including lycopene andβ-carotene. Comparing with other tested carotenoids, the higher antioxidant effect of deinoxanthin may be attributed to its distinct chemical structure which has an extended conjugated double bonds and the presence of a hydroxyl group at C-1'position.Reactive oxygen species (ROS) induced by water radiolysis is the most important cause of DNA damage. The ROS scavenging system in D. radiodurans consists of antioxidant enzymes and nonenzymic antioxidants. As nonenzymic antioxidants, carotenoids are efficient scavengers of ROS and play an important role in the resistant mechanism of D. radiodurans.However, neither the effect of the carotenoids produced by D. radiodurans on biomacromolecules such as proteins, nor their potential pharmacology value has been evaluated. In the present study, purification and pharmacology function analysis of deinoxanthin were performed.1. On the basis of investigations of carotenogenesis and the recent progress toward identifying carotenoid biosynthetic enzymes and pathways in Deinococcus radiodurans, we constructed efficiently expression plasmids,such as pET28I,pUC 19-sdY and pUC 19-OsdY. Using the method of homologous genetic recombination, CrtI, CrtY and CrtO gens were transformed into E. coli. And then, we investigated the fermentation conditions including pH, culture medium composition for the genetic engeering strains. 2.Deinoxanthin, the major carotenoid of D. radiodurans, was isolated and purified. However, the solution of deinoxanthin is unstable to light and oxygen. The present study aims to investigating the effect of different delivery vehicles on the cellular uptake and the pharmacological effect of deinoxanthin in delivery vehicles on A2780 human ovarian cancer cells. The different effects of tetrahydrofuran (THF) and fetal bovine serum (FBS) on the cellular uptake of deinoxanthin were compared. Results demonstrated that FBS with a dilution fold of 10 was superior to THF on improving the stability and cellular uptake of deinoxanthin. Also, we found that FBS inhibited the growth of cancer cells significantly and showed a dose-dependent inhibitive effect at the concentrations higher than 1μmol/L.3. In previous work, deinoxanthin was shown to protect DNA against damage as it was a more efficient scavenger of H2O2 and singlet oxygen than other carotenes. In this part,we found. carotenoids from D. radiodurans R1ex scavenged more DPPH-radical than other carotenes. Analysis of the mutant strain that is deficient in carotenoid biosynthesis constructed by targeted mutagenesis of the phytoene synthase gene showed that the intracellular level of protein oxidation in mutant was significantly greater than that in the wild type following the treatment with H2O2. This suggested that carotenoids in D. radiodurans contribute to cell resistance against oxidative stress. Furthermore, the purified major carotenoid product (deinoxanthin) from the wild type showed a greater inhibition of oxidative damage in bovine serum albumin than lycopene or lutein.In conclusion, our results demonstrated that carotenoid (deinoxanthin) can prevent protein oxidation, and might contribute to the resistance of D. radiodurans to cell damage. Deinoxanthin significantly inhibit the growth of cancer cells, suggesting that it might have the potential of pharmacological values.