Antiarrhythmic Efficacy of Neferine Assessed by Programmed Electrical Stimulation in a Canine Model of Electropharmacology

An ishemic ventricular tachyarrhythmias canine model was established in open-chest dogs subjected to programmed electrical stimulation (PES)for 5-8 days after acute myocardial infarction. The electrophysiologic effects of neferine (Nef) and procainamide (PA) were observed in this model. With routine methods of PES,ventricular tachycardia (VT)and ventricular fibrillation (VF) could be reproducibly initiated. Both drugs lengthened the QTc interval (P【0.01) and effective refractory period(ERP)of normal and ischemic ventricular myocardia (NERP and IERP) respectively (P【0.01), decreased the dispersion of ERP in ischemic myocardium and the dispersion of ERP in left ventricle (P【0.01), and increased the diastolic excitability threshold of normal and ischemic ventricular myocardia (P【0.01). The two compounds prevented the PES-induced VT or VF (Nef group P【0.01, PA group P【0.05) and ischemia-induced VF (P【0.05). The results indicated that neferine and procainamide may be effective in preventing the onset of reentrant ventricular tachyarrhythmias after myocardial ischemic damage in dogs.

Reversal of Multidrug Resistance by Neferine in Adriamycin Resistant Human Breast Cancer Cell Line MCF-7/ADM

Objective: To study the reversal effect of neferine on adriamycin (ADM) resistant human breast cancer cell line MCF-7/ADM. Methods: The cytotoxic effect of Nef or ADM was determined by 3-[4, 5-dimethylthiazol-2.-yl], 5-diphenyl tetraxolium bromid (MTT) assay. Apoptosis and the expression of P-glycoprotein (P-gp) were detected by flow cytometry (FCM). The intracellular ADM concentration was measured by HPLC. Results: Nef at 1, 5, 10 mol/L decreased the IC50 of ADM to MCF-7/ADM from 11.63 g/mL to 4.59, 2.44, 0.27 g/mL respectively. MCF-7/ADM could resist the apoptosis induced by ADM while Nef (1-10 mol/L) could augment ADR-mediated apoptosis. Nef (10 mol/L) increased the accumulation of ADM up to 2.88 fold in MCF-7/ADM but not in sensitive cells MCF-7/S and reduced the expression of P-gp in MCF-7/ADM cells. Conclusion: Nef can circumvent multidrug resistance (MDR) of MCF-7/ADM cells and the mechanism was associated with the increase of intracellular accumulation of ADM and the reduced expression of P-gp in MCF-7/ADM cells.

Synergistic Effect of Hyperthermia and Neferine on Reverse Multidrug Resistance in Adriamycin-resistant SGC7901/ADM Gastric Cancer Cells

Multidrug resistance（MDR） plays a major obstacle to successful gastric cancer chemotherapy.The purpose of this study was to investigate the MDR reversal effect and mechanisms of hyperthermia in combination with neferine（Nef） in adriamycin（ADM） resistant human SGC7901/ADM gastric cancer cells.The MDR cells were heated at 42℃ and 45℃ for 30 min alone or combined with 10 μg/mL Nef.The cytotoxic effect of ADM was evaluated by MTT assay.Cellular plasma membrane lipid fluidity was detected by fluorescence polarization technique.Intracellular accumulation of ADM was monitored with high performance liquid chromatography.Mdr-1 mRNA,P-glycoprotein（P-gp）,γH2AX expression and γH2AX foci formation were determined by real-time PCR,Western blot and immunocytochemical staining respectively.It was found that different heating methods induced different cytotoxic effects.Water submerged hyperthermia had the strongest cytotoxicity of ADM and Nef combined with hyperthermia had a synergistic cytotoxicity of ADM in the MDR cells.The water submerged hyperthermia increased the cell membrane fluidity.Both water submerged hyperthermia and Nef increased the intracellular accumulation of ADM.The water submerged hyperthermia and Nef down-regulated the expression of mdr-1 mRNA and P-gp.The water submerged hyperthermia could damage DNA and increase the γH2AX expression of SGC7901/ADM cells.The higher temperature was,the worse effect was.Our results show that combined treatment of hyperthermia with Nef can synergistically reverse MDR in human SGC7901/ADM gastric cancer cells.

Effects of plant extract neferine on cyclic adenosine monophosphate and cyclic guanosine monophosphate levels in rabbit corpus cavernosum in vitro

Aim： To further investigate the relaxation mechanism of neferine （NED, a bis-benzylisoquinoline alkaloid extracted （isolated） from the green seed embryo of Nelumbo nucifera Gaertn in China, on rabbit corpus cavernosum tissue in vitro. Methods： The effects of Nef on the concentrations of cyclic adenosine monophosphate （cAMP） and cyclic guanosine monophosphate （cGMP） in isolated and incubated rabbit corpus cavernosum tissue were recorded using ^125I radioimmunoassay. Results： The basal concentration of cAMP in corpus cavernosum tissue was 5.67 ± 0.97 pmol/mg. Nef increased the cAMP concentration in a dose-dependent manner （P 〈 0.05）, but this effect was not inhibited by an adenylate cyclase inhibitor （cis-N-[2-phenylcyclopentyl]azacyclotridec-1-en-2-amine, MDL-12, 330A） （P 〉 0.05）. The accumulation of cAMP induced by prostaglandin Et （PGEt, a stimulator of cAMP production） was also augmented by Nef in a dose-dependent manner （P 〈 0.05）. The basal concentration of cGMP in corpus cavernosum tissue is 0.44 ± 0.09 pmol/mg. Nef did not affect this concentration of cGMP, either in the presence or in the absence of a guanyl cyclase inhibitor （1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one, ODQ） （P 〉 0.05）. Also, sodium nitroprusside （SNP, a stimulator of cGMP production）-induced cGMP production was not enhanced by Nef （P 〉 0.05）. Conclusion： Nef, with its relaxation mechanism, can enhance the concentration of cAMP in rabbit corpus cavernosum tissue, probably by inhibiting phosphodiesterase activity. （Asian JAndro12008 Mar; 10： 307-312）

Inhibitory Effects of Neferine on Na_v1.5 Channels Expressed in HEK293 Cells

Neferine, a bisbenzylisoquinoline alkaloid in Lotus Plumule, was proved to have a wide range of biological activities. In the present study, using whole-cell patch-clamp technique, we investigated the effects of neferine on Nav1.5 channels that are stably expressed in HEK 293 cells. We found that neferine potently and reversibly inhibited Nav1.5 currents in a concentration dependent manner with a half-maximal inhibition（IC50） being 26.15 μmol/L. The inhibitory effects of neferine on Nav1.5 currents were weaker than those of quinidine at the same concentration. The steady-state inactivation curve was significantly shifted towards hyperpolarizing direction in the presence of 30 μmol/L neferine, while the voltage-dependent activation was unaltered. Neferine prolonged the time to peak of activation, increased the inactivation time constants of Nav1.5 currents and markedly slowed the recovery from inactivation. The inhibitory effect of neferine could be potentiated in a frequency-dependent manner. These results suggested that neferine can block Nav1.5 channels under the open state and inactivating state and it is an open channel blocker of Nav1.5 channels.

The Effect of Neferine on Foam Cell Formation by Anti-low Density Liporotein Oxidation

Oxidatively modified low density lipoprtein (LDL) plays an important role in atheroslerosis (AS) development. To investigate the role of neferine (Nef) in anti-LDL oxidation and foam cell formation, the lipoprotein was derived and subjected to three different treatments: N-LDL (normal LDL), Cu(2+) +LDL and Cu(2+)+Nef+LDL. The LDLs were put at 25℃ for 24 h and the thiobarbituric acid reactive substance (TBARS) values were determined. They were 0. 57 ±0. 02, 6.01±0. 22 and 2. 26±0. 13 nmol/mg protein, respectively. The difference was very significant (P<0.01) for each two groups by t test. Mouse peritoneal macrophage (MΦ) were exposed to 50 μg protein/ml of Cu(2+) + LDL and Cu(2+)+Nef+LDL at 37℃ for 60 h. The tryglyceride (TG) and total cholesterol (TC) content in Mad were assayed. The results showed that Cu(2+) + LDL was more efficient than Cu(2+)+Nef+LDL in stimulating lipid accumulation in MΦ(P <0. 001). The study demonstrated that Nef could inhibit Cu(2+)-mediated LDL oxidation and thereby inhibiting macrophage-derived foam cell formation.

SENSITIVITY OF LEUKEMIC CELL LINE HL-60 TO COMBINATION OF NEFERINE AND ARSENIC

Objective： To determine whether neferine （Nef） enhances the sensitivity of human myeloid leukemia HL-60 cells to arsenic trioxide （ATO）. Methods： Apoptosis was detected by DNA electrophoresis. Giemsa staining was used to observe the apoptotic cells under microscope. The apoptotic rates of cells were analyzed using flow cytometry. The inhibitory rates of cell growth were assayed by MTT, and the expression of P-gp was determined by flow cytometry. Results： Low doses of ATO （1.0 μmol/L） only partially inhibitory percentage of cell growth at 72 h was （9.92±3.03） % （P〉0.05, vs control）. The combination of 1.0 μmol/L ATO with 2.0 μmol/L Nef inhibited （45.27±4.93） % of cell growth, and induced apoptosis in leukemic cells more significantly than wither ATO or Nef on their own （P〈0.01）. Moreover, ATO-induced expression of P-gp in leukemic cells was inhibited significantly by Nef. Conclusion： These results indicate that Nef significantly increases sensitivity of leukemic cells to ATO, which might be associated with inhibitory expression of P-gp gene. Combined use of the two agents could be a novel and attractive strategy in leukemia treatment.

Relaxation mechanisms of cavernosum tissue in vitro neferine on the rabbit corpus

Aim： To investigate the relaxation mechanisms of neferine （Nef） on the rabbit corpus cavemosum tissue in vitro. Methods： Strips of rabbit corpus cavemosum were mounted in organ chambers. The effects of Nef were examined on isolated muscle strips precontracted with phenylephrine （PE） alone, in the presence of NW-nitro-L-arginine （LNNA, a nitric oxide synthase inhibitor）, 1-H-[ 1,2,4]oxadiazolo[4,3-tx]quinoxalin- 1-one （ODQ, a guanylyl cyclase inhibitor）, indomethacin （cyclooxygenase inhibitor）, tetraethylammonium （Ca^2＋ -activated K^＋ channel blocker）, 4-aminopiridine （4-AP ,voltage dependent K^＋ channel blocker） and glibenclamide （ATP sensitive K^＋channel blocker）. The effects of Nef on KCl-induced contraction of isolated muscle strips were also investigated. The procedure of calcium absencecalcium addition was designed to observe the effect of Nef on two components of the contractile responses to PE based on the source of Ca^2＋ （extracellular vs. intracellular）. Results： Corpus cavemosum strips relaxed in response to Nef （10-9-10-4 mol/L） in a concentration-dependent manner with an IC50 of 4.60 × 10^-6 mol/L. However, they were not affected by LNNA, ODQ, indomethacin or K^＋-channel blockers. Nef （10^-6 mol/L, 10^-5 mol/L） concentration dependently reduced the maximal contraction response of isolated strips induced by KC1 to 79.3% ± 5.5% and 61.5% ±3.2%, respectively （P 〈 0.01）. In the calcium absence-calcium addition procedure, Nef 10.5 mol/L inhibited both intracellular calcium-dependent and extracellular calcium-dependent contraction induced by PE （2 × 10^5 mol/L） （P 〈 0.05）. The inhibition ratios were 26.2% ± 5.4% and 48.3% ±7.6%, respectively. Conclusion： The results of the present study suggest that Nef possesses a relaxant effect on rabbit corpus cavemosum tissues, which is attributable to the inhibition of extracellular Ca^2＋ influx and the inhibition of release of intracellular stored Ca^2＋, but not mediated by the release of nitric oxide, prostaglandins or by the activation of potassium channels.

Neferine inhibits the progression of diabetic nephropathy by modulating the miR-17-5p/nuclear factor E2-related factor 2 axis

OBJECTIVE:To investigate the effect of Neferine(Nef)on diabetic nephropathy(DN)and to explore the mechanism of Nef in DN based on miRNA regulation theory.METHODS:A DN mouse model was constructed and treated with Nef.Serum creatinine(Crea),blood urea(UREA)and urinary albumin were measured in mice by kits,and renal histopathological changes and fibrosis were observed by hematoxylin-eosin staining and Masson staining.Renal tissue superoxide dismutase(SOD),malondialdehyde(MDA)and glutathione peroxidase(GSH-Px)activities were measured by enzyme-linked immunosorbent assay(ELISA).Western blotting was used to detect the expression of nuclear factor E2-related factor 2(Nrf2)/heme oxygenase 1(HO-1)signaling pathway-related proteins in kidney tissues.Quantitative reverse transcription-polymerase chain reaction(q RT-PCR)was used to detect the expression of miR-17-5p in kidney tissues.Subsequently,a DN in vitro model was constructed by high glucose culture of human mesangial cells(HMCs),cells were transfected with miR-17-5p mimic and/or treated with Nef,and we used q RTPCR to detect cellular miR-17 expression,flow cytometry to detect apoptosis,ELISAs to detect cellular SOD,MDA,and GSH-Px activities,Western blots to detect Nrf2/HO-1 signaling pathway-related protein expression,and dual luciferase reporter gene assays to verify the targeting relationship between Nrf2 and miR-17-5p.RESULTS:Administration of Nef significantly reduced the levels of blood glucose,Crea,and UREA and the expression of miR-17-5p,improved renal histopathology and fibrosis,significantly reduced MDA levels,elevated SOD and GSH-Px activities,and activated Nrf2 expression in kidney tissues from mice with DN.Nrf2 is a post-transcriptional target of miR-17-5p.In HMCs transfected with miR-17-5p mimics,the m RNA and protein levels of Nrf2 were significantly suppressed.Furthermore,miR-17-5p overexpression and Nef intervention resulted in a significant increase in high glucose-induced apoptosis and MDA levels in HMCs and a significant decrease in the protein expression of HO-1 and Nrf2.CONCLUSION:Collectively,these results indicate that Nef has an ameliorative effect on DN,and the mechanism may be through the miR-17-5p/Nrf2 pathway.

Effects of co-administraton of neferine and doxorubicin on the pharmacokinetics of doxorubicin

Doxorubicin is one of the anthracycline anti-neoplastic drugs widely used to treat leukemia, liver, breast, and ovarian cancers and other solid tumors. However, its clinical applications have been limited by its serious cardio-cytotoxic effects. The aim of this study was to investigate the effect of neferine, a bisbenzylisoquinoline alkaloid extracted from the green embryo in the mature lotus seed, on the pharmacokinetics of doxorubicin. The levels of doxorubicin in plasma and tissues were measured using the high performance liquid chromatography（HPLC） method. The chromatographic separation was completed on a reversed-phase C18 column using acetonitrile–phosphate buffer（30：70, v/v） as the mobile phase at a flow rate of 1 mL /min and ultraviolet detection wave length was set at 233 nm. The pharmacokinetic study found that the co-administration of neferine and doxorubicin significantly affected the pharmacokinetics of doxorubicin. There were evident changes in area under the curve（AUC）, clearance（CL） and t1/2β in group of pretreatment neferine as compared with those in group treated with doxorubicin alone. Tissue distribution analysis showed that the concentrations of doxorubicin distributed to heart, liver and kidney were statistically significant higher in group of pretreatment with neferine plus doxorubicin than those in the doxorubicin alone-group at 0.5 h and 2 h after drug administration, respectively. While the doxorubicin concentrations in spleen and lung drug were slightly increased in the group of pretreatment with neferine plus doxorubicin as compared to that of group of doxorubicin alone, the difference between two groups were not statistically significant. Therefore, the dose of doxorubicin needs to be taken into consideration when it is administrated in combination with neferine.

Reversal of doxorubicin resistance in lung cancer cells by neferine is explained by nuclear factor erythroid-derived 2-like 2 mediated lung resistance protein down regulation

Aim:Development of multi drug resistance and dose limiting cardiotoxicity are hindering the use of Doxorubicin(Dox)in clinical settings.Augmented dox efflux induced by lung resistance protein(LRP)over expression has been related to multi drug resistance phenotype in various cancers.An alkaloid from lotus,Neferine(Nef)shows both anticancer and cardioprotective effects.Here,we have investigated the interconnection between nuclear factor erythroid-derived 2-like 2(NRF2)and LRP in Dox resistance and how Nef can overcome Dox resistance in lung cancer cells by altering this signaling.Methods:Anti-proliferative and apoptotic-inducing effects of Nef and Dox combination in Parental and Dox resistant lung cancer cells were determined in monolayers and 3D spheroids.Intracellular Dox was analyzed using flow cytometry,siRNA knockdown and western blot analysis were used to elucidate NRF2-LRP crosstalk mechanism.

A new bisbenzylisoquinoline alkaloid from Plumulanelumbinis

One new bisbenzylisoquinoline alkaloid, neferine N-oxide （1）, along with three known compounds, neferine （2）, liensinine （3）, and isoliensinine （4）, were isolated from Plumulanelumbinis - the embryo of the seed of Nelumbonucifera. Their structures were elucidated by extensive spectroscopic analysis （MS, UV, IR, NMR）, and the absolute configurations were determined by experimental circulardichroism （CD） spectra. Compound 1 is a new naturally occurring bisbenzylisoquinoline alkaloid with an N-oxide functionality, and the CD spectrum of （1R, 1＇R） neferine is first reported. The antioxidant activities of compounds 1-4 were evaluated using the ORAC assay, which illustrated that all these compounds showed the different levels of oxygen radical absorbance capacity.

Development of a cell-based HTS adaptable calcium fluorescent assay in FlexStation3 for the screening of TRPV3 inhibitors

To develop a cell-based high-throughput calcium fluorescent assay for screening of TRPV3 channel modulators, we employed the FlexStation3 microplate reader and optimized conditions of the high-throughput screening （HTS） adaptable calcium fluorescent assay, such as cell density, incubation time and concentration of Cal-520 calcium fluorescent dye. The optimized FlexStation3 assay included the cell density of 40 000 cells per well, 5.0% of Cal-520 calcium fluorescent dye and 1.5 h of incubation time. Using the FlexStation3 assay in a 96-well format, we screened and identified a natural neferine from Nymphaeaceae plant that inhibited TRPV3 channel. To further confirm the inhibitory effect of neferine on TRPV3, we utilized the whole-cell patch clamp recordings and determined the dose-dependent inhibition of TRPV3 current by neferine with an ICs0 at 24.5~4.1 p.M （n = 6） without inhibition of TRPV1 or TRPV4 channels. Taken together, our data showed that this validated HTS adaptable calcium fluorescent assay in FlexStation3 format could be used for screening and identification of modulators for either TRPV3 channel or other calcium permeable TRP channels. The identified natural neferine could be used as a tool for pharmacological investigations of TRPV3 channel function.