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Maria A. Stander
Department of Biochemistry, Stellenbosch University, Private Bag X1, Matieland, Stellenbosch 7602, South Africa

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Journal article
Published: 13 July 2021 in Antioxidants
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‘Wonderful’ pomegranate (Punica granatum L.) peel contains a wide range of phytochemicals including vitamins, dietary fibre, phenolic compounds, and antioxidant properties. Yet, it is often used as animal feed or discarded in landfills, which is not the best eco-friendly way to utilize this phenolic-rich bioresource. Finding novel ways of utilizing pomegranate peel waste could prove a more profitable and eco-friendlier alternative that is far more beneficial to the economy. Adding a blanching pre-treatment step at optimal conditions prior to processing of pomegranate peel aids in the inactivation of quality changing enzymes such as polyphenol oxidase (PPO) and peroxidase (POD), which are accountable for the degradation reactions that cause breakdown of nutrients and phytochemicals. This study aimed to determine the effect of blanching at 80 °C for 3 min on the yield, polyphenol content, antioxidant properties, enzyme inactivation, and antibacterial activity of ‘Wonderful’ pomegranate peel ethanolic extracts from three different harvest maturities (unripe, ripe, and over ripe), including a comprehensive characterization and quantification using liquid chromatography-mass spectrometry (LC-MS). The blanched unripe peel extracts exhibited the highest total phenolic content, total tannin content, 2,2-diphenyl-1-picryl hydrazyl (DPPH) antioxidant activity, 2,2-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid (ABTS) radical scavenging activity and ferric ion reducing antioxidant power (FRAP) at 14.0 mg gallic acid equivalent (GAE)/g dry mass (DM), 1.0 mg GAE/g DM, 359.1 µmol Trolox/g DM, 912.2 µmol Trolox/g DM and 802.5 µmol Trolox/g DM, respectively. There was significant (p< 0.05) decrease in PPO and POD activity of all blanched pomegranate peel extracts. The blanched unripe peel extracts had the lowest PPO activity at 0.2 U/g fresh weight (FW), with a 70% PPO inactivation compared to ripe and over ripe harvest, whereas the highest POD inactivation was recorded at 67% in over ripe peel extracts. All blanched peel extracts, irrespective of harvest maturity, had minimum inhibitory concentration (MIC) values at 160 µg/mL against all four bacteria strains tested, which included two Gram-positive bacterial strains (Bacillus subtilis ATCC 6051 and Staphylococcus aureus ATCC 12600) and two Gram-negative bacteria (Escherichia coli 11775 and Klebsiella pneumonia ATCC 13883). A total of 25 metabolites including phenolic acids (4), organic acids (1), flavonoids (4), ellagitannins (13), and other polyphenols (3) in all three pomegranate peel samples were tentatively identified after LC-MS profiling. The blanched unripe peel extracts showed significantly higher punicalin α and β, β punicalagin, catechin, epicatechin content at 414 mg/g, and 678 mg/g, 151 mg/g, 229 mg/g, respectively, compared to peel extracts from other harvest maturities. This study provides supportive information for the commercial utilization of pomegranate fruit peel as source of value-added ingredients for the development of novel food, cosmetics, and pharmacological products.

ACS Style

Tandokazi Magangana; Nokwanda Makunga; Chris la Grange; Maria Stander; Olaniyi Fawole; Umezuruike Opara. Blanching Pre-Treatment Promotes High Yields, Bioactive Compounds, Antioxidants, Enzyme Inactivation and Antibacterial Activity of ‘Wonderful’ Pomegranate Peel Extracts at Three Different Harvest Maturities. Antioxidants 2021, 10, 1119 .

AMA Style

Tandokazi Magangana, Nokwanda Makunga, Chris la Grange, Maria Stander, Olaniyi Fawole, Umezuruike Opara. Blanching Pre-Treatment Promotes High Yields, Bioactive Compounds, Antioxidants, Enzyme Inactivation and Antibacterial Activity of ‘Wonderful’ Pomegranate Peel Extracts at Three Different Harvest Maturities. Antioxidants. 2021; 10 (7):1119.

Chicago/Turabian Style

Tandokazi Magangana; Nokwanda Makunga; Chris la Grange; Maria Stander; Olaniyi Fawole; Umezuruike Opara. 2021. "Blanching Pre-Treatment Promotes High Yields, Bioactive Compounds, Antioxidants, Enzyme Inactivation and Antibacterial Activity of ‘Wonderful’ Pomegranate Peel Extracts at Three Different Harvest Maturities." Antioxidants 10, no. 7: 1119.

Original article
Published: 13 February 2021 in Plant Cell, Tissue and Organ Culture (PCTOC)
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Plants under different environmental regimes exhibit phenotypic plasticity, sometimes producing more secondary metabolites when microenvironmental conditions are manipulated but these responses may be species, cultivar and/or genotype dependent. To test the hypothesis of whether in vitro plants of S. rebaudiana Bertoni would accumulate higher amounts of steviol glycosides when plants were growing under salt and drought stress, cultivar ST2100 plants were used. We thus applied 25 to 100 mM NaCl and polyethylene glycol 6000 (PEG) at 2.5% to 10.0% (w/v) to generate different Murashige and Skoog (Physiol Plant 15:473–497, 1962) media. Microplant cultures were also profiled for stevioside, rebaudioside A and steviol via LC–MS. Essential oil chemicals and fatty acids were assessed using GC–MS. Finally, a chemometric analysis of ethanolic extracts produced from treated and control plants is presented from MSE fragmentation data and various phenolic acids were tentatively identified using ion fragmentation patterns. Increasing amounts of both NaCl and PEG led to poor growth and development in cultures of S. rebaudiana. For example, the 25 and 50 mM NaCl-treated plants had fewer roots in comparison to controls and at even higher concentrations (75 and 100 mM NaCl), plants did not to root. Poor in vitro organogenesis was more pronounced with PEG. For instance, when plants were placed on a 10% PEG-medium, the ability for shoot regeneration was lost and callus became more apparent. Increasing levels of NaCl and PEG were also correlated to lowered levels of rebaudioside A and stevioside. In relation to the control plants that had 0.054 mg g−1 FW of steviol, the 25 mM NaCl treatment group had highest levels of this compound, recorded at 0.156 mg g−1 FW. All other salt treatments led to trace amounts of this chemical (0.005–0.009 mg g−1 FW) and it was not detected in any of the PEG-treated plants, except for the controls. The PCA loadings plots exposed stevioside, rebaudioside E and a steviol glycoside derivative as the MS signals that contributed to discriminant clusters segregating controls from the NaCl-treated groups. For PEG, segregation in the PCA is mostly influenced by dicaffeoylquinic acid as a marker ion, separating the controls from the treatment groups. PEG-treatments caused more prominent changes to the essential oil chemistry of Stevia plants. This was evident when 7.5 or 10% PEG was applied as sabinene, α-terpinolene, n-amyl isovalerate, 7-octen-4-ol, α-bergamotene, junipene, (+)-calarene, α-cadinol, β-pinene, α-bergamotene, (+)-calarene and junipene became undetectable. Changes of this nature may be undesirable when aromatic oils of S. rebaudiana are targetted for commercial markets as our data suggest adjustment to stresses may negatively impact volatile compounds leading to a loss of bioactive aromatic compounds. This study reports, for the first time, the effects of salinity and drought conditions in vitro on changed essential oil profiles of S. rebaudiana, providing new insights into the effects of stress on the essential oil chemistry of S. rebaudiana.

ACS Style

T. P. Magangana; M. A. Stander; N. A. Masondo; N. P. Makunga. Steviol glycoside content and essential oil profiles of Stevia rebaudiana Bertoni in response to NaCl and polyethylene glycol as inducers of salinity and drought stress in vitro. Plant Cell, Tissue and Organ Culture (PCTOC) 2021, 145, 1 -18.

AMA Style

T. P. Magangana, M. A. Stander, N. A. Masondo, N. P. Makunga. Steviol glycoside content and essential oil profiles of Stevia rebaudiana Bertoni in response to NaCl and polyethylene glycol as inducers of salinity and drought stress in vitro. Plant Cell, Tissue and Organ Culture (PCTOC). 2021; 145 (1):1-18.

Chicago/Turabian Style

T. P. Magangana; M. A. Stander; N. A. Masondo; N. P. Makunga. 2021. "Steviol glycoside content and essential oil profiles of Stevia rebaudiana Bertoni in response to NaCl and polyethylene glycol as inducers of salinity and drought stress in vitro." Plant Cell, Tissue and Organ Culture (PCTOC) 145, no. 1: 1-18.

Research note
Published: 10 November 2020 in BMC Research Notes
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Objective Current global trends on natural therapeutics suggest an increasing market interest toward the use and discovery of new plant-derived therapeutic compounds, often referred to as traditional medicine (TM). The Cannabis industry is currently one such focal area receiving attention, owing to the occurrence of phytocannabinoids (pCBs) which have shown promise in health-promotion and disease prevention. However, the occurrence of pCBs in other plant species are often overlooked and rarely studied. Leonotis leonurus (L.) R. Br. is endemic to South Africa with a rich history of use in TM practices amongst indigenous people and, has been recorded to induce mild psychoactive effects akin to Cannabis. While the leaves have been well-reported to contain therapeutic phytochemicals, little information exists on the flowers. Consequently, as part of a larger research venture, we targeted the flowers of L. leonurus for the identification of potential pCB or pCB-like compounds. Results Flower extracts were separated and analyzed using high performance thin layer chromatography (HPTLC). A single pCB candidate was isolated from HPTLC plates and, using liquid chromatography coupled to tandem mass spectrometry (LC–MS/MS), we could successfully group this compound as a fatty amide and tentatively identified as 7,10,13,16-Docosatetraenoylethanolamine (adrenoyl-EA), a known bioactive compound.

ACS Style

E. Hunter; M. Stander; J. Kossmann; S. Chakraborty; S. Prince; S. Peters; Bianke Loedolff. Toward the identification of a phytocannabinoid-like compound in the flowers of a South African medicinal plant (Leonotis leonurus). BMC Research Notes 2020, 13, 1 -6.

AMA Style

E. Hunter, M. Stander, J. Kossmann, S. Chakraborty, S. Prince, S. Peters, Bianke Loedolff. Toward the identification of a phytocannabinoid-like compound in the flowers of a South African medicinal plant (Leonotis leonurus). BMC Research Notes. 2020; 13 (1):1-6.

Chicago/Turabian Style

E. Hunter; M. Stander; J. Kossmann; S. Chakraborty; S. Prince; S. Peters; Bianke Loedolff. 2020. "Toward the identification of a phytocannabinoid-like compound in the flowers of a South African medicinal plant (Leonotis leonurus)." BMC Research Notes 13, no. 1: 1-6.

Research article
Published: 16 September 2020 in Journal of Agricultural and Food Chemistry
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The postharvesting disorder leaf blackening is the main cause of product rejection in Protea during export. In this study we report an investigation into metabolites associated with leaf blackening in Protea species. Methanol extracts of leaf and involucral bract tissue were analyzed by liquid-chromatography hyphenated to photodiode array and high resolution mass spectrometry (LC-PDA-HRMS). Analytical data obtained from 37 Protea species, selections and hybrids were investigated using metabolomics tools, which showed that stems susceptible to leaf blackening cluster together and contained features identified as benzenetriol and/or hydroquinone derived metabolites. On the other hand, species, selections and cultivars not prone to blackening were linked to metabolites with known protective properties against biotic and abiotic stressors. During the browning process, susceptible cultivars also produce these protective metabolites, yet at innately low levels, which may render these species and cultivars more vulnerable to blackening. Metabolites that were found to be correlated to the instigation of the browning process, all comprising benzenetriol- and hydroquinone-glycoside derivatives, are highlighted to provide preliminary insights to guide the development of new Protea cultivars not susceptible to leaf blackening.

ACS Style

Keabetswe Masike; André J. De Villiers; Eleanor W. Hoffman; Marietjie Stander. Application of Metabolomics Tools to Determine Possible Biomarker Metabolites Linked to Leaf Blackening in Protea. Journal of Agricultural and Food Chemistry 2020, 68, 12595 -12605.

AMA Style

Keabetswe Masike, André J. De Villiers, Eleanor W. Hoffman, Marietjie Stander. Application of Metabolomics Tools to Determine Possible Biomarker Metabolites Linked to Leaf Blackening in Protea. Journal of Agricultural and Food Chemistry. 2020; 68 (45):12595-12605.

Chicago/Turabian Style

Keabetswe Masike; André J. De Villiers; Eleanor W. Hoffman; Marietjie Stander. 2020. "Application of Metabolomics Tools to Determine Possible Biomarker Metabolites Linked to Leaf Blackening in Protea." Journal of Agricultural and Food Chemistry 68, no. 45: 12595-12605.

Journal article
Published: 13 February 2020 in Antioxidants
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Extracts of Sutherlandia frutescens (cancer bush) exhibit considerable qualitative and quantitative chemical variability depending on their natural wild origins. The purpose of this study was thus to determine bioactivity of extracts from different regions using in vitro antioxidant and anti-cancer assays. Extracts of the species are complex and are predominantly composed of a species-specific set of triterpene saponins (cycloartanol glycosides), the sutherlandiosides, and flavonoids (quercetin and kaempferol glycosides), the sutherlandins. For the Folin-Ciocalteu phenolics test values of 93.311 to 125.330 mg GAE/g DE were obtained. The flavonoids ranged from 54.831 to 66.073 mg CE/g DE using the aluminum chloride assay. Extracts from different sites were also assayed using the 2,2-diphenyl-1-picrylhydrazyl (DPPH•) radical scavenging method and ferric reducing anti-oxidant power (FRAP) methods. This was followed by an in vitro Cell Titer-Glo viability assay of various ecotypes using the DLD-1 colon cancer cell line. All test extracts displayed anti-oxidant activity through the DPPH• radical scavenging mechanism, with IC50 values ranging from 3.171 to 7.707 µg·mL−1. However, the degree of anti-oxidant effects differed on a chemotypic basis with coastal plants from Gansbaai and Pearly Beach (Western Cape) exhibiting superior activity whereas the Victoria West inland group from the Northern Cape, consistently showed the weakest anti-oxidant activity for both the DPPH• and FRAP methods. All extracts showed cytotoxicity on DLD-1 colon cancer cells at the test concentration of 200 µg·mL−1 but Sutherlandia plants from Colesburg (Northern Cape) exhibited the highest anti-cancer activity. These findings confirm that S. frutescens specimens display variability in their bioactive capacities based on their natural location, illustrating the importance of choosing relevant ecotypes for medicinal purposes.

ACS Style

Samkele Zonyane; Olaniyi A. Fawole; Chris La Grange; Maria A. Stander; Umezuruike L. Opara; Nokwanda P. Makunga. The Implication of Chemotypic Variation on the Anti-Oxidant and Anti-Cancer Activities of Sutherlandia frutescens (L.) R.Br. (Fabaceae) from Different Geographic Locations. Antioxidants 2020, 9, 152 .

AMA Style

Samkele Zonyane, Olaniyi A. Fawole, Chris La Grange, Maria A. Stander, Umezuruike L. Opara, Nokwanda P. Makunga. The Implication of Chemotypic Variation on the Anti-Oxidant and Anti-Cancer Activities of Sutherlandia frutescens (L.) R.Br. (Fabaceae) from Different Geographic Locations. Antioxidants. 2020; 9 (2):152.

Chicago/Turabian Style

Samkele Zonyane; Olaniyi A. Fawole; Chris La Grange; Maria A. Stander; Umezuruike L. Opara; Nokwanda P. Makunga. 2020. "The Implication of Chemotypic Variation on the Anti-Oxidant and Anti-Cancer Activities of Sutherlandia frutescens (L.) R.Br. (Fabaceae) from Different Geographic Locations." Antioxidants 9, no. 2: 152.

Research article
Published: 05 December 2019 in Journal of Agricultural and Food Chemistry
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In this study we report a detailed investigation of the polyphenol composition of Protea pure (P. cynaroides and P. neriifolia) and hybrid cultivars (Black beauty and Limelight). Aqueous methanol extracts of leaf and bract tissues were analyzed by ultra-high pressure liquid chromatography hyphenated to photodiode array and ion mobility-high resolution mass spectrometric (UHPLC-PDA-IM-HR-MS) detection. A total of 67 metabolites were characterized based on their relative reversed phase (RP) retention, UV-Vis spectra, low and high collision energy HR-MS data and collisional cross section (CCS) values. These metabolites included 41 phenolic acid esters and 25 flavonoid derivatives, including 5 anthocyanins. In addition, an undescribed hydroxycinnamic acid-polygalatol ester, caffeoyl-O-polygalatol (1,5-anhydro-[6-O-caffeoyl]- sorbitol(glucitol)) was isolated and characterized by 1D and 2D NMR for the first time. This compound and its isomer are shown to be potential chemo-taxonomic markers.

ACS Style

Keabetswe Masike; André J. de Villiers; Eleanor W. Hoffman; D. Jacobus Brand; Tim Causon; Marietjie Stander. Detailed Phenolic Characterization of Protea Pure and Hybrid Cultivars by Liquid Chromatography–Ion Mobility–High Resolution Mass Spectrometry (LC-IM-HR-MS). Journal of Agricultural and Food Chemistry 2019, 68, 485 -502.

AMA Style

Keabetswe Masike, André J. de Villiers, Eleanor W. Hoffman, D. Jacobus Brand, Tim Causon, Marietjie Stander. Detailed Phenolic Characterization of Protea Pure and Hybrid Cultivars by Liquid Chromatography–Ion Mobility–High Resolution Mass Spectrometry (LC-IM-HR-MS). Journal of Agricultural and Food Chemistry. 2019; 68 (2):485-502.

Chicago/Turabian Style

Keabetswe Masike; André J. de Villiers; Eleanor W. Hoffman; D. Jacobus Brand; Tim Causon; Marietjie Stander. 2019. "Detailed Phenolic Characterization of Protea Pure and Hybrid Cultivars by Liquid Chromatography–Ion Mobility–High Resolution Mass Spectrometry (LC-IM-HR-MS)." Journal of Agricultural and Food Chemistry 68, no. 2: 485-502.

Journal article
Published: 19 July 2019 in Molecules
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Wildly grown in most regions of the world, Carissa edulis is a highly underutilised fruit with significant antioxidant characteristics. The phyto and physicochemical properties of C. edulis berries at different stages of ripening are evaluated in this work. Total flavonoids (TF), total phenolic content (TPC) and antioxidant activity were determined spectrophotometrically, while concentration of polyphenols was determined using liquid chromatography coupled to diode array detection and electrospray ionization mass spectrometry. Results showed that antioxidant activity was lowest (18.36 ± 0.12 mg TE/g) in RS3 and decreased with TPC upon increased ripening. Conversely, TF increased with ripening progression with TF found to be highest in RS3 (5.92 ± 0.03 mg CE/g). Identified phenolic acids in C. edulis were quinic acid, protocatechuoyl-hexose, neochlorogenic acid, chlorogenic acid, cryptochlorogenic acid and dicaffeoylquinic acid. Identified flavonoids included rutin, catechin, procyanidin dimer, procyanidin trimer, quercetin-3-O-glucosyl-xyloside, quercetin-3-O-robinobioside, quercetin-3-O-glucoside and quercetin-3-OH-3-methylglutaryl-glucoside. Physicochemical properties of C. edulis varied among samples with sugar/acid ratio of C. edulis ranging from 25.70 for RS1 to 50.36 for RS3. Ripening stage of C. edulis undoubtedly affects the phyto and physicochemical properties of C. edulis.

ACS Style

Fulufhelo P. Makumbele; Malcolm Taylor; Marietjie Stander; Tonna A. Anyasi; Afam I.O. Jideani. Polyphenolic and Physicochemical Properties of Simple-Spined Num-Num (Carissa edulis) Fruit Harvested at Ripe Stage of Maturation. Molecules 2019, 24, 2630 .

AMA Style

Fulufhelo P. Makumbele, Malcolm Taylor, Marietjie Stander, Tonna A. Anyasi, Afam I.O. Jideani. Polyphenolic and Physicochemical Properties of Simple-Spined Num-Num (Carissa edulis) Fruit Harvested at Ripe Stage of Maturation. Molecules. 2019; 24 (14):2630.

Chicago/Turabian Style

Fulufhelo P. Makumbele; Malcolm Taylor; Marietjie Stander; Tonna A. Anyasi; Afam I.O. Jideani. 2019. "Polyphenolic and Physicochemical Properties of Simple-Spined Num-Num (Carissa edulis) Fruit Harvested at Ripe Stage of Maturation." Molecules 24, no. 14: 2630.

Journal article
Published: 26 June 2019 in Molecules
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As a contribution towards a better understanding of phenolic variation in the genus Cyclopia (honeybush tea), a collection of 82 samples from 15 of the 23 known species was analysed using liquid-chromatography-high resolution mass spectrometry (UPLC-HRMS) in electrospray ionization (ESI) negative mode. Mangiferin and isomangiferin were found to be the main compounds detected in most samples, with the exception of C. bowiena and C. buxifolia where none of these compounds were detected. These xanthones were found to be absent from the seeds and also illustrated consistent differences between species and provenances. Results for contemporary samples agreed closely with those based on analysis of a collection of ca. 30-year-old samples. The use of multivariate tools allowed for graphical visualizations of the patterns of variation as well as the levels of the main phenolic compounds. Exclusion of mangiferin and citric acid from the data was found to give better visual separation between species. The use of UPLC-HRMS generated a large dataset that allowed for comparisons between species, provenances and plant parts (leaves, pods, flowers and seeds). Phenetic analyses resulted in groupings of samples that were partly congruent with species but not with morphological groupings within the genus. Although different provenances of the same species were sometimes found to be very variable, Principle Component Analysis (PCA) indicated that a combination of compounds have some (albeit limited) potential as diagnostic characters at species level. 74 Phenolic compounds are presented, many of which were identified for the first time in Cyclopia species, with nine of these being responsible for the separation between samples in the PCAs.

ACS Style

Maria. A. Stander; Herman Redelinghuys; Keabetswe Masike; Helen Long; Ben-Erik Van Wyk. Patterns of Variation and Chemosystematic Significance of Phenolic Compounds in the Genus Cyclopia (Fabaceae, Podalyrieae). Molecules 2019, 24, 2352 .

AMA Style

Maria. A. Stander, Herman Redelinghuys, Keabetswe Masike, Helen Long, Ben-Erik Van Wyk. Patterns of Variation and Chemosystematic Significance of Phenolic Compounds in the Genus Cyclopia (Fabaceae, Podalyrieae). Molecules. 2019; 24 (13):2352.

Chicago/Turabian Style

Maria. A. Stander; Herman Redelinghuys; Keabetswe Masike; Helen Long; Ben-Erik Van Wyk. 2019. "Patterns of Variation and Chemosystematic Significance of Phenolic Compounds in the Genus Cyclopia (Fabaceae, Podalyrieae)." Molecules 24, no. 13: 2352.

Journal article
Published: 02 January 2019 in Chemosphere
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The widespread implementation of antiretroviral therapy medication has made antiretroviral drugs (ARVDs) a significant pharmaceutical class in regions of high HIV infection rates. However, relatively little is known regarding the environmental occurrence of these emerging contaminants, and this is especially true for their metabolites. In this work, we report analytical methods to study the simultaneous occurrence of a range of common ARVDs and some of their known metabolites in surface water and wastewater. A novel direct injection liquid chromatography-tandem mass spectrometry (LC-MS/MS) method is reported for the analysis of ARVDs of different therapeutic classes and their selected metabolites in wastewater samples. In addition, a solid phase extraction (SPE) procedure was developed for pre-concentration of ARVs and metabolites from surface water samples. The respective methods proved suitable for the quantitative analysis of six parent ARVDs from three ARV classes, as well as three metabolites. Method validation showed average recoveries of 86% for the direct injection method, and 64% for the SPE method. With the exception of Zidovudine and the metabolites of Zidovudine and Ritonavir, all target ARVDs were detected in wastewater samples from two wastewater treatment plants in the Western Cape, South Africa. Higher concentrations were generally measured in influent compared to effluent samples, in the dry compared to the wet season as well as in chlorinated compared to uv-irradiated effluents. This study contributes for the first time quantitative data on the environmental occurrence of the known metabolites of Nevirapine (12-hydroxy-Nevirapine) and Efavirenz (8,14-dihydroxy-Efavirenz).

ACS Style

Tlou Thatayotlhe Mosekiemang; Maria A. Stander; André de Villiers. Simultaneous quantification of commonly prescribed antiretroviral drugs and their selected metabolites in aqueous environmental samples by direct injection and solid phase extraction liquid chromatography - tandem mass spectrometry. Chemosphere 2019, 220, 983 -992.

AMA Style

Tlou Thatayotlhe Mosekiemang, Maria A. Stander, André de Villiers. Simultaneous quantification of commonly prescribed antiretroviral drugs and their selected metabolites in aqueous environmental samples by direct injection and solid phase extraction liquid chromatography - tandem mass spectrometry. Chemosphere. 2019; 220 ():983-992.

Chicago/Turabian Style

Tlou Thatayotlhe Mosekiemang; Maria A. Stander; André de Villiers. 2019. "Simultaneous quantification of commonly prescribed antiretroviral drugs and their selected metabolites in aqueous environmental samples by direct injection and solid phase extraction liquid chromatography - tandem mass spectrometry." Chemosphere 220, no. : 983-992.

Short communication
Published: 07 December 2018 in Journal of Food Composition and Analysis
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Two endemic South African herbal teas, namely rooibos (Aspalathus linearis) and honeybush (Cyclopia spp.), are especially valued for their caffeine-free status. No recent evidence based on state-of-the-art analytical methodology with low limits of detection (e.g. below 1 μg/L) is available. The current study provides such evidence. Randomly selected samples of fermented rooibos (n = 10) and honeybush herbal teas from four species (n = 10 each), namely C. intermedia, C. subternata, C. genistoides and C. longifolia, were analysed and no caffeine detected. Similarly, no caffeine was detected in green rooibos and C. genistoides herbal teas (n = 10 each) indicating that it is absent in the plant. Method specificity was shown to be important since peaks with molecular ion [M+H]+ and product ions resembling those of caffeine were detected, although the retention time and accurate mass did not match those of an authentic reference standard for caffeine.

ACS Style

Maria A. Stander; Elizabeth Joubert; Dalene De Beer. Revisiting the caffeine-free status of rooibos and honeybush herbal teas using specific MRM and high resolution LC-MS methods. Journal of Food Composition and Analysis 2018, 76, 39 -43.

AMA Style

Maria A. Stander, Elizabeth Joubert, Dalene De Beer. Revisiting the caffeine-free status of rooibos and honeybush herbal teas using specific MRM and high resolution LC-MS methods. Journal of Food Composition and Analysis. 2018; 76 ():39-43.

Chicago/Turabian Style

Maria A. Stander; Elizabeth Joubert; Dalene De Beer. 2018. "Revisiting the caffeine-free status of rooibos and honeybush herbal teas using specific MRM and high resolution LC-MS methods." Journal of Food Composition and Analysis 76, no. : 39-43.

Journal article
Published: 13 November 2018 in Journal of Food Composition and Analysis
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In an investigation into the historical use of various plant species as herbal teas in South Africa and the commercialization of rooibos (Aspalathus linearis), 37 tea samples from a depository of 1933 were analysed. These samples are known as the Nortier collection and were put in the depository by Benjamin Ginsberg. Nortier and Ginsberg were instrumental in the commercialisation of Rooibos tea. Liquid-chromatography–high resolution mass spectrometry (LC–HRMS) was used with electrospray ionisation (ESI) in negative mode to compare the flavonoids and phenolic acids and identify marker compounds in the samples. The positively identified marker compounds together with multivariate data tools were used to distinguish between the different teas and group similar ones together. The LC–HRMS chromatogram of the 1933 Nortier tea, the tea from which cultivated rooibos emanated, is virtually identical to a commercial cultivated tea from 2016. The selection of teas is an interesting look into the history of herbal tea in South Africa, the species used and the decision-making process of Nortier in developing the industry. The historic “reed tea” (riettee) was identified for the first time as Thesium macrostachyum and other Thesium species and is the same as the tea that is still used in the Wupperthal area as “lidjiestee”.

ACS Style

M.A. Stander; T. Brendler; H. Redelinghuys; B.-E. Van Wyk. The commercial history of Cape herbal teas and the analysis of phenolic compounds in historic teas from a depository of 1933. Journal of Food Composition and Analysis 2018, 76, 66 -73.

AMA Style

M.A. Stander, T. Brendler, H. Redelinghuys, B.-E. Van Wyk. The commercial history of Cape herbal teas and the analysis of phenolic compounds in historic teas from a depository of 1933. Journal of Food Composition and Analysis. 2018; 76 ():66-73.

Chicago/Turabian Style

M.A. Stander; T. Brendler; H. Redelinghuys; B.-E. Van Wyk. 2018. "The commercial history of Cape herbal teas and the analysis of phenolic compounds in historic teas from a depository of 1933." Journal of Food Composition and Analysis 76, no. : 66-73.

Research article
Published: 07 September 2018 in Analytical Chemistry
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Comprehensive two-dimensional liquid chromatography (LC × LC) and ion mobility spectrometry–mass spectrometry (IMS–MS) are increasingly being used to address challenges associated with the analysis of highly complex samples. In this work, we evaluate the potential of the combination of these techniques in the form of a comprehensive three-dimensional LC × LC × IMS separation system. As application, hydrophilic interaction chromatography (HILIC) × reversed phase LC (RP-LC) × IMS–high-resolution MS (HR-MS) was used to analyze a range of phenolic compounds, including hydrolyzable and condensed tannins, flavonoids, and phenolic acids in several natural products. A protocol for the extraction and visualization of the four-dimensional data obtained using this approach was developed. We show that the combination of HILIC, RP-LC, and IMS offers excellent separation of complex phenolic samples in three dimensions. Benefits associated with the incorporation of IMS include improved MS sensitivity and mass-spectral data quality. IMS also provided separation of trimeric procyanidin isomeric species that could not be differentiated by HILIC × RP-LC or HR-MS. On the traveling wave IMS (TWIMS) system used here, both IMS separation performance and the extent of second dimension (2D) undersampling depend on the upper mass scan limit, which might present a limitation for the analysis of larger molecular ions. The performance of the LC × LC × IMS system was characterized in terms of practical peak capacity and separation power, using established theory and taking undersampling and orthogonality into account. An average increase in separation performance by a factor of 13 was found for the samples analyzed here when IMS was incorporated into the HILIC × RP-LC–MS workflow.

ACS Style

Pieter Venter; Magriet Muller; Jochen Vestner; Maria A. Stander; Andreas G. J. Tredoux; Harald Pasch; André de Villiers. Comprehensive Three-Dimensional LC × LC × Ion Mobility Spectrometry Separation Combined with High-Resolution MS for the Analysis of Complex Samples. Analytical Chemistry 2018, 90, 11643 -11650.

AMA Style

Pieter Venter, Magriet Muller, Jochen Vestner, Maria A. Stander, Andreas G. J. Tredoux, Harald Pasch, André de Villiers. Comprehensive Three-Dimensional LC × LC × Ion Mobility Spectrometry Separation Combined with High-Resolution MS for the Analysis of Complex Samples. Analytical Chemistry. 2018; 90 (19):11643-11650.

Chicago/Turabian Style

Pieter Venter; Magriet Muller; Jochen Vestner; Maria A. Stander; Andreas G. J. Tredoux; Harald Pasch; André de Villiers. 2018. "Comprehensive Three-Dimensional LC × LC × Ion Mobility Spectrometry Separation Combined with High-Resolution MS for the Analysis of Complex Samples." Analytical Chemistry 90, no. 19: 11643-11650.

Journal article
Published: 30 August 2018 in Foods
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Wine varietal thiols are important contributors to wine aroma. The chemical nature of thiols makes them difficult to measure due to low concentrations, high sensitivity to oxidation, and low ionization. Methods for the measurement of thiols usually consist of multiple steps of sample preparation followed by instrumental measurement. Studies have collected large datasets of thiols in white wine but not in red wine, due to the lack of availability of suitable methods. In this study, for the first time, convergence chromatography was used to measure thiols in red wine at ultratrace levels with improved sensitivity compared to previous methods. Performance parameters (selectivity, linearity, limits of detection, precision, accuracy) were tested to demonstrate the suitability of the method for the proposed application. Red wine thiols were measured in South African Pinotage, Shiraz, and Cabernet Sauvignon wines (n = 16 each). Cultivar differentiation using the thiol profile was demonstrated.

ACS Style

Mpho Mafata; Maria A. Stander; Baptiste Thomachot; Astrid Buica. Measuring Thiols in Single Cultivar South African Red Wines Using 4,4-Dithiodipyridine (DTDP) Derivatization and Ultraperformance Convergence Chromatography-Tandem Mass Spectrometry. Foods 2018, 7, 138 .

AMA Style

Mpho Mafata, Maria A. Stander, Baptiste Thomachot, Astrid Buica. Measuring Thiols in Single Cultivar South African Red Wines Using 4,4-Dithiodipyridine (DTDP) Derivatization and Ultraperformance Convergence Chromatography-Tandem Mass Spectrometry. Foods. 2018; 7 (9):138.

Chicago/Turabian Style

Mpho Mafata; Maria A. Stander; Baptiste Thomachot; Astrid Buica. 2018. "Measuring Thiols in Single Cultivar South African Red Wines Using 4,4-Dithiodipyridine (DTDP) Derivatization and Ultraperformance Convergence Chromatography-Tandem Mass Spectrometry." Foods 7, no. 9: 138.

Journal article
Published: 01 August 2018 in Antioxidants
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Indigenous and non-commercial fruits can be an important source of antioxidant polyphenols; however, the identity and content of polyphenols from non-commercial fruits are often poorly described. The study aimed to extract, identify, and quantify polyphenols from the skin of the indigenous Africa fruit Ximenia caffra, using solvent extraction. Three solvents (hexane, acetone, and 70% v/v ethanol) over three extraction times (30, 60 and 120 min) were used in a 32 full factorial experimental design to determine effects on polyphenol recovery, and individual polyphenolics were characterised using liquid chromatography high-resolution mass spectrometry (LC-HRMS). Ethanol was the most effective extraction solvent, and extracts had high levels of total phenolics and flavonoids (65 mg gallic and 40 mg catechin equivalents per gram dry sample respectively), and high antioxidant activity (18.2 mg mL−1 ascorbic acid equivalents). LC-HRMS positively identified 16 compounds, of which 14 were flavonoids including flavonoid glycosides, and indicated that concentrations of some flavonoids decreased for extraction times beyond 60 min. It was concluded that the fruit of Ximenia caffra is rich in natural polyphenolic antioxidants; the present work identified and quantified a number of these, while also establishing suitable solvent extraction conditions for the recovery of these potentially high-value compounds.

ACS Style

Dewald Oosthuizen; Neill J. Goosen; Maria A. Stander; Aliyu Dabai Ibrahim; Mary-Magdalene Pedavoah; Grace O. Usman; Taiwo Aderinola. Solvent Extraction of Polyphenolics from the Indigenous African Fruit Ximenia caffra and Characterization by LC-HRMS. Antioxidants 2018, 7, 103 .

AMA Style

Dewald Oosthuizen, Neill J. Goosen, Maria A. Stander, Aliyu Dabai Ibrahim, Mary-Magdalene Pedavoah, Grace O. Usman, Taiwo Aderinola. Solvent Extraction of Polyphenolics from the Indigenous African Fruit Ximenia caffra and Characterization by LC-HRMS. Antioxidants. 2018; 7 (8):103.

Chicago/Turabian Style

Dewald Oosthuizen; Neill J. Goosen; Maria A. Stander; Aliyu Dabai Ibrahim; Mary-Magdalene Pedavoah; Grace O. Usman; Taiwo Aderinola. 2018. "Solvent Extraction of Polyphenolics from the Indigenous African Fruit Ximenia caffra and Characterization by LC-HRMS." Antioxidants 7, no. 8: 103.

Randomized controlled trial
Published: 25 July 2018 in American Journal of Obstetrics and Gynecology
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Preterm preeclampsia has high rates of fetal death or disability. There is no treatment to slow the disease, except delivery. Preclinical studies have identified proton pump inhibitors as a possible treatment. To examine whether esomeprazole could prolong pregnancy in women diagnosed with preterm preeclampsia We performed a double blind, randomised controlled trial at Tygerberg Hospital in South Africa. Women with preterm preeclampsia (gestational age 26 weeks+0 days to 31 weeks+6 days) were randomly assigned to 40 mg daily esomeprazole or placebo. The primary outcome was a prolongation of gestation of five days. Secondary outcomes were maternal and neonatal outcomes. We compared circulating markers of endothelial dysfunction associated with preeclampsia and performed pharmacokinetic studies. This trial is registered with the Pan African Clinical Trials Registry, PACTR201 504000771349. Between January 2016 and April 2017, we recruited 120 participants. One participant was excluded due to incorrect randomisation, leaving 59 in the esomeprazole, and 60 in the placebo group. Median gestational age at enrolment was 29+4 weeks gestation. There were no between-group differences in median time from randomization to delivery (11·4 days [interquartile range, 3·6-19·7]) in the esomeprazole group, and 8·3 days [interquartile range, 3·8-19·6] in the placebo group (3 days longer in the esomeprazole arm, 95% confidence interval -2·9-8·8, P=0·31). There were no placental abruptions in the esomeprazole group and 6 (10%) in the placebo group (P=0·01, P=0·14 adjusted). There were no differences in other maternal or neonatal outcomes, or markers of endothelial dysfunction. Esomeprazole and its metabolites were detected in maternal blood among those treated with esomeprazole, but only trace amounts in the umbilical cord blood. 40mg of daily esomeprazole did not prolong gestation in pregnancies with preterm preeclampsia or decrease circulating sFlt-1 concentrations. Higher levels in the maternal circulation may be needed for clinical effect.

ACS Style

Catherine A. Cluver; Natalie J. Hannan; Erika van Papendorp; Richard Hiscock; Sally Beard; Ben W. Mol; Gerhard B. Theron; David R. Hall; Eric Decloedt; Marietjie Stander; Kim T. Adams; Megan Rensburg; Pawel Schubert; Susan P. Walker; Stephen Tong. Esomeprazole to treat women with preterm preeclampsia: a randomized placebo controlled trial. American Journal of Obstetrics and Gynecology 2018, 219, 388.e1 -388.e17.

AMA Style

Catherine A. Cluver, Natalie J. Hannan, Erika van Papendorp, Richard Hiscock, Sally Beard, Ben W. Mol, Gerhard B. Theron, David R. Hall, Eric Decloedt, Marietjie Stander, Kim T. Adams, Megan Rensburg, Pawel Schubert, Susan P. Walker, Stephen Tong. Esomeprazole to treat women with preterm preeclampsia: a randomized placebo controlled trial. American Journal of Obstetrics and Gynecology. 2018; 219 (4):388.e1-388.e17.

Chicago/Turabian Style

Catherine A. Cluver; Natalie J. Hannan; Erika van Papendorp; Richard Hiscock; Sally Beard; Ben W. Mol; Gerhard B. Theron; David R. Hall; Eric Decloedt; Marietjie Stander; Kim T. Adams; Megan Rensburg; Pawel Schubert; Susan P. Walker; Stephen Tong. 2018. "Esomeprazole to treat women with preterm preeclampsia: a randomized placebo controlled trial." American Journal of Obstetrics and Gynecology 219, no. 4: 388.e1-388.e17.

Original article
Published: 03 April 2018 in Plant Cell, Tissue and Organ Culture (PCTOC)
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The commercialization of Stevia rebaudiana Bertoni (Asteraceae) extracts as a natural sweetener is driving interest in the use of in vitro propagation systems as an alternative source of steviol glycosides. Out of this suite of chemicals, stevioside is the most abundant but rebaudioside A is the sweetest. We established an in vitro propagation method from germinated seedlings on a Murashige and Skoog (MS) (Physiol Plant 15:473–497, 1962) medium with aims to study the effects of nitrogen and phosphate on the growth and metabolite profiles of S. rebaudiana plants. Generally, NH4NO3 is supplied at a concentration of 20.61 mM in MS medium and together with 18.79 mM KNO3, provide nitrogen to in vitro growing plants. In this study, we used a range of 0.3–72.1 mM NH4NO3 and 9.4–65.8 mM KNO3 and generated six different media with altered nitrogen. Similarly, six different concentrations of KH2PO4, ranging from 0.6 to 4.4 mM were tested for the phosphate treatments and the control medium had 1.25 mM KH2PO4. By reducing the nitrogen and phosphate levels to half, respectively, this led to the tallest plants. Increasing concentrations of nitrogen in the medium significantly lowered the amount of rebaudioside A as plants on the control medium accumulated 270 mg g−1 rebaudioside A compared to those that were on a medium with 3.5 times the nitrogen supply (30 mg g−1 rebaudiose A). Steviol increased with increasing nitrogen available to the microplants. The highest levels of stevioside (740 mg g−1) quantified was linked to microplants on a medium with half the phosphate concentration. To further assess changes to the metabolomic profiles of treated microplants, LC–MS/MS was used in combination with multivariate statistical analyses. Two distinct clusters were revealed after principal component analysis. Steviol hydrate, stevioside hydrate and rebaudioside A contributed significantly to the separation of phosphate-treated plants from those with variable nitrogen concentrations. Chlorogenic acid and its derivatives were linked to changing phosphate concentrations. The clustering suggests different molecular mechanisms at play that are affected by nitrogen and phosphate supply which serve to alter secondary metabolic flux, resulting in different chemical profiles.

ACS Style

Tandokazi P. Magangana; Marietjie A. Stander; Nokwanda P. Makunga. Effect of nitrogen and phosphate on in vitro growth and metabolite profiles of Stevia rebaudiana Bertoni (Asteraceae). Plant Cell, Tissue and Organ Culture (PCTOC) 2018, 134, 141 -151.

AMA Style

Tandokazi P. Magangana, Marietjie A. Stander, Nokwanda P. Makunga. Effect of nitrogen and phosphate on in vitro growth and metabolite profiles of Stevia rebaudiana Bertoni (Asteraceae). Plant Cell, Tissue and Organ Culture (PCTOC). 2018; 134 (1):141-151.

Chicago/Turabian Style

Tandokazi P. Magangana; Marietjie A. Stander; Nokwanda P. Makunga. 2018. "Effect of nitrogen and phosphate on in vitro growth and metabolite profiles of Stevia rebaudiana Bertoni (Asteraceae)." Plant Cell, Tissue and Organ Culture (PCTOC) 134, no. 1: 141-151.

Journal article
Published: 01 March 2018 in Journal of Chromatography B
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In the present study an ultra-performance convergence chromatography tandem mass spectrometry (UPC2-MS/MS) analytical method was developed and validated for the determination of 17 C19 and 14 C21 steroids, including C11-oxy C19 and C11-oxy C21 steroids. The limit of detection and limit of quantification ranged from 0.01 to 10 ng/mL and from 0.01 to 20 ng/mL, respectively, and the method shows the recovery, matrix effect and process efficiency of steroids isolated from a serum matrix to be within acceptable limits. Good accuracy, repeatability and reproducibility were also shown and the method provided excellent sensitivity and selectivity as stereoisomers and regioisomers were also resolved and quantified accurately. Clinical conditions such as congenital adrenal hyperplasia, polycystic ovary syndrome in females and disorders of sex development in neonates and in children, amongst others, are characterized by abnormal steroid levels. Steroid profiling is essential to accurately diagnose steroid levels in the above settings as well as in androgen excess or deficiency in adrenal-linked endocrine diseases. Our method, separating C19 and C21 steroids in a single chromatographic step, offers a reduced sample turnover rate in the clinical setting, while providing comprehensive steroid profiles of in vivo steroids in the nmol/L range. This is, to our knowledge, the first method reported to simultaneously separate C19 and C21 steroids, together with their C11-hydroxy and C11-keto metabolites –one which may hold promise in the identification of new steroid markers in steroid-linked endocrine diseases, in addition to profiling steroid metabolism and abnormal enzyme activity in patients.

ACS Style

Therina Du Toit; Marietjie Stander; Amanda C. Swart. A high-throughput UPC2-MS/MS method for the separation and quantification of C19 and C21 steroids and their C11-oxy steroid metabolites in the classical, alternative, backdoor and 11OHA4 steroid pathways. Journal of Chromatography B 2018, 1080, 71 -81.

AMA Style

Therina Du Toit, Marietjie Stander, Amanda C. Swart. A high-throughput UPC2-MS/MS method for the separation and quantification of C19 and C21 steroids and their C11-oxy steroid metabolites in the classical, alternative, backdoor and 11OHA4 steroid pathways. Journal of Chromatography B. 2018; 1080 ():71-81.

Chicago/Turabian Style

Therina Du Toit; Marietjie Stander; Amanda C. Swart. 2018. "A high-throughput UPC2-MS/MS method for the separation and quantification of C19 and C21 steroids and their C11-oxy steroid metabolites in the classical, alternative, backdoor and 11OHA4 steroid pathways." Journal of Chromatography B 1080, no. : 71-81.

Journal article
Published: 01 January 2018 in Crop Protection
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Adéle McLeod; Siyethemba Lindokuhle Masikane; Precious Novela; Jing Ma; Philemon Mohale; Makomborero Nyoni; Marietjie Stander; J.P.B. Wessels; Pieter Pieterse. Quantification of root phosphite concentrations for evaluating the potential of foliar phosphonate sprays for the management of avocado root rot. Crop Protection 2018, 103, 87 -97.

AMA Style

Adéle McLeod, Siyethemba Lindokuhle Masikane, Precious Novela, Jing Ma, Philemon Mohale, Makomborero Nyoni, Marietjie Stander, J.P.B. Wessels, Pieter Pieterse. Quantification of root phosphite concentrations for evaluating the potential of foliar phosphonate sprays for the management of avocado root rot. Crop Protection. 2018; 103 ():87-97.

Chicago/Turabian Style

Adéle McLeod; Siyethemba Lindokuhle Masikane; Precious Novela; Jing Ma; Philemon Mohale; Makomborero Nyoni; Marietjie Stander; J.P.B. Wessels; Pieter Pieterse. 2018. "Quantification of root phosphite concentrations for evaluating the potential of foliar phosphonate sprays for the management of avocado root rot." Crop Protection 103, no. : 87-97.

Journal article
Published: 01 December 2017 in Functional Foods in Health and Disease
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Background: Brassica vegetables and leafy greens are consumed globally due to their health promoting phytochemicals. Diplotaxis tenuifolia (wild rocket or arugula) is a popular Brassica leafy green, with a diverse range of phytochemicals (in mature plants). Immature plants (micro-greens, 2-4 true leaves) accumulate phytochemicals up to 10 times more than plants grown to maturity. Although plants accumulate phytochemicals ubiquitously, environmental stimuli can further enhance this phenomenon of accumulation, which is part of a global stress mechanism in plants. In this study, we describe a simple method toward the bio-fortification of a wild rocket micro-green system, via environmental manipulation (using high light). Objective: To establish a high light-induced bio-fortification strategy to augment the accumulation of bio-active compounds in Brassica micro-greens (wild rocket), with the purpose of developing a ‘designer’ micro-green melange (functional food product) containing a diverse range of bio-active (disease preventative) compounds.Results: High light stimulated wild rocket micro-greens to achieve a significant increase of known phytochemicals (documented in relevant Brassica leafy greens). Furthermore, undocumented phytochemicals (resveratrol, catechin, epicatechin, and kaempferol, among others) also accumulated to adequate concentrations. Plant extracts from bio-fortified micro-greens displayed increased anti-oxidant capacity (up to 3-fold, when compared to control), a key component in future cancer cell research.Conclusion: The use of high light resulted in successful bio-fortification of wild rocket micro-greens, evidenced by the accumulation of previously undocumented polyphenols (such as resveratrol, catechin and epicatechin) and improved anti-oxidant capacity.Key Words: anti-oxidant, high light, micro-greens, resveratrol, wild rocket

ACS Style

Bianke Loedolff; Jolene Brooks; Marietjie Stander; Shaun Peters; Jens Kossmann. High light bio-fortification stimulates de novo synthesis of resveratrol in Diplotaxis tenuifolia (wild rocket) micro-greens. Functional Foods in Health and Disease 2017, 7, 859 .

AMA Style

Bianke Loedolff, Jolene Brooks, Marietjie Stander, Shaun Peters, Jens Kossmann. High light bio-fortification stimulates de novo synthesis of resveratrol in Diplotaxis tenuifolia (wild rocket) micro-greens. Functional Foods in Health and Disease. 2017; 7 (11):859.

Chicago/Turabian Style

Bianke Loedolff; Jolene Brooks; Marietjie Stander; Shaun Peters; Jens Kossmann. 2017. "High light bio-fortification stimulates de novo synthesis of resveratrol in Diplotaxis tenuifolia (wild rocket) micro-greens." Functional Foods in Health and Disease 7, no. 11: 859.

Comparative study
Published: 13 November 2017 in Journal of Agricultural and Food Chemistry
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Tea samples from 17 populations of “wild tea” ecotypes Aspalathus linearis (rooibos tea) and 2 populations of Aspalathus pendula were analyzed. Recent advances in column technology together with high-resolution mass spectrometry were applied to improve resolution, facilitating the identification of several new compounds as well as grouping of the wild tea ecotypes according to their chemical composition. The collisional cross-section data obtained from ion mobility-mass spectrometry is reported for the flavonoids in rooibos for the first time. Enzyme pathways for the synthesis of the unique flavonoids found in rooibos tea are also proposed. A. linearis and A. pendula produce similar combinations of main phenolic compounds, with no diagnostically different discontinuities between populations or species. Northern resprouters (Gifberg and Nieuwoudtville) contain higher phenylpropenoic acid glucoside levels while teas from Wupperthal and surrounding areas were found to contain unique dihydrochalcones (phloridzin and a sieboldin analog), which are reported here for the first time.

ACS Style

Maria A. Stander; Ben-Erik Van Wyk; Malcolm J. C. Taylor; Helen S. Long. Analysis of Phenolic Compounds in Rooibos Tea (Aspalathus linearis) with a Comparison of Flavonoid-Based Compounds in Natural Populations of Plants from Different Regions. Journal of Agricultural and Food Chemistry 2017, 65, 10270 -10281.

AMA Style

Maria A. Stander, Ben-Erik Van Wyk, Malcolm J. C. Taylor, Helen S. Long. Analysis of Phenolic Compounds in Rooibos Tea (Aspalathus linearis) with a Comparison of Flavonoid-Based Compounds in Natural Populations of Plants from Different Regions. Journal of Agricultural and Food Chemistry. 2017; 65 (47):10270-10281.

Chicago/Turabian Style

Maria A. Stander; Ben-Erik Van Wyk; Malcolm J. C. Taylor; Helen S. Long. 2017. "Analysis of Phenolic Compounds in Rooibos Tea (Aspalathus linearis) with a Comparison of Flavonoid-Based Compounds in Natural Populations of Plants from Different Regions." Journal of Agricultural and Food Chemistry 65, no. 47: 10270-10281.