Hydrophilic carotenoids

There are two approaches to synthesizing hydrophilic carotenoids (1) appending a hydrophilic group to the carotenoid scaffold (Foss et al. 2006a) or (2) joining a carotenoid to a hydrophilic compound, Scheme 3.3 (Foss et al. 2003). Whereas the Scheme 3.3 intuitively explains the difference, these techniques cannot be clearly separated in praxis the distinction may appear more emotional than conceptual. Both methods are habitually hampered by low yields, find their limits in the availability of functionalized carotenoids, and cause problems in the work-up procedure due to the amphiphilic character of the products. 

Hydrophilic carotenoids behave as typical amphiphiles. The contact angle of a water drop on a dry film of the phospholipid, 3.15, and its lifetime before spreading were signs of noticeable surfactant properties (Foss et al. 2005a). When amphiphiles are in contact with water, the molecules move to... 

The size of carotenoid aggregates have been determined by dynamic light scattering (DLS), a noninvasive method (Santos and Castanho 1996). DLS also allows distinguishing between spherical or cylindrical aggregates. The hydrodynamic radii rH of hydrophilic carotenoids in water are given in Table 3.1. Size and molecular structure of the bolaamphiphiles crocin, 3.7, and Cardax,... 

BIOPHYSICAL AND BIOLOGICAL ACTIVITY OF HYDROPHILIC CAROTENOIDS AND CAROTENOID AGGREGATES... 

Concentration of Hydrophilic Carotenoids in Water for Almost Complete Inhibition of Aqueous Superoxide Anion (02 )... 

Carotenoid aggregation has now been studied for over 77 years, but it is only in the last 7 years that numerous hydrophilic carotenoids have been synthesized. It is too early to predict whether research in hydrophilic carotenoids will become an established part within traditional carotenoid... 

Breukers S, 0pstad CL, Sliwka HR, and Partali V. 2009. Hydrophilic carotenoids Surface properties and aggregation behaviour of the potassium salt of the highly unsaturated diacid norbixin. Helvetica Chimica Acta 92(9) 1741-1747. 

Foss BJ. 2005. Synthesis and physical properties of hydrophilic carotenoid derivatives, PhD thesis, Norwegian University of Science and Technology, Trondheim, Norway. 

Foss BJ, Sliwka HR, Partali V, Nalum Naess S, Elgsaeter A, Mel0 TB, and Naqvi KR. 2005a. Hydrophilic carotenoids Surface properties and aggregation behavior of a highly unsaturated carotenoid lysophos-pholipid. Chemistry and Physics of Lipids 134(2) 85-96. 

Foss BJ, Nadolski G, and Lockwood SF. 2006a. Hydrophilic carotenoid amphiphiles Methods of synthesis and biological applications. Mini-Reviews in Medicinal Chemistry 6(9) 953-969. 

Sliwka HR, Melp TB, Foss BJ, Abdel-Hafez SH, Partali V, Nadolski G, Jackson H, and Lockwood SE. 2007. Electron- and energy-transfer properties of hydrophilic carotenoids. Chemistry—A European Journal 13(16) 4458 1466. 

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