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Polyphenols, ascorbate and antioxidant capacity of the Kei-apple (Dovyalis caffra) / Tersia de BeerDe Beer, Tersia January 2006 (has links)
There is a close relationship between the susceptibility to disease and nutritional state, in the
sense that an adequate diet enhances resistance to disease. There is an increasing interest in this
beneficial relationship among scientists, food manufacturers and consumers. The trend is
moving towards functional foods and their specific health benefits.
The results of numerous epidemiological studies and recent clinical trials provide consistent
evidence that diets rich in fruits and vegetables can reduce the risk of chronic diseases. These
protective effects are mediated through multiple groups of beneficial nutrients contained in the
fruits and vegetables, one of these being polyphenol antioxidants. The intake of the polyphenols
plays an important role in the reduction and prevention of coronary heart disease (CHD),
cardiovascular disease and cancer, as a consequence of their associated antioxidant properties.
Fruits contain an array of polyphenols with antioxidant capacity. Polyphenols may be classified
in two broad groups namely: flavonoids and non-flavonoids. Flavonoid subgroups in fruits are
further grouped as catechins, anthocyanins, procyanidins and flavonol among others. Phenolic
acids occur as hydroxylated derivatives of benzoic acid and cinnarnic acid, and are classified as
non-flavonoids. Polyphenols have redox properties allowing them to act as reducing agents,
hydrogen donators and singlet oxygen quenchers, and thus contribute to the antioxidant capacity
of fruits and vegetables. Because of the numerous beneficial effects attributed to these
antioxidants, there is renewed interest in finding vegetal species with high phenolic content and
relevant biological activities.
In view of the importance of these substances towards health and food chemistry, this study will
focus on the polyphenol and Vitamin C characterisation and quantification of an indigenous
South African fruit, the Kei-apple (Dovyalis cafra), thought to have antioxidant properties. Due
to the fact that polyphenol content influences the colour, taste and possible health benefits of the
fruit / processed food product, this study will supply valuable information to industry in choosing
the best fruit processing methods to attain the desired end product. The exploitation of
indigenous South African fruits (Marula and Kei-apple) is receiving increasing prominence, not
only due to their health benefits, but also the opportunities these present to rural based
economics. Furthermore, this research will serve as a platform for further research on the Kei-apple
and other indigenous South African fruits with possible health benefits.
Aims: The overall aim of this study is the quantification and characterisation of various nutritionally
important antioxidants (polyphenols and ascorbate) in the Kei-apple fruit in its entirety, as well
as in its individual fruit components (peel, flesh and seeds). In addition, the total antioxidant
capacity of the entire fruit and the various fruit components will be determined in the
unfractionated and fractionated fruit extracts. Gas chromatography coupled mass spectrometry
(GC-MS) characterisation of the individual polyphenol components will also be analyzed in
order to speculate on possible specific health benefits which the Kei-apple may possess.
Methods: The study was designed to ensure that a representative fruit sample was collected.
Approximately 100 kg Kei-apples were picked in the month of November 2004 from the
Bloemhof area in South Africa. A sample of 50 fruits was rinsed and separated into the various
components (peel, flesh and seeds). An additional 50 fruits were randomly selected, cleaned and
used in their entirety for data representative of the entire fruit. The sample extracts were
prepared, after being grounded and lyophilized, by a method described by Eihkonen et al.
(1999) using 70% aqueous acetone. The C18-fractionation on the fruit and separated fruit
components resulted in four fractions containing (1) phenolic acids; (2) procyanidins, catechins
and anthocyanin monomers; (3) flavonols and (4) anthocyanin polymers.
The total polyphenol content of the fruit and fruit components as well as the above mentioned
C18-fractions were determined by Folin-Ciocalteu's method (Singleton & Rossi, 1965). Both
free and total ascorbate concentrations in these samples were determined as described by Beutler
(1984), in addition to total sugar content of these via standard methods. Apart from their
nutritional interest, both these measurements are necessary for the correction of the total
polyphenol concentrations. The total antioxidant capacity of the entire fruit and various fruit
components was determined by measuring the oxygen radical absorbance capacity (ORAC) and
ferric reducing antioxidant power (FRAP) of the unfractionated and fractionated extracts. Using
GC-MS analysis, the various individual polyhenol compounds contributing to the total
polyphenol content of the Kei-apple was separated, identified and quantified.
This quantitative data was captured and statistically analysed. The analysis of variation was
performed using the Tukey Honest Significant Difference test for post-hoc comparison. ORAC,
FRAP and polyphenol Pearson correlation analyses were performed using Statistics (Statsoft
Inc., Tulsa, Oklahoma, USA) with significance set at P ≤ 0.05.
Results and discussion: This study determined the presence of various nutritionally important antioxidants (polyphenols
and ascorbate), the total antioxidant capacity in the entire fruit as well as in the individual fruit
components (peel, flesh and seeds) and their polyphenol sub group fractions.
Total phenol content: The Kei-apple, in its entirety, has a polyphenol concentration of 943 ±
20.3 mg GAE/100g dry weight. Comparison of the individual fruit components showed the
seeds to have the highest total polyphenol concentration with 1990 ± 31.3 mg GAE/100g dry
weight, followed by that of the peel, 1126 ± 45.8 mg GAE/100g dry weight and then that of the
flesh, 521 ± 1.01 mg GAE/100g dry weight.
Total, L-ascorbic (ASC) and L-dehydroascobic (DHA) concentration: The total ascorbate of
Kei-apple fruit is 517 ± 0.92 mg/100g dry weight. In contrast to the polyphenol content, the
flesh of the Kei-apple had significantly the highest concentration of total ascorbate 778 ± 1.20
mg/100g dry weight, Gascorbic 241 ± 21.0 mg/100g dry weight, as well as Gdehydroascobic
537 ± 22.2 mg/100g dry weight. The ratio of Lascorbic acidltotal ascorbate for the flesh, entire
fruit, peel and seed is 0.31,0.43,0.49,0.95, respectively, indicating the seeds are the most stable
source of biologically active Vitamin C, with 95% of the total ascorbate occurring as G
ascorbate. This is also in line with the total polyphenol content of these components, confirming
a polyphenol sparing effect on ascorbate.
C18-fractionation extracts: Solid phase (C18) fractionation of the Kei-apple fruit and fruit
components showed that the fruit, peels and seeds consist predominantly of phenolic acids,
followed by procyanidin, catechin and anthocyanin monomers and thereafter varying amounts of
anthocyanin polymers and flavonols.
Antioxidant capacity: The antioxidant capacity of the entire fruit and individual fruit
components as determined by ORAC, (r=0.76) and FRAP, (r=0.95) significantly correlated with
the total polyphenol content, as well as to each other (r=0.88), indicating both to be good
predictors of antioxidant capacity.
GC-MS polyphenol characterisation of the Kei-apple: Caffeic acid and hydro-p-coumaric
acid were seen to be the phenolic acids occurring in the highest concentrations in the Kei-apple
fruit. The majority of these are concentrated in the flesh and in the case of caffeic acid, also in
the peel. The order of predominance of other major non-flavonoid components in the whole fruit
analysis are m-hydroxybenzoic acid > p-hydroxyphenyl acetic acid > 3-methoxy-4-
hydroxyphenylpropionic acid > p-coumaric acid. The peel of the Kei-apple, apart from caffeic
acid, has exceptionally high concentrations of ferulic acid and also serves as a source of
protocatechuic acid. Syringic acid was most prominent in the seeds. Although the total
flavonoid concentration in the Kei-apple was low, taxifolin and catechin were identified and the
seeds almost entirely accounting for these.
Conclusion: From this study it was concluded the Kei-apple is a rich source of antioxidant compounds
(polyphenols and ascorbate), with a strong antioxidant capacity, and hence may be associated
with health promotion properties, particularly in the prevention of cancer, cardiovascular disease,
and neurodegeneration. Additionally, due to the increased scientific and commercial interest in
this fruit, it is essential to take into consideration the various factors (agronomic, genomic, pre- and
post harvest condition and processing) and tissues. This might affect the chemical
composition of the final marketed product, which may play a significant role in determining the
polyphenol and ascorbate composition and bioactivity of these compounds during food
processing procedures. Hence, the polyphenol composition of the various fruit components
should be taken into consideration when selecting a method of fruit processing into the desired
end product. / Thesis (M.Sc. (Nutrition))--North-West University, Potchefstroom Campus, 2007.
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Concentration and derivatization in silicone rubber traps for mass spectrometric and gas chromatographic analysis of air and water pollutantsFernandes-Whaley, Maria Jose January 2008 (has links)
Thesis (PhD.(Chemistry)--University of Pretoria, 2008. / On title page: Submitted in partial fulfilment of the requirements for the degree Doctor of Philosophy in Chemistry in the faculty of Natural and Agricultural Sciences of the University of Pretoria. Includes bibliographical references.
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Comparison of two methods for differentiating negative from inconclusive GC-MS test results using an isotopic analog of the analyte as the internal standard -- 11-nor-[delta]⁹-tetrahydrocannabinol-9-carboxylic acid exampleWaters, Laura S. January 2008 (has links) (PDF)
Thesis (M.S.)--University of Alabama at Birmingham, 2008. / Description based on contents viewed June 2, 2008; title from title screen. Includes bibliographical references (p. 32).
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Diagnosis of Helicobacter pylori infection with the 13c-urea breath test analysis by means of gas chromatography with mass selective detection / by Maraliese Jordaan.Jordaan, Maraliese January 2008 (has links)
Thesis (MSc.(Chemical Pathology)--Faculty of Health Sciences))-University of Pretoria, 2008. / Summary in English and Afrikaans. Includes bibliographical references.
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Elemental speciation using pulsed glow discharge time-of-flight mass spectrometryZhang, Na, January 1900 (has links)
Thesis (Ph. D.)--West Virginia University, 2009. / Title from document title page. Document formatted into pages; contains xvi, 162 p. : ill. (some col.). Includes abstract. Includes bibliographical references.
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Analysis of airborne organic compounds using thermal desorption- gas chromatography-mass spectrometry methods /Ho, Sai Hang. January 2004 (has links)
Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2004. / Includes bibliographical references (leaves 273-303). Also available in electronic version. Access restricted to campus users.
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Association and discrimination of diesel fuels using chemometric procedures for forensic arson investigationsMarshall, Lucas James. January 2008 (has links)
Thesis (M.S.)--Michigan State University. School of Criminal Justice, 2008. / Title from PDF t.p. (viewed on Aug. 5, 2009) Includes bibliographical references (p.158-160). Also issued in print.
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Applications of extractive-derivatization sample preparation in a clinical toxicology laboratory settingMarais, Adriaan Albertyn Scheepers. January 2009 (has links)
Thesis (MSc.(Chemical pathology))--University of Pretoria, 2009. / Includes bibliographical references.
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Urinary Volatile Organic Compounds for Detection of Breast Cancer and Monitoring Chemical and Mechanical Cancer Treatments in MiceTeli, Meghana 05 1900 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / The aim of this study is to identify metabolic transformations in breast cancer through urinary volatile organic compounds in mammary pad or bone tumor mice models. Subsequently, it focuses on investigating the efficacy of therapeutic intervention through identified potential biomarkers. Methods for monitoring tumor development and treatment responses have technologically advanced over the years leading to significant increase in percent survival rates. Although these modalities are reliable, it would be beneficial to observe disease progression from a new perspective to gain greater understanding of cancer pathogenesis. Analysis of cellular energetics affected by cancer using bio-fluids can non-invasively help in prognosis and selection of treatment regimens. The hypothesis is altered profiles of urinary volatile metabolites is directly related to disrupted metabolic pathways. Additionally, effectiveness of treatments can be indicated through changes in concentration of metabolites. In this ancillary experiment, mouse urine specimens were analyzed using gas chromatography-mass spectrometry, an analytical chemistry tool in identifying volatile organic compounds. Female BALB/c mice were injected with 4T1.2 murine breast tumor cells in the mammary fat pad. Consecutively, 4T1.2 cells were injected in the right iliac artery of BALB/c mice and E0771 tumor cells injected in the tibia of C57BL/6 mice to model bone tumor. The effect of two different modes of treatment: chemical drug and mechanical stimulation was investigated through changes in compound profiles. Chemical drug therapy was conducted with dopamine agents, Triuoperazine, Fluphenazine and a statin, Pitavastatin. Mechanical stimulation included tibia and knee loading at the site of tumor cell injection were given to mice. A biological treatment mode included administration of A5 osteocyte cell line. A set of potential volatile organic compounds biomarkers differentiating mammary pad or bone confined tumors from healthy controls was identified using forward feature selection. Effect of treatments was demonstrated through hierarchical heat maps and multivariate data analysis. Compounds identified in series of experiments belonged to the class of terpenoids, precursors of cholesterol molecules. Terpene synthesis is a descending step of mevalonate pathway suggesting its potential role in cancer pathogenesis. This thesis demonstrates the ability of urine volatilomics to indicate signaling pathways inflicted in tumors. It proposes a concept of using urine to detect tumor developments at two distinct locations as well as to monitor treatment efficacy.
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Detection of Illicit Drugs in Various Matrices Via Total Vaporization Solid-Phase MicroextractionDavis, Kymeri Elizabeth 08 1900 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / In Headspace Solid-Phase Microextraction (Headspace SPME), a sample is heated to encourage a portion of the analyte into the headspace of a vial. A coated fiber is introduced into the sample headspace and the analyte is adsorbed onto the fiber coating. Total Vaporization Solid-Phase Microextraction (TV-SPME) is a technique that is derived from this technique. In TV-SPME, liquid samples are completely vaporized allowing for better adsorption and fewer matrix effects. This method does not require any sample preparation, utilizes minimal supplies and can be automated, making it both an efficient and cost-effective method. Chapter 1 will discuss the theory of SPME and TV-SPME.
In Chapter 2, the detection of ɣ-hydroxybutyric acid (GHB) and ɣ-butyrolactone (GBL) in beverages is discussed. The detection of these compounds in beverages is of importance because these drugs may be used to facilitate sexual assault. This crime utilizes substances that cause sedation and memory loss. The derivatization of GHB as well as the properties that make GHB difficult to detect will be discussed.
Chapter 3 will discuss the detection of methamphetamine and amphetamine (as their trifluoroacetyl derivatives), GBL, and the trimethylsilyl derivative of GHB in human urine. Amphetamine is a metabolite of methamphetamine, therefore, both drugs should be identified within biological samples. GHB and GBL are metabolites of one another and interconvert when in aqueous solution. This interconversion will be discussed.
Chapter 4 will cover method optimization of the Total Vaporization Solid-Phase Microextraction method. Analytes of interest for these analyses were methamphetamine, amphetamine, GHB, and GBL. The optimal extraction temperature ranging from 60-160°C of each drug will be discussed as well as why higher temperatures may not be suitable for this method. A limit of detection study for methamphetamine and amphetamine will also be covered.
Chapter 5, the future work chapter, will discuss future analyses using the Total Vaporization Solid-Phase Microextraction method including the analysis of powder materials, plant material, and toxicological samples. Powder material will include the analysis of individual powdered drugs as well as realistic drug mixtures. Some analyses on individual powder samples has already been completed and will be shown. Plant material will include the analysis of naturally occurring compounds found in marijuana plants as well as synthetic cannabinoids. Toxicological samples will expand on previously mentioned urine samples to include drugs such as benzoylecgonine and THC-COOH.
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