Turbo-extraction of glycosides from Stevia rebaudiana using a fractional factorial design

Paula M. Martins, Aurea D. Lanchote, Bhaskar N. Thorat, Luis A.P. Freitas
2017 Revista Brasileira de Farmacognosia  
Stevia rebaudiana (Bertoni) Bertoni, Asteraceae, leaf extract has recently called the attention of food industry as a proposal for natural sweetener. The sweet flavor is attributed to the glycosides, in especial stevioside and rebaudioside A, which are the plant main chemical markers. The aim of the work reported here was to optimize the turbo-extraction of stevia leaves using water, ethanol 70% and 90% (w/w) as green solvents. A 2 5-2 factorial design was applied to study the linear effects of
more » ... the drug size, solvent to drug ratio, temperature, time and also the turbolysis speed on the extraction of glycosides. The glycosides exhaustive extraction showed that ethanol 70% gave better results and was used for turbo-extraction. The stevioside and rebaudioside A contents were quantified by a validated method by high performance liquid chromatographic with photodiode array detector. The contents of stevioside and rebaudioside A in fluid extract increased with the drug size, but decreased at high shearing speeds and solvent to drug ratio, while their yields decreased at higher temperature and were not affected by turbo speed. An increase in solvent to drug ratio reduced significantly the glycosides percent in dried extract. Optimal solution for S. rebaudiana leaves turbo-extraction was determined by desirability functions. The optimal extraction condition corresponded to drug size of 780 m, solvent to drug ratio of 10, extraction time of 18 min; temperature of 23 • C and turbo speed of 20,000 rpm, resulting in yields of 4.98% and 2.70%, for stevioside and rebaudioside A, respectively. These yields are comparable to the ones recently published for dynamic maceration, but with the advantage of shorter extraction times. This work demonstrates that turbolysis is promising for S. rebaudiana glycosides extraction and stimulate new research on the purification of these extracts, which may become an interesting source of income for developing countries such as India and Brazil. (L.A. Freitas). surrounded by epicalyces housing, color wine, light and pentamerous. The fruit is striated (Madan et al., 2010) . Stevia leaves contain eight terpene glycosides, identified as stevioside, rebaudoside A, B, C, D and E, dulcoside A and C. The main glycosides are stevioside and rebaudoside A, summing up to 5-10% of the drug (Singh and Rao, 2005; Abou-Arab et al., 2010; Yadav et al., 2011) and give a pronounced sweet flavor. Stevia is described in the Brazilian Pharmacopoeia 5th Ed. (Farmacopeia Brasileira, 2010) indicating dried leaves as the part used and must contain at least 12% of total carbohydrates and 4% steviosides. According to Madan et al. (2010) , the species has been used for centuries by the Guarani Indians as a sweetener in some drinks, especially the mate tea, and the active component that has the highest sweetness index is rebaudoside A while stevioside is the main component and gives a post digestive bitter taste. The
doi:10.1016/j.bjp.2017.02.007 fatcat:bzv2pjck3bholpcj4fl2lqvcvm