Hyphenation of aqueous two-phase and microwave extraction of solasonine and solamargine from leaves of Solanum mauritianum characterized by UHPLC-qTOF-MS

The biomass Solanum mauritianum (S. mauritianum) is an invasive weed specie; however, it is a source of medicinally important metabolites, as reported in literature, such as solasonine and solamargine. The study was directed at the optimization of microwave and aqueous two-phase-based extraction techniques which involved microwave-assisted extraction (MAE), aqueous two-phase extraction followed by microwave-assisted extraction (ATPE + MAE), and the “one-pot” microwave-assisted aqueous two-phase extraction (MA-ATPE) for extraction of solasonine and solamargine from leaves of S. mauritianum which was evaluated. The microwave-assisted extraction of solasonine and solamargine yielded optimums at 5.00 min, microwave power of 270 W, and solid/liquid of 0.1 g L−1 at an ethanol concentration of 60%. Application of a two-stage extraction (MAE + ATPE) in CaO-dried alcohol resulted in decreased amounts of solasonine and solamargine extracted. The best yields of solasonine and solamargine were achieved in the MA-ATPE method. Extraction of solamargine and solasonine using Na2CO3 in CaO-dried ethanol during MA-ATPE was approximately threefold and twofold greater than that of MAE + ATPE, respectively. Furthermore, extraction of solamargine and solasonine using NaCl in CaO-dried ethanol during MA-ATPE was approximately twofold greater than that of MAE + ATPE. The synergy of microwaves and salting-out in the “one-pot” MA-ATPE technique was shown to be a contributing factor for enhanced extraction of solamargine and solasonine from leaves of S. mauritianum. Application of this time- and energy-efficient extraction method could potentially be expanded for enrichment of medicinally important compounds from biomass of other medicinal plants.