Avaliação do perfil químico de Merremia cissoides e avaliação de seu potencial biológico

• Ano de defesa: 2025
• Autor(a) principal: Maciel, Laís de Souza
• Orientador(a): Thomasi, Sérgio Scherrer
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Lavras; Instituto de Ciências Naturais (ICN)
• Programa de Pós-Graduação: Programa de Pós-Graduação em Agroquímica
• País: brasil
• Palavras-chave em Português: Planta daninha; Merremia sp; Alelopatia; Metabólitos secundários; Weed; Allelopathy; Secondary metabolites.
• Área do conhecimento CNPq: Ciências Naturais
• Link de acesso: https://repositorio.ufla.br/handle/1/60346

Merremia cissoides is an annual herbaceous plant from tropical America, considered a weed due to its competition with several agricultural crops. In the literature, there are numerous reports of biological activities for the genus Merremia, attributed to the presence of secondary metabolites. This study aimed to evaluate the antioxidant and allelopathic activities of M. cissoides extracts, a species still little explored. In addition, it sought to investigate the chemical profile of the crude extract from the aerial parts of this species by LC-MS/MS, quantify the levels of phenolics and flavonoids in its extracts, and propose biosynthetic pathways for the main classes of secondary metabolites annotated. M. cissoides seeds were cultivated for three months, after which aerial parts and roots were collected for extraction in HPLC-grade methanol, assisted by ultraturrax. Antioxidant capacity was assessed using the DPPH radical, while allelopathic potential was determined by inhibition of germination and early growth of Amaranthus lividus seedlings. Phenolic compounds were quantified using the Folin-Ciocalteu reagent, and flavonoids were determined by the aluminum chloride method. The aerial extract was analyzed via LC-MS/MS, and the data processed on the Global Natural Products Social Molecular Networking (GNPS) online platform, in Molecular Networking experiments. The root extract exhibited natural herbicidal potential at 400 ppm, reducing the germination rate to 2% and inhibiting hypocotyl development by 87% and radicle growth by 85%. Regarding antioxidant activity, the aerial extract showed greater potential, with an IC50 of 58.53 ppm, a result close to values reported in the literature for species of the same genus, while the root extract presented an IC50 of 133.32. The levels of phenolics compounds (96.5 mg GAE/g) and flavonoids (60 QE/g) were higher in the aerial extracts, consistent with or exceeding values reported in other studies, whereas the roots showed lower concentrations, with 62.6 mg GAE/g and 11 QE/g, respectively. Among the metabolites identified, two were flavonoids (quercetin 3-glycoside and rutin), three coumarins, and one fatty acid, important classes also found in other species of the genus. These results revealed that Merremia cissoides has antioxidant and allelopathic potential, directly related to the secondary metabolites produced by this species, thus highlighting its importance in natural products research with agricultural and biological applications.