A herbal formula containing roots of Salvia miltiorrhiza (Danshen) and Pueraria lobata (Gegen) inhibits inflammatory mediators in LPS-stimulated RAW 264.7 macrophages through inhibition of nuclear factor κB (NFκB) pathway

Ethnopharmacological relevance

The herbal formula DG, containing roots of Salvia miltiorrhiza (Danshen) and Pueraria lobata (Gegen), has long history in treating cardiovascular diseases. It has been shown to be able to reduce intima-media thickening in coronary patients in our previous clinical study. Since intima-media thickening is the hallmark of atherosclerotic disease, the etiology of which is inflammation of the arterial wall, the mechanism underlying the effect of DG may be related to its anti-inflammatory activities.

Aim of study

The present study aims to determine the anti-inflammatory activity of DG and elucidate its underlying mechanisms with regards to its molecular basis of action.

Materials and method

The anti-inflammatory effect of DG was studied by using lipopolysaccharide (LPS)-stimulated activation of nuclear factor κB (NFκB) pathway and subsequent production of inflammatory mediators, including nitric oxide (NO), prostaglandin E₂ (PGE₂), interleukin-1 beta (IL-1β), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α) and macrophage chemotactic protein-1 (MCP-1), in mouse RAW 264.7 macrophages.

Results

The present study demonstrated that DG could suppress the production of NO and PGE₂ through the inhibition of iNOS and COX-2 genes. DG could also inhibit the production of IL-1β, IL-6 and MCP-1, but not TNF-α, through the inhibition of respective mRNA expressions. Further investigations showed the inhibitory effect of DG on activation of IKKα/β and degradation of IκBα, thus preventing nuclear translocation of NFκB. All these results suggested the inhibitory effects of DG on the production of inflammatory mediators through the inhibition of the NFκB pathway.

Conclusions

The inhibitory effects of DG on the production of inflammatory mediators by LPS-stimulated RAW 264.7 macrophages, are accomplished by inhibiting the nuclear translocation of NFκB through inactivating IKKα/β and preventing degradation of IκBα.     

Effect of Rhizoma Polygonati on 12-O-tetradecanoylphorbol-acetate-induced ear edema in mice

Ethnopharmacological relevance

Rhizoma Polygonati is originated from the dried rhizomes of Polygonatum sibircum Red. It has long been used in traditional Chinese medicine for the treatment of inflammatory disorders.

Aim of the study

The present study aims to investigate the anti-inflammatory effect of aqueous extract of Rhizoma Polygonati (ERP) in a mouse model of inflammation induced by 12-O-tetradecanoylphorbol-acetate (TPA).

Materials and methods

The anti-inflammatory effect was evaluated by measuring the ear thickness and activity of myeloperoxidase (MPO). The anti-inflammatory mechanism was explored by determining the protein and mRNA levels of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, and IL-6.

Results

The results showed that ERP significantly decreased the ear thickness and MPO activity in mouse model of inflammation induced by TPA. In addition, ERP also remarkably inhibited the protein and mRNA levels of iNOS, COX-2, TNF-α, IL-1β, and IL-6.

Conclusions

These results indicate that ERP has potential anti-inflammatory effect on TPA-induced inflammatory in mice, and the anti-inflammatory effect may be mediated, at least in part, by inhibiting the mRNA expression of a panel of inflammatory mediators including iNOS, COX-2, TNF-α, IL-1β, and IL-6.     

Mechanisms of anti-inflammatory property of Anacardium occidentale stem bark: Inhibition of NF-κB and MAPK signalling in the microglia

Ethnopharmacological relevance

Anacardium occidentale is used in traditional African medicine for the treatment of arthritis, fever, aches, pains, and inflammation of the extremities.

Aim of the study

In this study, we investigated the molecular mechanisms responsible for anti-inflammatory effects of a stem bark extract of A. occidentale (ANE) in LPS-stimulated microglia.

Materials and methods

Nitric oxide (NO), prostaglandin E₂ and cytokine (TNFα and IL-6) production were evaluated in supernatants from LPS-stimulated BV-2 cells. Cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS) and microsomal prostaglandin E2 synthase (mPGES-1) protein expressions in rat primary microglia were measured using western blot. The effects of ANE on NF-κB activation and nuclear translocation were evaluated in the luciferase reporter gene assay and ELISA, while ability of ANE to influence IκB phosphorylation was determined using ELISA specific for phospho-IκB. The involvement of MAPK phosphorylation in the anti-inflammatory actions of ANE was evaluated using specific ELISA for phospho-p38, phospho-p42/44 and phospho-JNK. The MTT assay was used to determine the effect of ANE on BV-2 microglia viability.

Results

ANE (25–100 μg/ml) produced significant (p<0.05) reduction in the production of NO, PGE₂, TNFα and IL-6 in BV-2 microglia stimulated with LPS for 24 h. Pre-treatment with ANE caused a significant (p<0.05) inhibition of COX-2, iNOS and mPGES-1 protein expressions in the rat primary microglia. Further experiments showed that ANE inhibited COX-2 and iNOS protein expression via IκB-mediated nuclear translocation and transactivation of NF-κB. Our studies also revealed that ANE produced significant (p<0.05) and dose-dependent inhibition of p38, p42/44 and JNK MAPK phosphorylation in LPS-activated BV-2 microglia.

Conclusions

We conclude that ANE has an anti-inflammatory property related to inhibition of inflammation-associated cytokine production as well as iNOS and COX-2 gene expression by blocking NF-κB and MAPK pathways in the microglia. It is also suggested that mPGES-1 inhibition contributes to the effect of ANE on PGE₂ production in the microglia.     

Chrysanthemum indicum Linné extract inhibits the inflammatory response by suppressing NF-κB and MAPKs activation in lipopolysaccharide-induced RAW 264.7 macrophages

Aims of study

Although the flowers of Chrysanthemum indicum Linné (Asteraceae) have long been used in traditional Korean and Chinese medicine to treat inflammatory diseases, the underlying mechanism(s) by which these effects are induced remains to be defined. We investigated the effects of a 70% ethanolic extract of C. indicum (CIE) on the activities of cellular signaling molecules that mediate inflammatory responses.

Materials and methods

Production of NO, PGE₂, TNF-α, and IL-1β by ELISA, mRNA and protein expression of iNOS and COX-2, phosphorylation of MAPKs, and activation of NF-κB by RT-PCR and Western blotting were examined in LPS-induced RAW 264.7 macrophages.

Results

The CIE strongly inhibited NO, PGE₂, TNF-α, and IL-1β production, and also significantly inhibited mRNA and protein expression of iNOS and COX-2 in LPS-induced RAW 264.7 macrophages, in a dose-dependent manner. Furthermore, the CIE clearly suppressed nuclear translocation of NF-κB p65 subunits, which correlated with an inhibitory effect on IκBα phosphorylation. The CIE also attenuated the activation of ERK1/2 and JNK in a dose-dependent manner.

Conclusion

Our results suggest that the anti-inflammatory properties of CIE might result from the inhibition of inflammatory mediators, such as NO, PGE₂, TNF-α, and IL-1β, via suppression of MAPKs and NF-κB-dependent pathways.     

Anti-inflammatory effects of methanol extracts of the root of Lilium lancifolium on LPS-stimulated Raw264.7 cells

Aim of the study

Lilium lancifolium is commonly used to treat bronchitis, pneumonia, etc. In this study, we investigated the anti-inflammatory effects of methanol extracts of the root of Lilium lancifolium (LL extracts) in LPS-stimulated Raw264.7 cells.

Material and methods

Levels of NO, PGE₂ and pro-inflammatory cytokines (IL-6 and TNF-α) in the supernatant fraction were determined using sandwich ELISA. Expression of COX-2 and iNOS, phosphorylation of MAPK subgroups (ERK and JNK), and NF-κB activation in extracts were detected via Western blot and immunocytochemistry assays.

Results

The LL extract significantly inhibited NO, PGE₂, IL-6 and TNF-α production in LPS-stimulated cells, and suppressed iNOS and COX-2 expression. A mechanism-based study showed that phosphorylation of ERK1/2 and JNK and translocation of the NF-κB p65 subunit into nuclei were inhibited by the LL extract. Furthermore, interleukin-4 and interleukin-13 production in Con A-induced splenocytes was suppressed.

Conclusion

These results indicate that anti-inflammatory effects of methanol extracts from Lilium lancifolium are due to downregulation of iNOS and COX-2 via suppression of NF-κB activation and nuclear translocation as well as blocking of ERK and JNK signaling in LPS-stimulated Raw264.7 cells.     

Characterisation of the anti-inflammatory potential of Vitex trifolia L. (Labiatae), a multipurpose plant of the Pacific traditional medicine

Aim of the study

Vitex trifolia L. (Labiatae) is a plant commonly employed against Ciguatera Fish Poisoning (CFP) in the Pacific region. Here, the anti-inflammatory potential of an aqueous extract of Vitex trifolia leaves was evaluated by monitoring its effects on the modulation of cytokines, the mediators of inflammation, as well as on the expression profiles of inducible nitric oxide synthase (iNOS) which produces the free radical nitric oxide (NO).

Materials and methods

We prepared an aqueous extract from Vitex trifolia leaves and evaluated its anti-inflammatory potency by monitoring its effect on the lipopolysaccharide (LPS)-induced cytokines and iNOS mRNA over-production in RAW 264.7 macrophages using quantitative Polymerase Chain Reaction (qPCR) and Enzyme-Linked Immunosorbent Assay (ELISA) methods.

Results

Aqueous extract of Vitex trifolia leaves showed significant dose- and time-dependent inhibitory activity on interleukin (IL)-1β, IL-6 and iNOS mRNA synthesis, but slight effect on tumor necrosis factor (TNF)-α, all of which are involved in the inflammatory response. Moreover, the plant extract seemed to induce the LPS-dependant IL-10 anti-inflammatory cytokine. These results were further confirmed by ELISA using specific antibodies to mouse IL-6, IL-10 and TNF-α.

Conclusion

The anti-inflammatory effects of Vitex trifolia could validate its utilization as a traditional remedy against CFP and emphasises its potential therapeutic value against other inflammatory diseases. Therefore, this plant is a promising candidate for further screening of its active compounds through activity-guided fractionation.     

Biomolecular evidence of anti-inflammatory effects by Clematis mandshurica Ruprecht root extract in rodent cells

Ethnopharmacological relevance

Clematis mandshurica Ruprecht root is widely used in Asia as an analgesic and anti-inflammatory agent. This research investigated the anti-inflammatory effects of Clematis mandshurica Ruprecht root extract (CRE) using RAW 264.7 macrophage cells and carrageenan- (CA-) induced rat paw edema.

Materials and methods

Production of tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, IL-6, nitric oxide (NO) and prostaglandin E₂ (PGE₂) in the culture supernatant, mRNA expression of TNF-α, IL-1β, IL-6, iNOS and COX-2, protein expression of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), nuclear factor-kappa B (NF-κB) and mitogen-activated protein kinases (MAPKs) in the extract were assayed. In addition, the effect of CRE on acute inflammation in vivo was observed using CA-induced rat hind paw edema assay. The changes on the histopathology and histomorphometry of hind paw skins—dorsum and ventrum pedis were observed using CA-treated rats.

Results

Treatment with CRE (0.25, 0.5, and 1 mg/mL) resulted in inhibited levels of protein expression of lipopolysaccharide- (LPS-) induced iNOS, COX-2, NF-κB, and MAPKs (ERK, JNK, and p38) as well as production of TNF-α, IL-1β, IL-6, NO, and PGE₂ induced by LPS. Consistent with these results, CRE reduced the LPS-induced expressions of these cytokines, iNOS and COX-2 at the mRNA levels in a dose-dependent manner. In particular, results of the CA-induced rat hind paw edema assay showed an anti-edema effect of CRE. In addition, treatment with CRE resulted in dose-dependent inhibition of CA-induced increases of skin thickness, mast cell degranulation, and infiltrated inflammatory, TNF-α, IL-1β, iNOS, and COX-2-positive cells in both dorsum and ventrum pedis skin, respectively.

Conclusions

These results demonstrate that CRE exhibits anti-inflammatory activities via decreasing production of pro-inflammatory mediators through suppression of the pathways of NF-κB and MAPKs in LPS-induced macrophage cells. In addition, results of the CA-induced rat hind paw edema assay show an anti-edema effect of CRE. Our findings also support the traditional use of CRE in the inflammatory symptoms of rheumatic arthritis and acute icteric hepatitis. Thus, CRE may have therapeutic potential for a variety of inflammation-mediated diseases and may be developed into potent anti-inflammatory drugs.     

Red ginseng extract inhibits the expression of MCP-1 and iNOS in Helicobacter pylori-infected gastric epithelial cells by suppressing the activation of NADPH oxidase and Jak2/Stat3

Ethnopharmcological relevance

Helicobacter pylori induced oxidative stress represents an important mechanism leading to expression of inflammatory mediators. Korean red ginseng is used in traditional medicine to inhibit inflammation. However, the anti-inflammatory mechanism of red ginseng is still under investigation. Thus, we investigated whether Korean red ginseng extract (RGE) inhibits NADPH oxidase, a source of reactive oxygen species (ROS), and the Jak2/Stat3 pathway, which mediates the expression of inflammatory mediators, in Helicobacter pylori-infected gastric epithelial cells.

Materials and methods

A standardized RGE was supplied by the Korea Ginseng Corporation. Human gastric epithelial cells (AGS) were treated with RGE and stimulated with Helicobacter pylori. NADPH oxidase activity, ROS levels, activation of Jak2/Stat3, and induction of MCP-1 and iNOS were determined.

Results

Helicobacter pylori infection resulted in an increase in ROS and activation of NADPH oxidase and Jak2/Stat3, which induced the expression of MCP-1 and iNOS in AGS cells. The induction of MCP-1 and iNOS was inhibited by both the Jak2/Stat3 inhibitor AG490 and RGE in Helicobacter pylori-infected cells. RGE suppressed NADPH oxidase activity by inhibiting translocation of cytosolic subunits p67phox and p47phox to the membrane and reduced ROS levels in Helicobacter pylori-infected cells.

Conclusion

RGE inhibits the expression of MCP-1 and iNOS by suppressing the activation of NADPH oxidase and Jak2/Stat3 in Helicobacter pylori-infected gastric epithelial cells.     

Immunomodulatory properties of Xylaria nigripes in peritoneal macrophage cells of Balb/c mice

Ethnopharmacological relevance

Wu Ling Shen, a folklore name for Xylaria nigripes (XN), is a high value medicinal fungus used in traditional Chinese medicine.

Aim of study

The present study aimed to examine the immunomodulatory properties of aqueous (XN-H) and ethanol (XN-E) XN extracts in lipopolysaccharide (LPS)-induced peritoneal macrophage cells of Balb/c mice.

Materials and methods

After treating the macrophage cells with LPS (1 μg/ml) and different XN extracts, the immunomodulatory properties were determined by the responses of inflammatory mediators, namely nitrite oxide (NO), prostaglandin E2 (PGE₂) and cytokine (IL-1β, IL-6, TNF-α and IFN-γ) production, iNOS, COX-2 and IκB-α expression, and NF-κB activation.

Results

Results showed that treatment of macrophages with 5-30 μg/ml of XN-H or XN-E plus 1 μg/ml LPS exhibited no cytotoxic effect on cell viability. At these concentrations, although both XN-H and XN-E showed a dose-dependent inhibitory effect on NO, PGE₂, IL-1β, IL-6, TNF-α and IFN-γ production in LPS-stimulated macrophages, a greater potency was noted in the XN-H treated group. RT-PCR assay also showed that XN-H possessed a greater inhibition than XN-E on iNOS and COX-2 RNA expression. Furthermore, XN-H also showed a significant stronger suppression than XN-E on the LPS-induced IκB-α phosphorylation and NF-κB activation. XN-E showed a higher total flavonoid and phenol contents but a lower β-glucan content than XN-H.

Conclusion

Taken together, these results conclude that XN-H possesses a stronger anti-inflammatory activity than XN-E, and its mechanism of action could be mediated by inhibiting iNOS and COX-2 expression via the NF-κB signaling pathway, and these activities could be contributed by the β-glucan content.     

Lilium lancifolium Thunb. extract attenuates pulmonary inflammation and air space enlargement in a cigarette smoke-exposed mouse model

Ethnopharmacological relevance

Lilium lancifolium Thunb. (Liliaceae) has long been used as a traditional medicine in Korea and China to treat bronchitis, pneumonia, and other pulmonary ailments.

Aim of the study

Cigarette smoke (CS) is a major risk factor for the development of pulmonary inflammatory response; it also triggers pulmonary alveoli enlargement. In the present study, we investigate the effects of Lilium lancifolium Thunb. root extract on pulmonary inflammatory responses in a CS-exposed mouse model.

Materials and methods

Water extract of Lilium lancifolium Thunb. root was fed to C57BL/6 mice prior CS exposure every day for 3 weeks. The numbers of macrophages and neutrophils in bronchoalveolar lavage fluid (BALF) were counted. The relative inflammatory factors, tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), interleukin-1 beta (IL-1β), monocyte chemotactic protein-1 (MCP-1), and matrix metalloproteinase-12 (MMP-12) were measured by real-time PCR, ELISA, or Western blot analysis. The average alveoli size was determined by lung histology.

Results

Lilium lancifolium Thunb. root extract was found to significantly inhibit the numbers of macrophages and neutrophils in BALF due to CS exposure. Lilium lancifolium Thunb. root extract also reduced the protein secretion levels of TNF-α, IL-6, IL-1β, and MCP-1 in BALF and the RNA expression levels of TNF-α, IL-6, IL-1β, MCP-1, and MMP-12 in lung tissue compared with mice only exposed to CS. Moreover, MMP-12 in serum was down regulated in Lilium lancifolium Thunb. root extract treated mice compared with CS-exposed mice. Finally, a morphometric analysis of the lungs of Lilium lancifolium Thunb. root extract treated mice demonstrated a significant reduction in airspace size compared to mice only exposed to CS.

Conclusion

Our results show that Lilium lancifolium Thunb. root extract reduces lung inflammation and airspace enlargement in a CS-exposed mouse model. These data indicate that Lilium lancifolium Thunb. root extract is a therapeutic candidate for pulmonary inflammation and emphysema caused by CS.     

Inhibitory effects of the root extract of Litsea cubeba (lour.) pers. on adjuvant arthritis in rats

Ethnopharmacological relevance

The dried root of Litsea cubeba (Lour.) Pers. (Family Lauraceae) has long been used as a folk remedy in Traditional Chinese Medicine (TCM) and Dai Ethnopharmacy for the treatment of rheumatic diseases in southwestern China.

Aim of the study

This study investigated the preventive efficacy of Litsea cubeba root in treating rheumatoid arthritis using Freund's complete adjuvant (CFA) induced arthritis (AA) in rat model.

Materials and methods

Arthritis was induced in male Wistar rats by immunization with CFA. Ethanol extract (EELC) and water extract (WELC) of Litsea cubeba root both at 50 mg/kg and 200 mg/kg were orally administered from a day after the induction of arthritis. Paw swelling, arthritic score, body weight growth rate, index of thymus and spleen were observed, and the production of TNF-α, IL-1β, IL-6 and IL-10 in serum were measured by enzyme-linked immunosorbent assay. The expression levels of inflammatory enzymes like cyclooxygenase and lipoxygenase were also measured by enzyme-linked immunosorbent assay. Moreover, histological changes in the ankle joint were analyzed in AA rats.

Results

Both EELC and WELC significantly suppressed paw swelling and arthritic score, increased the loss in body weight and decreased the index of thymus. Histopathological improvement in joint architecture was also observed in EELC, WELC-treated AA rats. The expression levels of cyclooxygenase-2 (COX-2) and 5-lipoxygenase (5-LOX) were decreased on treatment with EELC and WELC. Furthermore, the overproduction of TNF-α, IL-1β and IL-6 were remarkably attenuated in serum of all Litsea cubeba-treated rats, however, IL-10 was markedly increased at doses of 50 mg/kg of EELC and WELC.

Conclusions

These results indicate that extract of Litsea cubeba root significantly attenuates adjuvant arthritis in rats by decreasing the levels of TNF-α, IL-1β and IL-6 and increasing of IL-10 in serum as well as down-regulate the levels of inflammatory enzymes such as COX-2 and 5-LOX. This suggests that Litsea cubeba root might be used as a therapeutic agent for the treatment of human arthritis.     

Bioassay-guided isolation of anti-inflammatory components from the root of Rehmannia glutinosa and its underlying mechanism via inhibition of iNOS pathway

Ethnopharmacological relevance

The root of Rehmannia glutinosa (RR) is commonly used to reduce inflammation in various traditional Chinese herbal formulae; however, little is known regarding its active component(s).Aim of study: The objective of the present study was to examine the active component(s) responsible for the anti-inflammatory activity of RR via anti-nitric oxide production assay-guided fractionation; and the underlying anti-inflammatory mechanism of action of such component(s) was further investigated.

Materials and methods

Anti-nitric oxide (NO) activities with lipopolysaccharides (LPS)-stimulated RAW264.7 murine macrophages was used as screening platform. Gene, protein and inflammatory mediators' expression were also studied using real-time PCR, western blotting and ELISA, respectively.

Results

Using anti-NO assay-guided fractionation, sub-fraction C3 (from 31.25 to 62.5 μg/ml, p=0.001 to 0.01) possessed 100-fold more potent anti-inflammatory effect than that of the aqueous extract of RR. Characterization of C3 showed that the anti-inflammatory effect could be partly due to the presence of rehmapicrogenin, which could significantly inhibit NO production (p<0.001). C3 was further demonstrated in blocking inflammation by inhibiting gene (p<0.001) and protein expression of inducible NO synthase (iNOS) dose-dependently. Besides, C3 also significantly inhibited the production of prostaglandin E₂ (p<0.001 to 0.01), IL-6 (p<0.001 to 0.05) and COX-2 (p<0.05).

Conclusions

Rehmapicrogenin was, for the first time, shown to possess nitric oxide inhibitory activities. Bioassay-guided fractionation demonstrated that rehmapicrogenin-containing subfraction C3 exhibited potent anti-inflammatory effect by inhibiting iNOS, COX-2 and IL-6, while rehmapicrogenin was only partially responsible for the anti-inflammatory effect of RR.     

Anti-inflammatory effect of Inonotus obliquus, Polygala senega L., and Viburnum trilobum in a cell screening assay

Aim of the study

The purpose of the study was to assess the anti-inflammatory effects of the mushroom Inonotus obliquus (Chaga), Polygala senega (Senega) and Viburnum trilobum (Cranberry) bark extract fractions from locally produced materials in lipopolysaccharide (LPS) induced murine macrophage RAW 164.7 cells.

Materials and methods

Four fractions from each of the three extracts were obtained: (80% ethanol extracted; Fa), (water-soluble polysaccharide fraction; Fb), (Polyphenolic fraction; Fc) and (ETOAc/H₂O extracted fraction; Fd). These extract fractions were tested in the cell screening system at 50,100 and 500 μg/ml for their ability to inhibit LPS induced inflammatory cytokines IL-1β, TNFα and IL-6. Supernatants from LPS alone treated cells were used as control. The cytokines in the cell culture supernatants following treatments with extract fractions were quantified by ELISA method, using 96 well ELISA plates.

Results

All fractions of the extracts significantly inhibited (p < 0.05) the levels of IL-1β, IL-6 and TNFα except the polyphenolic Fc fraction of Senega which showed an increased production of IL-6. Furthermore, each fraction showed a dose-dependant anti-inflammatory effect. Nitric oxide production was not affected by cranberry and senega, while Chaga significantly reduced NO production in murine macrophage cell assay.

Conclusions

These results demonstrate that the extracts obtained from the root of Polygala senega L., bark of Viburnum trilobum, and the mushroom Inonotus obliquus possess anti-inflammatory properties when tested in a RAW 264.7 macrophage cell system.     

In vitro anti-inflammatory effects of arctigenin,a lignan from Arctium lappa L., through inhibition on iNOS pathway

Ethnopharmacological relevance

Arctigenin, a bioactive constituent from dried seeds of Arctium lappa L. (Compositae) which has been widely used as a Traditional Chinese Medicine for dispelling wind and heat included in Chinese Pharmacophere, was found to exhibit anti-inflammatory activities but its molecular mechanism remains unknown yet.

Aim of the study

To investigate the anti-inflammatory mechanism of arctigenin.

Materials and methods

Cultured macrophage RAW 264.7 cells and THP-1 cells were used for the experiments. Griess assay was used to evaluate the inhibitory effect of arctigenin on the overproduction of nitric oxide (NO). ELISA was used to determine the level of pro-inflammatory cytokines including tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6). The inhibitory effect on the enzymatic activity of cyclooxygenase-2 (COX-2) was tested by colorimetric method. Western blot was used to detect the expression of inducible nitric oxide synthase (iNOS) and COX-2.

Results

Arctigenin suppressed lipopolysaccharide (LPS)-stimulated NO production and pro-inflammatory cytokines secretion, including TNF-α and IL-6 in a dose-dependent manner. Arctigenin also strongly inhibited the expression of iNOS and iNOS enzymatic activity, whereas the expression of COX-2 and COX-2 enzymatic activity were not affected by arctigenin.

Conclusions

These results indicated that potent inhibition on NO, TNF-α and IL-6, but not COX-2 expression and COX-2 activity, might constitute the anti-inflammatory mechanism of arctigenin. Arctigenin suppressed the overproduction of NO through down-regulation of iNOS expression and iNOS enzymatic activity in LPS-stimulated macrophage.