ULTRA VIOLET-INDUCED CELLULAR INJURY AND POSSIBLE PARTICIPATION OF SULFUR-CONTAINING GLYCOLIPID IN ITS PREVENTION

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A purpose of the present research was to examine whether Euglena gracilis Z as a plant model and E.gracilis SMZ as animal model might show different response under oxidative stress or not. And if any difference could be found, the possible participation of sulfur containing glycolipid, sulfoquinovosyldiglyceride (SQDG) was studied. Firstly, the extent of UV-B-induced lipid peroxidation on strains of Z and SMZ grown under illumination, and those grown in the dark were compared by measuring intracellular lipid peroxide level on fluorescence microscopy using photon probe. The Z strain grown under illumination was found most resistant against UV-B-induced cell damage. SQDG by itself was found in liposomal system to exhibit radical scavenger, however, it rather stimulated UV-B-induced lipid peroxidation. In vivo, the mode of antioxidative effect must be exerted in complicated. The levels of 8-OH-dG in Z and SMZ strains grown under light and/or dark was compared. Its level in Z grown under illumination was the lowest among examined. Interestingly, 8-OH-dG level of Euglena was far higher (more than two orders of magnitude higher of ten to the power) than that of human, the level of 8-OH-dG of Euglena reflects close link to the extent of aging. It may be due to short generation time of Euglena as short as 24 hours. It seems likely that Euglena cell would be a useful tool for aging research and its prevention. In conclusion, SQDG would exhibit antioxidative role in two ways ; i.e., radical scavenger against radical-induced peroxidation and peroxidized more preferentially than other biomembrane lipid so as to be eliminated and degraded by antioxidative enzymes such as Ascorbate Peroxidase.