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Aspalathin a unique phytochemical from the South African rooibos plant (Aspalathus linearis): A mini Review


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Aspalathus linearis (rooibos) is a plant which grows in a limited habitat in South Africa. The plant is mainly renowned for the beverage (herbal tea) which is made from its aerial parts. The popularity of the herbal tea is not confined to South Africa as significant amounts of the tea are exported to many countries worldwide. Rooibos reportedly has several health benefits which have been attributed to its constituent phytochemicals. One of the major phytochemicals in rooibos is aspalathin. Aspalathin makes up between 4-12% of the plant. Aspalathin is a dihydrochalcone glycoside which has thus far only been isolated from Aspalathus linearis. Aspalathin has been shown to possess biological activity which imparts it with multiple health beneficial effects. This mini review highlights the recent findings on the biological properties of aspalathin. These include antioxidant, antidiabetic, cardioprotective, antihypertensive and antimutagenic effects. Given its multiplicity of biological effects, aspalathin is a natural phytochemical which has potential to be incorporated into current medical therapeutic regimes in light of recent preferences for the use of natural medicines.
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J. Afr. Ass. Physiol. Sci 5 (1): 1-6, July 2017
Journal of African Association of Physiological Sciences
Official Publication of the African Association of Physiological Sciences
Aspalathin a unique phytochemical from the South African
rooibos plant (Aspalathus linearis): A mini Review
K.H. Erlwanger1* and K.G. Ibrahim1,2
1School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, Parktown 2193,
Johannesburg, South Africa and 2Department of Physiology, College of Health Sciences, Usmanu Danfodiyo
University, P.M.B. 2254, Sokoto, Nigeria
Rooibos, Aspalathus
linearis, aspalathin,
flavonoid, biological
activity, antioxidant,
Aspalathus linearis (rooibos) is a plant which grows in a limited habitat in South Africa. The
plant is mainly renowned for the beverage (herbal tea) which is made from its aerial parts. The
popularity of the herbal tea is not confined to South Africa as significant amounts of the tea are
exported to many countries worldwide. Rooibos reportedly has several health benefits which
have been attributed to its constituent phytochemicals. One of the major phytochemicals in
rooibos is aspalathin. Aspalathin makes up between 4-12% of the plant. Aspalathin is a
dihydrochalcone glycoside which has thus far only been isolated from Aspalathus linearis.
Aspalathin has been shown to possess biological activity which imparts it with multiple health
beneficial effects. This mini review highlights the recent findings on the biological properties
of aspalathin. These include antioxidant, antidiabetic, cardioprotective, antihypertensive and
antimutagenic effects. Given its multiplicity of biological effects, aspalathin is a natural
phytochemical which has potential to be incorporated into current medical therapeutic regimes
in light of recent preferences for the use of natural medicines.
Aspalathus linearis
The legume Aspalathus linearis is confined to the
north-western to western region of the Fynbos biome in
the Cape Floristic Region of South Africa (Hawkins et
al., 2011; Lötter and le Maitre, 2014). ‘Rooibos’ is a
term used when making reference to the plant or to the
herbal beverage (tea) made from the plant (Hawkins,
Malgas and Biénabe, 2011). Whilst there is limited
harvesting of wild uncultivated rooibos, it is also
cultivated and grown commercially. Hawkins et al.,
(2011) have described in detail the ecotypes and
ecology of the plant. Apart from the beverage which is
made from rooibos, it has found use in several other
products such as soaps, cosmetics and skin lotions
(Chuarienthong et al., 2010).
There are several reports on the health benefits of
rooibos. The earliest reports of its use are from the late
1700s when the local Khoi-Khoi people were observed
using the plant medicinally (Gadow et al., 1997).
Subsequent research has confirmed the health benefits
of rooibos. It has been shown to have antidiabetic and
hypoglycaemic effects (Jin et al., 2013; Kamakura et
al., 2015; Van Der Merwe et al., 2015; Mahmood et
al., 2016), antioxidant (Canda et al., 2014) as well as
anti-HIV effects in vitro (Nakano et al., 1997). In
addition, rooibos also has demonstrated anti-
inflammatory effects (Baba et al., 2009), it has been
shown to reduce colitis and modulate immune function
in vitro (Hendricks and Pool, 2010) as well as in vivo
where it has been shown to promote antigen-specific
antibody production through augmentation of
interleukin-2 production (Kunishiro et al., 2001). The
bronchodilatory effects of rooibos have been attributed
to the phytochemical chrysoeriol which also has
antispasmodic, antiviral and antimicrobial effects
(Khan and Gilani, 2006). The chemoprotective effects
of rooibos have been demonstrated in rat liver using the
cancer initiator diethylnitrosamine (Marnewick et al.,
2009). Rooibos is further reported to have
anticarcinogenic and antiallergic activities (Standley et
© Copyright 2017 African Association of Physiological Sciences -ISSN: 2315-9987; e-ISSN: 2449-108X All rights reserved
*Address for correspondence:
Aspalathin: A unique phytochemical from Aspalathus linearis
2 J. Afr. Ass. Physiol. Sci. 5 (1): July, 2017 Erlwanger and Ibrahim
Fig.1. Chemical structure of aspalathin.
Source: Pubchem. Weblink
al., 2001; Marnewick, 2010). The multiplicity of effects
of rooibos is attributed to its constituent
Phytochemicals in rooibos
The plant contains several biologically active
phytochemicals which include polyphenols and
flavonoids (McKay and Blumberg, 2007).
Phytochemicals isolated from rooibos include
isoorientin, orientin, chryoseriol, isovitexin, nothofagin,
rutin, isoquercetin and hyperoside (McKay and
Blumberg, 2007). There are several recent studies
which provide further detail on the phytochemicals in
rooibos (Ligor et al., 2008; Breiter et al., 2011; Joubert
and de Beer, 2011). It is important to note that
processing the rooibos eg fermentation significantly
reduces the content of some of the phytochemicals
including aspalathin. It has been reported that
fermentation oxidizes over 90% of the aspalathin
mainly to dihydro-iso-orientin (Perold, 2009).
Unfermented rooibos is called green rooibos whilst the
fermented form is called red rooibos.
There are numerous studies on the health benefits of
crude and purified extracts of rooibos however the
focus of this review will be specifically on aspalathin, a
flavonoid which is uniquely found in rooibos (Van Der
Merwe et al., 2015). Aspalathin constitutes about 4-
12% of the dry rooibos plant material (Gadow et al.,
1997; Kreuz et al., 2008).
Structurally aspalathin is a C-linked dihydrochalcone
glycoside. The molecular formula for aspalathin is
C21H24O11. The biochemical structure is shown in figure
1 above.
Gastrointestinal and skin absorption of aspalathin
A study using pigs, showed that aspalathin was
absorbed as a C-glycoside (Kreuz et al., 2008). Liquid
chromatography-mass spectrometry identified in urine,
metabolites of aspalathin which were “methylated
aspalathin, glucuronidated and methylated aspalathin, a
glucuronidated aglycone of aspalathin, as well as a
metabolite of eriodictyol” (Kreuz et al., 2008).
In vitro studies with intestinal epithelial Caco-2 (human
epithelial colorectal adenocarcinoma) cells showed that
absorption was dose dependant (Huang et al., 2008).
However, percutaneous studies using human abdominal
skin cells showed that less than 0.01% of the initial
dose was transported across the skin (Huang et al.,
2008). Thus the cutaneous absorption is significantly
lower than absorption from the gastrointestinal tract.
Biological activity of aspalathin
Antidiabetic effects
Aspalathin has shown potential for use as an
antidiabetic agent due to its glucose lowering effect
(Han et al., 2014). Aspalathin from green rooibos tea
was found to prevent postprandial hyperglycaemia by
suppressing glucose absorption and inhibiting
carbohydrate hydrolyzing enzymes (Mikami et al.,
2015). When KK-Ay type 2 diabetic mice were fed
with aspalathin rich green rooibos extract for five
weeks, it suppressed increases in plasma glucose
(Kamakura et al., 2015). An in vitro study by the same
investigators also showed green rooibos to increase
uptake of glucose and induce phosphorylation of 5Ꞌ
adenosine monophosphate protein kinase (AMPK) in
L6 myotubes (Kamakura et al., 2015). In mice with
impaired glucose tolerance, aspalathin improved
Aspalathin: A unique phytochemical from Aspalathus linearis
3 J. Afr. Ass. Physiol. Sci. 5 (1): July, 2017 Erlwanger and Ibrahim
glucose tolerance (Kawano et al., 2009). Aspalathin
was further shown to reduce hyperglycaemia induced
vascular inflammation in rats by reducing
hyperpermeability and expression of cell adhesion
molecules (Ku et al., 2014). In the same study
aspalathin was noted to decrease activation of nuclear
factor (NF)-κB in vivo (Ku et al., 2014).
Antioxidant effects
Aspalathin showed high antioxidant capacity when it
was compared with other flavonoids in rooibos using
ABTS [2,2′-Azino-bis(3-ethylbenzothiazoline-6-
sulfonic acid) diammonium salt] radical cation, metal
chelating and Fe (II)-induced microsomal lipid
peroxidation assays (Snijman et al., 2009). When
rooibos was administered to rats ad libitum, it
suppressed the accumulation of lipid peroxides in the
brain, which is usually associated with ageing (Inanami
et al., 1995). Rooibos tea also partially prevented
oxidative stress in streptozocin-induced diabetic rats
(Ulicna et al., 2006). Recently aspalathin rich tea was
shown to decrease oxidative stress induced by
immobilization of rats. Several mechanisms were
proposed including the restoration of stress induced
protein degradation, regulation of glutathione and
modulation of superoxide dismutase and catalase, both
of which are antioxidant enzymes (Hong et al., 2014).
However, a study in which aspalathin enriched green
roobios extracts were fed to rats for up to 90 days
showed that blood monitoring in the assessment of
biosafety of phytochemicals is not sensitive and
specific and hence there is need to use molecular
techniques e.g. Quantitative Real Time polymerase
chain reaction analysis, to investigate gene expression
and the activity of regulatory proteins (Van Der Merwe
et al., 2015). By these means the authors observed that
the aspalathin enriched green rooibos extracts caused
some oxidative stress and possibly biliary dysfunction
(Van Der Merwe et al., 2015). The implications of this
finding need further investigation.
Antihypertensive effects
In vitro, aspalathin-rich rooibos tea caused a significant
increase in the production of nitric oxide (Persson et
al., 2006) in human endothelial cells; however,
compared to green tea (Camillia sinensis) it was shown
to not have any effect on angiotensin converting
enzyme (ACE) in vitro, a finding which was attributed
to it lacking catechins (Persson et al., 2006).
Interestingly in vivo, in a randomized three-phase cross
over study, rooibos tea was shown to have a 6%
inhibitory activity (vs 16% for chronic enalpril) of
angiotensin converting enzyme in healthy volunteers
(Persson et al., 2010). The findings may be related to
the impact of NO on ACE. Further noteworthy
findings from the study were that there were
differences in responses to the interventions based on
ACE genotype whereby individuals with genotypes II
and ID showed a significant inhibition of ACE activity
following the drinking of rooibos tea with aspalathin,
whereas those with ACE genotype DD were less
responsive (Persson et al., 2010). Thus it is important
to note that genotypes may play a role in responses to
prophylactic and therapeutic interventions and hence
stresses the importance of the need for greater use of
personalized medicine which takes individual
variability into account in the provision of treatments
(Collins and Varmus, 2015).
Anti-obesity effects
Aspalathin from rooibos showed potential as a weight
loss inductive agent with associated reduction in food
intake (Mahmood et al., 2016). Whilst boiled
fermented rooibos tea was shown to decrease leptin
secretion, inhibit adipogenesis and alter the metabolism
of adipocytes in vitro, the phytochemical profile
showed the extracts to contain mainly isoorientin,
orientin, quercetin-3-O-robinobioside and enolic
phenylpyruvic acid-2-O-β-d-glucoside (Sanderson et
al., 2014). Thus due to processing (fermentation) it is
likely that aspalathin was oxidized as described in an
earlier section of this review and thus unlikely to have
contributed to the anti-obesity effects noted.
Cardio-protective effects
Asapalathin has been shown to protect isolated
cardiomyocytes from hyperglycaemia-induced
metabolic substrate shifts and apopotosis (Dludla et al.,
2017). The possible mechanisms were elucidated using
an H9c2 cardiomyocyte model (Johnson et al., 2016).
Aspalathin modulated several key lipid metabolism
regulators and mechanistically it activated Adipoq
while modulating the expression of the glitazone
receptor peroxisome proliferator-activated receptor
gamma (PPARG and Srebf1/2. Inflammation was
decreased through the proinflammatory IL-6 cytokine
and Jak2 signaling pathway. In addition, the expression
of Bcl2 (aregulator proteins for cell death) was
increased thus preventing apoptosis of the myocardium
(Johnson et al., 2016).
Hypouricaemic effects
The hypouricaemic activity of aspalathin-rich fraction
and purified aspalathin from rooibos on mice was
investigated. These polyphenols significantly
suppressed increased plasma uric acid concentration in
a dose dependent manner (Kondo et al., 2013).
Antimutagenic effects
The antimutagenic effects of rooibos have been
explored and demonstrated in murine experimental
models. Using a Salmonella typhimurium mutagenicity
assay, it was shown that aspalathin showed mild
Aspalathin: A unique phytochemical from Aspalathus linearis
4 J. Afr. Ass. Physiol. Sci. 5 (1): July, 2017 Erlwanger and Ibrahim
antimutagenic activity (Snijman et al., 2007). Topical
application of aspalathin rich green rooibos tea extracts
significantly inhibited tumorigenesis in ICR mice
(Marnewick et al., 2005). Further investigations using
other tumours are necessary.
Rooibos is an important plant in the economy of South
Africa. Given the popularity of rooibos as a herbal tea,
and the increasing use of rooibos extracts in cosmetics,
it is important that more research be undertaken on its
long term effects. Aspalathin which is one of the major
phytochemicals in rooibos has been shown to have
multiple health benefits and impacts several organs.
Given its multiple targets, there is need to also explore
the potential adverse effects of aspalathin.
The developmental origins of health and disease have
now been well established wherein interventions and
events in early life (conception, gestation and neonatal
periods) can impact health outcomes later in life
(Gillman, 2005). Phytochemicals are increasingly
gaining prominence as prophylactics, and as therapeutic
interventions for many diseases. For example, a recent
study showed that resveratrol administered to lactating
mice attenuated hepatic lipid synthesis in the offspring
when they were adults (Tanaka et al., 2017). We have
also shown that neonatal administration of oleanolic
acid also prevented lipid accumulation in high fructose
diet-induced metabolic dysfunction (Nyakudya et al.,
2017). In light of the popularity of rooibos, there is
need to investigate whether consumption of aspalathin
during periods of developmental plasticity can induce
intergenerational health (or disease) outcomes through
epigenetic changes.
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... Termin rooibos używany jest zarówno w odniesieniu do rośliny, jak i naparu sporządzanego z czerwonokrzewu. Herbata rooibos produkowana jest z nadziemnych części afrykańskiej rośliny Aspalathus linearis (Burman f.) R. Dahlgren (aspalat prosty), znanej także jako czerwonokrzew, rooibostee, a w języku afrykańskim speldtee lub swarttee [1,2]. Czerwonokrzew jest rozgałęzionym krzewem z rodziny bobowatych (Fabaceae). ...
... Najliczniejszą grupę związków biologicznie czynnych zawartych w A. linearis stanowią dihydrochalkony ( aspalatyna i notofagina) [2]. Rooibos jest także uważany za "zdrowy" ze względu na brak alkaloidów ( ...
... Napar może stanowić alternatywę dla napojów kofeinowych, takich jak kawa i herbata. Poza przemysłem spożywczym rooibos znajduje także zastosowanie w kosmetyce jako dodatek do mydeł, balsamów do ciała i innych kosmetyków [2]. ...
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Aspalathus linearis (Burman f.) R. Dahlgren is a shrub of the Fabaceae family, growing endemically in southern Africa. Aspalathus linearis has transformed from a wild plant to a cultivated crop. Now it is commercially available as fermented (red) rooibos and the less common unfermented (green) rooibos. This article aimed to review the literature on the redbush with a focus on its health-promoting properties. Numerous laboratory investigations of extracts and infusions of A. linearis have shown that rooibos is a rich source of biologically active compounds, especially polyphenols. The active compounds present in redbush infusions and extracts include flavonoids, phenolic acids, and minute amounts of procyanidins, coumarins, lignans, phenylethanoids, and phenylpropanoids. The characteristic active compounds of rooibos are the C-glucosyl dihydrochalcone - aspalathin and notofagin. An important active compound found in the infusion is also PPAG (Z-2-(beta-D-glucopyranosyloxy)-3-phenylpropenoic acid), which significantly determines the sensory quality of the infusion and its hypoglycaemic properties. Rooibos is also a source of minerals. Studies in both experimental models and healthy volunteers have confirmed the multiple effects of the redbush. The antioxidant properties of A. linearis were especially well studied. The greater antioxidant activity has been reported for aspalathin-rich green rooibos. The consumption of redbush infusions has been reported to have beneficial effects on the parameters like total plasma antioxidant capacity, lipid peroxidation index, and blood glutathione levels. Rooibos has also been shown to alleviate the inflammatory process induced by lipopolysaccharides or that associated with colitis. This is underlined by reduced expression of pro-inflammatory factors, as well as antioxidant properties. Redbush may be used in supporting the treatment of glucose and lipid metabolism disorders, endocrine disorders, and metabolic syndrome. It has been proven to stimulate pancreatic cells to secrete insulin, regulate the expression of genes responsible for glucose metabolism, and affect the amount of glucose transporter protein type 4 (GLUT-4). Other health properties of rooibos may include antimutagenic and hepatoprotective properties and acceleration of skin healing. The bioavailability of redbush flavonoids and the interaction of rooibos ingredients with drugs were also investigated. Studying the mechanism of absorption of flavonoids contained in the redbush and their interactions with drugs will allow determining the appropriate dosage of the extracts. Precise recognition of the chemical composition and health-promoting properties of the redbush will enable its utilization as pharmacotherapy support.
... To date, there are only two literature reviews that focus on Asp, which were conducted based on traditional literature review methods (Erlwanger and Ibrahim 2017;Johnson et al. 2018). As the molecule occurs exclusively in A. linearis, it is difficult to review the molecule alone without considering the parent botanical plant. ...
... A detailed description of dihydrochalcones including Asp was recapitulated by Rivière (2016), as phytoconstituents are gradually receiving attention as prophylactics, and curative mediations for various diseases. Erlwanger and Ibrahim (2017) encapsulated the latest results on the pharmacological properties of Asp in a mini review. The increasing incidence in metabolic syndrome due to sedentary lifestyles and inadequate nutrition results in increased level of sugar and cholesterol in the blood. ...
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Aspalathin (2′,3,4,4′,6′-pentahydroxy-3′-C-β-D-glucopyranosyldihydrochalcone) is a natural C-linked glucosyl dihydrochalcone present in Aspalathus linearis (Burm.f.) R.Dahlgren (rooibos), a South African endemic plant, popularly consumed globally as a herbal tea. Aspalathin is reported to possess potent anti-oxidant properties that are believed to be responsible for the health benefits of rooibos. Other pharmacological properties ascribed to the molecule include antidiabetic, antimutagenic, anti-inflammatory, antithrombotic, and xanthine oxidase inhibitory activities. The role of aspalathin in limiting the progression of metabolic disorders and preventing diabetes-induced cardiovascular complications has been reported. The aforementioned potential health benefits of aspalathin have rendered it a popular natural ingredient that is incorporated in various nutraceutical and cosmeceutical products for protection against different conditions. Percutaneous permeation studies revealed some degree of absorption through the skin, supporting its use in cosmetic preparations. To perform an in-depth assessment of the scientific literature available on aspalathin, a bibliometric analysis was carried out on publications for the period 1965–2020, using the Scopus database. A total of 140 articles were retrieved, indicating that South African authors are major contributors to aspalathin research. The most common areas of investigation were identified as anti-oxidation, chemistry/chemical profiling, antidiabetic and anti-inflammatory activities. A comprehensive literature search showed that there are currently only two available reviews on aspalathin. Hence, the present review aims to explore the history and fill gaps with regards to collating aspects of the synthesis, quality control, metabolism and various biological activities of the molecule.
... However, herbal and dietary supplements regulations vary across the globe [20]. Rooibos tea is produced from a South African endemic plant Aspalathus linearis and has been proven to possess many health benefits [21][22][23]. The health benefits of Rooibos tea include anti-oxidant, anti-diabetic, anti-inflammatory [24,25], hepatoprotective, and chemoprotective effects [26][27][28][29]. ...
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Background The focus on traditional and complementary medicine for supplementation and treatment of diseases is high. Aspalathus linearis commonly known as Rooibos showed several beneficial effects, this led to the standardized production of a pharmaceutical grade green rooibos extract (Afriplex TM GRT) with enhanced polyphenolic content. The aim of this study was to assess toxicity of Afriplex TM GRT in HepG2/C3A cells and Sprague Dawley rats. Methods Afriplex GRT TM (0.1, 1, 10, 100, or 1000 μg/mL) in DMSO was added to the media to the final 0.01% DMSO for treatment of HepG2/C3A for 1, 24 and 48 hrs followed by MTT and ATP assays. Sprague Dawley rats were grouped to Control, Afriplex TM GRT treated (10, 100 and 300 mg/kg); and acute (24hrs tetrachloromethane (CCl 4) injected hepatotoxicity control). Serum biochemistry, histology and Western blot analysis on liver were performed. Results Afriplex TM GRT significantly reduced cell viability at 100 and 1000 mg/kg after 48 hrs. Acute CCl 4 treatment significantly increased serum alanine aminotransferase in rats. The highest extract treatment of 300 mg/kg significantly elevated aspartate amino transferase. There was severe macro vesicular in the CCl 4 group whereas mild to moderate micro vesicular steatosis was seen in the 300 mg/kg Afriplex TM GRT treated group. Highest extract treatment significantly reduced NFkB expression on Western blot analysis. Conclusion The beneficial effects of pharmaceutical grade Afriplex GRT TM are concentration and dosage based. Afriplex GRT TM exerts its beneficial effects via NFkB as demonstrated by the dose dependent reduction of NFkB on Western blot analysis. More work need to be done to explore the exact mechanism that occurs in the NFkB pathway.
... ASP derivatives are known to have a dihydrochalcone skeleton and are connected with a C-glycosidic linkage [11,24]. Several studies have demonstrated the potent antioxidant properties of ASP [24][25][26] with percutaneous permeation studies revealing some degree of absorption through the skin [27] which supports its use in cosmeceutical preparations. However, evidence on the role of ASP in UVB-induced skin damage is still lacking. ...
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Skin cells suffer continuous damage from chronic exposure to ultraviolet light (UV) that may result in UV-induced oxidative stress and skin thinning. This has necessitated the formulation of cosmeceutical products rich in natural antioxidants and free radical scavengers. Aspalathus linearis (rooibos) is an endemic South African fynbos plant growing naturally in the Western Cape region. The plant is rich in phenolics and other bioactives with a wide spectrum of health benefits. The chemical study of an acetonic extract of green A. linearis afforded a novel compound named linearthin (1) and two known dihydrochalcones, aspalathin (2) and nothofagin (3). The chemical structure of the novel compound was elucidated based on spectroscopic data analysis. The bio-evaluation of the isolated chalcones in vitro for protection against UVB-induced oxidative stress were systematically assessed by examining cell viability, metabolic activity, apoptosis, and cytotoxicity using HaCaT and SK-MEL-1 skin cells models. It was observed that pre-treatment with tested samples for 4- and 24 h at low concentrations were sufficient to protect skin cells from UVB-induced damage in vitro as evidenced by higher cell viability and improved metabolic activity in both keratinocytes (HaCaT) and melanocytes (SK-MEL-1). The results further show that the pre-treatment regimen employed by this study involved some degree of cellular adaptation as evidenced by higher levels of reduced glutathione with a concomitant decrease in lipid peroxidation and lowered caspase 3 activity. Furthermore, compound 1 was most cytoprotective against UVB irradiation of HaCaT cell line (over 24 h) with an IC50 of 282 µg/mL and SK-MEL-1 cell line with IC50 values of 248.3 and 142.6 µg/mL over 4 and 24 h, respectively. On the other hand, HaCaT cells exposed to 2 over 4 h before UVB irradiation showed the highest degree of cytoprotection with an IC50 of 398.9 µg/mL among the four studied samples. These results show that linearthin (1) and the two glycoside dihydrochalcone of A. linearis have the potential to be further developed as antioxidant cosmeceutical ingredients that may protect skin against UVB-induced damage.
... African herbal tea and its commercial production started more than a century ago (1). Several biological activities of rooibos including antimutagenic, anti-carcinogenic, anti-allergic, chemopreventive, antioxidant, antidiabetic, hypoglycemic, anti-obesity, cardio-protective, antihypertensive, anti-inflammatory, antispasmodic, bronchodilatory, antiviral, antimicrobial effects have been reported (2,3). The hepatoprotective effect of rooibos tea on animal model of hepatic injury using a chemical hepatotoxicant has also been reported (4) but there is paucity of scientific literature on its effect in non-alcoholic fatty liver disease. ...
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Rooibos tea obtained from the leaves of Aspalathus linearis, is a popular caffeine-free beverage with abundant flavonoids. Previous studies have reported antioxidant, anti-inflammatory and hepatoprotective effects. However, its effect on NAFLD rat model has not been explored. The present study therefore investigated the therapeutic effects of rooibos tea on high-fat diet (HFD)-induced NAFLD in rats. Twelve male albino rats were divided into three equal groups (A, B and C) (n=4) namely: Control, HFD and HFD + Rooibos tea (RBT) respectively. High-fat diet was prepared daily by mixing 40% Lard with 60% standard rat diet. Group A rats received a standard rat chow and water whereas groups B and C were given HFD daily for 28 days. Rats in Group C received RBT ad libitum from Day 15 to 28. On the last day of treatment, relative liver weights (RLW), serum biochemical liver markers and liver histomorphology were assessed. Results revealed that HFD feeding significantly increased serum alanine transaminase (ALT) and alkaline phosphatase (ALP) levels. Administration of RBT significantly decreased ALT, ALP and RLW, but increased total bilirubin levels. Aspartate transaminase and conjugated bilirubin were not altered significantly in different groups. Microscopical examination of the liver of HFD group showed severe hepatic degeneration, necrosis and inflammatory cellular infiltration. However, liver histology of HFD+RBT group showed significantly decreased lesions as compared to HFD group. In conclusion, the outcomes from the present study indicate that rooibos tea is efficient in inhibiting adverse hepatic damage caused by high-fat diet in rats. PhOL Azubuike, et al. 176 (pag 175-182)
... In addition, rooibos has anti-ageing, anticaries, hepatoprotective, nephroprotective, immunomodulating, antimicrobial, antispasmodic, antieczema activities, and may prevent DNA damage and inflammation in vivo (Baba et al., 2009;De Mejia et al., 2013;Morton, 1983;Yang et al., 2018). It has great potential of being included in the current medical therapeutic regime, especially with the global increase and preference for natural remedies to maintain and promote general well-being (Erlwanger and Ibrahim, 2017;Kreuz et al., 2008;Persson, 2013). ...
... In addition, rooibos has anti-ageing, anticaries, hepatoprotective, nephroprotective, immunomodulating, antimicrobial, antispasmodic, antieczema activities, and may prevent DNA damage and inflammation in vivo (Baba et al., 2009;De Mejia et al., 2013;Morton, 1983;Yang et al., 2018). It has great potential of being included in the current medical therapeutic regime, especially with the global increase and preference for natural remedies to maintain and promote general well-being (Erlwanger and Ibrahim, 2017;Kreuz et al., 2008;Persson, 2013). ...
Edited by J Van Staden A B S T R A C T This bibliometric assessment aimed to gain insight into the publication landscape over a 25-year period on one of South Africa's most coveted indigenous plants, Aspalathus linearis, known in commerce as rooibos tea. Despite the growing global market, and acceptance as a refreshing and health-promoting tea, scientific publications on rooibos, have not been subjected to scientometric analyses. A total of 421 relevant documents spanning the period 1994-2018 as indexed in the Scopus database were considered using VOSviewer. The global publication contribution on rooibos tea shows an average annual growth rate of 27.2%, and citation impact averaged 30 per publication. South African authors dominated the research landscape, contributing to approximately 60% of the total publication output. Prominent research themes include oxidative stress and inflammatory process mitigation using rooibos tea extracts, agronomy and fair trade in the rooibos tea industry, metabolic syndrome research, antioxidant activity, toxicity, quality control of rooibos tea and formulated products. More recently, a research focus has developed around bioavailability evaluation of rooibos tea components, green synthesis and nanoparticle formulations with the aim of improving the efficacy and potency of rooibos tea in the treatment of Type 2 Diabetes. We propose that research attention should be devoted to the mechanistic action of rooibos metabolites in mitigation of infectious diseases, diabetes, cardiovascular diseases and obesity which will inevitably lay the foundation for clinical studies to proceed.
Cardiac lipotoxicity results from the deleterious effects of excess lipid deposition in cardiomyocytes. Lipotoxic cardiomyopathy involves cardiac lipid overload leading to changes in myocardial structure and function. Cardiac dysfunction has been associated with cardiac lipotoxicity through abnormal lipid metabolism. Lipid accumulation, especially saturated free fatty acids (SFFAs), in cardiac cells can cause cardiomyocyte distress and subsequent myocardial contractile dysfunction. Reducing the excess FAs supply or promoting FA storage is beneficial for cardiac function, especially under a lipotoxic condition. The protective effects of several compounds against lipotoxicity progression in the heart have been investigated. A variety of mechanisms has been suggested to prevent or treat cardiac lipotoxicity, including improvement of calcium homeostasis, lipid metabolism, and mitochondrial dysfunction. Known targets and signaling pathways involving a select group of chemicals that interfere with cardiac lipotoxicity pathogenesis are reviewed.
As a result of increasing population, developing technology, and growing industrial activity year by year, the release of heavy metals to the environment is continually increasing. Therefore, the treatment of heavy metals is of great importance for the protection of the environment. Lignocellulosic agricultural waste can be used as a versatile, adsorbent material for heavy metals. This article aims to evaluate experimental results on the behavior of various tea wastes for removal of Cr⁶⁺ under internal and external factors affecting adsorption properties. The effects of different parameters such as initial pH (2-7), adsorbent quantity (0.5-5.0 g/100 mL), stirring speed (50-300 rpm), contact time (5-120 minutes) were assessed. The suitability of Cr⁶⁺ adsorption to different isotherms and kinetics was also investigated. According to the CalcPlot3D, the order of the parameters that profoundly affect adsorption was pH > adsorbent dose > time > temperature > stirring speed. An assessment of ΔHº, ΔSº, ΔGº obtained during the adsorption process showed that waste black tea (WBT), waste green tea (WGT), waste rooibos tea (WRT) were applicable, spontaneous, endothermic for Cr⁶⁺. The maximum removal efficiency for Cr⁶⁺ was achieved under optimum conditions as 88%, 83%, and 73%. According to the data obtained, the equilibrium adsorption was observed to fit Langmuir. The maximum adsorption capacity for WBT, WGT, WRT was 9.14, 8.56, and 5.12 mg/g, respectively. The adsorption of Cr⁶⁺ on WBT, WGT, WRT was defined by pseudo-second-order. All results showed that raw WBT, WGT, WRT was environmentally friendly, low cost, an easily available adsorbent in removing Cr⁶⁺ from aqueous solution.
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Aspalathin (ASP) can protect H9c2 cardiomyocytes against high glucose (HG)-induced shifts in myocardial substrate preference, oxidative stress, and apoptosis. The protective mechanism of ASP remains unknown. However, as one of possible, it is well known that phytochemical flavonoids reduce oxidative stress via nuclear factor (erythroid-derived 2)-like 2 (Nrf2) activation resulting in up-regulation of antioxidant genes and enzymes. Therefore, we hypothesized that ASP protects the myocardium against HG- and hyperglycemia-induced oxidative damage by up-regulating Nrf2 expression in H9c2 cardiomyocytes and diabetic (db/db) mice, respectively. Using an oxidative stress RT2 Profiler PCR array, ASP at a dose of 1 µM was demonstrated to protect H9c2 cardiomyocytes against HG-induced oxidative stress, but silencing of Nrf2 abolished this protective response of ASP and exacerbated cardiomyocyte apoptosis. Db/db mice and their non-diabetic (db/+) littermate controls were subsequently treated daily for six weeks with either a low (13 mg/kg) or high (130 mg/kg) ASP dose. Compared to nondiabetic mice the db/db mice presented increased cardiac remodeling and enlarged left ventricular wall that occurred concomitant to enhanced oxidative stress. Daily treatment of mice with ASP at a dose of 130 mg/kg for six weeks was more effective at reversing complications than both a low dose ASP or metformin, eliciting enhanced expression of Nrf2 and its downstream antioxidant genes. These results indicate that ASP maintains cellular homeostasis and protects the myocardium against hyperglycemia-induced oxidative stress through activation of Nrf2 and its downstream target genes.
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Resveratrol (3,5,4-trihydroxystilbene) is a natural polyphenolic compound found in grapes and red wine and has been shown to exert protective effects on the liver preventing lipid accumulation induced by a high-fat diet. However, no studies have shown that the nutritional resveratrol intake by the parental generation has modified lipogenesis in an adult offspring. The aim of this study was to investigate whether maternal resveratrol intake during lactation affects lipogenesis in adult male rat offspring, and if it does, what is the molecular mechanistic basis. Six male pups born from mothers given a control diets during lactation (CC group) and six male pups born from mothers given a control diet as well as resveratrol during lactation (CR group) were fed a standard diet until sacrifice at 36 weeks. Adult male offspring from mothers given resveratrol during lactation (CR group) had lower body weight from the fourth week of lactation until adulthood, but no significant change was observed in the relative food intake. Low levels of plasma triacylglycerol were found in the CR group compared to the CC group. Histopathological analysis of the livers of adult male rat offspring revealed lipid accumulation in hepatocytes in the CC group, whereas lipid droplets were rare in the CR group. Hepatic protein levels of AMPK-phosphorylated at ser403, Sirt1, and Nampt in the CR group were upregulated significantly compared to the CC group. These results indicated the maternal resveratrol intake during lactation-induced activation of AMPK through Sirt1 upregulation. In this study, significant upregulation of the levels of precursor of sterol regulatory element binding protein-1c (SREBP-1c) and downregulation of the ratio of active-SREBP-1c/precusor-SREBP-1c were observed in the CR group compared to the CC group. These results suggested that proteolytic processing of SREBP-1c was suppressed by AMPK in the livers of the CR group. It is well known that SREBP-1c regulates the lipogenic pathway by activating genes involved in triglyceride and fatty acid synthesis. The present study showed significant downregulation of hepatic fatty acid synthase (FAS) and acetyl-CoA carboxylase (ACC) levels in the CR group. These results indicated that maternal resveratrol intake during lactation suppressed SREBP-1c cleavage and nuclear translocation and repressed SREBP-1c target gene expression such as FAS and ACC in the livers of adult male offspring. These changes attenuate hepatic triacylglycerol and fatty acid synthesis in adult male offspring.
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Background Flavonoids have been reported as mammalian alpha-amylase inhibitors, a property which could be useful in the management of postprandial hyperglycemia in diabetes and its related disorders. Objectives In the present study the inhibitory effect of aspalathin as a flavonoid on alpha amylase activity and levels of sugar and lipids in rats, has been investigated. Methods In this experimental study, type inhibition of aspalatin on amylase and in the part of in vivo, the effect of aspalathin orally doses 5, 10, 20 and 40 mg/kg body weight on sugar and lipids levels was tested in a streptozotocin-induced model of diabetes and normal rats. The data were analyzed by one-sample Kolmogrov-Smirnov, Levene and ANOVA tests through SPSS version 22. Results The results showed that aspalathin is a competitive inhibitor for alpha amylase with Ki = 37.0 μM. In both diabetic and normal groups in all doses nearly dose dependent manner reduced blood glucose levels and beneficial effect on dyslipidemia were observed in diabetic rats, as well as reduction of disturbing consequences of diabetes such as high urine volume and water intake. Aspalathin was observed to have a weight loss-inductive effect, alongside with a reduction in food intake. Conclusions It seems that, this compound could be proposed as an antihyperglycemic and antihyperlipidemic agent in diabetes and potential therapeutic in obesity.
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An aspalathin-enriched green rooibos (Aspalathus linearis) extract (GRE) was fed to male Fischer rats in two independent studies for 28 and 90 days. The average dietary total polyphenol (TP) intake was 756 and 627 mg Gallic acid equivalents (GAE)/kg body weight (bw)/day over 28 and 90 days, respectively, equaling human equivalent doses (HEDs) of 123 and 102 GAE mg/kg bw/day. Aspalathin intake of 295 mg/kg bw/day represents a HED of 48 mg/kg bw/day (90 day study). Consumption of GRE increased feed intake significantly (p < 0.05) compared to the control after 90 days, but no effect on body and organ weight parameters was observed. GRE significantly (p < 0.05) reduced serum total cholesterol and iron levels, whilst significantly (p < 0.05) increasing alkaline phosphatase enzyme activity after 90 days. Endogenous antioxidant enzyme activity in the liver, i.e., catalase and superoxide dismutase activity, was not adversely affected. Glutathione reductase activity significantly (p < 0.05) increased after 28 days, while glutathione (GSH) content was decreased after 90 days, suggesting an altered glutathione redox cycle. Quantitative Real Time polymerase chain reaction (PCR) analysis showed altered expression of certain antioxidant defense and oxidative stress related genes, indicative, among others, of an underlying oxidative stress related to changes in the GSH redox pathway and possible biliary dysfunction.
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Aspalathus linearis (Burm. f.) R. Dahlgren (rooibos) is endemic to the Fynbos Biome of South Africa, which is an internationally recognized biodiversity hot spot. Rooibos is both an invaluable wild resource and commercially cultivated crop in suitable areas. Climate change predictions for the region indicate a significant warming scenario coupled with a decline in winter rainfall. First estimates of possible consequences for biodiversity point to species extinctions of 23% in the long term in the Fynbos Biome. Bioclimatic modelling using the maximum entropy method was used to develop an estimate of the realized niche of wild rooibos and the current geographic distribution of areas suitable for commercially production. The distribution modelling provided a good match to the known distribution and production area of A. linearis. An ensemble of global climate models that assume the A2 emissions scenario of high energy requirements was applied to develop possible scenarios of range/suitability shift under future climate conditions. When these were extrapolated to a future climate (2041-2070) both wild and cultivated tea exhibited substantial range contraction with some range shifts southeastwards and upslope. Most of the areas where range expansion was indicated are located in existing conservation areas or include conservation worthy vegetation. These findings will be critical in directing conservation efforts as well as developing strategies for farmers to cope with and adapt to climate change.
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This study investigated the antioxidative effect of rooibos herbal tea and a rooibos-derived commercial supplement on tert-butyl hydroperoxide- (t-BHP-) induced oxidative stress in the liver. Forty male Wistar rats consumed fermented rooibos, unfermented rooibos, a rooibos-derived commercial supplement, or water for 10 weeks, while oxidative stress was induced during the last 2 weeks via intraperitoneal injection of 30 µmole of t-BHP per 100 g body weight. None of the beverages impaired the body weight gain of the respective animals. Rats consuming the rooibos-derived commercial supplement had the highest (P < 0.05) daily total polyphenol intake (169 mg/day) followed by rats consuming the unfermented rooibos (93.4 mg/day) and fermented rooibos (73.1 mg/day). Intake of both the derived supplement and unfermented rooibos restored the t-BHP-induced reduction and increased (P < 0.05) the antioxidant capacity status of the liver, while not impacting on lipid peroxidation. The rooibos herbal tea did not affect the hepatic antioxidant enzymes, except fermented rooibos that caused a decrease (P < 0.05) in superoxide dismutase activity. This study confirms rooibos herbal tea as good dietary antioxidant sources and, in conjunction with its many other components, offers a significantly enhanced antioxidant status of the liver in an induced oxidative stress situation.
Scope: Energy deprivation in the myocardium is associated with impaired heart function. This study aim to investigate if aspalathin can ameliorate hyperglycemic-induced shift in substrate preference and protect the myocardium against cell apoptosis. Methods and results: H9c2 cells were exposed to, either normal (5.5 mM) or high (33 mM) glucose concentrations for 48 hours. Thereafter, cells exposed to 33 mM glucose were treated with metformin (1 μM) or aspalathin (1 μM), as well as a combination of metformin and aspalathin for 6 hours. In vitro studies revealed that aspalathin improved glucose metabolism by decreasing fatty acid uptake and subsequent β-oxidation through the decreased expression of pAMPK (Thr(172) ) and CPT1, while increasing ACC and GLUT4 expression. Aspalathin inhibited high glucose-induced loss of membrane potential in H9c2 cells as observed by an increase in JC-1 ratio (orange\red fluorescence) and decreased apoptosis by reducing intracellular ROS and DNA nick formation, while increasing glutathione, superoxide dismutase, UCP2 and Bcl-2\Bax ratio. Conclusion: Our study provides evidence that aspalathin increases glucose oxidation and modulates fatty acid utilization producing a favorable substrate shift in H9c2 cardiomyocytes exposed to high glucose. Such a favorable shift will be of importance in the protection of cardiomyocytes in the diabetic heart. This article is protected by copyright. All rights reserved.
To evaluate the suppressive effects of green rooibos (Aspalathus linearis) unfermented tea on postprandial hyperglycemia, we orally administered four carbohydrates with or without green rooibos extract (GRE) and its major flavonoid aspalathin (Asp). GRE significantly suppressed the elevation of blood glucose levels after glucose, maltose, and starch intake. Asp also lowered the levels for all four carbohydrates. To clarify the mechanism underlying these results, we performed an intraperitoneal glucose tolerance test (IPGTT) and measured the ability of GRE and Asp to inhibit the activities of carbohydrate-hydrolyzing enzymes in vitro. In IPGTT, GRE and Asp did not show suppressive effects on blood glucose, while they dose-dependently inhibited the activities of α-glucosidase and α-amylase in vitro. These results showed that GRE and Asp suppress the elevation of blood glucose levels. It was indicated that these effects may result from the suppression of glucose absorption and the inhibition of carbohydrate-hydrolyzing enzyme activities by GRE and Asp.
"Tonight, I'm launching a new Precision Medicine Initiative to bring us closer to curing diseases like cancer and diabetes - and to give all of us access to the personalized information we need to keep ourselves and our families healthier." - President Barack Obama, State of the Union Address, January 20, 2015 President Obama has long expressed a strong conviction that science offers great potential for improving health. Now, the President has announced a research initiative that aims to accelerate progress toward a new era of precision medicine ( We believe that the time is right for this visionary initiative, . . .
Vascular inflammation plays a key role in the initiation and progression of atherosclerosis, a major complication of diabetes mellitus. Aspalathin (Asp) and nothofagin (Not) are two major active dihydrochalcones found in green rooibos, which have been reported for their antioxidant activity. In this study, we assessed whether Asp or Not can suppress vascular inflammation induced by high glucose (HG) in human umbilical vein endothelial cells (HUVECs) and mice. We monitored the effects of Asp or Not on HG-induced vascular hyperpermeability, expression of cell adhesion molecules (CAMs), formation of reactive oxygen species (ROS), and activation of nuclear factor (NF)-κB in vitro and in vivo. Our data indicate that HG markedly increased vascular permeability, monocyte adhesion, expression of CAMs, formation of ROS, and activation of NF-κB. Remarkably, treatment of Asp or Not inhibited HG-mediated vascular hyperpermeability, adhesion of monocytes toward HUVECs, and expression of CAMs. In addition, Asp or Not suppressed the formation of ROS and the activation of NF-κB. Since vascular inflammation induced by HG is critical in the development of diabetic complications, our results suggest that Asp or Not may have significant benefits in the treatment of diabetic complications.