Green selective extraction of fucoxanthin from Phaedodactylum tricornutum employing the Hansen Solubility Parameters approach

Abstract

Phaedolactylum tricornutum is a marine diatom rich in valuable carotenoids such as fucoxanthin, a pigment with several biological activities. Thus, this compound has raised attention due to its potential use in the food and pharmaceutical industries. Recently, the commercial production of fucoxanthin from P. tricornutum has been explored, using conventional extraction with ethanol. However, many other compounds are co-extracted when using EtOH as solvent, thus making necessary the use of additional purification steps. New green processes can be proposed for a faster and more selective extraction that, in addition, complies with the principles of green chemistry. In this regard, a theoretical modelling of the Hansen solubility parameters (HSP) could provide a useful and accurate estimation for the solvent selection and to predicting the solubility of these natural bioactive compounds before the extraction processes. In the present work, a theoretical evaluation using the HSP was carried out aiming the selective extraction of fucoxanth in from P. tricornutum. D-limonene, ethyl lactate, ethyl acetate and ethanol were the selected green solvents tested in pressurized liquid extractions (PLE) at 40 and 100ºC. The concentration of fucoxanthin in the extracts was analyzed. The ratio among total carotenoids and total chlorophylls was used to evaluate the selectivity of the extractions. Results demonstrated that d-limonene was the most selective solvent to extract the fucoxanthin, as predicted by the theoretical approach, thus showing the usefulness of HSP to drive the work towards selective extractions. Moreover, additional extractions using supercritical C02 and d-lirnonene as co-solvent (50% v/v) were performed at 300 bar and 50ºC.