Skip to main content

The combination of red palm oil and rooibos show anti-inflammatory effects in rats

Abstract

Background

Red palm oil (RPO) and rooibos have been shown to exhibit cardioprotective properties. RPO is rich in essential fatty acids and fat soluble antioxidants while rooibos contains polyphenolic compounds with a unique composition of flavonoids. They exert their biological effects in different cellular compartments. Therefore the combination of these two natural food compounds has the potential to enhance the spectrum of available dietary antioxidants in different cellular compartments, which could result in an enhanced protection against certain pathological conditions such as inflammation.

Methods

Male Wistar rats weighing 150-200 g were supplemented with RPO, rooibos or their combination for 28 days. The Langendorff system and the lipoposaccharide (LPS)-induced inflammatory model were used to establish if RPO and rooibos, when supplemented alone or in combination, will reverse the negative effects of LPS on cardiac function at baseline. The effect of dietary intervention was also investigated on modulation of pro-inflammatory and anti-inflammatory cytokines in plasma and myocardial tissue.

Results and discussion

The LPS resulted in induction of systemic inflammation as evidenced by increased levels of IL-1β in plasma of LPS-treated rats compared to their non-treated control counterparts. Dietary supplementation and LPS treatment did not have an effect on baseline cardiac functional parameters. However, the elevation of IL-1β levels in plasma of LPS-induced rats consuming either RPO or rooibos alone were paralleled with increased levels of the anti-inflammatory cytokine, IL-10. The combination of rooibos and RPO was associated with enhanced endogenous production of myocardial IL-10 in LPS-induced rats.

Conclusion

The results of this study indicate that RPO and rooibos when supplemented individually showed anti-inflammatory effect at systemic level while their combination exhibited an enhanced anti-inflammatory effect in the myocardial tissue. Therefore, the findings in the current study argue that the combination of these two natural food substances could be beneficial in clinically relevant conditions where inflammation plays a role.

Background

Natural food substances have the potential to alter biological functions of cellular and molecular components’ mechanisms by either enhancing the endogenous antioxidant system or through altering the redox signalling status of the cell [1]. This could be beneficial in pathological conditions where oxidative stress and inflammation play an important role. Previous studies have shown that rooibos and red palm oil (RPO) protected the heart against the detrimental effects of ischaemia/reperfusion injury when supplemented individually to rats [2]–[7]. Experimental evidence has also shown that RPO has potential anti-hypertensive and hypoglycaemic properties [8]. Recent evidence showed that RPO alone or in combination with rooibos can alleviate oxidant-induced hepatotoxicity in male rats [9].

Red palm oil is a product from the fruits of the oil palm tree, Elaeis guineensis (Family Arecaceae) which has been shown to have protective effects against hypercholesterolemia and atherosclerotic plaque formation, despite being high in saturated fatty acids [10],[11]. In addition to the various fatty acids that RPO contains, it is also a rich source of a wide spectrum of different lipid soluble antioxidants such as tocopherols, tocotrienols, carotenoids, lycopene and co-enzyme Q10, among others [12]–[14]. The health benefits of RPO have been attributed to its unique composition of fatty acids and a high content of natural antioxidants [15],[13]. RPO is one of the richest sources of natural vitamin E, especially tocotrienols [16]. Vitamin E has been shown to regulate specific cell signalling pathways independent of its antioxidant properties, therefore some of its beneficial effects have been attributed to its ability to modulate signal transduction pathways [17],[18]. There is also credible evidence showing that palm oil vitamin E have potential anti-inflammatory properties [19]–[22].

Rooibos is a uniquely South African herbal tea made from the leaves and stems of the shrub-like leguminous bush, Aspalathus linearis (Brum.f) Dahlg (Fabaceae, Tribe Crotalarieae). It’s flavonoids are unique in that it contains the C-C linked dihydrochalcone glucoside, aspalathin which is oxidized to the flavanones dihydro-iso-orientin and dihydro-orientin during fermentation, the cyclic dihydrochalcone, aspalalinin, the rare 3-dehydroxy dihydrochalcone glucoside, nothofagin, the C-glycosyl flavones orientin, isoorientin, vitexin, isovitexin, and the flavones hemiphlorin and chrysoeriol, luteolin and luteolin-7-O-glucoside and flavonols quercetin and its O-linked glycosides quercetin-3-robinobioside, hyperoside, isoquercitrin and rutin [23]–[25]. The health effects of rooibos have been proposed to be mostly attributed to the unique polyphenolic composition and its related antioxidant activities [26]–[30]. Animal and recent human studies have shown that consumption of rooibos or its phenolic components had positive effects on cardiovascular health and inflammation [31]–[38]. Studies have shown that rooibos may have potential preventive and therapeutic effects against vascular complications in diabetic rats [39]. Aspalathin, the main and unique polyphenol in rooibos, has been shown to positively modulate glucose homeostasis in type 2 diabetes [30], while the antioxidant activity of rooibos has also been linked to its potential anti-inflammatory and DNA protective effects in a rat colitis model [33].

RPO (fat soluble) and rooibos (water soluble) contain different types of antioxidants which reside and exert their biological effects in different cellular compartments [12],[13],[24],[40]. Therefore, it is tempting to speculate that supplementation with a combination of these two natural food compounds can enhance the spectrum of available dietary antioxidants in different cellular compartments and hence offer a better protection against certain pathological conditions such as inflammation. Accumulating scientific evidence shows that inflammation is the underlying pathological cause for most chronic diseases, including cardiovascular diseases, cancer and rheumatoid arthritis [41]–[45]. Ischaemic heart disease is the commonest form of cardiovascular disease leading to increased morbidity and mortality [46]. The majority of heart attacks and strokes are caused by rupturing of the atherosclerotic plaque in the arterial wall and the tendency of clot formation, which results from plaque rupture [46],[42]. It is now a scientifically accepted fact that inflammation in the lining of the artery is the triggering factor in the pathogenesis of atherosclerosis [42]. It is becoming increasingly evident that the use of non-toxic dietary supplements either alone or in combination with pharmacological agents could present an effective strategy in treatment and prevention of the onset of acute and chronic inflammatory diseases [47]–[50]. In this respect, Haines and co-workers [47] reported that the combination of different phytonutrients provided a more profound anti-inflammatory effect than individual components acting independently. In another study it has been shown that whole tart cherry extract and specific anthrocyanins contained in the tart cherry exhibited synergistic anti-inflammatory effects with lipitor in reducing LPS-IL-6 induced secretion from adipose stem cells [49]. Dietary intervention with a Jerte Valley cherry-based beverage which is a rich source of anthocyanin pigments and other phenolic compounds has been shown to modulate the balance between the levels of pro and anti-inflammatory cytokines in young and old ringdoves by down-regulating the levels of pro-inflammatory cytokines and up-regulating the levels of anti-inflammatory cytokines [48].

Administration of lipopolysaccharide (LPS) to animals is widely used to study responses to in vivo-induced acute systemic inflammation [51],[52]. The inflammatory response forms part of the host innate immune response, which represents the first line of defense against invading pathogens or to injury [53]. The cytokine system forms an integral part of the initial response to microbial agents. Cytokines are also important pathophysiological mediators of cardiovascular pathologies such as atherosclerosis and systemic sepsis-induced cardiac dysfunction [54],[55]. The isolated rat heart model and the LPS-induced inflammatory model were used to determine if rooibos and RPO supplementation could protect against the negative effect of LPS-induced inflammation on baseline cardiac function.

Materials and methods

Animals received humane care in accordance with the Principle of Laboratory Animal Care of the National Society of Medical Research and the Guide for the care and use of Laboratory animals of the National Academy of Sciences (National Institutes of Health Publications no. 80–23, revised 1978). The rats had free access to water or rooibos and rat chow. They were individually caged in an experimental animal facility at a constant room temperature of 27°C and exposed to a twelve-hour artificial day-night cycle. The ethical clearance for this study was granted by the Faculty of Health and Wellness Science’s Research Ethics Committee of the Cape Peninsula University of Technology: Ethics Certificate No (CPUT/HW-REC 2010/A004).

Experimental model

Male Wistar rats weighing 150–200 g were randomly divided into 8 groups and supplemented with fermented/traditional rooibos, red palm oil (RPO) or their combination for 28 days. The four groups were further subdivided into two groups, either receiving 1) No-LPS or 2) LPS injection. Group 1 which is the NO-LPS group consisted of the control group receiving standard rat chow and water, rooibos group receiving standard rat chow and rooibos, RPO group receiving standard rat chow supplemented with RPO 0.2 mL (7 g/kg diet) daily and water. The RPO concentrate was supplied by Carotino SND BHD (Company no. 69046-T) Malaysia. The composition of RPO consumed by the rats is shown in (Table 1).

Table 1 Composition of Carotino RPO premium consumed by the rats

The rooibos + RPO group received a combination of rooibos and RPO (without LPS treatment). Group 2 which is the LPS group consisted of the control group receiving standard rat chow and water, rooibos group receiving standard rat chow and rooibos, RPO group receiving standard rat chow supplemented with RPO 0.2 mL (equivalent to 7 g/kg diet) daily and rooibos + RPO group receiving the combination of rooibos and RPO (with LPS treatment). Superior grade fermented rooibos was provided by Rooibos Ltd (Clanwilliam, South Africa). The rooibos aqueous extract was prepared by the addition of 100 ml of freshly boiled water to 10 g of tea leaves, filtered and stored at −40°C, and diluted 5 times, a concentration customarily used for tea consumption purposes, before being given to the rats [56]. Phenolic content, antioxidant capacity and flavonoids composition of the rooibos consumed by the animals are as analyzed by Ajuwon et al. [9]. The animals were given 100 ml of the freshly diluted rooibos every second day. The rooibos and water consumption was monitored throughout the feeding period and there were no statistical differences observed in either rooibos or water consumption among the experimental groups (data not shown). At the end of the feeding period (28 days), 18 hours prior to sacrificing, animals in the LPS group were injected (intraperitoneal) with lipopolysaccharide (Escherichia coli serotype) to induce inflammation. The LPS was dissolved in sterile filtered phosphate buffered saline (PBS) to obtain 0.5 mg/kg body weight in 0.1 ml [51]. The animals in the NO-LPS were injected (intraperitoneal) with 0.1 ml of PBS (Table 2).

Table 2 Study design illustrating the experimental groups and study protocol

At the end of the feeding period and inflammation injection protocol, rats were fasted for 16 hours before sacrificed and anaesthetized with an intraperitoneal injection of 2 mg/kg intraval sodium (sodium pentobarbital). Blood was collected from the abdominal aorta (approximately 5–8 ml) and placed into plain tubes for cytokine analysis. Serum was then separated immediately by centrifuging at 5000 g for 5 min at 4°C, the samples were then stored at −80°C till analysis were performed. Hearts were rapidly excised and placed in ice-cold Krebs-Henseleit buffer and transferred to the Langendorff perfusion system. Hearts were perfused with a Krebs-Henseleit buffer equilibrated with 95% O2 and 5% CO2 at 37°C (118.5 mM NaCl; 4.75 mM KCl; 1.2 mM MgCl 6 H2O; 1.36 mM CaCl2; 25.0 mM NaHCO3; 1.2 mM KH2PO4; 11.0 mM glucose) and a perfusion pressure of 100cmH2O was maintained throughout the protocol. Hearts were mounted to the Langendorff system and perfused for 15 minutes. Coronary flow, heart rate, LVDevP, RPP, ±dp/dt max derivatives, EDLVP were documented at baseline phase. LVDevP was measured with the aid of a balloon made from transparent sandwich wrap film inserted into the left ventricle through the opening of the left atrium. The balloon was connected to a power lab system (AD Instruments Pty Ltd., Castle Hill, Australia). After insertion, the balloon was inflated to 2 mmHg, and the contraction force of the heart against the balloon caused water displacement that was converted to pressure. The systolic and diastolic pressures as well as the heart rate and minimum and maximum derivatives were documented on the computer. At the end of the perfusion protocol hearts were removed from the system and stored at −80°C till biochemical analysis were performed.

Immunoassay for plasma and myocardial cytokine analysis

Analyses of samples were performed on undiluted myocardial tissue homogenates which were originally prepared in phosphate buffer at a dilution of 1:4. In order to analyze the myocardial cytokines, hearts from all the 8 groups were freeze-clamped with Wollenberger clamp pre-cooled in liquid nitrogen. The heart samples were then grinded into powder and 100 mg of heart tissue powder was diluted with 500 μl of phosphate buffer. The mixture was homogenized by ultrasonic homogenizer at maximum power (2×20 sec), and the homogenate was centrifuged at 4°C for 20 minutes at 5000 g. The supernatant was collected and stored at −80°C till analyses were carried out. Protein tissue content was determined using Bradford technique [57]. Plasma and myocardial IL-1 beta, IL-6 and IL-10 levels were measured using the Bio-Plex bead array system (Bio Rad Laboratories, USA). Assays were carried out in 96-well filter plates, while the rat cytokine kits, (Cat#: RCYTO-80 K) were obtained from Millipore (USA). Samples were evaluated in duplicate. All levels of analytes in quality control reagents included in the kits were within the expected references ranges.

Data analysis

Results were expressed as mean ± standard error of the mean (SEM). Differences between the NO-LPS control group and the LPS control group were determined using an unpaired Student’s t-test. To compare differences in multiple groups, ANOVA followed by FisherLSD post hoc test was used. P < 0.05 was considered to be statistically significant difference.

Results

Plasma cytokine levels

IL-1 β

The plasma pro-inflammatory cytokine IL-1β was significantly increased (#p < 0.05) in LPS control (positive controls) rats (367.52 ± 60 pg/ml) when compared to the NO-LPS control (negative controls) rats (63.71 ± 10 pg/ml) (Figure 1a). No differences were observed in plasma.

Figure 1
figure 1

Effects of inflammation, rooibos and RPO on plasma IL-1β (a), IL-6 (b), and IL-10 (c) levels. Results are means ± SEM, n = 4-8/group. #p < 0.05: LPS control vs NO- LPS control, *p < 0.05: treated vs. corresponding control. RPO: Red palm oil.

IL-1β of the rooibos and RPO-supplemented LPS-treated rats compared to the LPS control. No significant differences were observed between RPO alone and the combination treatment compared to the LPS control (Figure 1a).

IL-6

The level of plasma pro-inflammatory cytokine, IL-6 in the positive control rats was not significantly different from the levels in the negative control animals. There were also no differences observed in plasma IL-6 of LPS-induced rooibos and RPO-supplemented rats compared to the positive control (Figure 1b).

IL-10

The plasma anti-inflammatory cytokine, There were no differences observed in plasma IL-10 levels between the negative control and the positive control, however, a significant increase (*p < 0.05) in plasma IL-10 level observed in LPS-induced rats consuming rooibos (4082.19 ± 180 pg/ml) compared to the positive control (1462.63 ± 372 pg/ml). A similar pattern of results were also observed for LPS-induced rats supplemented with RPO, where the plasma IL-10 level was significantly (*p < 0.05) increased (2375.28 ± 264 pg/ml) compared to the positive control (1462.63 ± 372 pg/ml). There were no differences observed in plasma IL-10 level of the LPS-induced rats consuming the combination of rooibos and RPO compared to the positive control (Figure 1c).

Myocardial cytokine levels

IL-1 β

When considering the myocardial IL-1β levels, there were no differences observed between the NO-LPS control and the LPS control animals. The level of myocardial IL-1β was significantly (*p < 0.05) increased in LPS-induced rats consuming the rooibos (172.36 ± 23 pg/ml) when compared to the LPS control (73.29 ± 14 pg/ml) rats (Figure 2a).

Figure 2
figure 2

Effects of inflammation, rooibos and RPO on myocardial IL-1β (a), IL-6 (b), and IL-10 (c) levels. Results are means ± SEM, n = 5-7/group. #p < 0.05: LPS control vs NO- LPS control, *p < 0.05: treated vs. corresponding control. RPO: Red palm oil.

IL-6

Myocardial IL-6 was significantly (#p < 0.05) lower in the positive control (121.53 ± 23 pg/ml) compared to the negative control (233.85 ± 38 pg/ml) rats. The level of myocardial IL-6 was significantly (*p < 0.05) increased in LPS-treated rats consuming rooibos (235.58 ± 38 pg/ml) compared to the positive control (121.53 ± 23 pg/ml). The LPS-induced rats which consumed the combination of rooibos and RPO also showed a significant (*p < 0.05) increase in myocardial IL-6 (283.50 ± 29 pg/ml) compared to the LPS control (121.53 ± 23 pg/ml), (Figure 2b).

IL-10

When considering the myocardial IL-10 levels, significantly (#p < 0.05) increased levels of myocardial IL-10 were measured in the negative control (915.60 ± 71 pg/ml) compared to the positive control (468 ± 60 pg/ml). While the combination of rooibos and RPO significantly (*p < 0.05) increased myocardial IL-10 levels (739.09 ± 48 pg/ml) compared to positive control. The LPS-induced rats consuming either rooibos or RPO alone did not show significant differences in induction of myocardial IL-10 compared to the positive control (Figure 2c).

Discussion

The aim of the current study was to induce inflammation in vivo and to establish if dietary supplementation with rooibos and RPO would reverse or suppress the effects of inflammation. We have shown that administration of LPS induced systemic inflammation as evidenced by elevated levels of IL-1β, the inflammation marker, in the plasma of LPS-treated animals compared to non-treated animals. Consumption of either rooibos or RPO alone was associated with elevated levels of plasma anti-inflammatory cytokine (IL-10) in the LPS-induced rats. The results indicate a potential anti-inflammatory property of rooibos and RPO at systemic level when supplemented individually. However, the combination of rooibos and RPO significantly enhanced endogenous myocardial IL-10 level in LPS-induced rats, arguing for potential protection against inflammation on organ level.

Effects of inflammation, rooibos and RPO on IL-1β

The increased levels of plasma IL-1β in the LPS-induced rats indicate that there was induction of inflammation in response to the presence of the endotoxin (LPS), (Figure 1a). IL-1β is one of the initial pro-inflammatory cytokines to be released in response to the invading microbial pathogens (specifically the lipopolysaccharide, an endotoxin embedded within the bacterial membrane) and it plays a crucial role in the induction of inflammation [58]. Therefore, increased levels of circulating IL-1β are indicative of a systemic inflammatory response [59],[60]. The response to LPS is initiated upon the recognition of LPS by the LPS-binding protein, following the binding of LPS to its binding protein a series of multiple complex signalling pathways is initiated. This will ultimately result in activation of the Toll-like Receptor (TLR) 4 through various adaptor proteins leading to NF-κB activation and eventual induction of inflammatory cytokines [61]–[64]. LPS triggers the release of inflammatory cytokines from various cells of the immune system, the released cytokines leads to an acute inflammatory response directed towards the invading pathogen [65]–[67]. The finding of elevated plasma levels of IL-1β therefore confirms that inflammation was induced in the current model. Our results are in agreement with previous reports by Ohsaki and co-workers [51] which used a similar dose of LPS and showed increased IL-6 mRNA levels indicating that inflammation was induced. Our results also show that supplementation of either rooibos or red palm oil, together and separate, could not prevent an increase in plasma IL-1β.

However, in the myocardium, our results show that consumption of rooibos in the LPS-induced rats was associated with increased myocardial levels of IL-1β compared to the positive control, while RPO and rooibos + RPO did not affect the induction of myocardial IL-1β (Figure 2a). Myocardial and endothelial cells have the capacity to respond to LPS via activation of the TLRs leading to induction of inflammatory cytokines [67]. The role of cytokines in inflammation is complex and is determined by various factors such as the magnitude of cytokine induction, the presence of receptors to cytokines and also by the presence of antagonist mediators such as anti-inflammatory cytokines. The increased levels of myocardial levels of IL-1β in the LPS-induced rats consuming rooibos may represent a normal cellular response to the presence of the endotoxin [68], especially because the observed increases in myocardial levels of IL-1β in LPS-induced rats consuming rooibos were not associated with alterations cardiac function.

Effects of inflammation, rooibos and RPO on IL-6

Dietary intervention with rooibos, RPO or their combination did not have any effect on plasma IL-6 levels in LPS-treated animals and their non-treated counterparts (Figure 1b). There was differential modulation of myocardial IL-6 by the dietary supplements in the LPS-induced supplemented rats. Consumption of rooibos and that of the combination of rooibos and RPO in LPS-induced rats caused an increased in myocardial IL-6 compared to the positive control level comparative to that of the negative control animals (Figure 2b). Even though IL-6 is classically characterized as a pro-inflammation cytokine, it has been shown to have both pro-inflammatory and anti-inflammatory features [69],[70]. IL-6 can evoke an anti-inflammatory environment by inducing the production of anti-inflammatory cytokines, such as IL-10 and IL-1ra in humans [70]. Our results show that the increase in myocardial IL-6 in the LPS-induced rats consuming rooibos and rooibos + RPO was associated with enhanced up-regulation of myocardial IL-10. Therefore the elevation of both IL-6 and IL-10 indicates that in this instance, IL-6 might be acting as an anti-inflammatory cytokine leading to enhancement of IL-10 production. There is evidence showing that in some instances acute elevation of IL-6 may be beneficial, especially following exercise in humans [70]. Xing and co-workers [71] showed that endogenous IL-6 plays an anti-inflammatory role in both local and systemic acute inflammatory responses in mice. This mechanism acts by controlling the level of pro-inflammatory, but not anti-inflammatory, cytokines [72]. Others have also shown that blockade of IL-6 in patients with rheumatoid arthritis led to enhanced cholesterol and plasma glucose levels, indicating a role for IL-6 in modulation of glucose and lipid metabolism [73],[74]. Results in the current study would therefore indicate that endogenous IL-6 rather protected than harmed the heart against induction of LPS, especially in the local organ region as is presented in Figure 2b. The results further show that dietary intervention can influence the levels of IL-6 in cardiac tissue. There is also a difference between systemic and local response to IL-6 levels with LPS induction in the presence of dietary supplements such as red palm oil and rooibos. This needs to be further investigated and clarified.

Effect of inflammation, rooibos and RPO on IL-10

The current results report that plasma IL-10 levels were significantly elevated in the two LPS-treated groups consuming either rooibos or RPO when compared to the LPS control. However, the LPS-induced rats consuming the combination of rooibos and RPO did not show any effect on plasma IL-10 levels indicating that there was no additional benefit on plasma IL-10 levels when rooibos and RPO were given in combination (Figure 1c). The results indicate that dietary supplementation with rooibos and RPO up-regulated the production of IL-10 in response to the presence of inflammation. IL-10 is a potent anti-inflammatory cytokine whose role is to counteract the effects of pro-inflammatory mediators in various forms of shock and inflammation [75]. Inflammatory cells in the circulation are activated in response to invasion of LPS and the initial induction of inflammatory cytokines in response to LPS is aimed at clearing local effect of the invading pathogen [76]. However, the body has also evolved regulatory systems to maintain the balance between the levels of pro-inflammatory mediators and anti-inflammatory mediators in order to sustain cellular homeostasis and immune system integrity. We have shown that rooibos and RPO, when supplemented individually, enhanced production of IL-10 in the blood, suggesting a potential anti-inflammatory effect at systemic level. Therefore the concomitant release of IL-1 β and IL-10 in plasma of LPS-induced rats consuming rooibos and RPO indicate that dietary intervention with rooibos and RPO modulated the inflammatory response in the model of inflammation by enhancing systemic production of the anti-inflammatory cytokine. Rooibos is rich in various polyphenolic compounds, some unique to the plant as well, of which flavonoids are the most predominant [77]. Various polyphenolic molecules have been shown to exhibit anti-inflammatory activity [78],[79]. Polyphenols have a wide range of biological effects which include antioxidant and anti-inflammatory effects [80]–[83]. In the current study we have shown that rooibos consumption was associated with increased levels of plasma IL-10. This is in line with previous studies where polyphenols were associated with enhanced production of IL-10 and suppression of IL-1β [81].

Just as polyphenols form a vital part of a healthy diet, vitamins are also equally essential for human health. RPO is rich in various forms of vitamin E and carotenoids which function as cellular antioxidants [84],[13]. Inflammation and oxidative stress are closely related and are usually common features underlying etiological and pathological mechanisms for most chronic diseases including cardiovascular diseases [85],[86]. Both tocotrienols and tocopherol are potent antioxidants and have also been shown to possess potential anti-inflammatory properties [19],[22].

Dietary supplementation with the combination of rooibos and RPO resulted in increased myocardial levels of IL-10 in the LPS-induced rats compared to the positive control while, when supplemented individually, rooibos and RPO in the presence of LPS, did not have any effect on myocardial IL-10 levels (Figure 2c), this result could be indicative of a threshold needed to exert the effect, i.e. that of increased IL-10 levels. To our knowledge this is the first evidence showing that the combination of rooibos and RPO resulted in up-regulation of myocardial IL-10 levels. Elevated myocardial levels of IL-10 have been linked to cardio-protection [87]. Endogenous production of IL-10 has been shown to play an important role in maintaining myocardial integrity during ischaemia-reperfusion via modulation of the inflammation response. In this regard Yang et al. [88], reported that genetic deletion of IL-10 was associated with enhanced inflammation and increased myocardial infarction and necrosis.

Effects of inflammation, rooibos and RPO on baseline cardiac functional parameters

LPS treatment and dietary supplementation with rooibos and RPO did not have an effect on baseline cardiac functional parameters. The increases in plasma IL 1β levels and in myocardial tissue of the LPS-induced rooibos group were not associated with ventricular dysfunction or reduction in coronary flow (Table 3). This is contrary to reports that IL-1β has a negative inotropic effect and that it also leads to endothelial dysfunction [89],[54]. The reason for this could be that the dose of LPS that we used in this study was sufficient to induce inflammation but not high enough to induce cardiac dysfunction. In previous studies where ventricular dysfunction was reported, higher doses of LPS were used [90],[91]. Lew et al. [92], also reported that sub-lethal dose of LPS had minimal effect on cardiac function. Another plausible reason could be that low doses or sub-lethal doses of LPS have been shown to have a pre-conditioning effect [93]–[95].

Table 3 Effects of inflammation, rooibos and RPO on baseline cardiac functional parameters in the NO-LPS group and the LPS group

Conclusion

In this study we have shown that the model that we used to induce inflammation has worked, as evidenced by increased levels of IL-1β in the blood. Evidence presented here, show for the first time, that the dietary combination of rooibos and RPO significantly enhanced the up-regulation of endogenous myocardial anti-inflammatory IL-10 levels, a phenomenon shown to have great potential in cardio-protection. This study also showed that IL-6 in this model acted more like an anti-inflammatory rather than pro-inflammatory mediator. It was also evident from the results that there is a difference in response to LPS injection between the myocardium and the systemic circulation. Therefore, the results argue that the combination of these two natural food substances exhibit potential anti-inflammatory properties worth investigating further.

References

  1. Halliwell B: Free radicals and antioxidants - quo vadis?. Trends Pharmacol Sci. 2011, 32 (3): 125-130. 10.1016/j.tips.2010.12.002.

    Article  PubMed  CAS  Google Scholar 

  2. Pantsi WG, Marnewick JL, Esterhuyse AJ, Rautenbach F, Van Rooyen J: Rooibos (Aspalathus linearis) offers cardiac protection against ischaemia/reperfusion in the isolated perfused rat heart. Phytomedicine. 2011, 18: 1220-1228. 10.1016/j.phymed.2011.09.069.

    Article  PubMed  CAS  Google Scholar 

  3. Esterhuyse AJ, van Rooyen J, Strijdom H, Bester D, du Toit EF: Proposed mechanisms for red palm oil induced cardioprotection in a model of hyperlipidaemia in the rat. Prostaglandins Leukot Essent Fatty Acids. 2006, 75: 375-384. 10.1016/j.plefa.2006.07.001.

    Article  PubMed  CAS  Google Scholar 

  4. Engelbrecht AM, Esterhuyse AJ, du Toit EF, Lochner A, van Rooyen J: p38-MAPK and PKB/Akt, possible role players in red palm oil-induced protection of the isolated perfused rat heart?. J Nutr Biochem. 2006, 17 (4): 265-271. 10.1016/j.jnutbio.2005.05.001.

    Article  PubMed  CAS  Google Scholar 

  5. Engelbrecht AM, Odendaal L, du Toit EF, Kupai K, Tamás C, Ferdinandy P, van Rooyen J: “The effect of dietary red palm oil on the functional recovery of the ischaemic/reperfused isolated rat heart: the involvement of the PI3-Kinase signaling pathway. Lipids Health Dis. 2009, 8: 1-8. 10.1186/1476-511X-8-18.

    Article  Google Scholar 

  6. van Rooyen J, Esterhuyse AJ, Engelbrecht AM, du Toit EF: Health benefits of a natural carotenoid rich oil: a proposed mechanism of protection against ischaemia/reperfusion injury. Asia Pac J Clin Nutr. 2008, 17 (S1): 316-319.

    PubMed  CAS  Google Scholar 

  7. Bester DJ, Kupai K, Csont T, Szucs G, Csonka C, Esterhuyse AJ, Ferdinandy P, Van Rooyen J: Dietary red palm oil supplementation reduces myocardial infarct size in an isolated perfused rat heart model. Lipids Health Dis. 2010, 9 (64): 1-9.

    Google Scholar 

  8. Bačová Barbara J, Viczenczová C, Knezl V, Dosenko V, Beňova T, Navarová J, Gonçalvesová E, van Rooyen J, Weismann P, Slezák J, Narcis T: Up-regulation of myocardial connexin-43 in spontaneously hypertensive rats fed red palm oil is most likely implicated in its ant-arrhythimic effects. Can J Physio Phamarcol. 2012, 90: 1235-1245. 10.1139/y2012-103.

    Article  Google Scholar 

  9. Ajuwon OR, Katengua-Thamahane E, Van Rooyen J, Oguntibeju O, Marnewick JL: Protective Effects of Rooibos (Aspalathus linearis) and/or Red Palm Oil (Elaeis guineensis) Supplementation on tert-Butyl Hydroperoxide-Induced Oxidative Hepatotoxicity in Wistar Rats. Evid-Based Compl Alt. 2013, 2013: 984273-10.1155/2013/984273.

    Article  Google Scholar 

  10. Hariharan K, Purushothama S, Raina PL: Studies on the red palm oil: Effect of partial supplementation of saturated fats upon lipids and lipoproteins. Nutr Res. 1996, 16 (8): 1381-1392. 10.1016/0271-5317(96)00145-5.

    Article  CAS  Google Scholar 

  11. Kritchevsky D, Tepper SA, Kuksis A, Wright S, Czarnecki SK SK: Cholesterol Vehicle in experimental Atherosclerosis. 22. Refined, Bleached, Deodorized (RBD) Palm oil, Randomized palm oil and red palm oil. Nutr Res. 2000, 20 (6): 887-892. 10.1016/S0271-5317(00)00166-4.

    Article  CAS  Google Scholar 

  12. Nagendran B, Unnithan UR, Choo YM, Sundram K: Characteristics of red palm oil, a carotene- and vitamin E–rich refined oil for food uses. Food Nutr Bull. 2000, 21 (2): 189-194.

    Article  Google Scholar 

  13. Sundram K, Sambanthamurthi R, Tan Y: Palm fruit chemistry and nutrition. Asia Pacific J Clin Nutr. 2003, 12 (3): 355-362.

    CAS  Google Scholar 

  14. Sambanthamurthi R, Sundram K, Tan YA: Chemistry and biochemistry of palm oil. Prog Lipid Res. 2000, 39 (6): 507-558. 10.1016/S0163-7827(00)00015-1.

    Article  PubMed  CAS  Google Scholar 

  15. Packer L, Weber SU, Rimbach G: Molecular aspects of a-tocotrienol antioxidant action and cell signalling. J Nutr. 2001, 131: 369S-373S.

    PubMed  CAS  Google Scholar 

  16. Theriault A, Chao JT, Wang Q, Gapor A, Adeli K: Tocotrienol; A review of its therapeutic potential. Clin Biochem. 1999, 32: 309-319. 10.1016/S0009-9120(99)00027-2.

    Article  PubMed  CAS  Google Scholar 

  17. Sen CK, Rink C, Khanna S: Palm oil-derived natural vitamin E alpha tocotrienol in brain health and disease. J Am Coll Nutr. 2010, 29: S314-S323. 10.1080/07315724.2010.10719846.

    Article  Google Scholar 

  18. Aggarwal BB, Sundaram C, Prasad R: Kannappan. Tocotrienols, the vitamin E of the 21st century: its potential against cancer and other chronic diseases. Biochem Pharmacol. 2010, 80: 1613-1631. 10.1016/j.bcp.2010.07.043.

    Article  PubMed  CAS  PubMed Central  Google Scholar 

  19. Jiang Q, Elson-Schwab I, Courtemanche Ames BN C: γ-Tocopherol and its major metabolite, in contrast to α-tocopherol, inhibit cyclooxygenase activity in macrophages and epithelial cells. Proc Natl Acad Sci U S A. 2000, 97 (21): 11494-11499. 10.1073/pnas.200357097.

    Article  PubMed  CAS  PubMed Central  Google Scholar 

  20. Theriault A, Chao JT, Gapor A: Tocotrienol is the most effective vitamin E for reducing endothelial expression of adhesion molecules and adhesion to Monocytes. Atherosclerosis. 2002, 160: 21-23. 10.1016/S0021-9150(01)00540-8.

    Article  PubMed  CAS  Google Scholar 

  21. Jiang Q, Ames BN: γ-Tocopherol, but not α-tocopherol, decreases proinflammatory eicosanoids and inflammation damage in rats. FASEB J. 2003, 17: 816-822. 10.1096/fj.02-0877com.

    Article  PubMed  CAS  Google Scholar 

  22. Noguchi N, Hanyu R, Nonaka A, Okimoto Y, Kodama T: Inhibition of THP-1 cell adhesion to endothelial cell by α-tocopherol and α-tocotrienol is dependent on intracellular concentration of the antioxidants. Free Radic Biol Med. 2003, 34 (12): 1614-1620. 10.1016/S0891-5849(03)00216-8.

    Article  PubMed  CAS  Google Scholar 

  23. McKay DL, Blumberg JB: Review of the bioactivity of south african herbal teas: rooibos (Aspalathus linearis) and honeybush (Cyclopia intermedia). Phytother Res. 2007, 21: 1-16. 10.1002/ptr.1992.

    Article  PubMed  CAS  Google Scholar 

  24. Joubert E, Gelderblom WCA, Louw A, de Beer D: South African herbal teas: Aspalathus linearis. Cyclopia spp. and Athrixia Phylicoides-A review. J Ethnopharmacol. 2008, 119: 376-412. 10.1016/j.jep.2008.06.014.

    Article  PubMed  CAS  Google Scholar 

  25. Marnewick JL: Rooibos and honeybush: recent advances in chemistry, biological activity and pharmacognosy. African Natural Plant Products: New Discoveries and Challenges in Chemistry and Quality. Edited by: Juliana HR, Simon JE, Ho C-T. 2009, Oxford University Press, Oxford, United Kingdom, 277-294.

    Google Scholar 

  26. Duthie GG, Gardner PT, Kyle JAM: Plant polyphenols: are they the new magic bullet?. Proc Nutr Soc. 2003, 62: 599-603. 10.1079/PNS2003275.

    Article  PubMed  CAS  Google Scholar 

  27. Joubert E, Winterton P, Britz TJ, Ferreira D: Superoxide anion and a; a-diphenyl-b-picrylhydrazyl radical scavenging capacity of rooibos (Aspalathus linearis) aqueous extracts, crude phenolic fractions, tannin and flavonoids. Food Res Int. 2004, 37: 133-138. 10.1016/j.foodres.2003.09.011.

    Article  CAS  Google Scholar 

  28. Liu CM, Zheng YL, Lu J, Zhang ZF, Fan SH, Wu DM, Ma JQ: Quercetin protects rat liver against lead-induced oxidative stress and apoptosis. Environ Toxicol Pharmacol. 2010, 29: 158-166. 10.1016/j.etap.2009.12.006.

    Article  PubMed  CAS  Google Scholar 

  29. Nikolova V, Petrova S, Petkova V, Pavlova S, Michailova A, Georgieva T: Antioxidant effects of rooibos tea on workers occupationally exposed to lead. Toxicol Lett. 2007, 172: S120-S121. 10.1016/j.toxlet.2007.05.320.

    Article  Google Scholar 

  30. Kawano A, Nakamura H, Hata S, Minakawa M, Miura Y, Yagasaki K: Hypoglycemic effect of aspalathin, a rooibos tea component from Aspalathus linearis, in type 2 diabetic model db/db mice. Phytomedicine. 2009, 16: 437-443. 10.1016/j.phymed.2008.11.009.

    Article  PubMed  CAS  Google Scholar 

  31. Schulz H, Joubert E, Schütze W: Quantification of quality parameters for reliable evaluation of green rooibos (Aspalathus linearis). Eur Food Res Technol. 2003, 216: 539-543.

    CAS  Google Scholar 

  32. Marnewick JL, Joubert E, Joseph S, Swanevelder S, Swart P, Gelderblom W: Inhibition of tumour promotion in mouse skin by extracts of rooibos (Aspalathus linearis) and honeybush (Cyclopia intermedia), unique South African herbal teas. Cancer Lett. 2005, 224: 193-202. 10.1016/j.canlet.2004.11.014.

    Article  PubMed  CAS  Google Scholar 

  33. Baba H, Ohtsuka Y, Haruna H, Lee T, Nagata S, Maeda M, Yamashiro Y, Shimizu T: Studies of anti-inflammatory effects of Rooibos tea in rats. Pediatr Int. 2009, 51: 700-704. 10.1111/j.1442-200X.2009.02835.x.

    Article  PubMed  Google Scholar 

  34. Villaño D, Pecorari M, Testa MF, Raguzzini A, Stalmach A, Crozier A, Tubili C, Serafini M: Unfermented and fermented rooibos teas (Aspalathus linearis) increase plasma total antioxidant capacity in healthy humans. Food Chem. 2010, 123: 679-683. 10.1016/j.foodchem.2010.05.032.

    Article  Google Scholar 

  35. Persson IAL, Persson K, Hägg S, Anderson RGG: Effects of green tea, black tea and rooibos tea on angiotensin-converting enzyme and nitric oxide in healthy volunteers. Publ Health Nutr. 2010, 13 (5): 730-737. 10.1017/S1368980010000170.

    Article  Google Scholar 

  36. Persson IAL: The pharmacological mechanism of angiotensin-converting enzyme inhibition by green tea, rooibos and enalaprilat - a study on enzyme kinetics. Phytother Res. 2012, 26: 517-521. 10.1002/ptr.3588.

    Article  PubMed  CAS  Google Scholar 

  37. Marnewick JL, Rautenbach F, Venter I, Neethling H, Blackhurst DM, Wolmarans P, Macharia M: Effects of rooibos (Aspalathus linearis) on oxidative stress and biochemical parameters in adults at risk for cardiovascular disease. J Ethnopharmacol. 2011, 133: 46-52. 10.1016/j.jep.2010.08.061.

    Article  PubMed  Google Scholar 

  38. Petrova A, Davids LM, Rautenbach F, Marnewick JL: Photoprotection by honeybush extracts, hesperidin and mangiferin against UVB-induced skin damage in SKH-1 mice. J. Photochem Photobiol B. 2011, 103: 126-139. 10.1016/j.jphotobiol.2011.02.020.

    Article  PubMed  CAS  Google Scholar 

  39. Uličná O, Vančova O, Božek P, Cársky J, Sebeková K, Boor P, Nakano M, Greksák M: Rooibos tea (Aspalathus linearis) partially prevents oxidative stress in streptozotocin-induced diabetic rats. Physiol Res. 2006, 55: 157-164.

    PubMed  Google Scholar 

  40. Joubert E: HPLC quantification of the dihydrochalcones, aspalathin and nothofagin in rooibos tea (Aspalathus linearis) as affected by processing. Food Chem. 1996, 55 (4): 40-11. 10.1016/0308-8146(95)00166-2.

    Article  Google Scholar 

  41. Willerson JT, Ridker PM: Inflammation as a cardiovascular risk factor. Circulation. 2004, 109: II2-II10. 10.1161/01.CIR.0000122867.89751.59.

    Article  PubMed  Google Scholar 

  42. Libby P: Inflammation and cardiovascular disease mechanisms. Am J Clin Nutr. 2006, 83: 456S-460S.

    PubMed  CAS  Google Scholar 

  43. Gelfand JM, Neimann AL, Shin DB, Wang X, Margolis DJ, Troxel AB: Risk of myocardial infarction in patients with psoriasis. JAMA. 2006, 296: 1735-1741. 10.1001/jama.296.14.1735.

    Article  PubMed  CAS  Google Scholar 

  44. Balkwill F, Mantovani A: Inflammation and cancer: back to Virchow?. Lancet. 2001, 357: 539-545. 10.1016/S0140-6736(00)04046-0.

    Article  PubMed  CAS  Google Scholar 

  45. Wallberg-Jonsson S, Johansson H, Ohman ML, Rantapaa- Dahlqvist S: Extent of inflammation predicts cardiovascular disease and overall mortality in seropositive rheumatoid arthritis. A retrospective cohort study from disease onset. J Rheumatol. 1999, 26 (12): 2562-2571.

    PubMed  CAS  Google Scholar 

  46. Callow AD: Cardiovascular disease 2005-the global picture. Vasc Pharmacol. 2006, 45 (5): 302-307. 10.1016/j.vph.2006.08.010.

    Article  CAS  Google Scholar 

  47. Haines DD, Varga B, Bak I, Juhasz B, Mahmoud FF, Kalantari H, Gesztelyi R, Lekli I, Czompa A, Tosaki A: Summative interaction between astaxanthin, Ginkgo biloba extract (EGb761) and vitamin C in suppression of respiratory infl ammation: a comparison with ibuprofen. Phytother Res. 2011, 25: 128-136. 10.1002/ptr.3160.

    Article  PubMed  CAS  Google Scholar 

  48. Delgado J, del Pilar TM, Garrido M, Barriga C, Paredes SD, Espino J, Rodríguez AB: Systemic Inflammatory load in young and old ringdoves is modulated by consumption of a Jerte Valley Cherry-Based Product. J Med Food. 2012, 15 (8): 707-712. 10.1089/jmf.2011.0233.

    Article  PubMed  CAS  PubMed Central  Google Scholar 

  49. Zhou Z, Nair MG, Claycombe KJ: Synergistic inhibition of interleukin-6 production in adipose stem cells by tart cherry anthocyanins and atorvastatin. Phytomedicine. 2012, 19: 878-881. 10.1016/j.phymed.2012.05.001.

    Article  PubMed  CAS  Google Scholar 

  50. Mahmoud FF, Al-Awadhi R, Haines DD, Dashti A, Dashti H, Al-Ozairi E, Bak I, Tosaki A: Sour Cherry Seed Kernel Extract increases Heme Oxygenase-1 expression and decreases representation of CD3+ TNF-α + and CD3+ IL-8+ subpopulations in peripheral blood leukocyte cultures from Type 2 Diabetes patients. Phytother Res. 2013, 27: 767-774. 10.1002/ptr.4783.

    Article  PubMed  Google Scholar 

  51. Ohsaki Y, Shirakawa H, Hiwatashi K, Furukawa Y, Mizutani T, Komal M: Vitamin K suppresses lipopolysaccharide-induced inflammation in the rat. Biosci Biotechnol Biochem. 2006, 70 (4): 926-932. 10.1271/bbb.70.926.

    Article  PubMed  CAS  Google Scholar 

  52. Du J, An J, Wei N, Guan T, Pritchard KA, Shi Y: Increased resistance to LPS-induced myocardial dysfunction in the Brown Norway Rats versus Dahl S Rats: Role of inflammatory cytokines and nuclear factor kB pathway. Shock. 2010, 33 (3): 332-336. 10.1097/SHK.0b013e3181b7819e.

    Article  PubMed  CAS  PubMed Central  Google Scholar 

  53. Medzhitov R, Janeway CA: Innate immunity: impact on the adaptive immune response. Curr Opin Immunol. 1997, 9: 4-9. 10.1016/S0952-7915(97)80152-5.

    Article  PubMed  CAS  Google Scholar 

  54. Zeuke S, Ulmerb AJ, Kusumoto S, Katus HA, Heine H: TLR4-mediated inflammatory activation of human coronary artery endothelial cells by LPS. Cardiovasc Res. 2002, 56: 126-134. 10.1016/S0008-6363(02)00512-6.

    Article  PubMed  CAS  Google Scholar 

  55. Kelly RA, Smith TW: Cytokines and cardiac contractile function. Circulation. 1997, 95: 778-781. 10.1161/01.CIR.95.4.778.

    Article  PubMed  CAS  Google Scholar 

  56. Marnewick JL, Joubert E, Swart P, Der Westhuizen FV, Gelderblom WC: Modulation of hepatic drug metabolizing enzymes and oxidative status by rooibos (Aspalathus linearis) and honeybush (Cyclopia intermedia), green and black (Camellia sinensis) teas in rats. J Agricult Food Chem. 2003, 51 (27): 8113-8119. 10.1021/jf0344643.

    Article  CAS  Google Scholar 

  57. Bradford MM: A rapid and sensitive method for quantitation of microgram quantities of protein utilizing the principle of protein-dye binding. Anal Biochem. 1976, 71: 248-254. 10.1016/0003-2697(76)90527-3.

    Article  Google Scholar 

  58. Kadokami T, Mctiernan CF, Kubota T, Frye CS, Bounoutas GS, Robbins PD, Watkins SC, Feldman AM: Effects of soluble TNF receptor treatment on lipopolysaccharide-induced myocardial cytokine expression. Am J Physiol Heart Circ Physiol. 2001, 280: H2281-H2291.

    PubMed  CAS  Google Scholar 

  59. Gruys E, Toussaint MJM, Niewold T, Koopmans SJ: Acute phase reaction and acute phase proteins. Zhejiang Univ SCI. 2005, 6B (11): 1045-1056. 10.1631/jzus.2005.B1045.

    Article  CAS  Google Scholar 

  60. Fearon WF, Fearon DT: Inflammation and cardiovascular disease; role of the interleukin-1 receptor antagonist. Circulation. 2008, 117: 2577-2579. 10.1161/CIRCULATIONAHA.108.772491.

    Article  PubMed  Google Scholar 

  61. Qureshi ST, Larivière L, Leveque G, Clermont S, Moore KJ, Gros P, Malo D: Endotoxin-tolerant mice have mutations in Toll-like receptor 4 (Tlr4). J Exp Med. 1999, 189 (4): 615-625. 10.1084/jem.189.4.615.

    Article  PubMed  CAS  PubMed Central  Google Scholar 

  62. Frantz S, Kobzik L, Kim YD, Fukazawa R, Medzhitov R, Lee RT, Kelly RA: Toll4 (TLR4) expression in cardiac myocytes in normal and failing myocardium. J Clin Invest. 1999, 104: 271-280. 10.1172/JCI6709.

    Article  PubMed  CAS  PubMed Central  Google Scholar 

  63. Wright SD: Toll, a new piece in the puzzle of innate immunity. J Exp Med. 1999, 189 (4): 605-609. 10.1084/jem.189.4.605.

    Article  PubMed  CAS  PubMed Central  Google Scholar 

  64. Akira S: Toll-like receptor signaling. J Biol Chem. 2003, 278 (40): 38105-38108. 10.1074/jbc.R300028200.

    Article  PubMed  CAS  Google Scholar 

  65. Sweet MJ, Hume DA: Endotoxin signal transduction in macrophages. J Leukoc Biol. 1996, 60 (1): 8-26.

    PubMed  CAS  Google Scholar 

  66. Feng Y, Zhao H, Xu X, Buys ES, Raher MJ, Bopassa JC, Thibault H, Scherrer-Crosbie M, Schmidt U, Chao W: Innate immune adaptor MyD88 mediates neutrophil recruitment and myocardial injury after ischemia-reperfusion in mice. Am J Physiol Heart Circ Physiol. 2008, 295: H1311-H1318. 10.1152/ajpheart.00119.2008.

    Article  PubMed  CAS  PubMed Central  Google Scholar 

  67. Chao W: Toll-like receptor signaling: a critical modulator of cell survival and ischemic injury in the heart. Am J Physiol Heart Circ Physiol. 2009, 296: H1-H12. 10.1152/ajpheart.00995.2008.

    Article  PubMed  CAS  PubMed Central  Google Scholar 

  68. Irwin MW, Mak S, Mann DL, Qu R, Penninger JM, Yan A, Dawood F, Wen WH, Shou Z, Liu P: Tissue expression and immunolocalization of tumor necrosis factor-alpha in postinfarction dysfunctional myocardium. Circulation. 1999, 99: 1492-1498. 10.1161/01.CIR.99.11.1492.

    Article  PubMed  CAS  Google Scholar 

  69. Damas P, Ledoux D, Nys M, Vrindts Y, De Groote D, Franchimont P, Lamy M: Cytokine serum level during severe sepsis in human IL-6 as a marker of severity. Ann Surg. 1992, 215: 356-362. 10.1097/00000658-199204000-00009.

    Article  PubMed  CAS  PubMed Central  Google Scholar 

  70. Steensberg A, Fischer CP, Keller C, Moller K, Pedersen BK: IL-6 enhances plasma IL-1ra, IL-10, cortisol in humans. Am J Physiol Endocrinol Metab. 2003, 285: E433-E437.

    Article  PubMed  CAS  Google Scholar 

  71. Xing Z, Gauldie J, Cox G, Baumann H, Jordana M, Lei XF, Achong MK: IL-6 is an anti-inflammatory cytokine required for controlling local or systemic acute inflammatory responses. J Clin Invest. 1998, 101: 311-320. 10.1172/JCI1368.

    Article  PubMed  CAS  PubMed Central  Google Scholar 

  72. Tilg H, Trehu E, Atkins MB, Dinarello CA, Mier JW: Interleukin-6 (IL-6) as an anti-inflammatory cytokine: induction of circulating IL-1 receptor antagonist and soluble tumor necrosis factor receptor p55. Blood. 1994, 1 (83): 113-118.

    Google Scholar 

  73. Yasukawa H, Ohishi M, Mori H, Murakami M, Chinen T, Aki D, Hanada T, Takeda K, Akira S, Hoshijima M, Hirano T, Chien KR, Yoshimura A: IL6 induces an antiinflammatory response in the absence of SOCS3 in macrophages. Nat Immunol. 2003, 4: 551-556. 10.1038/ni938.

    Article  PubMed  CAS  Google Scholar 

  74. Choy EH, Isenberg DA, Garrood T, Farrow S, Ioannou Y, Bird H, Cheung N, Williams B, Hazleman B, Price R, Yoshizaki K, Nishimoto N, Kishimoto T, Panayi GS: Therapeutic benefit of blocking interleukin-6 activity with an anti-interleukin-6 receptor monoclonal antibody in rheumatoid arthritis: a randomized, double-blind, placebo-controlled, dose-escalation trial. Arthritis Rheum. 2002, 46: 3143-3150. 10.1002/art.10623.

    Article  PubMed  CAS  Google Scholar 

  75. Nishimoto N, Yoshizaki K, Miyasaka N, Yamamoto K, Kawai S, Takeuchi T, Hashimoto J, Azuma J, Kishimoto T: Treatment of rheumatoid arthritis with humanized anti-interleukin-6 receptor antibody: a multicenter, double-blind, placebo-controlled trial. Arthritis & Rheum. 2004, 50 (6): 1761-1769. 10.1002/art.20303.

    Article  CAS  Google Scholar 

  76. Rennick DM, Fort MM, Davidson NJ: Studies with IL-10−/− mice: an overview. J Leukoc Biol. 1997, 61: 389-396.

    PubMed  CAS  Google Scholar 

  77. Heumann D, Galley P, Barras C, Zaech P, Ulevitch RJ, Tobias PS, Glauser MP, Baumgartner JD: Control of lipopolysaccharide (LPS) binding and LPS-induced tumor necrosis factor secretion in human peripheral blood monocytes. J Immunol. 1992, 148: 3505-3512.

    PubMed  CAS  Google Scholar 

  78. Rabe C, Steenkamp JA, Joubert E, Burger JFW, Ferrema D: Phenolic metabolites from rooibos tea (Aspalathus Linearis). Phytochemistry. 1994, 35 (6): 1559-1565. 10.1016/S0031-9422(00)86894-6.

    Article  CAS  Google Scholar 

  79. Rotelli AE, Guardia T, Juárez AO, de la Rocha NE, Pelzer LE: Comparative study of flavonoids in experimental models of inflammation. Pharmacol Res. 2003, 48: 601-606. 10.1016/S1043-6618(03)00225-1.

    Article  PubMed  CAS  Google Scholar 

  80. Wang L, Tu YC, Lian TW, Hung JT, Yen JH, Wu MJ: Distinctive antioxidant and anti-inflammatory effects of flavonols. J Agric Food Chem. 2006, 54: 9798-9804. 10.1021/jf0620719.

    Article  PubMed  CAS  Google Scholar 

  81. Crouvezier S, Powell B, Keir D, Yaqoob P: The effects of phenolic components of tea on the production of pro- and anti-inflammatory cytokines by human leukocytes in vitro. Cytokine. 2001, 13: 280-286. 10.1006/cyto.2000.0837.

    Article  PubMed  CAS  Google Scholar 

  82. Kim HP, Kun HS, Chang HW, Kang SS: Anti-inflammatory plant flavonoids and cellular action mechanisms. J Pharmacol Sci. 2004, 96: 229-245. 10.1254/jphs.CRJ04003X.

    Article  PubMed  CAS  Google Scholar 

  83. Comalada M, Ballester I, Bailon E, Sierra S, Xaus J, Gálvez J, de Medina FS, Zarzuelo A: Inhibition of pro-inflammatory markers in primary bone marrow-derived mouse macrophages by naturally occurring flavonoids: analysis of the structure-activity relationship. Biochem Pharmacol. 2006, 72: 1010-1021. 10.1016/j.bcp.2006.07.016.

    Article  PubMed  CAS  Google Scholar 

  84. Mutalib MSA, Khaza’ai H, Wahle KWJ: Palm-tocotrienol rich fraction (TRF) is a more effective inhibitor of LDL oxidation and endothelial cell lipid peroxidation than α-tocopherol in vitro. Food Res Int. 2003, 36: 405-413. 10.1016/S0963-9969(02)00173-4.

    Article  CAS  Google Scholar 

  85. Conner EM, Grisham MB: Inflammation, free radicals, and antioxidants. Nutrition. 1996, 12: 274-277. 10.1016/S0899-9007(96)00000-8.

    Article  PubMed  CAS  Google Scholar 

  86. Ceriello A, Motz E: Is oxidative stress the pathogenic mechanism underlying insulin resistance, diabetes, and cardiovascular disease? The common soil hypothesis revisited. Arterioscler Thromb Vasc Biol. 2004, 24: 816-823. 10.1161/01.ATV.0000122852.22604.78.

    Article  PubMed  CAS  Google Scholar 

  87. Jones SP, Trocha SD, Lefer DJ: Cardioprotective actions of endogenous IL-10 are independent of iNOS. Am J Physiol Heart Circ Physiol. 2001, 281: H48-H52.

    PubMed  CAS  Google Scholar 

  88. Yang Z, Zingarelli B, Szabo C: Crucial role of endogenous interleukin-10 production in myocardial ischemia/reperfusion injury. Circulation. 2000, 101: 1019-1026. 10.1161/01.CIR.101.9.1019.

    Article  PubMed  CAS  Google Scholar 

  89. Rietschel ET, Brade H: Bacterial endotoxins. Sci Am. 1992, 267: 53-61. 10.1038/scientificamerican0892-54.

    Article  Google Scholar 

  90. Wang YP, Sato C, Mizoguchi K, Yamashita Y, Maeta MOH: Lipopolysaccharide triggers late preconditioning against myocardial infarction via inducible nitric oxide synthase. Cardiovasc Res. 2002, 56: 33-42. 10.1016/S0008-6363(02)00506-0.

    Article  PubMed  CAS  Google Scholar 

  91. Yao YW, Zhang GH, Zhang YY, Li WD, Wang CH, Yin CY, Zhang FM: Lipopolysaccharide pretreatment protects against ischemia/reperfusion injury via increase of HSP70 and inhibition of NF-κB. Cell Stress Chaperon. 2011, 16: 287-296. 10.1007/s12192-010-0242-6.

    Article  CAS  Google Scholar 

  92. Lew WYW, Bayna E, Molle ED, Dalton ND, Lai NC, Bhargava V, Mendiola V, Clopton P, Tang T: Recurrent exposure to subclinical lipopolysaccharide increases mortality and induces cardiac fibrosis in mice. PLoS One. 2013, 8 (4): e61057-10.1371/journal.pone.0061057.

    Article  PubMed  CAS  PubMed Central  Google Scholar 

  93. Yao Y, Zhang F, Wang L, Zhang G, Wang Z, Chen J, Gao X: Lipopolysaccharide preconditioning enhances the efficacy of mesenchymal stem cells transplantation in a rat model of acute myocardial infarction. J Biosoc Sci. 2009, 16 (74): 1-11.

    Google Scholar 

  94. Lastres-Becker I, Molina-Holgado FJ: Endotoxin preconditioning protects neurons from in vitro ischemia: role of endogenous IL-1beta and TNF-alpha. J Neuroimmunol. 2006, 173: 108-116. 10.1016/j.jneuroim.2005.12.006.

    Article  PubMed  CAS  Google Scholar 

  95. Rosenzweig HL, Minami M, Lessov NS, Coste SC, Stevens SL, Henshall DC, Meller R, Simon RP, Stenzel-Poore MP: Endotoxin preconditioning protects against the cytotoxic effects of TNFalpha after stroke: a novel role for TNFalpha in LPS-ischemic tolerance. J Cereb Blood Flow Metab. 2007, 27 (10): 1663-1674. 10.1038/sj.jcbfm.9600464.

    Article  PubMed  CAS  Google Scholar 

Download references

Acknowledgements

We would like to thank the following grants for sponsoring this study: The URF Grant RH71, Cape Peninsula University of Technology, Cape Town, the SA NRF (Grant UID 72374), the Hungarian NDA (Grant TET 10-1-2011-0009). We also thank Carotino SND BHD for the provision of the red palm oil and Mr Arend Redelinghuys of Rooibos Ltd for generously supplying the rooibos. Csaba Csonka was supported by the János Bolyai Research Scholarship of the Hungarian Academy of Sciences.

Author information

Authors and Affiliations

Authors

Corresponding author

Correspondence to Emma Katengua-Thamahane.

Additional information

Competing interests

The authors declare that they have no competing interests.

Authors’ contributions

EKT: Was involved in all experiments, acquisition and analysis of data and played a significant role in writing and editing of the manuscript. MJL: Made substantial contributions to conception and designing of the study, also played an important role in editing of the manuscript. ORA: Made substantial role in experimental work and data analysis. He was also involved in the editing of the manuscript. CNN: Contributed significantly in analysis of the cytokine analysis and their interpretation. GS: substantial contribution in drafting and editing the manuscript and also helped with the study design. PF: Made substantial contribution in study design and planning as well as interpretation of data. CT: Made substantial contribution in study design and planning as well as interpretation of data. CC: Made substantial contribution in study planning, data analysis and interpretation of data. JVR: Made substantial contributions in conception and design of the study, and interpretation of data, also played an important role in editing the manuscript. All Authors read and approved the manuscript.

Authors’ original submitted files for images

Rights and permissions

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Katengua-Thamahane, E., Marnewick, J.L., Ajuwon, O.R. et al. The combination of red palm oil and rooibos show anti-inflammatory effects in rats. J Inflamm 11, 41 (2014). https://doi.org/10.1186/s12950-014-0041-4

Download citation

  • Received:

  • Accepted:

  • Published:

  • DOI: https://doi.org/10.1186/s12950-014-0041-4

Keywords