Co-precipitation of fluorescein with extracts of mango leaves by supercritical antisolvent process

Abstract

Fluorescein was coprecipitated together antioxidant compounds from mango leaves by the supercritical antisolvent process (SAE). The ethanol extract rich in antioxidant compounds was previously obtained by enhanced extraction. The influence of temperature (35–55 °C), pressure (150–200 bar) and CO2 flow rate (10–30 g/min) on the SAE process were investigated. The decrease in pressure contributed to a decrease in particle size, while an increase in temperature and the flow rate of CO2 contributed, in general, to the production of smaller particles diameter. SEM images revealed the formation of coprecipitates composed by a mixture of spherical (extract of mango leaves) and irregular (fluorescein) particles confirming the presence of both precipitates. The analysis with DPPH showed that the SAE technique is valid to obtain particles of high antioxidant activity even though the fluorescein is present in the process. By using the fluorimeter assay it was demonstrated that the coprecipitates could be detected by UV-Vis due to the presence of fluorescein.