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DOI: 10.1055/s-0039-3399911
Natural deep eutectic solvents: an eco-friendly alternative for the extraction of naphthoquinones from Alkanna tinctoria roots
Publication History
Publication Date:
20 December 2019 (online)
Plant derived natural products have an important role in pharmaceutical, cosmeceutical and food supplements industries. Their increasing demand is leading to the over-exploitation of plant resources and to the over-consumption of organic solvents, widely recognized to be of great environmental concern. For this reason, the design of green extraction methods of natural products is currently a key research topic. [1]-[3]
In order to address this issue an eco-friendly natural deep eutectic solvents (NADESs) were used instead of organic solvents for the extraction of naphthoquinones from the roots of Alkanna tinctoria Tausch, a Greek endemic plant from Boraginaceae family. More than twenty NADESs containing choline chloride-, and betaine-, as hydrogen bond acceptor combined with different hydrogen bond donors (sugars, organics acids) were investigated for their potential to extract this particular class of compounds. As a result of the statistical evaluation, the most relevant deep eutectic mixture with the highest extraction efficiency was found to be composed of lactic acid and sucrose (LaS). To maximize the extraction yield, a further optimization step of extraction parameters was followed, including the optimum LaS ratio (w/w), the solid-to-solvent ratio, temperature, water content as well as the application of solid phase extraction techniques for the recovery of the naphtoquinone fraction from the NADES extraction solution. Our results revealed the optimized LaS mixture as a valid green alternative for the extraction of naphthoquinones from Alkanna tinctoria. In fact, by using a ratio of lactic acid-sucrose 5:1 (w/w), a solid-to-solvent ratio of 60:1 (w/v) at 40°C, with 30% of water content, targeted compounds were successfully recovered.
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References
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