Triterpenes in elms in Spain

Abstract

Diethyl ether-petroleum ether extracts were prepared from 49 samples of bark from four elm species (Ulmus glabra Hudson, Ulmus laevis Pall, Ulmus minor Miller, and Ulmus pumila L.) and hybrids from crosses between three of these species. Chemical analyses were performed by gas chromatography – mass spectrometry. Ten triterpenes and three sterols were identified. These compounds are discussed in terms of chemotaxonomy of the genus and identification of hybrids, and in relation to the differential attractivity for elm bark beetle feeding. Separation of the four pure species was successfully achieved by the use of the multivariate discriminant analysis. Ulmus minor × U. pumila hybrids were clearly segregated from their parental species, while U. minor × U. glabra trees were misclassified as U. minor by a multivariate discriminant analysis. Three compounds are described for the first time in the family Ulmaceae and two more in the genus Ulmus. Some of the triterpenes and sterols isolated only in U. glabra and U. laevis may be responsible for the deterrence of bark beetles to feed on these least preferred species.