Valorization of Biomass Generated by Weeding of Flaveria bidentis: Optimization of the Process of Extraction Sulfated Flavonoids Using a Doehlert Experimental Design

Abstract

The object of this study is to intensify the process of obtaining of sulfated flavonoids (SFs) from Flaveria bidentis by conventional reflux method. F. bidentis widely distributed in the American Continent is a frequent and highly invasive plant considered weed by farmers and whose weeding generates high vegetal residues. This plant contains SFs in its aerial parts, mostly, 3,7,3′,4′-quercetin tetrasulfate (QTS) and Quercetin 3-acetyl-7,3′,4′-trisulfate (ATS), with important therapeutic potential. In this work, was analyzed the influence of different operation conditions: solvent composition, solvent/sample ratio, time and particle size, on the extraction yield of QTS and ATS. First, solvent composition was selected and later a response surface methodology involving the Doehlert experimental design was applied to determine the effect of the remaining variables. Our results showed that the optimal reflux extraction conditions were 134 mL/g solvent/sample ratio, 0.9 h and a particle size range of 0 to < 420 µm for leaves, and 55 mL/g solvent/sample ratio, 2.8 h and a particle size range of 420 to < 1190 µm for flowers. Under these optimal conditions a total yield of 46.67 and 16.56 mg SFs/100 g of leaves and flowers, respectively, was obtained. As a conclusion, it was possible to optimize the extraction of these SFs from F. bidentis, with the conventional reflux extraction, managing to exceed the extraction of these compounds by 53.5%, compared to the maximum values previously reported in the literature, thus providing greater added value to this vegetal residue.