55 research outputs found
Assessment of the Antidiabetic Potential of an Aqueous Extract of Honeybush (Cyclopia intermedia) in Streptozotocin and Obese Insulin Resistant Wistar Rats
Urinary peptidomics and pulse wave velocity: The African-PREDICT study
Increased arterial stiffness is related to early vascular aging and is an independent predictor for cardiovascular disease and mortality. Molecular mechanisms underlying increased arterial stiffness are largely unexplored, especially at the proteome level. We aimed to explore the relationship between pulse wave velocity and urinary proteomics. We included 919 apparently healthy (no chronic illnesses) Black and White men and women (equally distributed) between 20 and 30 years from the African-PREDICT study. Capillary electrophoresis time-of-flight mass spectrometry was used to analyze the urinary proteome. We measured the carotid-femoral pulse wave velocity to estimate arterial stiffness. In the total group, pulse wave velocity correlated positively with collagen-derived peptides including collagen types I, II, III, IV, V, and IX and inversely with collagen type XI (adjusted for mean arterial pressure). Regarding noncollagen-derived peptides, pulse wave velocity positively correlated with polymeric immunoglobulin receptor peptides (n = 2) (all q-value â€0.05). In multivariable adjusted analyses, pulse wave velocity associated positively and independently with seven urinary peptides (collagen type I, n = 5) (all p-value â€0.05). We found significant positive and independent associations between pulse wave velocity and the collagen type I-derived peptides, suggesting that dysregulation of collagen type I in the extracellular matrix scaffold could lead to early onset of increased arterial stiffness
Model development for predicting in vitro bio-capacity of green rooibos extract based on composition for application as screening tool in quality control
CITATION: Viraragavan, A. et al. 2020. Model development for predicting in vitro bio-capacity of green rooibos extract based on composition for application as screening tool in quality control. Food & Function, 11:3084-3094. doi:10.1039/C9FO02480HThe original publication is available at http://pubs.rsc.org/en/Journals/Journal/FOMounting evidence of the ability of aspalathin to target underlying metabolic dysfunction relevant to the development or progression of obesity and type 2 diabetes created a market for green rooibos extract as a functional food ingredient. Aspalathin is the obvious choice as a chemical marker for extract standardisation and quality control, however, often the concentration of a single constituent of a complex mixture such as a plant extract is not directly related to its bio-capacity, i.e. the level of in vitro bioactivity effected in a cell system at a fixed concentration. Three solvents (hot water and two EtOHâwater mixtures), previously shown to produce bioactive green rooibos extracts, were selected for extraction of different batches of rooibos plant material (n = 10). Bio-capacity of the extracts, tested at 10 ÎŒg mlâ1, was evaluated in terms of glucose uptake by C2C12 and C3A cells and lipid accumulation in 3T3-L1 cells. The different solvents and inter-batch plant variation delivered extracts ranging in aspalathin content from 54.1 to 213.8 g kgâ1. The extracts were further characterised in terms of other major flavonoids (n = 10) and an enolic phenylpyruvic acid glucoside, using HPLC-DAD. The 80% EtOHâwater extracts, with the highest mean aspalathin content (170.9 g kgâ1), had the highest mean bio-capacity in the respective assays. Despite this, no significant (P â„ 0.05) correlation existed between aspalathin content and bio-capacity, while the orientin, isoorientin and vitexin content correlated moderately (r â„ 0.487; P < 0.05) with increased glucose uptake by C2C12 cells. Various multivariate analysis methods were then applied with Evolution Program-Partial Least Squares (EP-PLS) resulting in models with the best predictive power. These EP-PLS models, based on all quantified compounds, predicted the bio-capacity of the extracts for the respective cell types with RMSECV values †11.5, confirming that a complement of compounds, and not aspalathin content alone, is needed to predict the in vitro bio-capacity of green rooibos extracts. Additionally, the composition of hot water infusions of different production batches of green rooibos (n = 29) at âcup-of-teaâ equivalence was determined to relate dietary supplementation with the extract to intake in the form of herbal tea.Publishers versio
A urinary peptidomics approach for early stages of cardiovascular disease risk: the African-PREDICT study
Cardiovascular disease (CVD) affects individuals across the lifespan, with multiple cardiovascular (CV) risk factors increasingly present in young populations. The underlying mechanisms in early cardiovascular disease development are complex and still poorly understood. We therefore employed urinary proteomics as a novel approach to gain better insight into early CVD-related molecular pathways based on a CVD risk stratification approach. This study included 964 apparently healthy (no self-reported chronic illnesses, free from clinical symptoms of CVD) black and white men and women (aged 20â30 years old) from the African Prospective study on the Early Detection and Identification of Cardiovascular disease and Hypertension (African-PREDICT) study. Cardiovascular risk factors used for stratification included obesity, physical inactivity, tobacco use, high alcohol intake, hyperglycemia, dyslipidemia and hypertension. Participants were divided into low (0 risk factors), medium (1â2 risk factors) and high (â„3 risk factors) CV risk groups. We analyzed urinary peptidomics by capillary electrophoresis time-of-flight mass spectrometry. After adjusting for ethnicity, sex and age, 65 sequenced urinary peptides were differentially expressed between the CV risk groups (all q-valuesââ€â0.01). These peptides included a lower abundance of collagen type I- and III-derived peptides in the high compared to the low CV risk group. With regard to noncollagen peptides, we found a lower abundance of alpha-1-antitrypsin fragments in the high compared to the low CV risk group (all q-valuesââ€â0.01). Our findings indicate lower abundances of collagen types I and III in the high compared to the low CV risk group, suggesting potential early alterations in the CV extracellular matrix
Identifying a urinary peptidomics profile for hypertension in young adults: the African-PREDICT study
Hypertension is one of the most important and complex risk factors for cardiovascular diseases (CVDs). By using urinary peptidomics analyses, we aimed to identify peptides associated with hypertension, building a framework for future research towards improved prediction and prevention of premature development of CVD. We included 78 hypertensive and 79 normotensive participants from the African-PREDICT study (aged 20â30 years), matched for sex (51% male) and ethnicity (49% black and 51% white). Urinary peptidomics data were acquired using capillary-electrophoresis-time-of-flight-mass-spectrometry. Hypertension-associated peptides were identified and combined into a support vector machine-based multidimensional classifier. When comparing the peptide data between the normotensive and hypertensive groups, 129 peptides were nominally differentially abundant (Wilcoxon p < 0.05). Nonetheless, only three peptides, all derived from collagen alpha-1(III), remained significantly different after rigorous adjustments for multiple comparisons. The 37 most significant peptides (all p †0.001) served as basis for the development of a classifier, with 20 peptides being combined into a unifying score, resulting in an AUC of 0.85 in the ROC analysis (p < 0.001), with 83% sensitivity at 80% specificity. Our study suggests potential value of urinary peptides in the classification of hypertension, which could enable earlier diagnosis and better understanding of the pathophysiology of hypertension and premature cardiovascular disease development
Development of On-Line High Performance Liquid Chromatography (HPLC)-Biochemical Detection Methods as Tools in the Identification of Bioactives
Biochemical detection (BCD) methods are commonly used to screen plant extracts for specific biological activities in batch assays. Traditionally, bioactives in the most active extracts were identified through time-consuming bio-assay guided fractionation until single active compounds could be isolated. Not only are isolation procedures often tedious, but they could also lead to artifact formation. On-line coupling of BCD assays to high performance liquid chromatography (HPLC) is gaining ground as a high resolution screening technique to overcome problems associated with pre-isolation by measuring the effects of compounds post-column directly after separation. To date, several on-line HPLC-BCD assays, applied to whole plant extracts and mixtures, have been published. In this review the focus will fall on enzyme-based, receptor-based and antioxidant assays
The antioxidant activity of South African wines in different test systems as affected by cultivar and ageing
Thesis (M. Sc.Voedselwet.)--University of Stellenbosch, 2001.ENGLISH ABSTRACT: Phenolic compounds in wine, due to their antioxidant activity, are reportedly
responsible for the health-promoting properties of wines. The effect of cultivar
and in-bottle ageing on the antioxidant activity of South African wines in
different types of antioxidant assays was, therefore, investigated.
The antioxidant activity of commercial South African red (Cabernet
Sauvignon, Ruby Cabernet, Pinotage, Shiraz, Merlot) and white (Sauvignon
blanc, Chenin blanc, Chardonnay, Colombard) cultivar wines was compared
using the 2,2â-azino-di-(3-ethylbenzothialozine-sulphonic acid) radical cation
(ABTS·+) scavenging, 2,2-diphenyl-1-picrylhydrazyl radical (DPPH·)
scavenging and microsomal lipid peroxidation (MLP) assays. The red wines
was more effective than the white wines on an âas-isâ and an equal total
phenol content. The total antioxidant activity (TAAABTS and TAADPPH) of Ruby
Cabernet was the lowest of the red wines, but the antioxidant potency (APABTS
and APDPPH) of red wine phenolic fractions did not differ (P Âł 0.05). Ruby
Cabernet and Pinotage were the least effective inhibitors of MLP, while Merlot
was the most effective of the red wines. Pinotage phenolic fractions had
lower (P < 0.05) APMLP than that of other red wines. Of the white wines,
Chardonnay and Chenin blanc had the highest and lowest effectivity
respectively according to all antioxidant parameters. Ascorbic acid present in
some wines increased and decreased their TAA and % MLP inhibition
respectively. TAA and % MLP inhibition correlated well (r Âł 0.7, P < 0.001)
with total phenol content of red and white wines, as well as with flavanol
content of red wines and tartaric acid ester content of white wines. The
% MLP inhibition also correlated well with flavanol content of white wines. No
correlation (P > 0.01) was obtained between TAA or % MLP inhibition and
monomeric anthocyanin content of red wines. In the deoxyribose assay, red
wines were more pro-oxidant and exhibited lower hydroxyl radical scavenging
and metal chelating abilities than white wines.
The effect of in-bottle ageing on antioxidant activity of wines was
determined using the ABTS·+ and DPPH· scavenging assays. The TAA and
total phenol content of experimental red (Pinotage and Cabernet Sauvignon)and white (Chardonnay and Chenin blanc) cultivar wines, decreased
(P < 0.05) during 12 months of storage at 0, 15 and 30 ÂșC. The TAAABTS of
Cabernet Sauvignon and Chardonnay, stored at 30 ÂșC were lower (P < 0.05)
than at 0 ÂșC. The APABTS and APDPPH of most wines also decreased during
storage. The monomeric anthocyanin content of red wines decreased
(P < 0.05) rapidly at 15 and 30 ÂșC. The flavanol content of wines (except
Chenin blanc) increased during the first 9 months, decreasing again after 12
months, while minor changes in the flavonol and tartaric acid ester content of
both red and white wines were observed. The TAAABTS exhibited a good
correlation (r Âł 0.7, P < 0.001) with total phenol content of red and white
wines, as well as with flavonol and tartaric acid ester content of red and white
wines and flavanol content of white wines. The monomeric anthocyanin
content of red wines correlated (r = 0.50, P < 0.001) weakly with TAAABTS.
The decrease in the TAAABTS of wines could thus be mainly attributed to a
decrease in their total phenol content.AFRIKAANSE OPSOMMING: Die antioksidant aktiwiteit van fenoliese komponente in wyn is waarskynlik
verantwoordelik vir die gesondheidsvoordele daarvan. Die studie het dus
gepoog om effek van kultivar en veroudering na bottelering op die
antioksidant aktiwiteit van Suid-Afrikaanse wyne te ondersoek.
Die antioksidant aktiwiteit van kommersiële Suid-Afrikaanse rooi
(Cabernet Sauvignon, Ruby Cabernet, Pinotage, Shiraz, Merlot) en wit
(Sauvignon blanc, Chenin blanc, Chardonnay, Colombard) kultivarwyne is
vergelyk deur middel van die 2,2â-azino-di-(3-etielbensotialosien-sulfoon
suur)-radikaal katioon (ABTS·+) vernietigingstoets, 2,2-difeniel-1-pikrielhidrasielradikaal
(DPPH·) vernietigingstoets en mikrosomale lipiedperoksidasietoets
(MLP). Die antioksidant aktiwiteit en die antioksidant
kragtigheid (AK) van die rooiwyne was beter as dié van witwyne in al drie
antioksidant toetse. Die totale antioksidant aktiwiteit (TAAABTS en TAADPPH)
van Ruby Cabernet was die laagste van die rooiwyne, terwyl die AKABTS en
AKDPPH van rooiwyn fenoliese fraksies nie van mekaar verskil (P Âł 0.05) het
nie. Van die rooiwyne, het Ruby Cabernet en Pinotage die laagste en Merlot
die hoogste effektiwiteit in die MLP toets getoon. Die AKMLP van Pinotage se
fenoliese fraksies was die laagste van die rooiwyne. Die witwyne,
Chardonnay en Chenin blanc, het onderskeidelik die beste en swakste
antioksidant aktiwiteit en AK van die witwyne getoon in al drie antioksidant
toetse. Askorbiensuur wat in sommige witwyne voorgekom het, het die TAA
van hierdie wyne verhoog, maar hul % MLP inhibisie verlaag. Die TAA en %
MLP inhibisie het goed gekorreleer (r Âł 0.7, P < 0.001) met die totale
fenolinhoud van rooi- en witwyne, asook die flavanolinhoud van rooiwyne en
die wynsteensuur-esterinhoud van witwyne. Die % MLP inhibisie het ook
goed gekorreleer met die flavanolinhoud van witwyne. Geen korrelasie
(P > 0.1) is waargeneem tussen antioksidant aktiwiteit van rooiwyne en hul
monomeriese antosianien-inhoud. Rooiwyn was meer pro-oksidatief in die
deoksieribose toets as witwyne, maar was die swakste hidroksieradikaalvernietigers
en metaalcheleerders.Die effek van veroudering na bottelering op die antioksidant aktiwiteit
van wyne soos bepaal met die ABTS·+ en DPPH· vernietigingstoetse, is
ondersoek. Die TAA en die totale fenolinhoud van eksperimentele rooi-
(Pinotage en Cabernet Sauvignon) en witwyne (Chardonnay en Chenin blanc)
het afgeneem (P < 0.05) tydens opberging na bottelering by 0, 15 en 30 ÂșC
oor 12 maande. Opberging by 30 ÂșC het ân groter vermindering (P < 0.05) in
die TAAABTS waarde vir Cabernet Sauvignon en Chardonnay veroorsaak as by
0 ÂșC. Die meeste wyne se APABTS en APDPPH waardes het ook verminder
(P < 0.05) na 12 maande. Drastiese vermindering (P < 0.05) in die
monomeriese antosianieninhoud van rooiwyne is opgemerk tydens opberging
by 15 en 30 ÂșC. Tydens die eerste 9 maande se opberging het die
flavanolinhoud van wyne toegeneem (P < 0.05) en daarna afgeneem
(P < 0.05) tot by 12 maande, terwyl flavonol- en wynsteensuuresterinhoud van
beide rooi- en witwyne min verandering ondergaan het. Die totale fenolinhoud
van rooi- en witwyne, asook die flavonol en wynsteensuur-esterinhoud van
rooi-en witwyne en die flavanolinhoud van witwyne, het goed gekorreleer
(r Âł 0.7, P < 0.001) met die TAAABTS. In teenstelling met die resultate vir
kommersiële kultivarwyne, was die TAAABTS van rooiwyne swak gekorreleer
(r = 0.5, P < 0.001) met hul monomeriese antosianieninhoud. Die afname in
TAAABTS van wyne tydens veroudering kon dus meestal toegeskryf word aan
die afname in hul totale fenolinhoud.Maste
Food Ingredient Extracts of Cyclopia subternata (Honeybush): Variation in Phenolic Composition and Antioxidant Capacity
Cyclopia subternata plants are traditionally used for the production of the South African herbal tea, honeybush, and recently as aqueous extracts for the food industry. A C. subternata aqueous extract and mangiferin (a major constituent) are known to have anti-diabetic properties. Variation in phenolic composition and antioxidant capacity is expected due to cultivation largely from seedlings, having implications for extract standardization and quality control. Aqueous extracts from 64 seedlings of the same age, cultivated under the same environmental conditions, were analyzed for individual compound content, total polyphenol (TP) content and total antioxidant capacity (TAC) in a number of assays. An HPLC method was developed and validated to allow quantification of xanthones (mangiferin, isomangiferin), flavanones (hesperidin, eriocitrin), a flavone (scolymoside), a benzophenone (iriflophenone-3-C-ÎČ-glucoside) and dihydrochalcones (phloretin-3\u27,5\u27-di-C-ÎČ-glucoside, 3-hydroxyphloretin-3\u27,5\u27-di-C-hexoside). Additional compounds were tentatively identified using mass spectrometric detection, with the presence of the 3-hydroxyphloretin-glycoside, an iriflophenone-di-O,C-hexoside, an eriodictyol-di-C-hexoside and vicenin-2 being demonstrated for the first time. Variability of the individual phenolic compound contents was generally higher than that of the TP content and TAC values. Among the phenolic compounds, scolymoside, hesperidin and iriflophenone-3-C-ÎČ-glucoside contents were the most variable. A combination of the measured parameters could be useful in product standardization by providing a basis for specifying minimum levels
Antioxidant capacity of Pinotage wine as affected by viticultural and enological practices
Thesis (PhD (Food Science))--University of Stellenbosch, 2006.The aim of the study was to provide the South African wine industry with guidelines for the production of
Pinotage wines with optimal total antioxidant capacity (TAC), while retaining sensory quality. The contribution of
individual phenolic compounds to the wine TAC is important in this regard. The wine TAC was measured with
the 2,2 -azino-di(3-ethylbenzo-thiazoline-sulphonic acid radical cation) (ABTS +) scavenging assay. The
contributions of individual phenolic compounds to the wine TAC were calculated from their content in the wines
and the Trolox equivalent antioxidant capacity (TEAC) of pure phenolic standards. The effects of climate region,
vine structure, enological techniques (pre-fermentation maceration, juice/skin mixing, addition of commercial
tannins, extended maceration) and maturation (oak barrels, alternative oak products, oxygenation) on the phenolic
composition, TAC and sensory quality of Pinotage wines were also investigated.
The TEAC values of quercetin-3-galactoside, isorhamnetin and peonidin-3-glucoside were reported for the
first time. TEAC values observed for most compounds were much lower than those reported previously, although
TEAC values for gallic acid, caftaric acid, caffeic acid and kaempferol were consistent with some previous
reports. Caftaric acid and malvidin-3-glucoside were the largest contributors to the wine TAC. The contents of
monomeric phenolic compounds and procyanidin B1, however, only explained a small amount (between 11 and
24%) of the wine TAC, with the remaining TAC attributed to oligomeric and polymeric phenolic compounds and
other unknown compounds. Some synergy between different monomeric phenolic compounds was also
demonstrated.
All the viticultural and enological factors investigated affected the phenolic composition of Pinotage wines,
while the wine TAC was only affected by some treatments. Changes in wine TAC could not always be explained
by changes in phenolic composition as the contribution of oligomeric, polymeric and unknown compounds could
not be assessed, but could play a large role. Differences in wine colour were also difficult to explain due to the
large number of factors involved and the dark wine colour, which made objective measurements difficult. The
concentration of vitisin A, an orange-red pyranoanthocyanin, was increased consistently as a result of prefermentation
maceration treatments and affected the wine colour of oxygenated wines. Increased wine TAC was
observed when cultivating Pinotage grapes on bush vines and in cooler climatic regions, compared to cultivation
on trellised vines in warmer climatic regions. All the climatic regions and vine structure treatments, however,
resulted in wines with good sensory quality. In terms of enological techniques, pumping-over, as opposed to
punching-down and rotor treatments, is not recommended as a juice/skin mixing technique, due to reduced wine
TAC, colour and sensory quality. Pre-fermentation maceration, addition of commercial tannin preparations, and
oak maturation using traditional and alternative treatments, resulted in improved sensory quality, but with no
change in wine TAC. However, optimisation of the tannin addition protocol may result in increased wine TAC if
additions are made after fermentation or higher dosages are used. Oxygenation of Pinotage wine needs further
investigation to optimise the protocol, as improvements to the wine colour and fullness were observed for some
treatments, but loss of sensory quality and TAC were observed in most cases
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