Abstract
The increasing interest towards greener antioxidants obtained via natural sources and more sustainable processes encourages the development of new theoretical and experimental methods in the field of those compounds. Two advanced separation methods using supercritical CO2 are applied to obtain valuable antioxidants from Salvia officinalis, and a first approximation to a QSAR model relating molecular structure with antioxidant activity is explored in order to be used, in the future, as a guide for the preselection of compounds of interest in these processes. Separation experiments through antisolvent fractionation with supercritical CO2 were designed using a Response Surface Methodology to study the effect of pressure and CO2 flow rate on both mass yields and capability to obtain fractions enriched in three antioxidant compounds: chlorogenic acid, caffeic acid and rosmarinic acid which were tracked using HPLC PDA. Rosmarinic acid was completely retained in the precipitation vessel while chlorogenic and caffeic acids, though distributed between the two separated fractions, had a major presence in the precipitation vessel too. The conditions predicted for an optimal overall yield and enrichment were 148 bar and 10 g/min. Although a training dataset including much more compounds than those now considered can be recommended, descriptors calculated from the σ-profiles provided by COSMO-RS model seem to be adequate for estimating the antioxidant activity of pure compounds through QSAR.
Highlights
The importance of antioxidants coming from natural sources as bioactive compounds, and their interest in the pharmaceutical, food and cosmetic industries, is increasingly [1,2,3]recognized worldwide
The extraction of bioactive compounds from natural sources and their subsequent fractionation or isolation have been conducted by means of conventional methods, many of which are based in the use of organic solvents that can be harmful for the environment and human health
Salvia officinalis leaves were defatted by means of CO2 supercritical fluid extraction (SFE), macerated in ethanol, being the yields of these processes 4.9% and
Summary
The importance of antioxidants coming from natural sources as bioactive compounds, and their interest in the pharmaceutical, food and cosmetic industries, is increasingly [1,2,3]recognized worldwide. The development of more sustainable processes, as free as possible of organic solvents, is of great importance For this reason, supercritical fluid, especially supercritical carbon dioxide (sc-CO2 ), technology has gained importance and is widely used for extraction, fractionation and isolation of bioactive compounds from plants [4] or animal parts [5]. CO2 is non-flammable, non-toxic, available at low cost with high purity and its critical pressure and temperature (Pc = 74 bar Tc = 31 ◦ C) are moderate [4]. This last circumstance makes it very suitable for the extraction of thermolabile compounds. As a result of its properties, sc-CO2 leads to effective and quick extractions and eliminates clean-up steps because it can be and completely removed by lowering the pressure in which case it becomes a gas
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