Morfoanatomia foliar e espectrofotometria de infravermelho com transformada de Fourier (FTIR) como um suporte à taxonomia e ao controle de qualidade das etnodrogas das espécies de Solanum seções Erythrotrichum Child, Micracantha Dunal e Polytrichum Child (Solanaceae), pro parte

Abstract

A morphoanatomic study and a Fourier-transform infrared spectroscopy (FTIR) and multivariate analysis were performed on leaves of eleven species of Solanum subg. Leptostemonum, belonging to the sections Erytrhrotrichum, Micracantha and Polytrichum, in order to find additional support to the taxonomy of these sections and also to the quality control of their ethnodrugs. Samples of fresh and dry specimens were used for the morphological studies. Dissociations of fragments of leaf blades were performed for the epidermis analysis, following the usual protocol in anatomy, in addition to scanning electron microscopy. For the mesophyll, midrib and petiole were performed cross sections, performed by free hand, stained with a solution of astra blue and safranin, analyzed and photographed under the light microscopy. A hierarchical grouping analysis was performed with a matrix of 61 characters. For IR spectrophotometry, the samples were prepared directly by pressing on a KBr pellets, placed and analyzed on the support on the Cary 630 FTIR Spectrometer. As results, it was observed that some characters were common to the studied species: leaves with discolored blades, epidermis with sinuous anticlinal walls, dorsiventral mesophyll, biconvex midrib with a central bicollateral bundle. However, some characters were distinctive for each section: in Erythrotrichum, predominated the elliptic to oval-elliptic leaf blade, the petioles are cylindrical and canaliculate, semicircular to circular with lateral projections; in Micracantha, acute-elliptic to lanceolate-elliptic leaf blades, canaliculate petiole with oval, circular or semicircular contour; in Polytrichum the oval-elliptic to oval-cordate leaf blade, cylindrical or winged petiole, circular or semicircular with or without lateral projections. The phenogram generated from the morpho- anatomical characters have nine artificial clusters and reunited the species into two large groups: Erythrotrichum-Micracantha and Polytrichum. The FTIR spectra of visual inspection sampling were similar. Eight species showed peaks suggestive for phenolic esters and / or methyl esters and only one species for amides. The study revealed the importance of FTIR spectroscopy to distinguish complex groups of Solanum species, as well as highlighting relevant characters that can be used as an additional tool to the sectional and interspecific delimitations of the species studied, especially indument, epidermal morphology and trichomes, leaf margins and petioles, which constitute a set of characters that support the taxonomy of the sections studied and Solanum subg. Leptostemonum, and also contribute to the quality control of their ethnodrugs.