Chemical profile of Stachytarpheta schottiana by LC-HRMS/MS dereplication and molecular networking

Abstract Restingas are extreme environments present in the Atlantic Rainforest biome. These ecosystems show peculiar characteristics, like sandy soil, high salinity, and high solar exposure, which brings scientific interest to their native species. Stachytarpheta schottiana is an endemic Brazilian species found in Jurubatiba Restinga, and just like other species of the genus Stachytarpheta, is used in folk medicine. In this paper, we describe, for the first time, 28 secondary metabolites from S. schottiana polar extract, among them iridoids, flavonoids, lignans and phenylethanoids, with the use of LC-HRMS/MS dereplication and molecular networking methodologies. Many of these compounds have not been described yet for the genus Stachytarpheta, like astragalin, taxifolin, lamiide and the lignans secondary metabolites class. Also, in this paper, High Speed Counter-Current Chromatography (HSCCC) isolation and Nuclear Magnetic Resonance (NMR) of two compounds were used to correct a misidentification in the dereplication procedure and to create seeds for molecular networking. Some of the suggested known compounds found in this work have had their biological activities described in the literature, such as the hepatoprotective activity of verbascoside, that matches those already related for the genus Stachytarpheta and for the folk use of Stachytarpheta schottiana itself. Resumo As restingas são ambientes com características extremas, que fazem parte do bioma da Mata Atlântica. Estes ambientes apresentam características peculiares, como solo arenoso e altas salinidade e exposição solar, o que torna as espécies presentes interessantes para a ciência. A espécie Stachytarpheta schottiana é endêmica do Brasil, presente em restingas e, assim como outras espécies do gênero, apresenta uso na medicina popular. Neste trabalho são descritos pela primeira vez 28 metabólitos secundários da espécie S. schottiana, como iridoides, lignanas, flavonoides e feniletanoides, através do uso de metodologias de desreplicação e molecular networking por LC-HRMS/MS. Destas substâncias, muitas sequer foram descritas para o gênero, como astragalina, taxifolina, lamiídeo e toda a classe de lignanas. Ainda neste trabalho, a Cromatografia Contracorrente de Alta Velocidade (High Speed Countercurrent Chromatography - HSCCC) e a Ressonância Magnética Nuclear (RMN) foram utilizadas para corrigir a identificação equivocada de duas substâncias, bem como para a criação de seeds que seriam posteriorment