Sterole in Blättern und Chloroplasten

Abstract

The nature and quantity of sterols in leaves and chloroplasts of Spinacia oleracea, Antirrhinum majus, and Allium porrum were determined. From dried leaves 0.05 - 0.18% free and esterified sterols were isolated, and 0.04-0.09% from chloroplasts. Although approximately half the lipids of leaves is localized in chloroplasts we found no more than a quarter of leaf sterols in the chloroplasts. The mixture of sterols contains a major sterol and minor sterols in these species. In spinach a-spinasterol is the major sterol and in Antirrhinum and Allium β-sitosterol. Moreover, we established Δ7-stigmastenol and cholesterol in spinach. Besides for free sterols, leaves contain sterol esters and glycosides. Palmitic acid is the binding partner in the sterol esters of spinach, and glucose and mannose are the binding partners in sterol glycosides. Chloroplasts contain the same sterols as leaves do. Only a trace of sterol glycosides could be detected in chloroplast preparations.