Extraction and purification of anthraquinones derivatives from Aloe vera L. using alcohol/salt aqueous two-phase system

Abstract

An alcohol/salt aqueous two-phase system (ATPS) composed of 1-propanol and (NH4)2SO4 was employed to purify anthraquinones (AQs) extracted from Aloe vera L. The main influencing system parameters such as type of alcohol, type and concentration of salt, temperature and pH were investigated in detail. Under the optimal extraction conditions, AQs can be extracted into alcohol-rich phase with high extraction efficiency, meanwhile majority polysaccharides, proteins, mineral substances and other impurities were extracted into salt-rich phase. Partitioning of AQs is dependent on hydrophobic interaction, hydrogen bond interaction, and salting-out effect in ATPS. Temperature also played a great role in the partitioning. After ATPS extraction, alcohol can be recycled by evaporation; moreover, salt can be recycled by dilution crystallization method. Compared with other liquid-liquid extractions, this alcohol/salt system is much simpler, lower in cost with easier recovery of phase-forming components, which has the potential scale-up in down-processing of active ingredients in plant.

Assessment of conventional and novel extraction techniques on extraction efficiency of five anthraquinones from Rheum emodi

“…Considering the methods of extraction for DHAQs from various plants, literature reveals several novel methods like supercritical fluid extraction (SCFE), aqueous two phase extraction (ATPS) and pressurised hot water extraction (Genovese et al 2010;Pongnaravanea et al 2006;Tan et al 2013). However SCFE fails to extract the anthraquinones perse as the DHAQs are polar compounds that cannot be extracted by the comparably less polar carbon dioxide, while the later methods need a very sophisticated setup that may not be viable at a higher scale of operation.…”

Aqueous two-phase systems based on cholinium salts and tetrahydrofuran and their use for lipase purification

“…However, their performance is significantly affected due to the small difference in polarity between the coexisting phases [18]. Currently, the number of systems capable of forming two aqueous phases is increasing and the alternatives include the use of alcohol/salt [19][20][21], acetonitrile/carbohydrates [22,23], polymers(polyvinyl alcohol -PVA)/dextran [24] and other combinations including ionic liquids (ILs) [25,26]. The numerous combinations of cations and anions that form ILs lead to a variety of physical properties, allowing the tailoring of their polarities, and for this reason have been regarded as important constituents of ATPS [27][28][29].…”

Phase separation in a salting-out extraction system of ethanol–ammonium sulfate

“…Additionally, the possibility of recycling phase-forming components (hydrophilic organic solvent and salt) makes salting-out extraction a promising and sustainable downstream method [3][4][5]. The application of salting-out extraction for the bio-based chemicals has been recently reviewed in detail [2].…”

“…However, even though a great amount of reports have been published on the separation of diverse target products with high partition coefficient and recovery on the laboratory scale, this technology has not been used in industrial scale, partially due to the limited engineering knowledge and understanding of this system. Almost all of the batch extraction experiments were conducted following an empirical procedure (centrifugation, settling overnight or achieve complete phase equilibrium) without considering the time of the phase separation process [5][6][7][8][10][11][12]. However, these data are necessary for industrial application because the rate of phase separation determines the equipment design and thus the operation costs.…”