46] Techniques for studying photoprotective function of carotenoid pigments

Abstract

This chapter describes how to perform experiments in various kinds of organisms to study the ability of carotenoid pigments to protect against photosensitization. These techniques can be used to determine if carotenoids of interest can give protection, as well as to study the mechanisms of protection. Carotenoid protection against photosensitization by either endogenous or exogenous photosensitizers can be easily studied in bacteria. For photobiological experiments to determine the protective ability of carotenoids, cultures of the wild type and mutant(s) to be studied are harvested in the logarithmic phase of growth, centrifuged, and resuspended in phosphate or Tris buffer to contain about 10 6 to 10 7 cells/ml. As far as mammals are concerned, various kinds of fibroblasts, including mammary cells and erythrocytes from protoporphyric patients have been studied; the former have been used to determine the ability of carotenoids to prevent various kinds of cellular and nuclear damage, and the latter to see if carotenoids can prevent photohemolysis. Continued studies of this most important function of carotenoids are well warranted.