Effect of an extract of Andrographis paniculata leaves on inflammatory and allergic mediators in vitro

Aim of study

Andrographis paniculata has been known to possess widespread traditional application in the treatment of allergy and inflammatory diseases. In the current study, we sought to examine the effects of an extract of Andrographis paniculata leaves on inhibition of lipopolysaccharide (LPS) induced [nitric oxide (NO), prostaglandin E₂ (PGE₂), interleukin-1beta (IL-1 beta), and interleukin-6 (IL-6)] and calcimycin (A23187) induced [leukotriene B₄ (LTB₄), thromboxane B₂ (TXB₂) and histamine] mediators in diverse cell based models.

Materials and methods

Effect of an extract of Andrographis paniculata leaves (AP) was studied on inhibition of LPS induced NO, PGE₂, IL-1 beta and IL-6 in J774A.1 murine macrophages; A23187 induced LTB₄ and TXB₂ in HL-60 promyelocytic leukemic cells and histamine in RBL-2H3 rat basophilic leukemia cells.

Results and conclusion

AP illustrated significant alleviation of pro-inflammatory, inflammatory, and allergic mediators. However, no inhibition was observed against histamine release. This outcome has been summed up to deduce that AP is fairly potent in attenuating the inflammation by inhibiting pro-inflammatory (NO, IL-1 beta and IL-6), inflammatory (PGE₂ and TXB₂) and allergic (LTB₄) mediators.     

In vivo and in vitro anti-inflammatory activity of Lentinus polychrous extract

Ethnopharmacological relevance

Lentinus polychrous is a Thai local edible mushroom, traditionally used for the treatments of fever and inflammation due to snake or scorpion envenomation.

Aim of study

The present study aimed to investigate an anti-inflammatory effect of Lentinus polychrous mycelial extract (LPME) both in vitro and in vivo.

Materials and methods

The cytotoxicity and suppressive effects of LPME on nitric oxide production, intracellular O₂⁻ production, pro-inflammatory mediator expression, TNF-α production were determined by using LPS-activated RAW 264.7 cells. In addition, Anti-inflammatory effect of LPME was evaluated by using carageenan-induced paw edema in rats.

Results

The LPME exhibited cytotoxicity with 50% inhibitory concentration (IC₅₀) of 280.25±10.10 μg/ml and significantly suppressed the productions of NO and intracellular O₂⁻ with dose-dependent manner. LPME decreased the expressions of iNOS, IL-1β, IL-6, TNF-α and COX-2 and significantly decreased the TNF-α production in LPS-activated macrophage with dose-dependent manners. Moreover, LPME showed significant suppressive effect on paw edema in rats.

Conclusion

The results clearly revealed that the LPME inhibited NO and pro-inflammatory productions by down-regulating the gene expressions of pro-inflammatory mediators leading to the decrease paw edema in rat which support the traditional use.     

Evaluating the anti-inflammatory potential of Tectaria cicutaria L. rhizome extract in vitro as well as in vivo

Ethnopharmacological relevance

The rhizome of Tectaria cicutaria has been used in the folklore system of Indian traditional medicine (Ayurveda) for the treatment of various disorders such as rheumatic pain, chest complaints, burns, sprain, poisonous bites, tonsilitis, toothache, gum complaints, cuts and wounds. The present work has for the first time tried to elucidate the anti-inflammatory potential of aqueous extract of Tectaria cicutaria rhizome (TCR_aq) in vitro as well as in vivo.

Materials and methods

Anti-inflammatory potential of TCR_aq was analyzed in vivo in carrageenan induced rat paw edema model. Serum antioxidant status in TCR_aq-treated as well as untreated control rodents was measured by oxygen radical absorbance capacity (ORAC) assay. In vitro experiments for analyzing the anti-inflammatory potential of TCR_aq were performed on murine macrophage cell line, RAW 264.7. Analysis of nitric oxide release in RAW 264.7 cells was done by Griess reaction. RT-PCR and western blotting experiment was performed to analyze the expression of iNOS. Expression of COX-2 and NFκB proteins was evaluated by western blotting.

Results

TCR_aq significantly reduced the paw volume in Sprague-Dawley rats at a dose of 200 mg/kg body weight, which was comparable with the standard diclofenac treatment. The rats treated with TCR_aq showed a significant increase in the serum antioxidant levels compared to the untreated control animals. TCR_aq was able to reduce the nitric oxide (NO) levels in RAW 264.7 cells that had been stimulated with lipopolysaccharide (LPS). This was accompanied by a corresponding decrease in iNOS expression at mRNA and protein level. Interestingly, TCR_aq was found to decrease the expression of COX-2 as well as the nuclear translocation of NFκB in RAW 264.7 cells.

Conclusion

Our study signifies the anti-inflammatory potential of Tectaria cicutaria and scientifically validates its traditional use in inflammatory conditions.     

Identification of Escherichia coli enterotoxin inhibitors from traditional medicinal herbs by in silico, in vitro, and in vivo analyses

Ethnopharmacological relevance

Glycyrrhiza uralensis has been used for the treatment of gastrointestinal disorders, such as diarrhea, in several ancient cultures. Glycyrrhizin is the principal component of liquorice and lots of pharmacological effects have been demonstrated.

Aim of the study

Heat-labile enterotoxin (LT), the virulence factor of enterotoxigenic Escherichia coli, induces diarrhea by initially binding to the G_M1 on the surfaces of intestinal epithelial cells and consequently leading to the massive loss of fluid and ions from cells. Therefore, we evaluated the inhibitory effects of traditional medicinal herbs (TMH) on the B subunit of LT (LTB) and G_M1 interaction.

Materials and methods

The inhibitory effects of TMH on LTB-G_M1 interaction were evaluated by G_M1-enzyme-linked immunosorbent assay (ELISA). The likely active phytochemicals of these TMH were then predicted by in silico model (docking) and analyzed by in vitro (G_M1-ELISA) and in vivo (patent mouse gut assay) models.

Results

We found that various TMH, which have been ethnomedically used for the treatment of diarrhea, inhibited the LTB-G_M1 interaction. Docking data showed that triterpenoids were the most active phytochemicals and the oleanane-type triterpenoids presented better LTB-binding abilities than other types of triterpenoids. Moreover, by in vitro and in vivo models, we demonstrated that glycyrrhizin was the most effective oleanane-type triterpenoid that significantly suppressed both the LTB-binding ability (IC₅₀ = 3.26 ± 0.17 mM) and the LT-induced fluid accumulation in mice.

Conclusions

We found an LT inhibitor, glycyrrhizin, from TMH by in silico, in vitro, and in vivo analyses.     

Hepatoprotective action of Orthosiphon diffusus (Benth.) methanol active fraction through antioxidant mechanisms: An in vivo and in vitro evaluation

Ethnopharmacological relevance

Preparations of Orthosiphon diffusus (Benth.) have been used by folk medicinal practitioners in the Western Ghats of India for treating inflammation, hepatitis and jaundice for many years and their effectiveness is widely acclaimed among the tribal communities.

Aim of the study

To evaluate the mechanisms behind the antioxidant and hepatoprotective potential of Orthosiphon diffusus methanol active fraction (MAF) using in vivo (rat) and in vitro (cell culture) models.

Materials and methods

Neutralization of CCl₄-induced hepatotoxicity by MAF was evaluated in rats. Towards this, serum levels of hepatic injury markers (lactate dehydrogenase and alkaline phosphatase), antioxidant enzymes in the liver homogenates, and histological examination were performed. In in vitro studies, mechanisms of neutralization of H₂O₂-induced toxicity by MAF using MTT, Comet assay and up-regulation of antioxidant enzymes at genetic level (RT-PCR) was performed in HepG2 cells.

Results

Rats pre-treated with Orthosiphon diffusus MAF demonstrated significantly reduced levels of serum LDH (1.3-fold, p<0.05) and ALP (1.6-fold, p<0.05). Similarly, multiple dose MAF administration demonstrated significantly enhanced levels (p<0.05) of antioxidant enzymes in the liver homogenates. Histological analysis revealed complete neutralization of CCl₄-induced liver injury by the extract. The in vitro studies demonstrated that, pre-treatment of MAF effectively prevented H₂O₂-induced oxidative stress, genotoxicity and significantly enhanced (~6-fold, p<0.01) expression of genes for antioxidant enzymes.

Conclusions

Orthosiphon diffusus MAF demonstrated significant hepatoprotection against CCl₄-induced hepatotoxicity by antioxidant mechanisms comparable to silymarin. H₂O₂-induced oxidative stress was completely neutralized by MAF through enhanced expression of genes for antioxidant enzymes. Therefore, this study validates the use of Orthosiphon diffusus by folk medicinal practitioners in India. Further, MAF of Orthosiphon diffusus can serve as a strong candidate for the development of herbal hepatoprotective agents.     

Antinociceptive effect of Lecythis pisonis Camb. (Lecythidaceae) in models of acute pain in mice

Ethnopharmacological relevance

Lecythis pisonis Camb., also known in Brazil as sapucaia, is used in folk medicine against pruritus, muscle pain and gastric ulcer.

Aim of the study

To investigate the antinociceptive effect of ethanol extract from Lecythis pisonis leaves (LPEE), fractions (hexane-LPHF, ether-LPEF and ethyl acetate-LPEAF) and mixture of triterpenes [ursolic and oleanolic acids (MT)] in mice.

Materials and methods

LPEE and LPEF were evaluated on the acetic acid induced writhings and formalin, capsaicin and glutamate tests. In addition, MT was investigated on the writhings induced by acetic acid, capsaicin and glutamate tests. In the study of some possible mechanisms involved on the antinociceptive effect of LPEF, it was investigated the participation of opioid system, K⁺_ATP channels and l-arginine-nitric oxide pathway.

Results

LPEE (12.5 and 25 mg/kg, p.o.), LPEF and MT (6.25, 12.5 and 25 mg/kg, p.o.) reduced the writhings in comparison to saline. LPEE (100 mg/kg, p.o.) and LPEF (50 mg/kg, p.o.) were effective in inhibiting both phases of formalin test. In capsaicin test, LPEE (100 and 200 mg/kg, p.o.), LPEF (12.5–50 mg/kg, p.o) and MT (6.25–25 mg/kg, p.o.) showed a significant antinociceptive effect compared to the control. LPEE (25 and 50 mg/kg, p.o.), LPEF (50 and 100 mg/kg, p.o.) and MT (12.5 and 25 mg/kg, p.o.) reduced the glutamate-evoked nociceptive response. Treatment with naloxone, l-arginine and glibenclamide reversed the effect of LPEF in glutamate test.

Conclusions

These results indicate the antinociceptive effect of Lecythis pisonis leaves and suggest that this effect may be related to opioid pathway, K⁺_ATP channels, and l-arginine-nitric oxide modulation. Furthermore, these data support the ethnomedical use of this plant.     

The effects of Sceletium tortuosum in an in vivo model of psychological stress

Aim of the study

Sceletium, and especially Sceletium tortuosum, is traditionally used as masticator and thought to have a sedative effect which may be beneficial to reduce symptoms of anxiety and/or depression. The current study evaluated the scientific merit of these anecdotal claims in an in vivo model of psychological stress.

Materials and methods

Male Wistar rats were administered either placebo, 5 or 20 mg/kg/day of Sceletium tortuosum extract for 17 days by daily oral gavage. 50% of rats were exposed to repeated restraint stress lasting 1 h for the last 3 days of treatment. Rat behavioral changes in response to stress were assessed using the elevated plus maze on the last day of restraint, immediately after the restraint session. Rats were sacrificed 24 h after the last restraint exposure and whole blood collected.

Results

Behavior indicated a limited effect of lower dose Sceletium to decrease restraint stress-induced self-soothing behavior, as well as to decrease stress-induced corticosterone levels. However, increased IL-1β levels argue against the claim that the plant may act as selective serotonin reuptake inhibitor, while this result combined with increased levels of C-reactive protein and prostaglandin E₂ suggest intolerance to the treatment. Decreased IL-2 and increased IL-10 levels in response to Sceletium treatment suggest a suppressive effect on T helper 1 immune function.

Conclusions

Although data indicates a limited positive effect of Sceletium on restraint-induced anxiety, numerous side-effects were evident. More research is required to derive an optimal therapeutic dose.     

Suppression of lipopolysaccharide-induced of inducible nitric oxide synthase and cyclooxygenase-2 by Sanguis Draconis, a dragon's blood resin, in RAW 264.7 cells

Sanguis Draconis (SD) is a kind of dragon's blood resin that is obtained from Daemomorops draco (Palmae). It is used in traditional medicine and has shown anti-inflammatory activity in some diseases. In this study, we examined the effects of Sanguis Dranonis ethanol extract (SDEE) on LPS-induced inflammation using RAW 264.7 cells. Our data indicated that SDEE inhibits LPS-stimulated NO, PGE2, IL-1 beta and TNF-alpha release, and iNOS and COX-2 expression. Furthermore, SDEE suppressed the LPS-induced p65 expression of NF-kappa B, which was associated with the inhibition of I kappa B-alpha degradation. We also found that the expression of HO-1 was significantly increased in RAW 264.7 cells by SDEE. These results suggest among possibilities of anti-inflammation that SDEE inhibits the production of NO and PGE2 by the down-regulation of iNOS and COX-2 gene expression via the suppression of NF-kappaB (p65) activation. SDEE can induce HO-1 over-expression in macrophage cells, which indicates that it may possess antioxidant properties. This result means that SEDD its anti-inflammatory effects in macrophages may be through a novel mechanism that involves the action of HO-1. Thus, SD could provide a potential therapeutic approach for inflammation-associated disorders.     

Effects of an aqueous extract of Crataegus pinnatifida Bge. var. major N.E.Br. fruit on experimental atherosclerosis in rats

Ethnopharmacological relevance

Atherosclerosis (AS) can result in severe cardiovascular diseases. Early indications of AS include disorders in lipid metabolism, inflammatory responses, and endothelial dysfunction. Statins are the preferred drugs for stabilizing atherosclerotic plaques because of their lipid-lowering, anti-inflammation and endothelial-protection activities. However, they can exhibit side effects and are effective in only one-third of patients. Many natural products (especially traditional Chinese medicines (TCMs)) possessing similar lipid-lowering, anti-inflammation and antioxidant activities are of interest in many studies exploring new AS drug therapy.The widely distributed hawthorn is used to prevent and cure heart disease not only in China but also in the United States and several European countries. For example, the fruit of Crataegus pinnatifida Bge. and Crataegus pinnatifida Bge. var. major N.E.Br. (a commonly used hawthorn fruit in China) is used in combination with other TCMs to treat AS. Studies have also shown that the water extracts of these two hawthorn fruits are effective against hyperlipidemia by lowering lipid levels, reducing endothelial dysfunction, and inhibiting inflammation. The aim of the study is to investigate the effect and possible mechanisms of the aqueous extract of Crataegus pinnatifida var. major on AS rats.

Materials and methods

The fruit of Crataegus pinnatifida var. major was extracted with 70% ethanol; the ethanol extract was chromatographed on a D101 macroporous resin to obtain a sugar-free aqueous extract (AECP). Atherosclerotic rats were fed a high-fat diet and injected with vitamin D₃ and ovalbumin. Rats were divided into five groups: normal, model, model plus simvastatin, model plus low-dose AECP, and model plus high-dose AECP. AECP and simvastatin were administered (via the intragastric route) to AECP groups and the simvastatin group. For normal and model groups, water was given for 4 weeks. After 12 weeks, levels of total cholesterol (TC), triglyceride (TG), low-density lipoprotein-cholesterol (LDL-C) and high-density lipoprotein-cholesterol (HDL-C) in blood were measured by an automatic biochemistry analyzer. Serum concentrations of interleukin (IL)-1β, IL-8, nitric oxide (NO), endothelin (ET), 6-keto-prostaglandin F_1α (6-keto-PGF_1α) and thromboxane B₂ (TXB₂) were determined by radioimmunoassay (RIA). Serum concentrations of C-reactive protein (CRP) and IL-18 were measured by enzyme-linked immunosorbent assay (ELISA). Pathological changes in arteries were observed using an optical microscope and the intima-media thickness (IMT) calculated. Cholesterol deposition was evaluated by filipin staining. Chemical ingredients in AECP were analyzed by qualitative and quantitative means by high-performance liquid chromatography (HPLC).

Results

AECP significantly reduced the levels of TC, TG and LDL-C but increased HDL-C levels. It also decreased the concentrations of CRP, IL-1β, IL-8 and IL-18. AECP increased levels of ET and TXB₂ but increased 6-keto-PGF_1α levels. Histopathological examination showed that AECP inhibited pathological changes in the arteries of AS rats and reduced IMT. Chemical analysis suggested that the main components of AECP were chlorogenic acid, procyanidin B₂, (−)-epicatechin, rutin and isoquercitrin.

Conclusions

These data suggest that AECP can inhibit AS progression in high-fat-diet-fed rats. Possible mechanisms of action include improvement of lipid metabolism, decrease in inflammatory cytokine responses, and protection of the endothelium.     

Anti-inflammatory and antitumoural effects of Uncaria guianensis bark

Ethnopharmacological relevance

Uncaria guianensis (Aublet) Gmell (Rubiaceae) is a medicinal plant from the jungles of South and Central America, used to treat cancer, arthritis, diabetes, and inflammation. Evaluate the anti-inflammatory and anti-tumor effects of Uncaria guianensis preparations.

Materials and methods

Bio-guided fractionation of a hydroethanolic extract of Uncaria guianensis was performed, evaluating the fractions and subfractions for their effect on inflammatory mediators, tumour necrosis factor alpha (TNF-α), interleukin 6 (IL-6) and prostaglandin E₂ (PGE₂) by ELISA and nitric oxide (NO) by the Griess reaction in cultured supernatant from RAW 264.7 macrophages stimulated with lipopolysaccharide (LPS). The expression of cyclooxygenase 2 (COX-2), inducible nitric oxide synthase (iNOS) and inhibitor of κB (IκB) were investigated in RAW 264.7 macrophages by flow cytometry. The activity of NF-κB in HeLa cells transfected with a luciferase reporter system was determined. The effect of Uncaria guianensis on the inflammatory response in vivo was assessed in BALB/c mice stimulated with LPS, on rat paw oedema induced by carrageenan, and on tumour growth and lung metastasis in BALB/c mice inoculated with 4T1 mammary tumour cells. Immune cell infiltrates and inflammatory mediators were evaluated in the tumour by immunohistochemistry.

Results

Sub-fraction Ug AIV inhibited, to varying degrees, NO, TNF-α, IL-6 and PGE₂ production by macrophages in vitro (30 μg/ml) and in the serum of LPS-challenged mice (5 mg/kg). Macrophage expression of Cox-2 was inhibited (35%), IκB degradation was completely inhibited and NF-κB activation was inhibited (70%) by Ug AIV at 30 μg/ml. Ug AIV decreased paw oedema by 86% (5 mg/kg) and serum NO and TNF-α by 45% and 65% respectively. Ug AIV reduced 4T1 mammary tumour growth by 91% on day 33 post-inoculation as well as the levels of serum NO, IL-6 and TNF-α in the same animals. Ug AIV decreased the number of tumour-infiltrating T lymphocytes, macrophages and neutrophils as well as the number of cells positive for COX-2, iNOS, IL-6, TNF-α and p65.

Conclusions

As Ug AIV was not cytotoxic for tumour cells or macrophages, its anti-tumour effect may be due to a reduction in pro-tumoural inflammatory processes in the tumour microenvironment, possibly mediated through NF-κB.     

Suppressive effects of wild bitter gourd (Momordica charantia Linn. var. abbreviata ser.) fruit extracts on inflammatory responses in RAW 264.7 macrophages

Aim of the study

Bitter gourd (Momordica charantia) is used to treat various diseases including inflammation. A wild species of bitter gourd, Momordica charantia Linn. var. abbreviata ser. (WBG), is considered to be more potent in disease prevention than is bitter gourd; however, little is known about the biological and physiological characteristics of WBG.

Materials and methods

The present study investigated the anti-inflammatory effect of WBG on lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages.

Results

Among the hot water, 95% ethanol, and ethyl acetate extracts of WBG, the ethanol extract showed the greatest reduction of LPS-induced nitric oxide (NO) and prostaglandin E₂ (PGE₂) production and inducible nitric oxide synthase (iNOS) and pro-interleukin-1β expression. LPS-induced cyclooxygenase-2 expression was not affected by WBG extracts. Compared with WBG, extracts from bitter gourd showed a lesser inhibition of LPS-induced events. Electrophoretic mobility shift assay further showed that both the hot water and the ethanol extracts of WBG inhibited NF-κB activation. Although information is lacking on the bioactive components of WBG, the phenolic compound contents of each extract significantly paralleled its anti-inflammatory ability (r = 0.74, 0.88 and 0.65 for NO, PGE₂ and iNOS expression, respectively, P < 0.05).

Conclusions

These results suggest that WBG is beneficial for reducing LPS-induced inflammatory responses by modulating NF-κB activation.     

Protective effects of astragaloside IV on porcine-serum-induced hepatic fibrosis in rats and in vitro effects on hepatic stellate cells

Ethnopharmacological relevance

Astragaloside IV is the primary pure saponin isolated from Astragalus membranaceus, one of the valuable traditional medical herbs. Antifibrotic activities of Astragalus membranaceus have been extensively proved.

Aim of the study

To investigate the effects of astragaloside IV on hepatic stellate cells (HSCs) and hepatic fibrosis in rats induced by porcine-serum (PS).

Materials and methods

Liver fibrosis was induced by PS injection (0.5 ml, twice a week) for 12 weeks. Astragaloside IV (2.0, 4.0 mg kg⁻¹) was administered intragastrically. Liver samples were subjected to histological and immunohistochemical studies. In vitro effects of astragaloside IV on primary cultured HSCs were detected by incorporation assays.

Results

Astragaloside IV delayed the formation of liver fibrosis and decrease the serum levels of hyaluronic acid (HA), procollagen type III (PCIII) and hydroxyproline (Hyp) content in liver. The levels of transforming growth factor-β₁ (TGF-β₁) in serum and expression in liver were significantly decreased by astragaloside IV. Collagen synthesis and proliferation were significantly inhibited by astragaloside IV (1.5, 3.0, 6.0, 12.0 and 24.0 mg L⁻¹) in HSCs.

Conclusion

The results showed that astragaloside IV displays antifibrotic effects in rats induced by PS, the mechanism by which might be associated with its inhibitory effects on collagen synthesis and proliferation in HSCs.     

In vivo hepatoprotective activity of the aqueous extract of Artemisia absinthium L. against chemically and immunologically induced liver injuries in mice

Aim of the study

This study aimed to evaluate in vivo hepatoprotective activity of the aqueous extract of Artemisia absinthium L. (AEAA), which has been used for the treatment of liver disorders in Traditional Uighur Medicine.

Materials and methods

Qualitative and quantitative phytochemical analysis of the AEAA was performed by means of thin layer chromatography and spectrophometric assays. Aqueous extract (50, 100 or 200 mg/kg body weight/day) was administered orally to experimental mice. Liver injury was induced chemically, by a single CCl₄ administration (0.1% in olive oil, 10 ml/kg, i.v.), or immunologically, by injection of endotoxin (LPS, 10 μg, i.v.) in BCG-primed mice. The levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), tumor necrosis factor-α (TNF-α) and interleukin-1 (IL-1) in mouse sera, as well as superoxide dismutase (SOD), glutathione peroxidase (GPx) and malondialdehyde (MDA) in mouse liver tissues were measured. The biochemical observations were supplemented by histopathological examination.

Results

Obtained results demonstrated that the pretreatment with AEAA significantly (P < 0.001) and dose-dependently prevented chemically or immunologically induced increase in serum levels of hepatic enzymes. Furthermore, AEAA significantly (P < 0.05) reduced the lipid peroxidation in the liver tissue and restored activities of defense antioxidant enzymes SOD and GPx towards normal levels. In the BCG/LPS model, increase of the levels of important pro-inflammatory mediators TNF-α and IL-1 was significantly (P < 0.01) suppressed by AEAA pretreatment. Histopathology of the liver tissue showed that AEAA attenuated the hepatocellular necrosis and led to reduction of inflammatory cells infiltration. Phytochemical analyses revealed the presence of sesquiterpene lactones, flavonoids, phenolic acids and tannins in the AEAA.

Conclusions

The results of this study strongly indicate the protective efect of AEAA against acute liver injury which may be attributed to its antioxidative and/or immunomodulatory activity, and thereby scientifically support its traditional use.     

Aloe-emodin from rhubarb (Rheum rhabarbarum) inhibits lipopolysaccharide-induced inflammatory responses in RAW264.7 macrophages

Ethnopharmacological relevance

Rheum rhabarbarum (rhubarb) has long been used for the treatment of inflammation in China and other Asian countries. However, the mechanism underlying the anti-inflammatory activity of this medicinal plant is not fully understood. The present study was designed to investigate the anti-inflammatory effects of anthraquinones, the major constituents in rhubarb, and the molecular mechanism involved in their anti-inflammatory effects.

Materials and methods

RAW264.7 cells were stimulated by lipopolysaccharide (LPS) in the presence or absence of the compounds examined. The proliferation of RAW264.7 cells was assayed by the Alamar-Blue method. The quantity of nitric oxide (NO) was determined by Griess assay. The expression of pro-inflammatory cytokines was determined by enzyme-linked immunosorbent assay (ELISA) and quantitative real-time PCR. Inducible nitric oxide synthase (iNOS), inhibitor of nuclear factor κBα (IκBα), extracellular signal-regulated kinase (ERK), p38 mitogen-activated protein kinase (MAPK), c-Jun NH2-terminal kinase (JNK), and Akt/phosphoinositide 3-kinase (PI3K) protein expression levels were determined by Western blotting.

Results

Aloe-emodin markedly suppressed the production of NO, interleukin-6 (IL-6), and interleukin-1β (IL-1β) in LPS-stimulated RAW264.7 cells with no apparent cytotoxicity. The mRNA expression levels of iNOS, IL-6, and IL-1β genes were also significantly inhibited by aloe-emodin. Western blot analysis showed that aloe-emodin suppressed LPS-induced iNOS protein expression, IκBα degradation, and the phosphorylation of ERK, p38, JNK, and Akt.

Conclusions

These results demonstrate that aloe-emodin is the bioactive component of rhubarb that confers an anti-inflammatory effect through a likely mechanism involving a decrease in pro-inflammatory cytokine production in LPS-induced RAW264.7 macrophages via inhibition of NF-κB, MAPK, and PI3K pathways.