CHARACTERIZATION OF ISOLATED HEDERA HELIX LEAF CUTICLE BY CARBON-13 NUCLEAR MAGNETIC RESONANCE

摘要

High resolution C-13 nuclear magnetic resonance was used to characterize isolated ivy (Hedera helix L.) leaf cuticle and its main components obtained after chloroform extraction and hydrolysis. Two types of samples have been studied. Solid samples consisted of whole isolated cuticle fragments, on the one hand, and the insoluble residue obtained after chloroform extraction and acid-hydrolysis, attributed to the cutin polymer, on the other. Their spectra were composed of a limited number of resonances corresponding to methylene groups, tertiary and quaternary carbons assigned to insaturations and ester or carbonyl functions. The liquid samples were wax solutions, cutin monomer extracts and acid-hydrolyzed components. The great diversity displayed by their spectra enables many functional groups to be identified. The spectrum resonances of the cutin monomeric fraction were characteristic of methylene groups in great proportion, methyl groups, terminal and in chain hydroxylations, insaturations, carboxylic and carbonyl functions. The wax fraction spectrum was relatively simple showing mainly resonances of methyl and methylene groups corresponding to the constitutive long aliphatic chains of the cuticular waxes. In the spectrum of the soluble fraction extracted by acid-hydrolysis, four zones were distinguished, assigned to protonated and saturated carbons, oxygenated carbons, protonated and unsaturated carbons and unprotonated carbons. In addition to resonances expected for polysaccharides, this spectrum showed resonances unambiguously assigned to fatty acids. [References: 31]