Chiral detection of carotenoid assemblies

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Abstract
Carotenoid assemblies were produced by aqueous dilution of ethanolic solutions. UV/VIS and CD spectroscopy revealed the formation of J‐ and H‐types of aggregates of both right‐ and left‐handed kinds. Simulation of UV/VIS spectra of the aggregates showed characteristic differences between the two types. 6′‐Epimers of capsanthol ((all‐E,3R,3′S,5′R)‐β,κ‐carotene‐3,3′,6′‐triols) formed assemblies with increased chirality in dilute solution. While the absorption of 6′R‐capsanthol giving H‐type aggregate does not depend on the concentration, 6′S‐capsanthol yielding J‐type assembly showed concentration‐dependent absorption intensity. Dilute aggregate of 6′R‐capsanthol is characterized by an extremely large A value of −6,600. The transformation of J‐ to H‐type assembly was observed in the mixtures of the epimers producing an intermediate kind of aggregate. A hypothetical structure for H‐type assemblies is proposed. Chirality 13:446–453, 2001.
Funding Information
  • Hungarian National Scientific Fund (OTKA T 030271, T 033109)