Stability of hydroalcoholic extracts of two species of guaco; Mikania glomerata SPRENG. and Mikania laevigata SCHULTZ. (Asteraceae), by UHPLC-MS

It is important to study the stability of plant extracts used as active ingredients in phytotherapic medicine, as degradation of the active principles directly affects the efficacy and safety of these products. Therefore, a stability study of the hydroalcoholic extract of the species: Mikania glomerata and Mikania laevigata was conducted in order to determine the speed of degradation and shelf life of these extracts, which are incorporated in cough syrup in Brazil. Leaves of both species were dried in an oven or by lyophilization (freeze-dried). Hydroalcoholic extracts underwent both accelerated stability study of six months and long-term stability study for 12 months. Samples were stored at different temperatures and every three months were analysed by ultra-high performance liquid chromatography-mass spectrometry (UHPLC-MS) to monitor their chemical profile, quantifying coumarin and chlorogenic acid. For all conditions of the study, a reduction of the content of the chemical marker of this species, coumarin, greater than 5% was observed, so a shelf life of two years cannot be assigned to the hydroalcoholic extracts of these species as observed in commercial extracts.

Radiation levels of UV-A and UV-B on growth parameters and coumarin content in guaco / Níveis de radiação UVA e UVB sobre parâmetros de crescimento e conteúdo de cumarina em guaco

ABSTRACT: Guaco is a medicinal plant species containing coumarin, a secondary metabolite whose concentration is influenced by various factors, such as the level of exposure to UVA (315-400 nm) and UVB (280-315 nm) radiation, age of the plant, and position of the storage organ in the plant. This study aimed to assess the effect of different blocking levels of UVA and UVB radiation on growth parameters and coumarin content of two guaco accessions. Treatments did not affect any of the growth parameters assessed, except leaf area. Coumarin content was higher in leaves collected from the upper canopy and with unblocked exposure to UVA and UVB.

RESUMO: Guaco é uma espécie medicinal que apresenta em sua composição a cumarina, um metabólito secundário cuja concentração no vegetal é influenciada por fatores como os níveis de radiação UV-A (315-400 nm) e UV-B (280-315 nm) incidentes, bem como pela idade e posição do órgão de armazenamento na planta. O objetivo deste estudo foi o de avaliar o efeito de diferentes níveis de bloqueio das radiações UV-A e UV-B sobre parâmetros de crescimento e teor de cumarina em dois acessos de guaco. Os tratamentos não apresentaram efeito sobre os parâmetros de crescimento avaliados, com exceção dos valores de área foliar. Em relação aos teores de cumarina, estes foram superiores nas folhas coletadas do dossel superior, bem como no tratamento sem bloqueio das radiações UV-A e UV-B incidentes.