Múltiplas abordagens usando espectrometria de massas, estudos de desreplicação, e métodos quimiométricos suportadas no desenvolvimento de estratégias para distinção, agrupamento e descoberta de compostos bioativos de espécies de Solanum subg. Leptostemonum (Solanaceae)

Abstract

Morphological and phylogenetic studies have not been sufficient to clarify the relationships between Solanum species and define limits between subordinate groups, such as the clades of the subgenus Leptostemonum. Thus, there is a need to use new approaches, such as the analysis of secondary metabolites, based on modern analytical methodologies and techniques, which can provide support to elucidate relationships and define interspecific and infrageneric limits, especially in relation to Brazilian species. Despite Brazil being recognized as one of the centers of diversity and endemism of the subgenus, information about its diversity is little known, with the occurrence of endemic species that have never been studied or included in morphological, phylogenetic and chemosystematic treatments already carried out. Many of them also have their chemical composition and biological potential completely unexplored. In the present study, several approaches are established, supported by the development of methodologies and strategies for screening and identification of metabolites (dereplication) of dried herbarium specimens, extract and fractions of the fresh plant, based on chemical profile studies by HPLC-MS and aided by statistical methods. In addition to using HPLC-MS data for the guided isolation of new compounds with bioactive potential. Thus, this work is divided into 4 chapters: In chapter one, metabolites from the aerial parts of Solanum jabrense Agra and Nee were analyzed, with the aid of molecular networks, with the aim of proving the hypothesis that studies using HPLC-MS and herbarium specimens are capable of determining the chemical profile of the species and identifying the presence of metabolites that can be used as distinctive metabolites and/or chemosystematic markers. This plant was chosen as a model due to its endemism and availability of material in our laboratory, in addition to being little explored regarding its bioactive potential. The second chapter describes the development and implementation of the HPLC-MS-based methodology for the analysis of the chemical profile of 72 herbarium specimens of Solanum subgenus Leptostemonum, verifying whether this approach, together with statistical methods, can be useful to distinguish and classify the species used, assisting in the chemotaxonomy of the subgenus Leptostemonum, comparing the groupings obtained in the statistical analyses to the existing taxonomic classifications. In chapter three, the plant material of S. jabrense was collected and the same extraction methodology was reproduced, on a proportional scale, carried out for the herbarium specimens to prepare the crude hydroalcoholic extract. The crude extract and the alkaloid-rich fraction obtained by precipitation of the crude extract were analyzed by HPLC-MS to determine the chemical content and compare it with herbarium specimens, and tested for larvicidal and repellent activity against Aedes aegypti. In chapter four, three chemical molecules with bioactive potential were isolated from the hydroalcoholic extract of S. jabrense, one new and two previously known. This is the first report of the three structures for the species. These isolated substances will later be used as seeds in dereplication studies.