Tannin-producing structures in Dimorphandra mollis Benth. and Stryphnodendron adstringens (Mart.) Coville (Leguminosae)

Abstract

Dimorphandra mollis (Cesapinoideae)and Stryphnodendron adstringens are commonly known as barbatimão. Their medicine properties (cicatrizant and astringent) are impute to the hight tannin concentration present in their barks which are extensively used in folk medicine. Tannis are involved in defense mechanism against herbivory and in the foliar movement in some legumes. They are accumulated in the vacuoles of a isolated plant cell, named idioblasts, or constitute pluricellular structures, as trichomes, ducts and secretory cavities. The aim of this study is localize in situ the tanniniferous substances found in the vegetative organ extracts of D. mollis and S. adstringens , to classify the tannin-producing structures, as well as to understand the way these substances are produced at the subcellular level. Then, origin and developmental stages of the tannin-producing structure will be compared between leaf and bark and among three species. Distribution and production of tannins will be accessed at two levels: (a) between bark and leaf of the same species, aiming an alternative use of the leaves for tannin extraction, contributing to the species and their environment conservation; (b) between Dimorphandra and Stryphnodendron species - aiming to study the taxonomic value of the tannin-producing structures in this group. For that, materials will be submitted to usual techniques on light (histology) and electron (ultra structure) microscopies. A recently produced phylogeny of Leguminosae, based in molecular data, indicates that Caesalpinoideae does not constitute a natural group, i. e., its circumscription was not supported. Therefore, morphological and chemical characters, in special those of secretory structures, can present taxonomic value to this family. In addition, the comparative study of the tannin-producing structures can supply information for the sustainable employ of the "Barbatimão" as a source of tannin. We hope that leaves are utilized instead of bark, helping with the conservation of these species, especially the endangered species S. adstringens.