Identification of plant extracts with potential antidiabetic properties: effect on human peroxisome proliferator‐activated receptor (PPAR), adipocyte differentiation and insulin‐stimulated glucose uptake

Thiazolidinediones (TZDs) are insulin sensitizing drugs used to treat type 2 diabetes. The primary target of the TZDs is the peroxisome proliferator‐activated receptor (PPAR) γ, a key regulator of adipogenesis and glucose homeostasis. Currently prescribed TZDs are full PPARγ agonists, and their use is associated with several side effects. Partial PPARγ agonists appear to be associated with fewer side effects but may still confer the desired insulin sensitizing action. Extracts from common medicinal/food plants were tested in a screening platform comprising a series of bioassays, including tests for PPARγ, α and δ transactivation, adipocyte differentiation and insulin‐stimulated glucose uptake, allowing identification of plants containing potentially interesting PPAR agonists. Twenty‐two plant extracts out of 133 were found to increase insulin‐stimulated glucose uptake and 18 extracts were found to activate PPARγ, 3 to activate PPARα and γ, 6 to activate PPARδ and γ, and 9 to activate PPARγ, α and δ. Among the 24 different plant species tested in the platform, 50% were shown to contain compounds capable of activating PPARγ and stimulating insulin‐dependent glucose uptake with no or little effect on adipocyte differentiation warranting further studies and characterization. Copyright © 2009 John Wiley & Sons, Ltd.     

Protective Effects of Turbinaria ornata and Padina pavonia against Azoxymethane‐Induced Colon Carcinogenesis through Modulation of PPAR Gamma,NF‐κB and Oxidative Stress

The aim of this study was to investigate the antiproliferative and protective effects of the brown seaweeds, Turbinaria ornata and Padina pavonia, against azoxymethane (AOM)‐induced colon carcinogenesis in mice. Both algal extracts showed anti‐proliferative effects on the human carcinoma cell line HCT‐116 in vitro, with T. ornata demonstrating a more potent effect. Male albino Swiss mice received intraperitoneal injections of AOM (10 mg/kg) once a week for two consecutive weeks and 100 mg/kg of either T. ornata or P. pavonia extracts. AOM‐induced mice exhibited alterations in the histological structure of the colon, elevated lipid peroxidation and nitric oxide, declined glutathione content and reduced activity of superoxide dismutase and glutathione peroxidase. In addition, AOM induced downregulation of peroxisome proliferator activated receptor gamma (PPARγ) and p53 mRNA expression, with concomitant upregulation of nuclear factor‐kappa B (NF‐κB) in colon tissue. Administration of either algal extract markedly alleviated the recorded alterations. In conclusion, the current study suggests that T. ornata and P. pavonia, through their antioxidant and anti‐inflammatory effects, are able to attenuate colon inflammation by downregulating NF‐κB expression. Furthermore, the protective effects of both algae against AOM‐initiated carcinogenesis were attributed, at least in part, to their ability to upregulate colonic PPARγ and p53 expression. Copyright © 2015 John Wiley & Sons, Ltd.     

5‐Hydroxyferulic acid methyl ester isolated from wasabi leaves inhibits 3T3‐L1 adipocyte differentiation

To investigate the compounds present in wasabi leaves (Wasabia japonica Matsumura) that inhibit the adipocyte differentiation, activity‐guided fractionation was performed on these leaves. 5‐Hydroxyferulic acid methyl ester ( 1 : 5‐HFA ester), one of the phenylpropanoids, was isolated from wasabi leaves as a compound that inhibits the adipocyte differentiation. Compound 1 suppressed the intracellular lipid accumulation of 3T3‐L1 cells without significant cytotoxicity. Gene expression analysis revealed that 1 suppressed the mRNA expression of 2 master regulators of adipocyte differentiation, PPARγ and C/EBPα. Furthermore, 1 downregulated the expression of adipogenesis‐related genes, GLUT4, LPL, SREBP‐1c, ACC, and FAS. Protein expression analysis revealed that 1 suppressed PPARγ protein expression. Moreover, to investigate the relationship between the structure and activity of inhibiting the adipocyte differentiation, we synthesized 12 kinds of phenylpropanoid analog. Comparison of the activity among 1 and its analogs suggested that the compound containing the substructure that possess a common functional group at the ortho position such as a catechol group exhibits the activity of inhibiting the adipocyte differentiation. Taken together, our findings suggest that 1 from wasabi leaves inhibits adipocyte differentiation via the downregulation of PPARγ.     

Umbelliferone Improves an Impaired Glucose and Lipid Metabolism in High‐Fat Diet/Streptozotocin‐Induced Type 2 Diabetic Rats

Umbelliferone (UMB) is a natural product that has several pharmacological effects including antihyperglycemic activity in diabetic rats. Thus, the objective of this study was to investigate the effect of UMB on insulin resistance and on the regulation of glucose and lipid metabolism in type 2 diabetic rats. Type 2 diabetes was induced in rats by feeding a high‐fat diet (45 kcal% fat) and a single dose of streptozotocin injection. After 8 weeks of treatment, UMB significantly reduced the elevated blood glucose levels and insulin resistance and increased the liver glycogen and serum adiponectin. Moreover, the serum lipid and the storages of triglyceride and non‐esterified fatty acid in liver tissue were reduced. From histological examination, the lipid droplets in liver tissue were clearly decreased, and the fat cell size in the fat tissue was smaller in diabetic rats treated with UMB. Interestingly, UMB increased fat cell adiponectin, plasma membrane glucose transporter 4 (GLUT4) and peroxisome proliferator‐activated receptor gamma (PPARγ), and liver PPARα protein expressions. Our findings demonstrate that UMB improves glucose and lipid metabolism in type 2 diabetes by stimulating the insulin secretion and the related mechanisms via stimulating expression of adiponectin, GLUT4, PPARγ, and PPARα‐protein expressions. Copyright © 2015 John Wiley & Sons, Ltd.     

In Vitro Inhibition of the Transcription Factor NF‐κB and Cyclooxygenase by Bamboo Extracts

Several bamboo species have been used in traditional medicine for the treatment of inflammatory conditions. The present study evaluates the in vitro anti‐inflammatory properties of the traditionally used bamboo species Phyllostachys nigra (Lodd.) Munro and Sasa veitchii (Carr.) Rehder to explore their future research opportunities and therapeutic potential as anti‐inflammatory agents. The extracts were evaluated for their potential inhibitory activity at the level of NF‐κB‐induced gene expression and suppression of cyclooxygenase (COX)‐1 and COX‐2 enzyme activities, representative pharmacological targets for the anti‐inflammatory action of glucocorticoids and non‐steroidal anti‐inflammatory drugs, respectively. The activity of P. nigra (Lodd.) Munro and S. veitchii (Carr.) Rehder was compared with bamboo species without traditional anti‐inflammatory indications. High‐performance liquid chromatography with diode‐array detection and liquid chromatography–tandem mass spectrometry analyses were performed to phytochemically characterize the extracts. P. nigra (Lodd.) Munro leaf extract potently inhibited NF‐κB‐induced gene expression, while S. veitchii (Carr.) Rehder leaf extract exerted a selective COX‐2 inhibition. The crude extracts consistently showed a more potent bioactivity than the solid phase extraction fractions. P. nigra (Lodd.) Munro and S. veitchii (Carr.) Rehder both exert anti‐inflammatory properties, but act via a different molecular mechanism. Copyright © 2013 John Wiley & Sons, Ltd.     

Anti‐inflammatory Activity of Constituents Isolated from Aerial Part of Angelica acutiloba Kitagawa

Recently, the resources of medicinal plants have been exhausting. The root of Angelica acutiloba is one of the most important ingredients in Japanese Kampo medicine for the treatment of gynecological diseases. In our search for alternative medicinal plant resources of the root of A. acutiloba, we found that its aerial part has the anti‐inflammatory potency as well as the root. Phytochemical investigation of the aerial part resulted in the isolation of four compounds including a new dimeric phthalide, namely tokiaerialide (2), along with Z‐ligustilide (1), falcarindiol (3), and bergaptol (4). Next, we investigated the in vitro anti‐inflammatory activity of 1–4 in lipopolysaccharide‐stimulated RAW264 macrophages. Among the isolated compounds, 1 exhibited the most potent inhibition against lipopolysaccharide‐induced production of prostaglandin E₂, nitric oxide, and pro‐inflammatory cytokines (interleukin‐6 and tumor necrosis factor‐α). Compounds 3 and 4 also inhibited all inflammatory mediators, but their inhibitory abilities were weaker than those of 1. Furthermore, 1, 3, and 4 strongly also induced heme oxygenase‐1. These results suggest that 1, 3, and 4 potentially exert anti‐inflammatory activity, and the aerial part of A. acutiloba may be considered to be a useful medicinal resource for inflammatory diseases. Copyright © 2015 John Wiley & Sons, Ltd.     

Upregulation of PPARγ by Aegle marmelos ameliorates insulin resistance and β-cell dysfunction in high fat diet fed-streptozotocin induced type 2 diabetic rats

The global epidemic of type 2 diabetes demands the rapid evaluation of new and accessible interventions. This study investigated whether Aegle marmelos fruit aqueous extract (AMF; 250, 500 and 1000 mg/kg) improves insulin resistance, dyslipidemia and β‐cell dysfunction in high fat diet fed‐streptozotocin (HFD‐STZ)‐induced diabetic rats by modulating peroxisome proliferator‐activated receptor‐γ (PPARγ) expression. The serum levels of glucose, insulin, homeostasis model assessment of insulin resistance (HOMA‐IR), homeostasis model assessment of β‐cell function (HOMA‐B), lipid profile, TNF‐α and IL‐6 were evaluated. Further, the TBARS level and SOD activity in pancreatic tissue and PPARγ protein expression in liver were assessed. In addition, histopathological and ultrastructural studies were performed to validate the effect of AMF on β‐cells. The HFD‐STZ treated rats showed a significant increase in the serum levels of glucose, insulin, HOMA‐IR, TNF‐α, IL‐6, dyslipidemia with a concomitant decrease in HOMA‐B and PPARγ expression. Treatment with AMF for 21 days in diabetic rats positively modulated the altered parameters in a dose‐dependent manner. Furthermore, AMF prevented inflammatory changes and β‐cell damage along with a reduction in mitochondrial and endoplasmic reticulum swelling. These findings suggest that the protective effect of AMF in type 2 diabetic rats is due to the preservation of β‐cell function and insulin‐sensitivity through increased PPARγ expression. Copyright © 2011 John Wiley & Sons, Ltd.     

Phenolic‐Linked Biochemical Rationale for the Anti‐Diabetic Properties of Swertia chirayita (Roxb. ex Flem.) Karst.

The crude extract of Swertia chirayita, an important medicinal plant of Nepal, is locally used for many diseases including type 2 diabetes. In this study, crude aqueous and 12% ethanol solution extracts of S. chirayita collected from nine districts of Nepal were analyzed for anti‐diabetic‐linked anti‐hyperglycemia potential using in vitro biochemical assays. There was moderate‐to‐high positive correlation between antioxidant activity and total phenolic content of both extracts and moderate‐to‐high α‐glucosidase inhibitory activity. Although the anti‐diabetic property of S. chirayita is mainly attributed to the phytochemical swerchirin present in its hexane fraction, we propose that the crude extract of this plant used in local healing also has anti‐hyperglycemia potential. The crude extracts indicated the presence of three main phytochemicals mainly mangiferin, swertiamarin, and amarogentin and their derivatives. Among the standard compounds (mangiferin, swertiamarin, and amarogentin), mangiferin showed α‐glucosidase and 2,2‐diphenyl‐1‐picrylhydrazyl radical inhibitory activity indicating anti‐hyperglycemia potential. Copyright © 2012 John Wiley & Sons, Ltd.     

罗格列酮与维A酸联合应用对MCF-7细胞相关蛋白表达的影响

 目的研究PPARγ激动剂罗格列酮(ROZ)与维A酸联合应用对人乳腺癌MCF-7细胞相关蛋白表达的影响,阐明PPARγ激活后的抗肿瘤作用以及相关机制。方法MTT法检测ROZ、维A酸及两者联合应用对MCF-7细胞生长的作用。用荧光染料Hochest33342对细胞单染观察MCF-7细胞凋亡形态。用流式细胞仪检测MCF-7细胞的细胞周期分布。采用Western Blot法测定药物对MCF-7细胞相关蛋白表达的影响。结果ROZ对MCF-7细胞有一定的生长抑制作用,与维A酸合用后能显著抑制MCF-7细胞增殖,且两者呈协同作用(q>1.15)。维A酸能增强ROZ的凋亡诱导作用,表现为核碎裂和核固缩的细胞增多。流式细胞术分析二者合用可导致G1期细胞周期阻滞,S期细胞减少。Western Blot结果显示,ROZ可促进PPARγ、P53、Erk1/2、p-ERK1/2及JNK的表达,抑制ERα、C-myc及p-JNK的表达;与维A酸联合应用时可显著升高PPARγ表达,降低ERα、Bcl-2、C-myc及p-JNK表达的作用增强,并且抑制ERK的磷酸化。结论ROZ与维A酸联合应用可显著抑制MCF-7细胞的增殖,具有协同作用,可通过对Bcl-2、C-myc、P53、ERα和MAPK信号传导通路的影响而发挥抑制细胞增殖、诱导凋亡的作用。     

Anti‐Ulcerative Colitis Activity of Compounds from Euphorbia granuleta Forssk

The aim of the present study was to evaluate the anti‐ulcerative colitis (UC) activity of the total alcohol extracts of Euphorbia granuleta Forssk. (Euphorpiaceae), isolate and identify the active compounds that could be responsible for the activity, in addition to determination of the possible mechanism of action. Six compounds were isolated and identified from this plant: three phenolic compounds (kampferol, kampferol‐3‐glucoside and kampferol‐3‐galactoside) in addition to three steroidal compounds (1‐ethoxypentacosane, heptacosan‐1‐ol and β‐sitosterol). Three compounds (heptacosan‐1‐ol, β‐sitosterol and kampferol‐3‐galactoside) were found to be responsible for the anti‐UC activity of E. granuleta extract. The anti‐UC activity of these compounds may be explained by reducing the pro‐inflammatory cytokine tumor necrosis factor‐alpha (TNF‐α), in addition to reduction of colonic malondialdehyde (MDA) contents. No side effects were reported on liver and kidney functions. The active compounds reduced both serum TNF‐α and mucosal MDA levels. Copyright © 2013 John Wiley & Sons, Ltd.     

Cannabidiol Promotes Amyloid Precursor Protein Ubiquitination and Reduction of Beta Amyloid Expression in SHSY5YAPP+ Cells Through PPARγ Involvement

The amyloidogenic cascade is regarded as a key factor at the basis of Alzheimer's disease (AD) pathogenesis. The aberrant cleavage of amyloid precursor protein (APP) induces an increased production and a subsequent aggregation of beta amyloid (Aβ) peptide in limbic and association cortices. As a result, altered neuronal homeostasis and oxidative injury provoke tangle formation with consequent neuronal loss. Cannabidiol (CBD), a Cannabis derivative devoid of psychotropic effects, has attracted much attention because it may beneficially interfere with several Aβ‐triggered neurodegenerative pathways, even though the mechanism responsible for such actions remains unknown. In the present research, the role of CBD was investigated as a possible modulating compound of APP processing in SHSY5Y^APP+ neurons. In addition, the putative involvement of peroxisome proliferator‐activated receptor‐γ (PPARγ) was explored as a candidate molecular site responsible for CBD actions. Results indicated the CBD capability to induce the ubiquitination of APP protein which led to a substantial decrease in APP full length protein levels in SHSY5Y^APP+ with the consequent decrease in Aβ production. Moreover, CBD promoted an increased survival of SHSY5Y^APP+ neurons, by reducing their long‐term apoptotic rate. Obtained results also showed that all, here observed, CBD effects were dependent on the selective activation of PPARγ. Copyright © 2013 John Wiley & Sons, Ltd.     

Inhibition of LPS‐Induced TNF‐α and NO Production in Mouse Macrophage and Inflammatory Response in Rat Animal Models by a Novel Ayurvedic Formulation,BV‐9238

Rheumatoid arthritis is a chronic crippling disease, where protein‐based tumor necrosis factor‐alpha (TNF‐α) inhibitors show significant relief, but with potentially fatal side effects. A need for a safe, oral, cost‐effective small molecule or phyto‐pharmaceutical is warranted. BV‐9238 is an Ayurvedic poly‐herbal formulation containing specialized standardized extracts of Withania somnifera, Boswellia serrata, Zingiber officinale and Curcuma longa. The anti‐inflammatory and anti‐arthritic effects of BV‐9238 were evaluated for inhibition of TNF‐α and nitric oxide (NO) production, in lipopolysaccharide‐stimulated, RAW 264.7, mouse macrophage cell line. BV‐9238 reduced TNF‐α and NO production, without any cytotoxic effects. Subsequently, the formulation was tested in adjuvant‐induced arthritis (AIA) and carrageenan‐induced paw edema (CPE) rat animal models. AIA was induced in rats by injecting Freund's complete adjuvant intra‐dermally in the paw, and BV‐9238 and controls were administered orally for 21 days. Arthritic scores in AIA study and inflamed paw volume in CPE study were significantly reduced upon treatment with BV‐9238. These results suggest that the anti‐inflammatory and anti‐arthritic effects of BV‐9238 are due to its inhibition of TNF‐α, and NO, and this formulation shows promise as an alternate therapy for inflammatory disorders where TNF‐α and NO play important roles. Copyright © 2014 John Wiley & Sons, Ltd.     

Ethnomedicinal,phytochemical and pharmacological updates on Peppermint (Mentha × piperita L.)—A review

Peppermint (Mentha × piperita L) is a perennial, glabrous and strongly scented herb belongs to the family Lamiaceae. It is cultivated in a temperate region of Europe, Asia, United States, India and Mediterranean countries due to their commercial value and distinct aroma. In addition to traditional food flavouring uses, M. × piperita is well recognized for their traditional use to treat fever, cold, digestive, anti‐viral, anti‐fungal and oral mucosa and throat inflammation. The scientific studies provide awareness on the use of M. × piperita for biological effects such as anti‐oxidant, anti‐microbial, anti‐viral, anti‐inflammatory, biopesticidal, larvicidal, anticancer, radioprotective effect, genotoxicity and anti‐diabetic activity have been ascribed. A wide spectrum of bioactive phytochemicals such as flavonoids, phenolics lignans and stilbenes and essential oils are expected to be responsible for the aroma effects. In this sense, this present review provides an extensive overview of the traditional medicinal, phytochemical and multiple biological activities of this “Peppermint.”     

Isolates from Alpinia officinarum Hance attenuate LPS‐induced inflammation in HepG2: Evidence from in silico and in vitro studies

In an attempt to connect the legacy of centuries of invaluable knowledge from traditional medicine and the current understanding to the molecular mechanism of diseases, we took the advantage of the emergence of in silico screening as a promising tool for identification of potential leads from libraries of natural products. Traditional Chinese Medicine database was subjected to structure based virtual screening for identification of anti‐inflammatory compounds using the 3D crystal structure of p38 alpha mitogen activated protein kinase. The molecular docking studies revealed the potential activity of several classes of compounds known to be the constituents of the rhizomes of Alpinia officinarum Hance (Lesser galangal). Five compounds, galangin, kaempferide, isorhamnetin, and two diarylheptanoids, were isolated from the rhizomes of the plant using vacuum liquid chromatography and flash chromatography techniques. The anti‐inflammatory activity of these compounds was investigated on HepG2 cells stimulated by lipopolysaccharide. The latter induced the gene expression of proinflammatory cytokines; interleukin‐1β, interleukin‐6, tumor necrosis factor alpha. Addition of the 5 isolated compounds downregulated this increased gene expression in a dose dependent manner. Thus, these results indicate that the isolated compounds from A. officinarum could be used as a beneficial source for preventing and treating inflammatory diseases.     

Effects of Lonicera japonica Thunb. on Type 2 Diabetes via PPAR‐γ Activation in Rats

Lonicera japonica Thunb. (Caprifoliaceae) is a traditional herbal medicine and has been used to treat diabetic symptoms. Notwithstanding its use, the scientific basis on anti‐diabetic properties of L. japonica is not yet established. This study is designed to investigate anti‐diabetic effects of L. japonica in type 2 diabetic rats. L. japonica was orally administered at the dose of 100 mg/kg in high‐fat diet‐fed and low‐dose streptozotocin‐induced rats. After the treatment of 4 weeks, L. japonica reduced high blood glucose level and homeostatic model assessment of insulin resistance in diabetic rats. In addition, body weight and food intake were restored by the L. japonica treatment. In the histopathologic examination, the amelioration of damaged β‐islet in pancreas was observed in L. japonica‐treated diabetic rats. The administration of L. japonica elevated peroxisome proliferator‐activated receptor gamma and insulin receptor subunit‐1 protein expressions. The results demonstrated that L. japonica had anti‐diabetic effects in type 2 diabetic rats via the peroxisome proliferator‐activated receptor gamma regulatory action of L. japonica as a potential mechanism. Copyright © 2015 John Wiley & Sons, Ltd.