Effects of rhaponticum carthamoides versus glycyrrhiza glabra and punica granatum extracts on metabolic syndrome signs in rats
© Dushkin et al.; licensee BioMed Central Ltd. 2014
Received: 7 June 2013
Accepted: 15 November 2013
Published: 20 January 2014
Rhaponticum cathamoides (RC) is an endemic wild Siberian herb with marked medicinal properties that are still poorly understood. The aim of this study is to investigate the therapeutic potential of RC extract (ERC) compared to the effects of Glycyrrhiza glabra (EGG) and Punica granatum extracts (EPG) in a rat model with high-fat diet-(HFD)-induced signs of metabolic syndrome; therefore, this study addresses a significant global public health problem.
Six-month-old male Wistar Albino Glaxo rats were subjected to eight weeks of a standard diet (SD), HFD, or HFD in which ERC, EGG, or EPG powders were incorporated at 300 mg/kg/day. The serum lipid profile, corticosterone and cytokine concentrations, glucose tolerance, systolic blood pressure, triacylglycerol accumulation, and PPARα DNA-binding activities in the liver samples were determined.
In contrast to EGG and EPG, an ERC supplement significantly reduced the weight of epididymal tissue (19.0%, p < 0.01) and basal serum glucose level (19.4%, p < 0.05). ERC improved glucose intolerance as well as dyslipidemia more efficiently than EGG and EPG. EGG but not ERC or EPG supplementation decreased systolic blood pressure by 12.0% (p < 0.05). All of the tested extracts reduced serum IL6 and corticosterone levels induced by HFD. However, the lowering effects of ERC consumption on the serum TNF-α level and its restoring effect on the adrenal corticosterone level significantly exceeded the improvements induced by EGG and EPG. ERC intake also reduced triacylglycerol accumulation and increased the PPARα DNA-binding activity in the liver more significantly than EGG and EPG.
ERC powder supplementation improved glucose and lipid metabolism more significantly than EGG and EPG in rats fed on HFD, supporting the strategy of R. carthamoides use for safe relief of metabolic syndrome and its related disturbances such as inflammation, stress, and hepatic steatosis.
KeywordsRhaponticum carthamoides Metabolic syndrome Corticosterone Inflammatory cytokines
Metabolic syndrome, a condition defined by a cluster of cardiometabolic risk factors including visceral adiposity, diabetes mellitus, dyslipidemia, and high blood pressure represents a significant global public health problem . Among environmental factors, the high-fat diet and sedentary lifestyle common in the Western world are considered to be the major causes of obesity-associated impaired glucose tolerance and dyslipidemia . Metabolic syndrome is also often characterized by chronic inflammation and hepatic steatosis . Early treatment of people with metabolic syndrome may prevent the development of cardiovascular disease. Current treatment strategies include lifestyle modifications with pharmacological interventions targeted at complex manifestations of the metabolic syndrome as necessary . Multiple biological targets controlling these manifestations will require a simultaneous application of different classes of drugs such as statins, thiazolidinediones, fibrates, biguanides, sulfonylureas, antihypertensive drugs, and many others for the attainment of beneficial effect. Although significant progress has been made in the development of therapeutic strategies for reducing risk factors for cardiovascular disease [5–7], the integrated management of metabolic syndrome is often an elusive goal in practice. The problem of integrated management of metabolic syndrome arises due to the long-term use of expensive medications that sometimes may result in adverse side effects. Recently, a number of innovative nutritional strategies based on a long and successful practice have been proposed as a safe alternative treatments to reduce the morbidity as well as the cost of metabolic syndrome treatment [8–10].
To date, more than 1000 officinal plant treatments for metabolic disorders have been reported, although only a small number of these have received scientific and medical evaluation to assess their comparative efficacy . Therefore, more screening trials of commercial herbal products are needed to develop functional as well as analytical bases for standardization of dietary supplements . Among herbs of this kind, nutritional ingredients of Glycyrrhiza glabra and Punica granatum are widely used in Indian and Chinese traditional medicine. The antidiabetic and anti-obesity effects of G. glabra[13, 14] and P. granatum[15, 16] are relatively well studied in animal models. In particular, the licorice flavonoids have recently been shown to suppress abdominal fat accumulation and increase in blood glucose level in obese rats  and mice . High total polyphenol content is related to antidiabetic and antioxidant effects of Punica granatum extracts observed in mice  and rats .
Rhaponticum carthamoides (Willd) Iljin, commonly known as maral root or Russian leuzea, has been widely used in the traditional Siberian medicine, mostly to treat overstrain and common weakness after illnesses, as a stimulant, and a remedy against male sex dysfunction. The principal bioactive constituents of this plant are ecdysteroids, flavonoids, and phenolic acids. The extracts and preparations from this plant, which are practically safe, exhibited various additional antioxidant, immunomodulatory, antitumor, and antimicrobial effects . However, relatively scarce literature is available on the medicinal properties of R. carthamoides as a treatment for metabolic disorders. In addition, the effect of R. carthamoides, especially on the high fat diet-induced metabolic syndrome development, remains to be clarified. The potential of R. carthamoides in the inhibition of the basic manifestations of metabolic syndrome is not sufficently studied. In the present study, we tested the effects of the ethanolic extract of R. carthamoides root versus the commercially available ethanolic extracts of G. glabra root and P. granatum peel with proclaimed antidiabetic and anti-obesity properties on the signs of metabolic syndrome in an obese rat model.
Plant materials and chemicals
Commercial ethanol extract powder from the root of R. carthamoides (wild-growing) (20-hydroxyecdisone content of 2.2% was standardized by HPLC analysis), licorice root extract powder (glycyrrhizic acid (15.0%) was conditioned by HPLC analysis) and pomegranate peel extract powder (ellagic acid (40.0%) was conditioned by HPLC analysis) were obtained from KIT Co., Ltd. (Altai State Technical University, Barnaul, Russia), Wixi Cima Science Co., Ltd. (Jiangsu, China (Mainland)), and Xian Yuensun Biological Technology Co., Ltd. (Shaanxi, China (Mainland)), respectively, and were stored at +4°C until use. All other chemicals were analytical grade.
Animals, diets, and experimental design
Male Wistar Albino Glaxo rats, six months old, were obtained from the Animal Center of the Institute of Cytology and Genetics (Novosibirsk, Russia) and were housed individually in cages in an air-conditioned room (24.2°C) with a 12 h light/dark cycle and food and water provided ad libitum. All animal experiments were performed according to the animal ethics guidelines of the European Communities Council Directive (86/609/EEC) and approved by the Animal Care Committee of the Institute of Internal Medicine, Novosibirsk, Russia. The animals were randomly split into 5 groups of 10 rats each. Group I was maintained on briquette feed standard diet (SD group) containing 10% fat-derived calories, while group II was fed a high-fat diet (HFD group) containing 60% fat-derived calories (Laboratorsnab, Moscow, Russia) for 8 weeks. The rats of groups III, IV, and V were fed an HFD supplemented with the powder extracts of R. carthamoides (ERC group), G. glabra (EGG group), and P. granatum (EPG group), respectively, at a daily dose of 300 mg/kg of body weight (b.w.) for 8 weeks. Animals were weighed once a week, and food intake was measured daily. At the end of each experimental period, rats were deprived of food for 16 h, then anesthetized with an intraperitoneal injection of sodium pentobarbital (50 mg/kg b.w.) and sacrificed. Epididymal adipose tissue, adrenal gland and liver were extracted and weighed.
Intraperitoneal glucose tolerance test
At week 8 of the experiment, rats were deprived of food overnight (16 h) and after collecting a fasting blood sample from a tail vein were injected intraperitoneally with D-glucose (50% stock solution in saline, 5 g/kg b.w.). Blood glucose concentration was measured at 60, 120, and 180 min after injection by One Touch Horizon glucometer (Lifescan, Johnson and Johnson, NJ, USA).
At baseline and further weekly, systolic and diastolic blood pressure were measured by a noninvasive pressure device using volume pressure recording, CODA 2 (Kent Scientific, Torrington, CT, USA), on non-anesthetized rats restrained in the thermic plastic chamber.
Determination of serum triacylglycerol, cholesterol, free fatty acid, corticosterone, and cytokine content
Blood samples were collected in tubes and centrifuged at 2400 g. Serum concentration of triacylglycerol (TG), total cholesterol (TC), and high-density cholesterol (HDL-C) were measured by an enzymatic colorimetric method using commercial enzyme assay kits (Olvex Diagnosticum, St. Petersburg, Russia). Low density lipoprotein cholesterol (LDL-C) content was calculated using the formula: LDL-C = TC - (HDL-C + TG/2.2). Serum concentration of free fatty acid (FFA) was measured by an enzymatic colorimetric assay according to the manufacturer’s protocol (free fatty acid, Half-micro test; Roche Diagnostics, Penzberg, Germany). Serum and adrenal homogenate corticosterone was assayed by enzyme-linked immunosorbent assays. Sensitivity limits were 30 pg/mL and coefficients of variation were 7-9% using the Enzyme Immunoassay (EIA) kit (Cayman Chemical, Ann Arbor, MI, USA). Serum tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) levels were measured by commercially available rat ELISA kits (eBioscience, CA, USA).
Determination of liver triacylglycerol content
Approximately 0.2 g of hepatic tissue was homogenized in 0.15 M NaCl solution and extracted using a hexane:isopropanol mixture (3:2, v/v), containing 0.005% (wt/vol) butylated hydroxytoluene, according to method of Hara and Radin . After 10 min centrifugation at 3,000 g and 10°C, the upper organic phase was collected and evaporated under liquid nitrogen. Dry total lipids were resuspended in 10% Triton X-100 and isopropanol, and TG content was measured using a commercial enzyme assay kit (Olvex Diagnosticum, St. Petersburg, Russia) on an automatic biochemical analyzer.
Preparation of liver nuclear protein extract
Nuclear protein was isolated according to the method of Kang et al. . Liver tissue (0.5 g) was homogenized in a buffer containing 0.32 M sucrose, 10 mM Tris · HCl, pH 7.4, 1 mM EGTA, 2 mM EDTA, 5 mM NaN3, 10 mM β-mercaptoethanol, 20 μM leupeptin, 0.15 μM pepstatin A, 0.2 mM PMSF, 50 mM NaF, 1 mM sodium orthovanadate, and 0.4 nM microcystin. The homogenates were centrifuged (1,000 g, 10 min). The pellets were solubilized in Triton buffer (1% Triton X-100, 150 mM NaCl, 10 mM Tris·HCl, pH 7.4, 1 mM EGTA, 1 mM EDTA, 0.2 mM sodium orthovanadate, 20 μM leupeptin A, 0.2 mM PMSF). The lysates were centrifuged (15,000 g, 30 min, 4°C), and the supernatant (nuclear extract) was stored at -80°C until use. Protein concentrations were estimated using the Bio-Rad (Hercules, CA) DC protein assay.
Determination of liver PPARα transcription factor activity
PPARα transcription factor activity in liver nuclear extracts was determined using ELISA-based Cayman Chemical PPAR-α transcription factor assay kit (Cayman Chemicals, Ann Arbor, MI, USA) that detects PPAR-α bound to PPAR response element-containing double-stranded DNA sequences. Nuclear extract protein sample (40–50 μg) was used for determination of PPARα activity using the protocol described in the product manual, and absorbance was measured at 450 nm.
Results are expressed as the means ± standard error (S.E.M.). Statistical analysis was performed by applying one-way analysis of variance (ANOVA) followed by the Tukey post hoc test. Difference between groups was considered significant at p < 0.05.
Effects on weight of epididymal adipose tissue
Effects on glucose tolerance test and blood lipids
Serum lipids content (mmol/L) in rats fed standard diet (SD), high-fat diet (HFD), and HFD supplemented with Rhaponticum cathamoides extract (ERC), Punica granatum extract (EPG) and Glycyrrhiza glabra extract (EGG) (300 mg/kg per day) for 8 weeks
HFD + ERC
HD + EGG
HFD + EPG
2.03 ± 0.21
2.82 ± 0.24#
2.31 ± 0.19*
2.89 ± 0.32
2.59 ± 0.22
0.47 ± 0.25
1.46 ± 0.35#
0.70 ± 0.24*
1.22 ± 0.34
1.08 ± 0.28*
1.20 ± 0.11
0.81 ± 0.21#
1.11 ± 0.14*
1.08 ± 0.24
0.95 ± 0.22
1.79 ± 0.14
3.27 ± 0.37#
2.53 ± 0.25*
2.45 ± 0.35*
2.82 ± 0.37
0.76 ± 0.09
1.43 ± 0.24#
1.11 ± 0.12*
1.04 ± 0.12*
1.39 ± 0.16
Effects on systolic blood pressure
Effects on serum and adrenal corticosterone
Effects on serum TNF-α and IL-6
Effects on liver TG Content, and DNA binding activity of PPARα
Feeding of rats on HFD is a useful tool for the induction of metabolic syndrome features including distinctive visceral adiposity, dyslipidemia, impaired glucose tolerance with diabetes type 2, and hepatic steatosis, which are typically associated with human obesity. This rat model of diet-induced obesity is often used to investigate the effects of metabolic syndrome ameliorating agents, including the medicinal plants, as possible sources of new drugs. Various types of extracts and individual compounds derived from R. carthamoides have been found to possess a broad spectrum of pharmacological effects [21, 24–27]. However, the possibility that extracts and individual compounds derived from R. carthamoides may inhibit the manifestation of metabolic syndrome has been studied scarcely, unlike many other herbs such as G. glabra and P. granatum[13–20]. Our comparative study seems to be the first evidence of the higher potential of the commercial ethanolic ERC extract, enriched in 20-hydroxyecdisone, to reduce the weight of epididymal adipose tissue and serum glucose level, to restore disturbances of serum lipids, corticosterone and inflammatory cytokine content in HFD-fed rats, compared to the commercial ethanolic EGG and EPG extracts, which enriched in glycyrrhizic acid and ellagic acid, respectively, and are believed to have antidiabetic and anti-obesity properties. This study also shows that ERC intake can ameliorate the hepatic steatosis that is associated with an increased expression of hepatic DNA binding activity of PPARα.
Supplementation of ERC, EGG and EPG to an HFD rat (300 mg/kg per day) did not change the body weight of rats in our experiment. However, the epididymal fat weight was significantly reduced by ERC only (Figure 1). In the present study, ERC normalized the plasma glucose level and improved glucose intolerance (Figure 2), decreased LDL-C, TC, TG, and FFA and increased HDL-C content (Table 1) to a significantly greater extent than EGG or EPG. In addition, ERC did not significantly change the systolic pressure of rats (Figure 3). ERC contains a relatively high concentration of phytoecdysteroids, mainly, 20-hydroxyecdysone (2.2% by HPLC data). Diverse extracts and ecdysteroids derived from R. carthamoides are widely used in sport medicine as anabolic substances strengthening biosynthesis in slow muscle fibers. The significant decrease of epididymal fat weight without change of body weight and improvement of glucose intolerance observed in rats receiving ERC (containing approximately 6.6 mg/kg per day 20-hydroxyecdysone) are most likely due to the activation of the pentose phosphate pathway and utilization of carbohydrates in protein synthesis stimulated by phytoecdysteroids. This assumption is consistent with the reduced hepatic glucose production and increased adiponectin production, as seen in mice fed with an HFD supplemented with 10 mg/kg per day 20-hydroxyecdisone . Recent trials in ovariectomized rats also showed that modest doses of 20-hydroxyecdysone (18 mg/day per animal) increased muscle mass and reduced visceral fat mass, lowered serum LDL content, raised serum HDL content, and did not elevate TG content .
Although the hypocholesterolemic action of phytoecdysteroids has been demonstrated before , the molecular mechanisms underlying the effects of ERC in mammals are insufficiently studied. It is known that 20-hydroxyecdisone is the insect steroid hormone, which controls lipid metabolism through a specific receptor complex ecdysone receptor (EcR) . EcRs are orthologs of farnesoid X receptors (FXR) and liver X receptors (LXR) , which play critical roles in the regulation of lipid metabolism in mammals. Keeping in mind that the EcR ligand binding domain is similar to the rat FXR and possesses high homology with LXR , it may be assumed that these receptors are the pharmacological targets of ERC phytoecdysteroids or their metabolites. Moreover, interaction of LXR with hormone responsive elements in the promoters of PPAR genes may provide for the mutual coordination of expression of these transcription factors.
Our finding of the significant beneficial effect of ERC on hepatic steatosis can be explained by an increase of PPARα DNA binding activity in liver (Figure 6). Mechanisms of this ERC action remain unclear. We can speculate that it is accomplished through direct interaction of phytosterols with FXR, LXR or other transcription factors, or indirectly (by changing blood hormonal levels). In the latter case, promotion of liver PPARα activity may be interconnected with reduction of insulin level. Indeed, insulin is known to strongly downregulate the PPARα mRNA level in rat hepatocytes . Decrease of insulin level by the action of 20-hydroxyecdisone can therefore upregulate PPARα and promote its hepatic activity as observed in the present study. Also, one cannot exclude that demonstrated hypolipidemic effects (decrease of serum TG, serum FFA, and liver TG content) of ERC might be due not only to phytosterols, but also to the individual or synergistic action of flavonoids and other active plant phytochemicals.
Considerable evidence from human studies [35, 36] and HFD-fed rodent models [37, 38] suggests that increased blood or tissue levels of glucocorticoids and pro-inflammatory cytokines play a critical role in the development of metabolic syndrome. In the present study, we found that ERC exhibited a significant ability to reduce serum corticosterone content and restore its adrenal content (Figure 4), as well as to decrease the HFD-induced serum TNF-α and IL-6 levels (Figure 5), while EGG and EPG exhibited significantly less activity of that kind. Our observations agree with the data obtained in cultured HeLa cells in which ERC efficiently inhibited nuclear factor kappa B (NF-κB)  involved in cellular responses to inflammatory stimuli and stress. Interestingly, 20-hydroxyecdisone inhibited NF-κB activation less efficiently than ERC , indicating the presence of the other anti-inflammatory compounds in ERC, which are more active, than 20-hydroxyecdisone.
While R. carthamoides contains natural and low toxicity compounds , ERC elicited excellent outcomes without inducing side effects such as diarrhea, and in the present study, none of the animals died in the course of experiment (data not shown). In this emerging context, there are case reports in the literature that suggest that extensive intake of licorice may cause development of hypokalemia, edema, hypertension, and thrombocytopenia . Ellagic acid (up to 40.0% in studied EPG) could induce a hypercoagulation state in mice, rats, and rabbits . Moreover, the ellagic acid-rich pomegranate extracts have a serious drawback of being unstable in aqueous solutions .
Thus, complex action of ERC ethanolic extract exceeds the compensatory effects of EGG and EPG ethanolic extracts upon the metabolic syndrome cluster, and, thus, ERC can be proposed for the use as an efficient therapeutic option for the patients who refuse a low-fat diet for treatment of metabolic syndrome.
Our findings obtained with an HFD rat model suggest that ERC may prevent and ameliorate the signs of metabolic syndrome as a result of the complex beneficial effects on abdominal obesity, glucose intolerance, dyslipidemia, hepatosis, corticosterone and pro-inflammatory cytokine content with no visible signs or symptoms of toxicity in rats indicating a high margin of safety. The extract of R. carthamoides roots exhibited complex beneficial activity, which exceeded that of the commercial ethanolic extracts of G. glabra roots and P. granatum plant enriched in glycyrrhizic acid and ellagic acid, respectively, with proclaimed antidiabetic and anti-obesity properties. Accordingly, extract of R. carthamoides traditionally used mainly as a restorative substance is expanded by data from this study supporting evidence that natural ingredients of R. carthamoides are promising candidates for drug and food constituents to prevent or ameliorate the most prevalent manifestation of lifestyle-related cluster diseases caused by an extensively HFD.
Extract of G. glabra
Extract of P. granatum
Extract of R. carthamoides
Free fatty acid
Farnesoid X receptors
- G. glabra:
High density lipoprotein cholesterol
Low-density lipoprotein cholesterol
Liver X receptors
- P. granatum:
Nuclear factor kappa B
Peroxisomal proliferator-activated receptor-α
- R. carthamoides:
Tumor necrosis factor-α.
This study was supported by the Russian Foundation for Basic Research (11-04-00555a). The authors wish to thank Prof. Vera Selyatitskaya for corticosterone measurement assistance.
- Mottilo S, Filion KB, Genest J, Joseph L, Pilote L, Poirier P, Rinfret S, Schiffrin EL, Eisemberg MJ: The metabolic syndrome and cardiovascular risk a systematic review and meta-analysis. J Am Coll Cardiol. 2010, 56 (14): 1113-1132. 10.1016/j.jacc.2010.05.034.View ArticleGoogle Scholar
- Pereira MA, Kottke TE, Jordan C, O’Connor PJ, Pronk NP, Carreon R: Preventing and managing cardiometabolic risk: the logic for intervention. Int J Environ Res Public Health. 2009, 6 (10): 2568-2584. 10.3390/ijerph6102568.View ArticlePubMedPubMed CentralGoogle Scholar
- Del Ben M, Baratta F, Polimeni L, Angelico F: Non-alcogolic fatty liver disease and cardiovascular disease: epidemiological, clinical and phathophysiological evidences. Intern Emerg Med. 2012, 7 (Suppl. 3): S291-S296.View ArticlePubMedGoogle Scholar
- Prasad H, Ryan DA, Celzo MF, Stapleton D: Metabolic syndrome: definition and therapeutic implication. Postgrad Med. 2012, 124 (1): 21-30. 10.3810/pgm.2012.01.2514.View ArticlePubMedGoogle Scholar
- Michos ED, Sibley CT, Baer JT, Blaha MJ, Blumental RS: Niacin and statin combination therapy for atherosclerosis regression and prevention of cardiovascular disease events: reconciling the AIM-HIGH (Aterothrombosis Intervention in Metabolic Syndrome With Low HDL/High Triglicerides: impact on global health outcomes) trial with previous surrogate endpoint trials. J Am Coll Cardiol. 2012, 59 (23): 2058-2064. 10.1016/j.jacc.2012.01.045.View ArticlePubMedGoogle Scholar
- Nseir W, Mograbi J, Ghali M: Lipid lowering agents in nonalcogol fatty liver disease and steatohepatitis: human studies. Dig Dis Sci. 2012, 57 (7): 1773-1781. 10.1007/s10620-012-2118-3.View ArticlePubMedGoogle Scholar
- Filippatos TD: A review of time courses and predictors of lipid changes with fenofibric acid-statin combination. Cardiovasc Drug Ther. 2012, 26 (3): 245-255. 10.1007/s10557-012-6394-0.View ArticleGoogle Scholar
- Power M, Pratley R: Alternative and complementary treatments for metabolic syndrome. Curr Diab Rep. 2011, 11 (3): 173-178. 10.1007/s11892-011-0184-0.View ArticlePubMedGoogle Scholar
- Huang TH, Teoh AW, Lin BL, Lin DS, Roufogalis B: The role of herbal PPAR modulators in the treatment of cardiomatabolic syndrome. Pharmacol Res. 2009, 60 (3): 195-206. 10.1016/j.phrs.2009.03.020.View ArticlePubMedGoogle Scholar
- Cherniak EP: Polyphenols: planting the seeds of treatment for metabolic syndrome. Nutrition. 2011, 27 (6): 617-623. 10.1016/j.nut.2010.10.013.View ArticleGoogle Scholar
- Laksmidevi N, Maharadeva MS, Prakash HS, Niranjana SR: Diabetes and medical plants-a review. Int J Pharm Biomed Sci. 2011, 2 (3): 65-80.Google Scholar
- Babich JG, Pacioretty LM, Bland JS, Minich DM, Hu J, Tripp ML: Antidiabetic screening of commercial botanical products in 3 T3-L1 adipocytes ad db/db mice. J Med Food. 2010, 13 (3): 535-547. 10.1089/jmf.2009.0110.View ArticleGoogle Scholar
- Eu CH, Lim WY, Ton SH, bin Abdul Kadir K: Glycyrrhizic acid improved lipoprotein lipase expression, insulin sensitivity, serum lipid and lipid lipid deposition in high-fat diet-induced obese rats. Lipid Health Dis. 2010, 9: 81-10.1186/1476-511X-9-81.View ArticleGoogle Scholar
- Jungbauer A, Medjakovic S: Phytoestrogens and the metabolic syndrome. J Steroid Biochem Mol Biol. 2014, 139: 277-289.View ArticlePubMedGoogle Scholar
- Al-Muammar MN, Khan F: Obesity: the preventive role of the pomegranate (Punica granatum). Nutrition. 2012, 28 (6): 595-604. 10.1016/j.nut.2011.11.013.View ArticlePubMedGoogle Scholar
- Medjakovic S, Jungbauer A: Pomegranate: a fruit that ameliorates metabolic syndrome. Food Funct. 2013, 4: 19-39. 10.1039/c2fo30034f.View ArticlePubMedGoogle Scholar
- Nakagawa K, Kishida H, Arai N, Nishiyama T, Mae T: Licorice flavonoids suppress abdominal fat accumulation and increase in blood glucose level in obese diabetic KK-A(y) mice. Biol Pharm Bull. 2004, 27 (11): 1775-1778. 10.1248/bpb.27.1775.View ArticlePubMedGoogle Scholar
- Honda K, Kamisoyama H, Tominaga Y, Yokota S, Hasegawa S: The molecular mechanism underlying the reduction in abdominal fat accumulation by licorice flavonoids oil in high fat diet-induced obesity rats. Anim Sci J. 2009, 80 (5): 362-569.View ArticleGoogle Scholar
- Parmar HS, Kar A: Antidiabetic potential of Citrus sinensis and Punica granatum peel extracts in alloxan treated male mice. Biofactors. 2007, 31 (1): 17-24. 10.1002/biof.5520310102.View ArticlePubMedGoogle Scholar
- Parmar HS, Kar A: Medical values of fruit peels from Citrus sinensis, Punica granatum, and Musa paradisiacal with respect to alterations in tissue lipid peraxidation and serum concentration of glucose, insulin, and thyroid hormones. J Med Food. 2008, 11 (2): 376-381. 10.1089/jmf.2006.010.View ArticlePubMedGoogle Scholar
- Kokoska L, Janovska D: Chemistry and pharmacology of Rhaponticum carthamodies: a review. Phytochemistry. 2009, 70 (7): 842-855. 10.1016/j.phytochem.2009.04.008.View ArticlePubMedGoogle Scholar
- Hara A, Radin NS: Lipid extraction of tissues with a low toxicity solvent. Anal Biochem. 1978, 90 (1): 420-426. 10.1016/0003-2697(78)90046-5.View ArticlePubMedGoogle Scholar
- Kang X, Zhong W, Liu J, Song Z, McClaim CJ, Kang YJ, Zhou Z: Zinc supplementation reverses alcohol-induced steatosis in mice through reactivating hepatocyte nuclear factor-4alpha and peroxisome proliferator-activated receptor-alpha. Hepatology. 2009, 50 (4): 1241-1250. 10.1002/hep.23090.View ArticlePubMedPubMed CentralGoogle Scholar
- Plotnikov MV, Vasilev AS, Aliev OI, Anishenko AM, Krasnov EA: Effect of Rhaponticum carthamodies exstact in combination with doses physical load on hemorheological parameters of rats with myocardial infarction. Eksp Klin Farmakol. 2011, 74 (9): 7-10.PubMedGoogle Scholar
- Peschel W, Kump A, Prieto JM: Effect of 20-hydroxyecdysone, Leuzea carthamodies exstracts, dexamethasone and their combinations on the NF-κB activation in HeLa cells. J Pharm Pharmacol. 2011, 63 (11): 1483-1495. 10.1111/j.2042-7158.2011.01349.x.View ArticlePubMedGoogle Scholar
- Nosáĺ R, Perečko T, Jančinová V, Drábiková K, Harmatha J, Sviteková K: Naturally appearing N-feruloyserotonine isomers suppress oxidative burst of human neutrophils at the protein kinase C level. Pharmacol Rep. 2011, 63 (3): 790-798.View ArticlePubMedGoogle Scholar
- Koleckar V, Opletal L, Macakova K, Jahodar L, Jun D, Kunes J, Kuca K: New antioxidants flovonoid isolated from Leuzea carthamoides. J Enzyme Inhib Med Chem. 2010, 25 (1): 143-145. 10.3109/14756360903090970.View ArticlePubMedGoogle Scholar
- Kizelstein P, Govorko D, Komarnytsky S, Evans A, Wang Z, Cefalu WT, Raskin I: 20-hydroxyecdysone decreases weight and hyperglycemia in diet-induced obesity mice model. Am J Physiol Endocrinol Metab. 2009, 296 (3): 433-439.View ArticleGoogle Scholar
- Seidlova-Wittke D, Ehrhardt C, Wuttke W: Metabolic effects of 20-OH-ecdisone in ovariectomized rats. J Steroid Biochem Mol Biol. 2010, 119 (3–5): 121-126.View ArticleGoogle Scholar
- Mironova VN, Kholodova ID, Skachkova TF, Bondar’ OP, Datsenko ZM: Hypocholesterolemic effect of phytoecdysones during experimental hypercholesterolemia in rats. Vopr Med Khim. 1982, 28 (2): 101-105.PubMedGoogle Scholar
- Wang S, Liu S, Liu H, Wang J, Zhou S, Jiang RJ, Bendena WG, Li S: 20-hydroxyecdysone reduces insect food consumption resulting in fat body lipolysis during molting and pupation. J Mol Cell Biol. 2010, 2 (3): 128-138. 10.1093/jmcb/mjq006.View ArticlePubMedGoogle Scholar
- King-Jones K, Thummel CS: Nuclear receptors – a perspective from Drosophila. Nat Rev Genet. 2005, 6 (4): 311-323. 10.1038/nrg1581.View ArticlePubMedGoogle Scholar
- Kumpun S, Girault JP, Dinan L, Blais C, Maria A, Dauphin-Villemant C, Yingyongnarongkul B, Suksamrarn A, Lafont R: The metabolism of 20-hydroxyecdysone in mice: relevance to pharmacological effects and gene switch applications of ecdisteroids. J Steroid Biochem Mol Biol. 2011, 126 (1–2): 1-9.View ArticlePubMedGoogle Scholar
- Steinberg HH, Sorensen HN, Tugwood JD, Skrede S, Spydevold O, Gautvik KM: Dexametasone and insulin demonstrate marcked and opposite regulation of the steady-state mRNA level of peroxisomal proliferator-activated receptor in hepatic cells. Hormonal modulation of fatty acid-induced transcription. Eur J Biochem. 1994, 225 (3): 967-974. 10.1111/j.1432-1033.1994.0967b.x.View ArticleGoogle Scholar
- Anagnostis P, Athyros VG, Tziomalos K, Karagiannis A, Mikhailidis DP: Clinical review: the pathogenetic role of cortisol in metabolic syndrome: a hypothesis. J Clin Endocrinol Metab. 2009, 94 (8): 2692-2701. 10.1210/jc.2009-0370.View ArticlePubMedGoogle Scholar
- Scarpellini E, Tack J: Obesity and metabolic syndrome: an inflammatory condition. Dig Dis. 2012, 30 (2): 148-153. 10.1159/000336664.View ArticlePubMedGoogle Scholar
- Pratchayasakul W, Kerdphoo S, Petsophonsakul P, Pongchaidecha A, Chattipakorn N, Chattipakorn SC: Effect of high-fat diet on insulin receptor function in rat hippocampus and the level of neuronal corticosterone. Life Sci. 2011, 88 (13–14): 619-627.View ArticlePubMedGoogle Scholar
- Fu JH, Xie SR, Kong SJ, Wang Y, Wei W, Shan Y, Luo YM: The combination of high-fat diet and chronic stress aggravates insulin resistance in Wistar male rats. Exp Clin Endocrinol Diabetes. 2009, 117 (7): 354-360. 10.1055/s-0028-1119406.View ArticlePubMedGoogle Scholar
- Celic M, Karakus A, Zeren C, Demir M, Bayarogullari H, Duru M, Al M: Licorice induced hypokalemia, edema, and thrombocytopenia. Hum Exp Toxicol. 2012, 31 (12): 1295-1298. 10.1177/0960327112446843.View ArticleGoogle Scholar
- Na L, Jun-tian L, Qiang-zong Z: Ellagic acid-induced hypercoagulable state in animals: a potentially useful animal hypercoagulable model for evaluation of anticoagulants. Clin Med Sci J. 2010, 25 (4): 237-242.Google Scholar
- Panichayupakaranant P, Itsuriya A, Sirikatitham A: Preparation method and stability of ellagic acid-rich pomegranate fruit peel extract. Pharm Biol. 2010, 48 (2): 201-205. 10.3109/13880200903078503.View ArticlePubMedGoogle Scholar
- The pre-publication history for this paper can be accessed here:http://www.biomedcentral.com/1472-6882/14/33/prepub
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