Bioactive compounds with antioxidant activity extracted from lignocellulosic biomass of Galium verum

The active ingredients present in Galium species, especially Galium verum, are represented by antioxidant compounds in variable proportions. This study aimed to obtain, by solid-liquid extraction of G. verum, biologically active compounds with antioxidant properties, such as polyphenols and flavonoids. Four classic extraction techniques were used (maceration-M, refluxation-R, sonoextraction-US and a combined method: sonoextraction with maceration – US+M). In the extraction process, glycerin was used in different forms: hydro-glycerin; and water and glycerin-ethanol mixtures with different concentrations. Other monitored parameters were the solid-liquid ratio (S/L) and the extraction time. The best results were obtained using the hydro-glycerin solution as extraction solvent: 85.0 µg GAE/g polyphenols (R: 50% concentration, 60 min, S/L=1:15) and 117 mg QE/g flavonoids ((R: 80% concentration, 60 min, S/L=1:15). This study brings new data about obtaining plant extracts from G. verum with important antioxidant properties, based on the use of a green solvent extraction.