Algal carotenoids. Part 64. Structure and chemistry of 4-keto-19′-hexanoyloxyfucoxanthin with a novel carotenoid end group

Einar Skarstad Egeland; José Luis Garrido; Manuel Zapata; Miguel Angel Maestro; Synnøve Liaaen-Jensen

doi:10.1039/A910345G

Algal carotenoids. Part 64.¹ Structure and chemistry of 4-keto-19′-hexanoyloxyfucoxanthin with a novel carotenoid end group

Einar Skarstad Egeland,^a José Luis Garrido,^b Manuel Zapata,^c Miguel Angel Maestro^d and Synnøve Liaaen-Jensen*^a

* Corresponding authors

^a Organic Chemistry Laboratories, Department of Chemistry, Norwegian University of Science and Technology, Gløshaugen, Trondheim, Norway

^b Instituto de Investigacións Mariñas, C.S.I.C., Av. Eduardo Cabello 6, Vigo, Spain

^c Centro de Investigacións Mariñas, Consellería de Pesca-Xunta de Galicia, Apdo. 13, Vilanova de Arousa, Spain

^d Servicios Xerais de Apoio á Investigación, Universidade da Coruña, Campus da Zapateira, Coruña, Spain

Abstract

The structural elucidation of a new carotenoid 4-keto-19′-hexanoyloxyfucoxanthin 5 from Emiliania huxleyi is documented by chromatographic (HPLC, TLC), spectroscopic (VIS, EIMS, FABMS, FABMSMS, 2D ¹H NMR) and chemical evidence. The novel carotenoid end group exhibits particular spectroscopic and chemical properties. In particular the reactions with base and acid are investigated.

Due to a very weak molecular ion upon electron impact and facile cleavage to paracentrone 20 related fragments, the new carotenoid was previously misidentified as 19′-hexanoyloxyparacentrone 3-acetate 8, also found in other prymnesiophytes (haptophytes).

This novel carotenoid readily undergoes cleavage to a C₃₁-skeletal paracentrone 20 related product upon storage, preferably in methanol solution.

The new end group represents a plausible precursor for C₃₁-skeletal methyl ketone apocarotenoid metabolites in animals, and differs from the previously suggested precursor.

Article information

https://doi.org/10.1039/A910345G

Article type

Paper

Submitted

20 Dec 1999

Accepted

22 Feb 2000

First published

29 Mar 2000

Download Citation

J. Chem. Soc., Perkin Trans. 1, 2000, 1223-1230

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