Solanesol sequential extraction from tobacco leaves using microwave-ultrasound-assisted extraction (MUAE): MAE optimization

Solanesol (C₄₅H₇₄O) is an aliphatic terpene alcohol of nine isoprene units found in the tobacco plant (Nicotiana Tabacum L.). The long and complex biosynthetic pathway of solanesol makes the extraction method still the best way to obtain solanesol. This work evaluates the optimum conditions for sequential extraction from tobacco leaves using microwave-ultrasound-assisted extraction (MUAE) as a green extraction method. There were two stages of extraction (sequential): first, microwave-assisted extraction (MAE), followed by ultrasound-assisted extraction (UAE). At the MAE stage, dry tobacco powder was extracted with variations of water-to-solid (feed) ratio (S/F) from 1:1 to 10:1 (mL/g), power from 200 to 800 W, and time from 0.5 to 2 min. Optimum conditions were obtained at 6:1 (mL/g), 400 W, and 1.5 min, respectively. The UAE stage was fixed with the solvent-to-solid (feed) ratio (S/F), solvent ratio (v/v), time, and temperature of 40:1, 1:2 (PE:ethanolic acid), 30 min, and 40 °C, respectively. The optimum solanesol yield was 3.0 % (w/w), and a nicotine yield of 1.41 % (%w/w) was obtained under the same conditions. The resulting crude solanesol was then purified using silica gel column chromatography (CC), resulting in a purity of 85 %. The yield of extracted solanesol is much higher than in other studies due to the use of fresh leaves and MUAE method.