Carotenoids in ripe green and in autumn senescing leaves of apple tree: I - Qualitative composition of free carotenoids,xanthophyll esters and fatty acids of esters

Abstract

By different chemical, spectral and chromatographic procedures seven carotenoids, two carotenes (α- and β-carotene) and five free xanthophylls (violaxanthin, lutein, antheraxanthin, zeaxanthin and neoxanthin) have been isolated and identified in green apple leaves. In autumn senescing leaves, besides the above seven carotenoids, the occurrence of at least seven xanthophyll esters has also been proved. Four esters, violaxanthin mono- and diester and lutein mono- and diester, (≥90% of total esters) and a minor component, neoxanthin triester, have been identified. Another minor component is most probably a monoester of antheraxanthin; the seventh, present in traces, has not been identified.

The fatty acids combined with the above xanthophyll esters have been analysed by gas-chromatography. The unusual presence of low molecular weight fatty acids, C7-C11, has been registered (1,5-8% of the total); caprilic and capric acids have been identified. Lauric acid with three minor homologous (2-7% and myristic acid (9-15%) are also present. The major component, palmitic acid, with palmitoleic and two other minor components, reaches 36-44%. In addition a remarkable presence of oleic acid (12-26%) has been observed together with stearic (8-10%), linolenic (5-6%), arachidic (0,7-2,5%) and linolenic-gadoleic acids (2,5-9,3%).