The chemical composition of cuticular waxes from leaves of the gboma eggplant (Solanum macrocarpon L.)

The gboma eggplant (Solanum macrocarpon L.) is an important but still underutilized African green leafy vegetable. During the screening of the leaf cuticular waxes from Solanum plants, an unusual profile with elevated sterols and low hydrocarbon contents was detected for S. macrocarpon cv. UVPP. Detailed analysis of waxes from two cultivars has shown that sterols are made up of 19 and 32% of total wax, which has not yet been reported for any other plant species. The large content of phytosterols in surface lipids may generally reflect a overall high level of these compounds in the whole plant. Moreover, among the common plant triterpenes, we also found δ-amyrin, which was not previously reported as a component of leaf cuticular waxes. The hydrocarbon content was 6–13 times lower than in surface lipids of the closely related eggplant (Solanum melongena L.). Plant long-chain hydrocarbons are believed to be non-toxic for mammals. However, several cases of massive deposits of plant n-alkanes in the livers and lungs of animals and humans have been reported in the past. Certain plant features are promoted over others during the domestication process. We suggest that the hydrocarbon level in the surface lipids, which could affect the roughness and appearance of the leaves, might be one such characteristic.