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Extraction and chromatography of bioactive compounds in complex samples using supercritical CO2 technology

Alhamimi, Said LU (2018)
Abstract
Bioactive compounds found in plants have been of interest to man since ancient times. These compounds have the ability to modulate the metabolic processes in our bodies, which suggests that they may promote better health. Bioactive compounds vary in their chemical structure, polarity, stability and biological activity. This diversity makes the study of bioactive compounds challenging from the perspective of analytical chemistry. The extraction of bioactive compounds using conventional solid–liquid extraction (SLE) is slow due to mass transfer limitations. While increasing the temperature speeds up the mass transfer, it also leads to degradation and oxidation. Supercritical CO2 (ScCO2) extraction offers high mass transfer at low... (More)
Bioactive compounds found in plants have been of interest to man since ancient times. These compounds have the ability to modulate the metabolic processes in our bodies, which suggests that they may promote better health. Bioactive compounds vary in their chemical structure, polarity, stability and biological activity. This diversity makes the study of bioactive compounds challenging from the perspective of analytical chemistry. The extraction of bioactive compounds using conventional solid–liquid extraction (SLE) is slow due to mass transfer limitations. While increasing the temperature speeds up the mass transfer, it also leads to degradation and oxidation. Supercritical CO2 (ScCO2) extraction offers high mass transfer at low temperature, but it has selective solubility towards nonpolar compounds.
This thesis describes the development of techniques and methods for the extraction and chromatographic analysis of bioactive compounds leading to improvements in mass transfer, solubility and resolution, using ScCO2 technology. Ultrahigh- pressure supercritical fluid extraction improved the solubility and extractability of oil from moringa seeds due to an increase in the density of the solvent. Extraction at 80 MPa increased the amount of oil extracted by about 30% in a short time, compared to extraction at 40 MPa. The selectivity was also affected, as higher content of polyunsaturated fatty acids and some phospholipid species were detected in the oil extracted at 80 MPa. CO2 expanded liquid extraction (CXLE) combined enhanced mass transfer and high solubility, which resulted in a high extraction rate. The addition of CO2 to a liquid organic solvent decreased the viscosity and changed the solubility parameters. CXLE showed a 10 times faster extraction rate of cis- verbenol from Boswellia sacra resin compared to supercritical fluid extraction (SFE) and SLE. A combination of sonication and CXLE improved the solubility and extractability of the oil from different berry seeds. Sonication increased the amount of oil extracted using CXLE 3-fold. The composition of the oil obtained using CXLE showed significant increases in the levels of phospholipids and glycolipids compared to the oil obtained by SLE.
A method of supercritical fluid chromatography (SFC) was developed based on a Diol column, which showed the highest peak height, a small peak width and high resolution between and within lipid classes. Stationary phases with a β-amino alcohol ligand showed a very strong retention of the zwitterionic lipids with terminal primary amines such as phosphatidylethanolamines. The sensitivity of mass spectrometry (MS) was found to be dependent on the composition of the SFC mobile phase. Optimization of the ion source settings in MS is important to achieve a compromise between the detection sensitivity of early and late eluting peaks.
The impact of bioactive compounds in lingonberries on metabolites in plasma was also investigated. The results showed that the intake of lingonberries could improve the liver function and decrease the effects of high-fat diet. The intake of lingonberries could also prevent the formation of metabolites associated with an unhealthy phenotype such as sphingomyelins by decreasing the level of serine. (Less)
Abstract (Swedish)
Medical doctors and nutritional specialists recommend to eat healthy foods including fruits and vegetables. Cosmetic experts also recommend to use cosmetic products obtained from natural products. The reason behind this is that natural products from plants contain chemical compounds which can promote health and protect our bodies from several diseases. These chemical compounds are called bioactive compounds. They act as antioxidant, antimicrobial and antiinflammation agents in our bodies. These compounds have diverse structures and found among thousands of other compounds in the plant sample. They have different properties, some are fat-like and others are water-like. Some of these compounds are unstable and sensitive to heat and light.... (More)
Medical doctors and nutritional specialists recommend to eat healthy foods including fruits and vegetables. Cosmetic experts also recommend to use cosmetic products obtained from natural products. The reason behind this is that natural products from plants contain chemical compounds which can promote health and protect our bodies from several diseases. These chemical compounds are called bioactive compounds. They act as antioxidant, antimicrobial and antiinflammation agents in our bodies. These compounds have diverse structures and found among thousands of other compounds in the plant sample. They have different properties, some are fat-like and others are water-like. Some of these compounds are unstable and sensitive to heat and light. These problems always challenge the analytical chemists to find methods selective to target compounds, fast, with high recovery and operate at relatively low temperature.
In this thesis, extraction methods have been developed to offer high solubility, high recovery in a short time, selective to target compounds and sustainable to the environment. Ultrahigh pressure supercritical fluid extraction (UHPSFE) was used to extract oil from Moringa seeds. It is well known that high-pressure causes CO2 molecules to come closer and that increases the density. High density increases the solubility and extractability properties of the fluid and that increases the extraction rate. The amount the oil obtained at 80 MPa was 400 mg/g seeds while at 40 MPa was 278 mg/g seeds. Also, the oil obtained at 80 MPa has high content of poly unsaturated fatty acids PUFAs.
In this thesis, CO2 is added to the liquid solvent in a technique called CO2 expanded liquid extraction (CXLE) to improve the mass transfer and solubility instead of using high temperature. This technique was used to obtain aroma compounds from plant resin (Boswellia Sacra). CXLE can extract the aroma compounds 10 times faster than supercritical fluid extraction (SFE). CXLE incorporated with ultrasound wave showed high and fast recovery of oil from berry seeds compared to CXLE only. The ultrasound wave improved the mass transfer and also allowed the solvent to penetrate into the sample to increase the solubility.
In supercritical fluid chromatography (SFC) the results reveal that some lipid species can interact very strong with the stationary phases which causes broadening of resulted peaks and lose the resolution and efficiency. Presence of β-amino alcohol on the stationary phases caused distortion of the peaks belong to lipids having terminal primary amines. Diol stationary phase showed the highest peak height and resolution for the most of the lipid species. The developed method can resolve more than 15 lipid classes within 11 min.
Lingonberry is rich fruit in bioactive compounds especially polyphenols. Lingonberry can reduce the impact of high fat diet and improve the liver function. Lingonberry suggested to have influence to alter the formation of unhealthy components in the body like sphingolipids (SMs). High level of SMs are associated with development of obesity and diabetes.
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Please use this url to cite or link to this publication:
author
supervisor
opponent
  • Professor Emmer, Åsa, KTH Royal Institute of Technology, Department of Chemistry, Stockholm
organization
alternative title
Extraktion och kromatografi av bioaktiva föreningar i komplexa prov med superkritisk CO2-teknik
publishing date
type
Thesis
publication status
published
subject
keywords
Supercritical CO2, Chromatography, Extraction, Mass transfer, Solubility
pages
81 pages
publisher
Lund University, Faculty of Science, Department of Chemistry
defense location
Hörsal B, Kemicentrum, Naturvetarvägen 14, Lund
defense date
2018-10-12 09:15:00
ISBN
9789174225938
9789174225945
language
English
LU publication?
yes
id
9f2f4ca2-e59c-4bf0-b37a-10cee9eddc07
date added to LUP
2018-09-14 08:47:48
date last changed
2020-04-08 11:31:10
@phdthesis{9f2f4ca2-e59c-4bf0-b37a-10cee9eddc07,
  abstract     = {Bioactive compounds found in plants have been of interest to man since ancient times. These compounds have the ability to modulate the metabolic processes in our bodies, which suggests that they may promote better health. Bioactive compounds vary in their chemical structure, polarity, stability and biological activity. This diversity makes the study of bioactive compounds challenging from the perspective of analytical chemistry. The extraction of bioactive compounds using conventional solid–liquid extraction (SLE) is slow due to mass transfer limitations. While increasing the temperature speeds up the mass transfer, it also leads to degradation and oxidation. Supercritical CO2 (ScCO2) extraction offers high mass transfer at low temperature, but it has selective solubility towards nonpolar compounds.<br/>This thesis describes the development of techniques and methods for the extraction and chromatographic analysis of bioactive compounds leading to improvements in mass transfer, solubility and resolution, using ScCO2 technology. Ultrahigh- pressure supercritical fluid extraction improved the solubility and extractability of oil from moringa seeds due to an increase in the density of the solvent. Extraction at 80 MPa increased the amount of oil extracted by about 30% in a short time, compared to extraction at 40 MPa. The selectivity was also affected, as higher content of polyunsaturated fatty acids and some phospholipid species were detected in the oil extracted at 80 MPa. CO2 expanded liquid extraction (CXLE) combined enhanced mass transfer and high solubility, which resulted in a high extraction rate. The addition of CO2 to a liquid organic solvent decreased the viscosity and changed the solubility parameters. CXLE showed a 10 times faster extraction rate of cis- verbenol from Boswellia sacra resin compared to supercritical fluid extraction (SFE) and SLE. A combination of sonication and CXLE improved the solubility and extractability of the oil from different berry seeds. Sonication increased the amount of oil extracted using CXLE 3-fold. The composition of the oil obtained using CXLE showed significant increases in the levels of phospholipids and glycolipids compared to the oil obtained by SLE.<br/>A method of supercritical fluid chromatography (SFC) was developed based on a Diol column, which showed the highest peak height, a small peak width and high resolution between and within lipid classes. Stationary phases with a β-amino alcohol ligand showed a very strong retention of the zwitterionic lipids with terminal primary amines such as phosphatidylethanolamines. The sensitivity of mass spectrometry (MS) was found to be dependent on the composition of the SFC mobile phase. Optimization of the ion source settings in MS is important to achieve a compromise between the detection sensitivity of early and late eluting peaks.<br/>The impact of bioactive compounds in lingonberries on metabolites in plasma was also investigated. The results showed that the intake of lingonberries could improve the liver function and decrease the effects of high-fat diet. The intake of lingonberries could also prevent the formation of metabolites associated with an unhealthy phenotype such as sphingomyelins by decreasing the level of serine.},
  author       = {Alhamimi, Said},
  isbn         = {9789174225938},
  language     = {eng},
  publisher    = {Lund University, Faculty of Science, Department of Chemistry},
  school       = {Lund University},
  title        = {Extraction and chromatography of bioactive compounds in complex samples using supercritical CO2 technology},
  url          = {https://lup.lub.lu.se/search/files/51402682/Thesis_Said_for_uploading.pdf},
  year         = {2018},
}