Chiral detection of carotenoid assemblies.
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)-beta,kappa-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.
Zsila
F
F
Department of Molecular Pharmacology, Institute of Chemistry, CRC, Budapest, POB 17, H-1525 Hungary.
Bikádi
Z
Z
Deli
J
J
Simonyi
M
M
D002338:Carotenoids / Q000737:chemistry*; D002942:Circular Dichroism; D003198:Computer Simulation; D000431:Ethanol / Q000737:chemistry; D008958:Models, Molecular; D012996:Solutions; D013056:Spectrophotometry, Ultraviolet; D013237:Stereoisomerism
D012996:Solutions; D002338:Carotenoids; D000431:Ethanol