Therapeutic action and underlying mechanisms of a combination of two pentacyclic triterpenes, alpha- and beta-amyrin, in a mouse model of colitis

Antihyperglycemic and hypolipidemic effects of α, β-amyrin, a triterpenoid mixture from Protium heptaphyllum in mice

Background

Pentacyclic triterpenes in general exert beneficial effects in metabolic disorders. This study investigated the effects of α, β-amyrin, a pentacyclic triterpene mixture from the resin of Protium heptaphyllum on blood sugar level and lipid profile in normal and streptozotocin (STZ)-induced diabetic mice, and in mice fed on a high-fat diet (HFD).

Findings

Mice treated with α, β-amyrin (10, 30 and 100 mg/kg, p.o.) or glibenclamide (10 mg/kg, p.o.) had significantly reduced STZ-induced increases in blood glucose (BG), total cholesterol (TC) and serum triglycerides (TGs). Unlike glibenclamide that showed significant reductions in BG, TC and TGs in normoglycemic mice, α, β-amyrin did not lower normal blood sugar levels but at 100 mg/kg, manifested a hypolipidemic effect. Also, α, β-amyrin effectively reduced the elevated plasma glucose levels during the oral glucose tolerance test. Moreover, the plasma insulin level and histopathological analysis of pancreas revealed the beneficial effect of α, β-amyrin in the preservation of beta cell integrity. In mice treated orally with α, β-amyrin (10, 30 and 100 mg/kg) or fenofibrate (200 mg/kg), the HFD-associated rise in serum TC and TGs were significantly less. The hypocholesterolemic effect of α, β-amyrin appeared more prominent at 100 mg/kg with significant decreases in VLDL and LDL cholesterol and an elevation of HDL cholesterol. Besides, the atherogenic index was significantly reduced by α, β-amyrin.

Conclusions

These findings reflect the potential antihyperglycemic and hypolipidemic effects of α, β-amyrin mixture and suggest that it could be a lead compound for drug development effective in diabetes and atherosclerosis.

Analgesic and Anti-Inflammatory Property of the Methanol Extract from Ligustrum morrisonense Leaves in Rodents

Ligustrum morrisonense Kaneh and Sasaki (abbreviated as LM), an endemic Ligustrum plant in Taiwan, is similar to Ligustrum lucidum, which is usually used for curing hepatic and inflammatory disorders. The aim of this study was to evaluate the analgesic and anti-inflammatory properties of LM by chemical-induced algesia and carrageenan-induced inflammation in rodents. Its triterpenoid contents were measured by using high performance liquid chromatography-photodiode array detector. LM leaf extracts effectively inhibited writhing responses induced by 1% acetic acid and biphasic-licking responses caused by 1% formalin. LM leaf extract also reduced the edema induced by 1% carrageenan. Furthermore, LM leaf extract reduced the abdominal Evan's blue extravasations caused by lipopolysaccharide (LPS), serotonin, histamine and bradykinin. LM leaf extract has higher contents of amyrin and lupeol among six assayed triterpenoid compounds. In conclusion, LM is a potential analgesic and anti-inflammatory Ligustrum plant, and its anti-inflammatory effects are partially related to decreasing microvascular permeability via inflammatory mediators and inhibiting cyclooxygenase-2 activity.

Preventive and therapeutic euphol treatment attenuates experimental colitis in mice

BACKGROUND

The tetracyclic triterpene euphol is the main constituent found in the sap of Euphorbia tirucalli. This plant is widely known in Brazilian traditional medicine for its use in the treatment of several kinds of cancer, including leukaemia, prostate and breast cancers. Here, we investigated the effect of euphol on experimental models of colitis and the underlying mechanisms involved in its action.

METHODOLOGY/PRINCIPAL FINDINGS

Colitis was induced in mice either with dextran sulfate sodium (DSS) or with 2,4,6-trinitrobenzene sulfonic acid (TNBS), and the effect of euphol (3, 10 and 30 mg/kg) on colonic injury was assessed. Pro-inflammatory mediators and cytokines were measured by immunohistochemistry, enzyme-Linked immunoabsorbent assay (ELISA), real time-polymerase chain reaction (RT-PCR) and flow cytometry. Preventive and therapeutic oral administration of euphol attenuated both DSS- and TNBS-induced acute colitis as observed by a significant reduction of the disease activity index (DAI), histological/microscopic damage score and myeloperoxidase (MPO) activity in colonic tissue. Likewise, euphol treatment also inhibited colon tissue levels and expression of IL-1β, CXCL1/KC, MCP-1, MIP-2, TNF-α and IL-6, while reducing NOS2, VEGF and Ki67 expression in colonic tissue. This action seems to be likely associated with inhibition of activation of nuclear factor-κB (NF-κB). In addition, euphol decreased LPS-induced MCP-1, TNF-α, IL-6 and IFN-γ, but increased IL-10 secretion from bone marrow-derived macrophages in vitro. Of note, euphol, at the same schedule of treatment, markedly inhibited both selectin (P- and E-selectin) and integrin (ICAM-1, VCAM-1 and LFA-1) expression in colonic tissue.

CONCLUSIONS/SIGNIFICANCE

Together, these results clearly demonstrated that orally-administered euphol, both preventive or therapeutic treatment were effective in reducing the severity of colitis in two models of chemically-induced mouse colitis and suggest this plant-derived compound might be a potential molecule in the management of inflammatory bowel diseases.

The precursor of resolvin D series and aspirin-triggered resolvin D1 display anti-hyperalgesic properties in adjuvant-induced arthritis in rats

BACKGROUND AND PURPOSE

Resolution of inflammation is mediated by endogenous molecules with anti-inflammatory and pro-resolving activities and they have generated new possibilities for the treatment of inflammatory diseases. Here, we have investigated the possible anti-hyperalgesic effects of two lipids, aspirin-triggered resolvin D1 (AT-RvD1) and its precursor, 17(R)-hydroxy-4Z,7Z,10Z,13Z,15E,17R,19Z-docosahexaenoic acid (17(R)HDoHE).

EXPERIMENTAL APPROACH

The anti-hyperalgesic effects of both lipid mediators were evaluated, using mechanical and thermal stimuli, at different time-points in adjuvant-induced arthritis in rats. Cytokine levels were measured, and immunohistochemistry and real-time PCR for pro-inflammatory mediators were also performed.

KEY RESULTS

The precursor of resolvin D series, 17(R)HDoHE, given systemically, inhibited the development and the maintenance of mechanical hyperalgesia in acute inflammation. Such effects were likely to be associated with modulation of both NF-κB and COX-2 in dorsal root ganglia and spinal cord. 17(R)HDoHE was also effective against sub-chronic pain. Unexpectedly, repeated treatment with 17(R)HDoHE did not modify paw and joint oedema in the sub-chronic model, while joint stiffness was prevented. Notably, AT-RvD1 exhibited marked anti-hyperalgesic effects in acute inflammation when given systemically. The efficacy of long-term treatment with either 17(R)HDoHE or AT-RvD1 was partly related to decreased production of TNF-α and IL-1β in rat hind paw.

CONCLUSIONS AND IMPLICATIONS

Our findings provide fresh evidence for the anti-hyperalgesic properties of 17(R)HDoHE and its pro-resolution metabolite AT-RvD1. Such lipid mediators might be useful for treating pain associated with acute or chronic inflammation. LINKED ARTICLE This article is commented on by Xu and Ji, pp. 274-277 of this issue. To view this commentary visit http://dx.doi.org/10.1111/j.1476-5381.2011.01348.x.

Gastrodin inhibits expression of inducible NO synthase, cyclooxygenase-2 and proinflammatory cytokines in cultured LPS-stimulated microglia via MAPK pathways

Background

Microglial activation plays an important role in neurodegenerative diseases by producing several proinflammatory enzymes and proinflammatory cytokines. The phenolic glucoside gastrodin, a main constituent of a Chinese herbal medicine, has been known to display anti-inflammatory properties. The current study investigates the potential mechanisms whereby gastrodin affects the expression of potentially pro-inflammatory proteins by cultured murine microglial BV-2 cells stimulated with lipopolysaccharide (LPS).

Methodology/Principal Findings

BV-2 cells were pretreated with gastrodin (30, 40, and 60 µM) for 1 h and then stimulated with LPS (1 µg/ml) for another 4 h. The effects on proinflammatory enzymes, inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), and proinflammatory cytokines, tumor necrosis factor-α (TNF-α), and interleukin-1β (IL-1β), are analysed by double-immunofluorescence labeling and RT-PCR assay. To reveal the mechanisms of action of gastrodin we investigated the involvement of mitogen-activated protein kinases (MAPKs) cascades and their downstream transcription factors, nuclear factor-κB (NF-κB) and cyclic AMP-responsive element (CRE)-binding protein (CREB). Gastrodin significantly reduced the LPS-induced protein and mRNA expression levels of iNOS, COX-2, TNF-α, IL-1β and NF-κB. LPS (1 µg/ml, 30 min)-induced phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2), c-Jun N-terminal protein kinase (JNK) and p38 mitogen-activated protein kinase (p38 MAPK) and this was inhibited by pretreatment of BV-2 cells with different concentrations of gastrodin (30, 40, and 60 µM). In addition, gastrodin blocked LPS-induced phosphorylation of inhibitor κB-α (IκB-α) (and hence the activation of NF-κB) and of CREB, respectively.

Conclusion and Implications

This study indicates that gastrodin significantly attenuate levels of neurotoxic proinflammatory mediators and proinflammatory cytokines by inhibition of the NF-κB signaling pathway and phosphorylation of MAPKs in LPS-stimulated microglial cells. Arising from the above, we suggest that gastrodin has a potential as an anti-inflammatory drug candidate in neurodegenerative diseases.

Beyond cholesterol-lowering effects of plant sterols: clinical and experimental evidence of anti-inflammatory properties

Inflammation is a strong risk factor for cardiovascular disease. Dietary plant sterols are known to reduce plasma cholesterol levels and thereby reduce cardiovascular risk. Recent observations from animal and human studies have demonstrated anti-inflammatory effects of phytosterols. For example, several animal and human studies report reductions in the levels of proinflammatory cytokines, including C-reactive protein, after consumption of dietary plant sterols. Although the cholesterol-lowering effects of phytosterols in humans are well documented, studies on the effects of phytosterols on inflammatory markers have produced inconsistent results. This review summarizes and discusses findings from recent animal and human studies with regard to the potential anti-inflammatory effects of dietary phytosterols. Findings on the effects of plant sterols on inflammation remain limited and confounding. Future research using better-designed and well-controlled laboratory studies and clinical trials are needed to fully understand the mechanisms through which phytosterols influence inflammation. Additional well-designed placebo-controlled studies are needed to better understand how and to what extent dietary plant sterols may modify the immune system and the production of inflammatory markers.

Activation of cannabinoid receptors by the pentacyclic triterpene α,β-amyrin inhibits inflammatory and neuropathic persistent pain in mice

In this study, we report that α,β-amyrin, a plant-derived pentacyclic triterpene, reduced persistent inflammatory and neuropathic hyperalgesia in mice by a direct activation of the CB(1) and CB(2) cannabinoid receptors (CB(1)R and CB(2)R). The oral treatment with α,β-amyrin (30 mg/kg) significantly reduced mechanical and thermal hyperalgesia and inflammation induced by complete Freund's adjuvant (CFA) and by partial sciatic nerve ligation (PSNL). The pretreatment with either CB(1)R or CB(2)R antagonists and the knockdown gene of the receptors significantly reverted the antinociceptive effect of α,β-amyrin. Of note, binding studies showed that α,β-amyrin directly bound with very high affinity to CB(1)R (K(i)=0.133 nM) and with a lower affinity to CB(2)R (K(i)=1989 nM). Interestingly, α,β-amyrin, ACEA (CB(1)R agonist), or JWH-133 (CB(2)R agonist), at doses that caused antinociception, failed to provoke any behavioral disturbance, as measured in the tetrad assay. In addition, α,β-amyrin largely decreased interleukin-1β (IL-1β), tumor necrosis factor α (TNF-α), keratinocyte-derived chemokine (KC) and interleukin 6 (IL-6) levels, and myeloperoxidase activity. Likewise, α,β-amyrin prevented the activation of the transcriptional factors: nuclear factor κB (NF-κB) and cyclic adenosine monophosphate response element binding (CREB) and the expression of cyclooxygenase 2 in mice footpads and spinal cords. The present results demonstrated that α,β-amyrin exhibits long-lasting antinociceptive and anti-inflammatory properties in 2 models of persistent nociception via activation of cannabinoid receptors and by inhibiting the production of cytokines and expression of NF-κB, CREB and cyclooxygenase 2.

β-Caryophyllene inhibits dextran sulfate sodium-induced colitis in mice through CB2 receptor activation and PPARγ pathway

Cannabinoid receptor 2 (CB2) activation is suggested to trigger the peroxisome proliferator-activated receptor-γ (PPARγ) pathway, and agonists of both receptors improve colitis. Recently, the plant metabolite (E)-β-caryophyllene (BCP) was shown to bind to and activate CB2. In this study, we examined the anti-inflammatory effect of BCP in dextran sulfate sodium (DSS)-induced colitis and analyzed whether this effect was mediated by CB2 and PPARγ. Oral treatment with BCP reduced disease activity, colonic macro- and microscopic damage, myeloperoxidase and N-acetylglucosaminidase activities, and levels and mRNA expression of colonic tumor necrosis factor-α, IL-1β, interferon-γ, and keratinocyte-derived chemokine. BCP treatment also inhibited the activation of extracellular signal-regulated kinase 1/2, nuclear factor κB, IκB-kinase α/β, cAMP response element binding and the expression of caspase-3 and Ki-67. Moreover, BCP enhanced IL-4 levels and forkhead box P3 mRNA expression in the mouse colon and reduced cytokine levels (tumor necrosis factor-α, keratinocyte-derived chemokine, and macrophage-inflammatory protein-2) in a culture of macrophages stimulated with lipopolysaccharide. The use of the CB2 antagonist AM630 or the PPARγ antagonist GW9662 significantly reversed the protective effect of BCP. Confirming our results, AM630 reversed the beneficial effect of BCP on pro-inflammatory cytokine expression in IEC-6 cells. These results demonstrate that the anti-inflammatory effect of BCP involves CB2 and the PPARγ pathway and suggest BCP as a possible therapy for the treatment of inflammatory bowel disease.

Triterpenoid contents and anti-inflammatory properties of the methanol extracts of ligustrum species leaves

Ligustrum (privet) plants are used by Chinese physicians to prevent and cure hepatitis and chronic bronchitis. Three common Ligustrum plant spp., namely Ligustrum lucidum Ait. (LL), L. pricei Hayata (LP) and L. sinensis Lour. (LS) were collected to assess their analgesic/anti-inflammatory properties on chemical-induced nociception and carrageenan-induced inflammation in rodents. The methanol extracts from Ligustrum plants leaves effectively inhibited nociceptive responses induced by 1% acetic acid and 1% formalin. LP and LL reduced the edema induced by 1% carrageenan. LP exhibited the best potency of the Ligustrum plants. Furthermore, LP reduced the abdominal Evan's blue extravasations caused by lipopolysaccharide, lipoteichoic acid, autocrines and sodium nitroprusside. The triterpenoid content of the three Ligustrum spp. was measured by high performance liquid chromatography using a photodiode array detector. LP contained the highest content of amyrin, betulinic acid and lupeol. LL had the highest content of oleanolic acid and ursolic acid. The various degrees of analgesic/anti-inflammatory effects among three Ligustrum plants may be related to their different triterpenoid contents. LP is a potential analgesic and anti-inflammatory Ligustrum plant. The effects of LP are partially related to the inhibition of cyclooxygenase-2 activity and a decrease in microvascular permeability via the actions of autocrines and kinins.

Cox-2 deletion in myeloid and endothelial cells, but not in epithelial cells, exacerbates murine colitis

Patients with inflammatory bowel diseases are at increased risk for colorectal cancer. Pharmacological inhibition of cyclooxygenase (COX) function exacerbates symptoms in colitis patients. Animal models of colitis using Cox-2-knockout mice and COX inhibitors also indicate that COX-2 has a protective role against colon inflammation. However, because conventional Cox-2 deletion and COX-2 inhibitors eliminate COX-2 function in all cells, it has not been possible to analyze the role(s) of COX-2 in different cell types. Here, we use a Cox-2(flox) conditional knockout mouse to analyze the role of COX-2 expression in distinct cell types in the colon in response to dextran sulfate sodium (DSS)-induced colitis. We generated Cox-2 conditional knockouts in myeloid cells with LysMCre knock-in mice, in endothelial cells with VECadCreERT2 transgenic mice and in epithelial cells with VillinCre transgenic mice. When treated with DSS to induce colitis, both myeloid cell-specific and endothelial cell-specific Cox-2-knockout mice exhibited greater weight loss, increased clinical scores and decreased epithelial cell proliferation after DSS injury when compared with littermate controls. In contrast, epithelial-specific Cox-2 knockouts and control littermates did not differ in response to DSS. These results suggest that COX-2 expression in myeloid cells and endothelial cells, but not epithelial cells, is important for protection of epithelial cells in this murine colitis model.

Cox-2 deletion in myeloid and endothelial cells, but not in epithelial cells, exacerbates murine colitis

Patients with inflammatory bowel diseases are at increased risk for colorectal cancer. Pharmacological inhibition of cyclooxygenase (COX) function exacerbates symptoms in colitis patients. Animal models of colitis using Cox-2-knockout mice and COX inhibitors also indicate that COX-2 has a protective role against colon inflammation. However, because conventional Cox-2 deletion and COX-2 inhibitors eliminate COX-2 function in all cells, it has not been possible to analyze the role(s) of COX-2 in different cell types. Here, we use a Cox-2(flox) conditional knockout mouse to analyze the role of COX-2 expression in distinct cell types in the colon in response to dextran sulfate sodium (DSS)-induced colitis. We generated Cox-2 conditional knockouts in myeloid cells with LysMCre knock-in mice, in endothelial cells with VECadCreERT2 transgenic mice and in epithelial cells with VillinCre transgenic mice. When treated with DSS to induce colitis, both myeloid cell-specific and endothelial cell-specific Cox-2-knockout mice exhibited greater weight loss, increased clinical scores and decreased epithelial cell proliferation after DSS injury when compared with littermate controls. In contrast, epithelial-specific Cox-2 knockouts and control littermates did not differ in response to DSS. These results suggest that COX-2 expression in myeloid cells and endothelial cells, but not epithelial cells, is important for protection of epithelial cells in this murine colitis model.

Targeting inflammatory pathways by triterpenoids for prevention and treatment of cancer

Traditional medicine and diet has served mankind through the ages for prevention and treatment of most chronic diseases. Mounting evidence suggests that chronic inflammation mediates most chronic diseases, including cancer. More than other transcription factors, nuclear factor-kappaB (NF-κB) and STAT3 have emerged as major regulators of inflammation, cellular transformation, and tumor cell survival, proliferation, invasion, angiogenesis, and metastasis. Thus, agents that can inhibit NF-κB and STAT3 activation pathways have the potential to both prevent and treat cancer. In this review, we examine the potential of one group of compounds called triterpenes, derived from traditional medicine and diet for their ability to suppress inflammatory pathways linked to tumorigenesis. These triterpenes include avicins, betulinic acid, boswellic acid, celastrol, diosgenin, madecassic acid, maslinic acid, momordin, saikosaponins, platycodon, pristimerin, ursolic acid, and withanolide. This review thus supports the famous adage of Hippocrates, “Let food be thy medicine and medicine be thy food”.

Modulating effect of Leptadenia reticulata (Retz) Wight & arn against chromate (VI)-induced immunosuppression and oxidative stress on mouse splenic lymphocytes and bone marrow derived macrophages

ETHNOPHARMACOLOGICAL RELEVANCE

Leptadenia reticulata (Retz) Wight & arn is mentioned in the ancient ayurvedic literature as an immune booster and rejuvenator.

AIMS OF THE STUDY

To investigate, the effects of different forms of the extract of Leptadenia reticulata [Aqueous extract (JAE), Padavashesha kashaya (JPK) and Tarpana kashaya (JTK)] to alleviate the experimental immunosuppression induced by the immunotoxicant chromate (VI) in vitro.

MATERIALS AND METHODS

Standard cell proliferation and cytotoxicity assays like MTT assay, trypan blue dye exclusion test, neutral red dye uptake test, NBT reduction test, determination of percentage cell survival and estimation of markers of oxidative stress were performed in the study. The study was conducted on primary cultures of mouse splenic lymphocytes and bone marrow derived macrophages.

RESULTS AND CONCLUSIONS

Treatment with all the three forms of the extract used in the study offered protection against chromate (VI)-induced immunosuppression and the overall protective effect was found to be superior in the case of the aqueous extract of Leptadenia reticulata (JAE). These results confirm that Leptadenia reticulata acts as a modulator and alleviates the immunosuppressive conditions induced by chromate (VI).

α,β-amyrin, a natural triterpenoid ameliorates L-arginine-induced acute pancreatitis in rats

AIM: To study the beneficial effects of triterpene α,β-amyrin and the underlying mechanisms in an experimental pancreatitis model.

METHODS: Acute pancreatitis was induced in five groups of rats (n = 8) by L-arginine (2 × 2.5 g/kg, intraperitoneal, 1 h apart) and 1 h later, they received a single oral dose of α,β-amyrin (10, 30 and 100 mg/kg), methylprednisolone (30 mg/kg) and vehicle (3% Tween 80). A saline (0.9% NaCl) treated group served as a normal control. Efficacy was assessed at 24 h by determination of serum levels of amylase, lipase and pro-inflammatory cytokines [tumor necrosis factor (TNF)-α and interleukin (IL)-6], pancreatic myeloperoxidase (MPO) activity, lipid peroxidation [thiobarbituric acid reactive substances (TBARS)], nitrate/nitrite levels, and the wet weight/body weight ratio. Tissue histology and the immunoreactivity for TNF-α and inducible nitric oxide synthetase (iNOS) were performed.

RESULTS: α,β-amyrin and methylprednisolone treatments significantly (P < 0.05) attenuated the L-arginine-induced increases in pancreatic wet weight/body weight ratio, and decreased the serum levels of amylase and lipase, and TNF-α and IL-6, as compared to the vehicle control. Also, pancreatic levels of MPO activity, TBARS, and nitrate/nitrite were significantly lower. Histological findings and TNF-α and iNOS immunostaining further confirmed the amelioration of pancreatic injury by α,β-amyrin.

CONCLUSION: α,β-amyrin has the potential to combat acute pancreatitis by acting as an anti-inflammatory and antioxidant agent.