Mechanochemical-assisted efficient extraction of rutin from Hibiscus mutabilis L.

Mechanochemical-assisted extraction (MCAE) technique was developed for the efficient extraction of rutin from Hibiscus mutabilis L. This process was carried out via mechanochemical pretreatment in AGO-2 high intensity planetary mill. Highest yield of rutin was obtained by grinding H. mutabilis with Na2CO3 (15.0 wt.%) and Na2B4O7·10H2O (1.5 wt.%) for 4 min, extraction temperature at 25 °C, total extraction time of 15 min (two cycles of 10 min and 5 min), acidification pH 5.0 and solvent/material ratio of 25 mL/g. Scanning electron microscopy, X-ray powder diffraction and diffuse-reflectance UV–Vis spectrum were applied to identify the physicochemical property changes. These changes mainly included the enhanced diffusivity and water solubility of rutin resulting from the breakage of cell walls and its transformation into a water-soluble salt form by the mechanochemical pretreatment. Compared with heat reflux and superfine grinding extraction, MCAE showed the advantages of efficiency, no organic solvent consumption and much lower extraction temperature.Industrial relevanceIn this study, mechanochemical-assisted extraction of rutin from H. mutabilis was developed and the physicochemical changes in this process were supervised. Owing to its great potential to transform the target compounds into water-soluble forms, MCAE provided a good alternative for efficient aqueous extraction of bioactive compounds, especially some poorly water-soluble natural products.

Research Highlights
► Mechanochemical-assisted extraction of rutin from H. mutabilis was developed.
► Process included milling with solid bases, extracting and reconverting to acid form.
► Rutin was transformed into a water-soluble salt by the mechanochemical pretreatment.
► Enhanced diffusivity and water solubility resulted in high extraction efficiency.
► Advantages are high efficiency, no organic solvent consumption and room temperature.