Intracellular localization of labelling of tocopherols with [U-14C]tyrosine in Calendula officinalis leaves.

The content of tocopherols in the cellular subfractions of C. officinalis leaves from plants kept in the light and dark was investigated. In addition to the previously detected alpha-, gamma- and delta-tocopherols a small amount of 7-monomethyltocol was found in the chloroplasts, mitochondria and microsomes of plants kept in the dark. Studies on the dynamics of labelling of tocopherols in the dark and in the light with [U-14C]tyrosine in the chloroplast, mitochondrial and microsomal fractions have shown that two isomers of monomethyltocol, i.e. 7- and 8-methyltocols are formed. gamma-Tocopherol originates from 7-MeT rather than from 8-MeT and is partly methylated to alpha-tocopherol and partly undergoes some unknown transformation. The light is not indispensable for condensation of aromatic ring with the phytyl chain, whereas it is indispensable for methylation of the aromatic ring of tocopherols.