Flotation separation of scheelite from calcite using luteolin as a novel depressant

This paper proposes luteolin(LUT)as a novel depressant for the flotation-based separation of scheelite and calcite in a sodium oleate(NaOL)system.The suitability of LUT as a calcite depressant is confirmed through micro-flotation testing.At pH=9,with LUT concentration of 50 mg·L^(-1) and NaOL concentration of 50 mg·L^(-1),scheelite recovery reaches 80.3%.Calcite,on the other hand,exhibits a recovery rate of 17.6%,indicating a significant difference in floatability between the two minerals.Subsequently,the surface modifica-tions of scheelite and calcite following LUT treatment are characterized using adsorption capacity testing,Zeta potential analysis,Fourier transform infrared spectroscopy(FT-IR),X-ray photoelectron spectroscopy(XPS),and atomic force microscopy(AFM).The study in-vestigates the selective depressant mechanism of LUT on calcite.Adsorption capacity testing and Zeta potential analysis demonstrate sub-stantial absorption of LUT on the surface of calcite,impeding the further adsorption of sodium oleate,while its impact on scheelite is min-imal.FT-IR and XPS analyses reveal the selective adsorption of LUT onto the surface of calcite,forming strong chemisorption bonds between the hydroxyl group and calcium ions present.AFM directly illustrates the distinct adsorption densities of LUT on the two miner-al types.Consequently,LUT can effectively serve as a depressant for calcite,enabling the successful separation of scheelite and calcite.

Enhancement of porcine in vitro embryonic development through luteolin‑mediated activation of the Nrf2/Keap1 signaling pathway

Background Oxidative stress,caused by an imbalance in the production and elimination of intracellular reactive oxygen species(ROS),has been recognized for its detrimental effects on mammalian embryonic development.Luteolin(Lut)has been documented for its protective effects against oxidative stress in various studies.However,its specific role in embryonic development remains unexplored.This study aims to investigate the influence of Lut on porcine embryonic development and to elucidate the underlying mechanism.Results After undergoing parthenogenetic activation(PA)or in vitro fertilization,embryos supplemented with 0.5μmol/L Lut displayed a significant enhancement in cleavage and blastocyst formation rates,with an increase in total cell numbers and a decrease in the apoptosis rate compared to the control.Measurements on D2 and D6 revealed that embryos with Lut supplementation had lower ROS levels and higher glutathione levels compared to the control.Moreover,Lut supplementation significantly augmented mitochondrial content and membrane potential.Intriguingly,activation of the Nrf2/Keap1 signaling pathway was observed in embryos supplemented with Lut,leading to the upregulation of antioxidant-related gene transcription levels.To further validate the relationship between the Nrf2/Keap1 signaling pathway and effects of Lut in porcine embryonic development,we cultured PA embryos in a medium supplemented with brusatol,with or without the inclusion of Lut.The positive effects of Lut on developmental competence were negated by brusatol treatment.Conclusions Our findings indicate that Lut-mediated activation of the Nrf2/Keap1 signaling pathway contributes to the enhanced production of porcine embryos with high developmental competence,and offers insight into the mechanisms regulating early embryonic development.

Luteolin alleviates sorafenib-induced ferroptosis of BRL-3A cells through modulation of the Nrf2/GPX4 signaling pathway

Background:Luteolin is a flavonoid chemical that exists in a variety of medicinal and edible plants and holds many biologically active properties in liver protection,anti-cancer,antioxidants,anti-inflammatory,neuroprotective,etc.According to its hepatoprotective properties,luteolin was selected to co-treat with sorafenib,one of the approved protein kinase inhibitors,to reduce sorafenib-induced normal liver cell damage.Methods:The BRL-3A cell line was treated with sorafenib to establish a liver injury model,followed by luteolin treatment.The cell viability was detected,and the mechanism of action was detected by immunofluorescence,western blotting,and real-time quantitative PCR.Results:The research findings demonstrated that luteolin could increase cystine/glutamate transporter xCT(SLC7A11)and glutathione peroxidase 4(GPX4)expression and display a chelating effect on iron,which led to increased glutathione and decreased malondialdehyde,Fe^(2+) and lipid reactive oxygen species contents in BRL-3A cells,and the sorafenib-induced mitochondrial membrane potential decrease was also inhibited.In addition,when sorafenib caused the accumulation of lipid reactive oxygen species,luteolin could help release this oxidative stress by activating nuclear factor E2-related factor 2(Nrf2)and up-regulating the expression of the associated genes heme oxygenase 1(HO-1)and quinone oxidoreductase 1(NQO1).Conclusion:Therefore,luteolin may ameliorate sorafenib-induced ferroptosis by activating the Nrf2-associated pathway without any impact on sorafenib anti-cancer activity.It can be used as an adjuvant to sorafenib to reduce liver injury in patients with hepatocellular carcinoma.

Unraveling the therapeutic mechanisms of myristic acid and luteolin 7-rutinoside in oral cancer: insights from network pharmacology and molecular docking analysis

Background:The compound Luteolin-7-rutinoside(L7R)is a flavone derivative of luteolin,predominantly identified in plant species belonging to the families Asteraceae.Conversely,Myristic acid is characterized by its structure as a 14-carbon,unsaturated fatty acid.In this investigation,we endeavor to elucidate the putative mechanisms underlying the therapeutic effects of Myristic Acid and Luteolin 7-rutinoside in the context of oral cancer treatment,employing network pharmacology coupled with molecular docking methodologies.Methods:The protein targets of Myristic Acid and Luteolin 7-rutinoside were identified through a search on the Swiss Target Database.Subsequently,a compound-target network was constructed using Cytoscape 3.9.1.Targets associated with OC were retrieved from the OMIM and GeneCards databases.The overlap between compound targets and OC-related targets was determined,and the resulting shared targets were subjected to protein-protein interaction(PPI)network analysis using the STRING database.Additionally,gene ontology(GO)and Kyoto Encyclopedia of Genes and Genomes(KEGG)enrichment analyses were conducted on the identified targets.Molecular docking were performed to investigate the interactions between the core target and the active compound.Results:The component target network comprises 103 nodes and 102 edges.Among the proteins in the protein-protein interaction(PPI)network,those with higher degrees are TNF,PPARG,and TP53.Analysis through Gene Ontology(GO)and Kyoto Encyclopedia of Genes and Genomes(KEGG)pathways indicates that the treatment of OC with Myristic Acid and Luteolin 7-rutinoside primarily involves the regulation of miRNA transcription and inflammatory response.The identified signaling pathways include Pathways in cancer,PPAR signaling pathway,EGFR signaling pathway,and TNF signaling pathway.Molecular docking studies reveal that Luteolin 7-rutinoside and Myristic acid exhibit higher affinity towards TNF,PPARG,TP53,and EGFR.Conclusion:This study reveals the potential molecular mechanism of Myristic Acid and Luteolin 7-rutinoside in the treatment of oral cancer,and provides a reference for subsequent basic research.

Luteolin attenuates diabetic nephropathy via inhibition of metalloenzymes in rats

Objective:To investigate the renoprotective effects of luteolin on diabetes in rats.Methods:One week after administration of streptozotocin 55 mg/kg intraperitoneally,rats were given 25,50,and 75 mg/kg/day of luteolin orally for another eight weeks.At the end of the experiment,body weight,blood glucose level,biochemical parameters for renal function(serum creatinine,blood urea nitrogen,uric acid,serum albumin,and total protein),kidney histology,matrix metalloproteinase(MMP)-2,MMP-9,and histone deacetylase 2(HDAC-2)expression,and malondialdehyde,myeloperoxidase,and hydroxyproline content in renal tissue were evaluated.High glucose-induced damage using NRK-52E cell line was studied to evaluate cell viability and metalloenzyme expression.Additionally,in silico studies including docking and molecular dynamics simulations were conducted.Results:MMP-2,MMP-9,and HDAC-2 expressions were significantly increased in high glucose-induced NRK-52E cells and the renal tissue of diabetic rats.However,these changes were reversed by luteolin at the administered doses.Additionally,luteolin significantly reduced oxidative stress,inflammation,and fibrosis,as well as improved biochemical parameters in diabetic rats.Furthermore,luteolin at the examined doses markedly alleviated diabetes-induced histopathological changes in renal tissues.Conclusions:Luteolin effectively attenuates streptozotocin-induced diabetic nephropathy in rats by inhibiting MMP-2,MMP-9,and HDAC-2 expression,and reducing oxidative stress and inflammation.

Anti-diabetic potential of apigenin,luteolin,and baicalein via partially activating PI3K/Akt/GLUT-4 signaling pathways in insulin-resistant HepG2 cells

Dietary flavonoids are abundant in natural plants and possess multiple pharmacological and nutritional activities.In this study,apigenin,luteolin,and baicalein were chosen to evaluate their anti-diabetic effect in high-glucose and dexamethasone induced insulin-resistant(IR)HepG2 cells.All flavonoids improves the glucose consumption and glycogen synthesis abilities in IR-HepG2 cells via activating glucose transporter protein 4(GLUT4)and phosphor-glycogen synthase kinase(GSK-3β).These fl avonoids signifi cantly inhibited the production of reactive oxygen species(ROS)and advanced glycation end-products(AGEs),which were closely related to the suppression of the phosphorylation form of NF-κB and P65.The expression levels of insulin receptor substrate-1(IRS-1),insulin receptor substrate-2(IRS-2)and phosphatidylinositol 3-kinase(PI3K)/protein kinase B(Akt)pathway in IR-HepG2 cells were all partially activated by the fl avonoids,with variable effects.Furthermore,the intracellular metabolic conditions of the fl avonoids were also evaluated.

Exploring the potential mechanisms of luteolin against ulcerative colitis and colorectal cancer via network pharmacology and molecular docking

Background:Patients diagnosed with ulcerative colitis(UC)are known to have an increased susceptibility to colorectal cancer(CRC).However,the shared underlying mechanisms between UC and CRC remain unclear.Given the therapeutic potential of luteolin in both UC and CRC,this study aims to elucidate the molecular targets and mechanisms through which luteolin exerts its effects against these diseases.Methods:The GeneCards database,DisGENet database,and Gene Expression Omnibus database were utilized to analyze the targets associated with UC and CRC.Subsequently,the Traditional Chinese Medicine Systems Pharmacology and SwissTargetPrediction databases were employed to identify luteolin-related targets.The identified luteolin-related targets were then mapped to official gene symbols using the UniProt database.The Cytoscape 3.9.0 software was utilized to construct a network of luteolin-associated targets.Venn diagram analysis was performed to identify common targets among UC,CRC,and luteolin.The common targets were further analyzed using the STRING database to construct a protein-protein interaction network.The“cytoHubba”plugin in Cytoscape 3.9.0 was employed to identify hub targets within the PPI network.Gene Ontology functional analysis and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis were conducted on the hub targets.Finally,molecular docking using AutoDock and PyMOL software was performed to assess the binding affinity between luteolin and the hub targets.Results:Luteolin was found to interact with a total of 149 pharmacological targets,while UC and CRC were associated with 1232 and 3278 targets,respectively.Forty-six common targets were identified among luteolin,UC,and CRC.Through the application of seven different algorithms,seven hub targets were identified,TP53,AKT1,TNF,SRC,EGFR,and MMP9.Bioinformatics enrichment analysis revealed 49 enriched pathways through Kyoto Encyclopedia of Genes and Genomes analysis,while Gene Ontology analysis yielded a total of 245 biological processes,4 cellular components,and 7 molecular functions.Molecular docking simulations demonstrated a good binding affinity between luteolin and the hub targets.Conclusion:This study identified multiple potential pharmacological targets and elucidated various biological pathways through which luteolin may exert its therapeutic effects in the treatment of UC and CRC.These findings provide a solid theoretical foundation for further experimental investigations in the treatment of UC and CRC.

luteolin对糖尿病大鼠心脏功能的保护作用及其可能机制

目的:研究luteolin对链脲佐菌素诱导的I型糖尿病大鼠心功能及心肌线粒体氧化应激的影响。方法:雄性SD大鼠,随机分成正常对照组,luteolin对照组,糖尿病模型组,低剂量luteolin(10 mg/(kg.d))灌胃治疗组,高剂量luteolin(100 mg/(kg.d))灌胃治疗组。各组大鼠饲养8周后,测体重、血糖、心功能、左心室重量、心肌胶原含量及活性氧自由基(ROS)水平,分离心肌线粒体检测ROS水平、超氧化物歧化酶(SOD)活性及线粒体肿胀程度。结果:luteolin处理对糖尿病大鼠血糖无明显影响,但可减少糖尿病引起的体重下降。高剂量luteolin可显著减小糖尿病大鼠心室与体重比值,提高左室发展压,降低左室舒张末压。高剂量luteolin治疗后,糖尿病大鼠心肌ROS及胶原含量,心肌线粒体ROS水平与肿胀程度均明显下降,心肌线粒体SOD活性明显增加。结论:luteolin处理可显著改善糖尿病大鼠心功能,其机制可能与减轻心肌线粒体氧化应激及抑制线粒体肿胀有关。

Luteolin抑制乳腺癌细胞MDA-MB231增殖及IL-8信号通路的实验研究

目的 :探讨木犀草素(Luteolin)对乳腺癌细胞MDA-MB231增殖及IL-8信号通路的抑制作用。方法:采用不同浓度的Luteolin处理乳腺癌细胞MDA-MB231,观察MDA-MB231细胞的增殖、IL-8蛋白和m RNA的表达以及AKT、ERK的表达。结果:Luteolin可抑制MDA-MB231细胞的增殖和IL-8的分泌,并明显抑制IL-8对乳腺癌细胞的激活。结论:Luteolin是重要的乳腺癌抑制剂,在预防乳腺癌复发及转移中可能有重要的作用。

Luteolin prevents f MLP-induced neutrophils adhesion via suppression of LFA-1 and phosphodiesterase 4 activity

Luteolin is an active ingredient found early from Fofium perillae and Flos Ionicerae, and has a specific inhibition on phosphodiesterase 4 （PDE4） activity in vitro. Researches show luteolin has pharmacological effects of anti-inflammation, anti-anaphylaxis, antitumor, antioxidant, protection of nervous system and so on, and has mainly been used for the treatment of respiratory inflammatory diseases, cancer and cardiovascular disease in clinic. PDE4, specific to hydrolyze cyclic AMP （cAMP）, is considered to be a new anti-inflammatory target due to the decisive role on cAMP signal in inflammatory cells such as neutrophils. In order to explore the anti-inflammatory mechanism, we further studied the effects of luteolin on the activity and expression of PDE4, the expression of lymphocyte function-associated antigen-1 （LFA-1） and macrophage-1 （MAC-l） in neutrophils, and the adhesion of neutrophils and endothelial cells. The results showed that luteolin had a dose-dependent inhibition on both bare PDE4 activity and PDE4 in cultured neutrophils, and had an obviously promotive effect on gene expressions of PDE4A, 4B and 4D in later period. Luteolin had a significant inhibitory effect on neutrophils adhesion and LFA-1 expression in early stage, and had no obvious effect on MAC-1 expression. Therefore, luteolin can inhibit LFA-1 expression of neutrophils, then inhibit the adhesion of neutrophils and endothelial cells, and the mechanism is at least related with the inhibition of PDE4 activity.

Anti-chikungunya activity of luteolin and apigenin rich fraction from Cynodon dactylon

Objective:To obtain Iuteolin and apigenin rich fraction from the ethanolic extract of Cynodon dactylon(L.)(C.dactylon) Pers and evaluate the fraction's cytotoxicity and anti-Chikungunya potential using Vero cells.Methods:The ethanolic extract of C.dactylon was subjected to silica gel column chromatography to obtain anti-chikungunya virus(CHIKV) fraction.Reverse phase-HPLC and GC-MS studies were carried out to identily the major phytochemicals in the fraction using phylochemical standards.Cytotoxicity and the potential of the fraction against CHIKV were evaluated in vitro using Vero cells.Reduction in viral replication was assessed by reverse transcriptase-polymerase chain reaction(RT-PCR) after treating the viral infected Vero cells with the fraction.Results:Reverse Phase-HPLC and GC-MS studies confirmed the presence of flavonoids,luteolin and apigenin as major phytochemicals in the anti-CHIKV ethanolic fraction of C.dactylon- The fraction was found to exhibit potent viral inhibitory activity(about 98%) at the concentration of 50 μg/mL as observed by reduction in cytopathic effect,and the cytotoxic concentration of the fraction was found to be 250 μg/mL.RT-PCR analyses indicated that the reduction in viral mRNA synthesis in fraction treated infected cells was much higher than the viral infected control cells.Conclusions:Luteolin and apigenin rich ethanolic fraction from C.dactylon can be utilized as a potential therapeutic agent against CHIKV infection as the fraction does not show cytotoxicity while inhibiting the virus.

Luteolin induces hippocampal neurogenesis in the Ts65Dn mouse model of Down syndrome

Studies have shown that the natural flavonoid luteolin has neurotrophic activity. In this study, we investigated the effect of luteolin in a mouse model of Down syndrome. Ts65 Dn mice, which are frequently used as a model of Down syndrome, were intraperitoneally injected with 10 mg/kg luteolin for 4 consecutive weeks starting at 12 weeks of age. The Morris water maze test was used to evaluate learning and memory abilities, and the novel object recognition test was used to assess recognition memory. Immunohistochemistry was performed for the neural stem cell marker nestin, the astrocyte marker glial fibrillary acidic protein, the immature neuron marker DCX, the mature neuron marker NeuN, and the cell proliferation marker Ki67 in the hippocampal dentate gyrus. Nissl staining was used to observe changes in morphology and to quantify cells in the dentate gyrus. Western blot assay was used to analyze the protein levels of brain-derived neurotrophic factor(BDNF) and phospho-extracellular signal-regulated kinase 1/2(p-ERK1/2) in the hippocampus. Luteolin improved learning and memory abilities as well as novel object recognition ability, and enhanced the proliferation of neurons in the hippocampal dentate gyrus. Furthermore, luteolin increased expression of nestin and glial fibrillary acidic protein, increased the number of DCX^+ neurons in the granular layer and NeuN^+ neurons in the subgranular region of the dentate gyrus, and increased the protein levels of BDNF and p-ERK1/2 in the hippocampus. Our findings show that luteolin improves behavioral performance and promotes hippocampal neurogenesis in Ts65 Dn mice. Moreover, these effects might be associated with the activation of the BDNF/ERK1/2 pathway.

Luteolin delays photoreceptor degeneration in a mouse model of retinitis pigmentosa

Luteolin is neuroprotective for retinal ganglion cells and retinal pigment epithelial cells after oxidative injury,whereby it can inhibit microglial neurotoxicity.Therefore,luteolin holds the potential to be useful for treatment of retinal diseases.The purpose of this study was to investigate whether luteolin exhibits neuroprotective effects on rod cells in rd10 mice,a slow photoreceptor-degenerative model of retinitis pigmentosa.Luteolin(100 mg/kg)intraperitoneally injected daily from postnatal day 14(P14)to P25 significantly enhanced the visual performance and retinal light responses of rd10 mice at P25.Moreover,it increased the survival of photoreceptors and improved retinal structure.Mechanistically,luteolin treatment attenuated increases in reactive oxygen species,photoreceptor apoptosis,and reactive gliosis;increased mRNA levels of anti-inflammatory cytokines while lowering that of pro-inflammatory and chemoattractant cytokines;and lowered the ratio of phospho-JNK/JNK.Application of the JNK inhibitor SP600125 exerted a similar protective effect to luteolin,suggesting that luteolin delays photoreceptor degeneration and functional deterioration in rd10 mice through regulation of retinal oxidation and inflammation by inhibiting the JNK pathway.Therefore,luteolin may be useful as a supplementary treatment for retinitis pigmentosa.This study was approved by the Qualified Ethics Committee of Jinan University,China(approval No.IACUC-20181217-02)on December 17,2018.

Luteolin prevents uric acid-induced pancreatic β-cell dysfunction

Elevated uric acid causes direct injury to pancreatic β-cells. In this study, we examined the effects of luteolin, an important antioxidant, on uric acid-induced β-cell dysfunction. We first evaluated the effect of luteolin on nitric oxide （NO） formation in uric acid-stimulated Min6 cells using the Griess method. Next, we performed transient transfection and reporter assays to measure transcriptional activity of nuclear factor （NF）-κB. Western blotting assays were also performed to assess the effect of luteolin on the expression of MafA and inducible NO synthase （iNOS） in uric acid-treated cells. Finally, we evaluated the effect of luteolin on uric acidinduced inhibition of glucose-stimulated insulin secretion （GSIS） in Min6 cells and freshly isolated mouse pancreatic islets. We found that luteolin significantly inhibited uric acid-induced NO production, which was well correlated with reduced expression of iNOS mRNA and protein. Furthermore, decreased activity of NF-κB was implicated in inhibition by luteolin of increased iNOS expression induced by uric acid. Besides, luteolin significantly increased MafA expression in Min6 cells exposed to uric acid, which was reversed by overexpression of iNOS. Moreover, luteolin prevented uric acidinduced inhibition of GSIS in both Min6 cells and mouse islets. In conclusion, luteolin protects pancreatic β-cells from uric acid-induced dysfunction and may confer benefit on the protection of pancreatic β-cells in hyperuricemiaassociated diabetes.

The basic helix-loop-helix transcription factor TabHLH1 increases chlorogenic acid and luteolin biosynthesis in Taraxacum antungense Kitag

Polyphenols are the main active components of the anti-inflammatory compounds in dandelion,and chlorogenic acid(CGA)is one of the primary polyphenols.However,the molecular mechanism underlying the transcriptional regulation of CGA biosynthesis remains unclear.Hydroxycinnamoyl-CoA:quinate hydroxycinnamoyl transferase(HQT2)is the last rate-limiting enzyme in chlorogenic acid biosynthesis in Taraxacum antungense.Therefore,using the TaHQT2 gene promoter as a probe,a yeast one-hybrid library was performed,and a basic helix-loop-helix(bHLH)transcription factor,TabHLH1,was identified that shared substantial homology with Gynura bicolor DC bHLH1.The TabHLH1 transcript was highly induced by salt stress,and the TabHLH1 protein was localized in the nucleus.CGA and luteolin concentrations in TabHLH1-overexpression transgenic lines were significantly higher than those in the wild type,while CGA and luteolin concentrations in TabHLH1-RNA interference(RNAi)transgenic lines were significantly lower.Quantitative real-time polymerase chain reaction demonstrated that overexpression and RNAi of TabHLH1 in T.antungense significantly affected CGA and luteolin concentrations by upregulating or downregulating CGA and luteolin biosynthesis pathway genes,especially TaHQT2,4-coumarate-CoA ligase(Ta4CL),chalcone isomerase(TaCHI),and flavonoid-3′-hydroxylase(TaF3′H).Dual-luciferase,yeast one-hybrid,and electrophoretic mobility shift assays indicated that TabHLH1 directly bound to the bHLH-binding motifs of proTaHQT2 and proTa4CL.This study suggests that TabHLH1 participates in the regulatory network of CGA and luteolin biosynthesis in T.antungense and might be useful for metabolic engineering to promote plant polyphenol biosynthesis.

Luteolin抑制血管生成的机制研究

目的:探讨luteolin对血管的抑制机制。方法:采用不同浓度luteolin处理人微血管内皮细胞,观察luteolin对内皮细胞生长,乳腺癌细胞MDA-MB 231培养液介导的内皮细胞趋化抑制作用。并探讨luteolin对内皮细胞中IL-8信号激活的抑制作用,及luteolin对血管生成抑制作用机制。结果:Luteolin对人微血管内皮细胞细胞增殖抑制作用明显(P<0.01)。Luteolin可抑制乳腺癌细胞MDA-MB 231培养液介导的内皮细胞趋化作用(P<0.01),并明显抑制IL-8对内皮细胞ERK及AKT的激活。结论:Luteolin可抑制人微血管内皮细胞增殖及乳腺癌细胞MDA-MB 231培养液介导的趋化作用,并可抑制IL-8对人微血管内皮细胞的信号激活作用,luteolin抗血管生成作用在预防恶性肿瘤复发及转移中可能有重要的作用。

Influence of luteolin on the apoptosis of esophageal cancer Eca109 cells and its mechanism of action

The present study was conducted to verify the influence of luteolin on apoptosis of Eca109 cells and to further investigate the possible mechanisms underlying its effect on apoptosis.The cells were exposed to different concentrations of luteolin(0,40,80,120,160,200,240M)for 24,48,and 72 h respectively.The influence of luteolin on proliferation of Eca109 cells was detected using MTT assay.Eca109 cells were then treated with luteolin(0,40,160,240M)for 24 h.The effect of luteolin on cell cycle progression and apoptosis was assayed by using flow cytometry(FCM).Expression of caspase9 and caspase3 mRNA and protein was analyzed by real-time PCR and Western blot respectively.The results showed that luteolin could inhibit the proliferation of Eca109 cells at all concentrations in a time-dependent manner and the relative inhibition rate showed an inverted U-shaped association with the concentration of luteolin.Further,the cell cycle was arrested in the S phase following treatment with luteolin.Apoptosis analysis indicated that luteolin could induce the apoptosis of Eca109 cells across the three concentration groups,which exhibited a trend of first promotional and then inhibitory with the increases in luteolin concentration.The effect of luteolin on the mRNA and protein expression of caspase 9 and caspase3 first manifested as promotion,then inhibition.Therefore,luteolin may serve a role in promoting cell apoptosis by inducing Eca109 cell apoptosis that involves the expression of caspase3,caspase9 mRNA and protein.This study provides theoretical basis for further study and clinical application of luteolin.The specific mechanism has not yet been clarified and the other activation pathways inducing apoptosis need to be further studied.

Effect of luteolin on apoptosis and vascular endothelial growth factor in human choroidal melanoma cells

AIM:To investigate the effects of luteolin on apoptosis,the cell cycle,and the expression and secretion of vascular endothelial growth factor(VEGF)in human choroidal melanoma cells(C918 and OCM-1).METHODS:C918 and OCM-1 cells cultured in vitro were treated with various concentrations of luteolin(0,5,10,15μmol/L).Cell growth was observed with an inverted microscope,and cell cycle arrest was detected by propidium iodide(PI)staining using flow cytometry.Apoptosis was detected by Hoechst33342 staining,and apoptosis rate was determined by Annexin V-FITC/PI experiments using flow cytometry.The expression of apoptosis-related proteins Bcl-2,Bax and VEGF was analyzed using Western blots.The levels of VEGF secreted by the cells into the supernatant was analyzed using ELISA.RESULTS:After treating with 5 to 15μmol/L luteolin for 48 h,the fusion degree of C918 and OCM-1 cells decreased,and more floating apoptotic cells appeared.Luteolin treatment increased the G0-G1 phase ratio of the C918 and OCM-1 cells,blocked cell cycle progression,and increased the apoptosis rate of the C918 and OCM-1 cells.Western blot showed that luteolin decreased the expression of Bcl-2 and VEGF in the C918 and OCM-1 cells and increased the expression of Bax protein.The ELISA results showed that 10 to 15μmol/L luteolin decreased the cell secretion of VEGF.CONCLUSION:Luteolin may induce apoptosis by regulating the levels of apoptosis-related proteins in C918 and OCM-1 cells.Luteolin can induce cell cycle arrest,decrease the expression of VEGF.

Luteolin attenuates neuronal apoptosis in the hippocampi of diabetic encephalopathy rats

Luteolin （3＇,4＇,5,7-tetrahydroxyflavone） has powerful anti-apoptotic and antioxidant properties. This study aimed to investigate the effects of luteolin on hyperglycemia-mediated apoptosis in the hippocampi of rats with streptozotocin-induced diabetic encephalopathy after injection into the tail veins, and the molecular mechanisms involved. Biochemistry and terminal deoxynucleotidyl transferase mediated dUTP nick end labelling detection results showed that luteolin treatment （given twice daily for 15 days） significantly inhibited hyperglycemia-mediated apoptosis, decreased malondialdehyde levels and increased glutathione levels in the hippocampi of streptozotocin- induced diabetic rats. Western blot analysis revealed that luteolin also inhibited the expression of apoptosis-related factors and cytochrome c release from mitochondria. Luteolin also improved the learning and memory abiJities of rats with diabetic encephalopathy in a water maze test. Further western blot analysis revealed that luteolin treatment facilitated neuronal cell survival through activation of the phosphatidylinositol 3-kinase/Akt signaling pathway, an extracellular signal pathway involved in the suppression of cell apoptosis and promotion of cell survival. These experimental findings indicate that luteolin can inhibit apoptosis of hippocampal nerve cells in rats with diabetic encephalopathy, and that this effect is mediated by an indirect antioxidative effect, the inhibition of activation of apoptosis-related factors and the activation of phosphatidylinositol 3-kinase/Akt signal pathway.

Research of Dyeing Thermodynamics and Supramolecular Structure of Luteolin on Wool Fabric

Natural dyestuff of luteolin was isolated and used to dye wool fabric in this paper. Ethanol extraction and high-speed countercurrent chromatography (HSCCC) were used to extract and purify the luteolin from the peanut shell, and the structure of the isolated luteolin was characterized with FTIR techniques. The interaction between dyestuff and fiber was preliminarily discussed through thermodynamic study and supramolecular structure simulation to explain the intrinsic reasons why the color fastness was low when luteolin was applied to dyeing wool fabric. The extraction condition and purification parameter were as follows: 65% ethanol, ratio of material to liquid 1:20, 80°C, 3 h, chloroform-methanol-water (4/3/2, V/V), 800 rmp/min, 2.0 Mkpa, 0.5 mL/ min and 280 nm. The results of dyeing thermodynamics showed that the sorption isotherm of luteolin on wool fabric was consistent with Nernst model and similar to the disperse dyestuff. With molecular simulation, luteolin and glycin composed 8 stable complexes whose Laplacian values all were greater than 0, which suggested typical hydrogen bonds existing. The complex with three hydrogen bonds was proved the most stable. Both studies on thermodynamics and supramolecular simulation revealed that luteolin on wool fabric mainly depended on the weak hydrogen bonds interaction that determined the low dyefastness.