Composition of epicuticular wax layer of two species of Mandevilla (Apocynoideae, Apocynaceae) from Rio de Janeiro, Brazil

Abstract

The chemical composition of epicuticular waxes of Mandevilla guanabarica and Mandevilla moricandiana was comparatively analyzed by extraction in n-hexane and chloroform. The mean wax content per unit of leaf area in the n-hexane extract was about 13–30 μg cm−2 for M. guanabarica, containing 20–28% n-alkanes and 55–63% triterpenes; for M. mori-candiana, the mean content was 19 μg cm−2, containing 73% n-alkanes and 14% triterpenes. In the chloroform extract, the wax yield was 40–80 μg cm−2 for M. guanabarica, with about 9–11% n-alkanes and 75–82% triterpenes; while for M. moricandiana, the wax yield was 110 μg cm−2, with 52% n-alkanes and 14% triterpenes. The major compounds identified were lupeol, pentacyclic triterpenes of the α- and β-amyrin class, and n-alkanes such as nonacosane, hentriacontane and tritriacontane. These results indicate that the quantitative chemical profiles of epicuticular waxes of M. guanabarica and M. moricandiana are distinct and could be used as an additional feature in taxonomic identification.