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

Phosphodiesterase 5 and Arginase Inhibitory Activities of the Extracts from Some Members of Nelumbonaceae and Nymphaeaceae Families

The objectives of this study were (1) to investigate the effect of extracts from some plants in the families Nelumbonaceae and Nymphaeaceae on phosphodiesterase 5 (PDE5) and arginase, which have been used in erectile dysfunction treatment, and (2) to isolate and identify the compounds responsible for such activities. The characterization and quantitative analysis of flavonoid constituents in the active extracts were performed by HPLC. Thirty-seven ethanolic extracts from different parts of plants in the genus Nymphaea and Victoria of Nymphaeaceae and genus Nelumbo of Nelumbonaceae were screened for PDE5 and arginase inhibitory activities. The ethanolic extracts of the receptacles and pollens of Nelumbo nucifera Gaertn., petals of Nymphaea cyanea Roxb. ex G.Don, Nymphaea stellata Willd., and Victoria amazonica (Poepp.) Sowerby and the petals and receptacles of Nymphaea pubescens Willd. showed IC50 values on PDE5 of less than 25 μg/mL while none of the extracts showed effects on arginase. The most active extract, N. pubescens petal extract, was fractionated to isolate and identify the PDE5 inhibitors. The results showed that six flavonoid constituents including quercetin 3'-O-β-xylopyranoside (1), quercetin 3-methyl ether 3'-O-β-xylopyranoside (2), quercetin (3), 3-O-methylquercetin (4), kaempferol (5) and 3-O-methylkaempferol (6) inhibited PDE5 with IC50 values at the micromolar level.

Protective Effect of Neferine in Permanent Cerebral Ischemic Rats via Anti-Oxidative and Anti-Apoptotic Mechanisms

Permanent cerebral ischemia is a consequence of prolonged cerebral artery occlusion that results in severe brain damage. Neurotoxicity occurring after ischemia can induce brain tissue damage by destroying cell organelles and their function. Neferine is a natural compound isolated from the seed embryos of the lotus plant and has broad pharmacological effects, including blockading of the calcium channels, anti-oxidative stress, and anti-apoptosis. This study investigated the ability of neferine to reduce brain injury after permanent cerebral occlusion. Permanent cerebral ischemia in rats was induced by instigation of occlusion of the middle cerebral artery for 24 h. The rats were divided into 6 groups: sham, permanent middle cerebral artery occlusion (pMCAO), pMCAO with neferine and nimodipine treatment. To investigate the severity of the injury, the neurological deficit score and morphological alterations were investigated. After 24 h, the rats were evaluated to assess neurological deficit, infarct volume, morphological change, and the number of apoptotic cell deaths. In addition, the brain tissues were examined by western blot analysis to calculate the expression of proteins related to oxidative stress and apoptosis. The data showed that the neurological deficit scores and the infarct volume were significantly reduced in the neferine-treated rats compared to the vehicle group. Treatment with neferine significantly reduced oxidative stress with a measurable decrease in 4-hydroxynonenal (4-HNE), nitric oxide (NO), neuronal nitric oxide (nNOS), and calcium levels and an upregulation of Hsp70 expression. Neferine treatment also significantly decreased apoptosis, with a decrease in Bax and cleaved caspase-3 and an increase in Bcl-2. This study suggested that neferine had a neuroprotective effect on permanent cerebral ischemia in rats by diminishing oxidative stress and apoptosis.

Neferine Protects Against Brain Damage in Permanent Cerebral Ischemic Rat Associated with Autophagy Suppression and AMPK/mTOR Regulation

Neferine is the major alkaloid compound isolated from the seed embryos of lotus. Neferine has many pharmacological effects, such as anti-inflammatory, antioxidative stress, and antiapoptotic effects, and it maintains autophagic balance. The purpose of this study was to explore the mechanism by which neferine attenuates autophagy after permanent cerebral ischemia in rats. We performed permanent cerebral ischemia in rats by middle cerebral artery occlusion (pMCAO) for 12 h with or without administration of neferine or nimodipine, a calcium (Ca²⁺) channel blocker. Neuroprotective effects were determined by evaluating the infarct volume and neurological deficits. Autophagy and its signaling pathway were determined by evaluating the expression of phosphorylated AMP-activated protein kinase alpha (AMPKα), phosphorylated mammalian target of rapamycin (mTOR), beclin-1, microtubule-associated protein 1A/1B-light chain 3 class II (LC3-II), and p62 by western blotting. Autophagosomes were evaluated by transmission electron microscopy. Neferine treatment significantly reduced infarct volumes and improved neurological deficits. Neferine significantly attenuated the upregulation of autophagy-associated proteins such as LC3-II, beclin-1, and p62 as well as autophagosome formation, all of which were induced by pMCAO. Neferine exerted remarkable protection against cerebral ischemia, possibly via the regulation of autophagy mediated by the Ca²⁺-dependent AMPK/mTOR pathway.

Vasodilation activity of dipfluzine metabolites in isolated rat basilar arteries and their underlying mechanisms

Identifying the metabolites of a drug has become an indispensable task in the development of new drugs. Dipfluzine (Dip) is a promising candidate for the treatment of cerebral vascular diseases and has 5 metabolites (M1∼M5) in rat urine and liver microsomes, but their biological activity is still unknown. Because selective cerebral vasodilation is a main role of Dip, we investigated the vasodilation of Dip and its 5 metabolites in isolated Sprague-Dawley (SD) male rat basilar arteries preconstricted with high-K⁺ or 5-HT. The results showed that only M1 possessed concentration-dependent inhibitory activity on the vasoconstriction of arteries with or without the endothelium, and M1 has a more potent vasodilatory effect than Dip on both contraction models. Like Dip, the vasodilatory mechanisms of M1 may be not only related to receptor-operated and voltage-dependent calcium ion channels of smooth muscle cells but also to the release of NO and EDHF from endothelial cells and the opening of Ca²⁺-activated K⁺ channels and ATP-sensitive potassium ion channels. Unlike Dip, the vasodilation mechanism of M1 is also related to the opening of voltage-sensitive K⁺ channel. Together with more selectivity to non-VDCC than Dip, this may partially explain why M1 has stronger vasodilatory effects than Dip. The mechanisms of vasodilation of Dip and M1 may result from the combined action of these or other factors, especially blocking non-endothelium dependent non-VDCC and endothelium dependent IK_Ca channels. These results point to the possibility that M1 provides synergism for the clinical use of Dip, which may inform the synthesis of new drugs.

Neferine and lianzixin extracts have protective effects on undifferentiated caffeine-damaged PC12 cells

BACKGROUND

The embryos of Nelumbo nucifera Gaertn seeds, lianzixin, are used in China as food and traditional herbal medicine. Principal therapeutic indications are insomnia, anxiety and pyrexia. Caffeine is a psychostimulant and excessive use predisposes to cell damage and neurotoxicity. We aimed to investigate the potential protect effect of Neferine and lianzixin extracts on undifferentiated caffeine-damaged phaeochromocytoma cells (PC12 cells).

METHODS

A cell damage model based on undifferentiated PC12 was established with caffeine. Effect of Lianzixin extracts (total alkaloids, alcohol extract and water extract) and neferine on caffeine-damaged PC12 cells was evaluated. Cell viability was assessed using the methyl thiazolyl tetrazolium (MTT) assay, cellular morphology by inverted microscope, the nucleus by Hoechst 33342 staining and cleaved poly ADP-ribose polymerase (PARP) expression by western blot analysis.

RESULTS

Lianzixin extracts (total alkaloids, alcohol extract and water extract) and neferine improved the viability of PC12 cells damaged by caffeine. The morphology of PC12 cells pretreated with neferine, or alcohol or water extract of lianzixin aggregated and attached better than caffeine-damaged cells, but cells pretreated with total alkaloids of lianzixin showed abnormal morphology. Compared with caffeine-damaged cells, cells pretreated with neferine, or alcohol or water extract of lianzixin showed a notable increase in nucleus staining and an obvious decrease in cleaved PARP expression.

CONCLUSIONS

Lianzixin extracts and neferine have protective effects against caffeine-induced damage in PC12 cells, which laid a foundation for finding a new medicine value of Lianzixin.

Neferine inhibits proliferation and collagen synthesis induced by high glucose in cardiac fibroblasts and reduces cardiac fibrosis in diabetic mice

Cardiac fibrosis is a common pathological process accompanying diabetes mellitus. In this report, we studied the effects of neferine (a major bisbenzylisoquinline alkaloid derived from lotus embryos) on cardiac fibrosis induced by diabetes mellitus, as well as the underlying molecular pathways. In vivo, type 1 diabetes mellitus was induced in mice by administering streptozotocin. Diabetic mice were treated with neferine through oral gavage, and cardiac function was assessed using echocardiography. Total collagen deposition was assessed by Masson's trichrome and Picrosirius staining. In vitro, cardiac fibroblasts were cultured in normal or high-glucose medium with or without neferine. Neferine attenuated left ventricular dysfunction and remodeling and reduced collagen deposition in diabetic mice. In vitro, neferine inhibited cardiac fibroblast proliferation, migration, and differentiation into myofibroblasts. In addition, neferine reduced high-glucose-induced collagen production and inhibited TGF-β1-Smad, ERK and p38 MAPK signaling activation in cardiac fibroblasts. These results suggest that neferine may have antifibrogenic effects in diabetes-related cardiac fibrosis.

Pharmacological benefits of neferine - A comprehensive review

This article recapitulates the existing in vitro and in vivo studies focusing on the effects of neferine-an alkaloid derivative of lotus plant, in various disease models and its effects on key signaling molecules. The review also compiles a large number of research studies that demonstrate methods for isolation and extraction, biosynthetic pathway, pharmacological activity and mode of action of neferine and their underlying mechanisms at cellular level. Neferine is a unique bis-benzylisoquinoline alkaloid that possesses a number of therapeutic effects such as anti-cancer, anti-diabetic, anti-aging, anti-microbial, anti-thrombotic, anti-arrhythmic, anti-inflammatory and even anti-HIV. It also enhances the anti-cancer properties of other anti-cancer drugs like cisplatin, adriamycin, taxol, etc. It is also reported to reverse chemo-resistance and enhance sensitivity of the cancer cells towards anti-cancer drugs. The underlying mechanisms for its activities mainly include apoptosis, autophagy and G1 arrest. Neferine protects them against the effect of drugs like cisplatin. The therapeutic properties of neferine is widely diverse, while it shows toxicity to cancer it also shows cyto-protective effects against cardio-vascular diseases, pulmonary disease, and is also effective against Alzheimer's disease and elicits anti-oxidative effect in many cellular systems. This article thus is the first ever attempt to review the therapeutic activities of neferine established in in vitro and in vivo models and to compile all the fragmented data available on the omnipotent activities of neferine.

Traditional Chinese medical therapy for erectile dysfunction

Traditional Chinese medicine (TCM), including acupuncture and Chinese herbs, is used as an alternative therapy to increase the curative effect for erectile dysfunction (ED). A large number of studies have been conducted to investigate the effect and mechanism of TCM for treating ED. The therapeutic effect of acupuncture on ED is still controversial at present. However, some Chinese herbs exhibited satisfying outcomes and they might improve erectile function by activating nitric oxide synthase (NOS)-cyclic guanosine monophosphate (cGMP) pathway, increasing cyclic adenosine monophosphate (cAMP) expression, elevating testosterone level, reducing intracellular Ca²⁺ concentration, down-regulating transforming growth factor β1 (TGFβ1)/Smad2 signaling pathway, or ameliorating the oxidative stress.

Phytochemical Profile and Biological Activity of Nelumbo nucifera

Nelumbo nucifera Gaertn. (Nymphaeaceae) is a potential aquatic crop grown and consumed throughout Asia. All parts of N. nucifera have been used for various medicinal purposes in various systems of medicine including folk medicines, Ayurveda, Chinese traditional medicine, and oriental medicine. Many chemical constituents have been isolated till the date. However, the bioactive constituents of lotus are mainly alkaloids and flavonoids. Traditionally, the whole plant of lotus was used as astringent, emollient, and diuretic. It was used in the treatment of diarrhea, tissue inflammation, and homeostasis. The rhizome extract was used as antidiabetic and anti-inflammatory properties due to the presence of asteroidal triterpenoid. Leaves were used as an effective drug for hematemesis, epistaxis, hemoptysis, hematuria, and metrorrhagia. Flowers were used to treat diarrhea, cholera, fever, and hyperdipsia. In traditional medicine practice, seeds are used in the treatment of tissue inflammation, cancer and skin diseases, leprosy, and poison antidote. Embryo of lotus seeds is used in traditional Chinese medicine as Lian Zi Xin, which primarily helps to overcome nervous disorders, insomnia, and cardiovascular diseases (hypertension and arrhythmia). Nutritional value of lotus is as important as pharmaceutical value. These days' different parts of lotus have been consumed as functional foods. Thus, lotus can be regarded as a potential nutraceutical source.

Effects of neferine on CCL5 and CCR5 expression in SCG of type 2 diabetic rats

Chemokines and their receptors have the key role in inflammatory responses. The phenomenon of low grade inflammation is associated with the development of type 2 diabetes. Postprandial hyperglycemia increases the systemic inflammatory responses, which promotes the development of type 2 diabetic associating autonomic nervous injuries or cardiovascular disease. Neferine is a bisbenzylisoquinline alkaloid isolated from a Chinese medicinal herb. The objectives of this study will examine the CCL5 and CCR5 expression in the superior cervical ganglion (SCG) of type 2 diabetic rats. The effects of neferine on the expression of CCL5 and CCR5 mRNA and protein in the superior cervical ganglion (SCG) of type 2 diabetic rats will also be observed. The studies showed that in type 2 diabetic rats, body weight, blood pressure, heart rates, fasting blood glucose, insulin, total cholesterol and triglyceride were enhanced and high density lipoprotein was decreased, and CCL5 and CCR5 expression levels in the SCG of type 2 diabetic rats were up-regulated. In type 2 diabetic rats treated with neferine, body weight, blood pressure, fasting blood glucose, insulin, total cholesterol and triglyceride were decreased and high density lipoprotein was increased. The elevated expressions of CCL5 and CCR5 in SCG were decreased after type 2 diabetic rats treated with neferine. The motor nerve conduction velocity (MNCV) in diabetic rats treated with neferine group showed a significantly increment in comparison with that in type 2 diabetic group. Neferine can decrease the expression of CCL5 and CCR5 in the SCG and reduce the SCG neuronal signaling mediated by CCL5 and CCR5 in regulating diabetic cardiovascular autonomic complications.

Effects of tetrandrine on cAMP and cGMP levels in rabbit corpus cavernosum in vitro

The aim of this study was to further investigate the relaxation mechanism of tetrandrine (Tet), a bis-benzylisoquinoline alkaloid isolated from the Chinese medicinal herb-root of Stephania tetrandra S Moore, on rabbit corpus cavernosum tissue in vitro. The effects of Tet on the concentrations of cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) in isolated and incubated rabbit corpus cavernosum tissue were recorded by means of (125)I radioimmunoassay. The basal concentration of cAMP in corpus cavernosum tissue was 5.67 +/- 0.97 pmol mg(-1). Tet 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 E(1) (PGE(1), a stimulator of cAMP production) was also augmented by Tet in a dose-dependent manner (p < 0.05). The basal concentration of cGMP in corpus cavernosum tissue is 0.44 +/- 0.09 pmol mg(-1). Tet did not affect this concentration of cGMP, neither in the presence nor the absence of a guanyl cyclase inhibitor (1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one, ODQ) (p > 0.05). Further, sodium nitroprusside (SNP, a stimulator of cGMP production)-induced cGMP production was not enhanced by Tet (p > 0.05). Tet, with its relaxation mechanism, can enhance the concentration of cAMP in rabbit corpus cavernosum tissue, probably by inhibiting PDEs activity.

Anti-amnesic activity of neferine with antioxidant and anti-inflammatory capacities, as well as inhibition of ChEs and BACE1

AIMS

the multifunctional potential of neferine derived from the embryo of Nelumbo nucifera seeds for the age-related neurodegenerative disorders, in vivo anti-amnesic activities and in vitro cholinesterases (ChEs)- and β-site APP cleaving enzyme 1 (BACE1)-inhibitory activities, as well as anti-inflammatory and antioxidant activities were investigated.

MAIN METHODS

in vivo anti-amnesic activities were performed via the passive avoidance, Y-maze, and Morris water maze tasks in a scopolamine-induced amnesia model. The cell-free antioxidant capacities were evaluated by in vitro scavenging activities against 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) radicals, and peroxynitrite (ONOO(-)), as well as inhibitory activities against nitric oxide (NO), superoxide anion (O(2)(-)), lipid peroxidation, and ONOO(-)-mediated tyrosine nitration. The intracellular antioxidant capacities were also determined via inhibitory activities of lipopolysaccharide (LPS)-induced NO generation and NF-κB activation in RAW 264.7 cells.

KEY FINDINGS

neferine showed significant improvement in cognitive impairment in scopolamine-induced amnesia animal models and moderate inhibitory activities in ChEs and BACE1 assays. In addition, it exhibited notable scavenging activities against DPPH, ABTS, NO, and O(2)(-) radicals, as well as ONOO(-). Neferine also demonstrated remarkable inhibitory activity against lipid peroxidation and protein nitration in cell-free antioxidant assays and moderate inhibitory activity of NO generation with exceptional suppression of NF-κB activation in cell-based assays.

SIGNIFICANCE

the results demonstrate that the anti-amnesic effect of neferine may be mediated via antioxidant and anti-inflammatory capacities, as well as inhibition of ChEs and BACE1.

Neferine inhibits angiotensin II-stimulated proliferation in vascular smooth muscle cells through heme oxygenase-1

AIM

To explore the effect of neferine on angiotensin II (Ang II)-induced vascular smooth muscle cell (VSMC) proliferation.

METHODS

Human umbilical vein smooth muscle cells (HUVSMCs) were used. Cell proliferation was determined by using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and flow cytometry analysis. Heme oxygenase (HO)-1 protein expression was tested by Western blot analysis. Extracellular signal-regulated protein kinase 1/2 (ERK1/2) activation was determined by using immunoblotting.

RESULTS

Pre-incubation of HUVSMCs with neferine (0.1, 0.5, 1.0, and 5.0 micromol/L) significantly inhibited Ang II-induced cell proliferation in a concentration-dependent manner and neferine 5.0 micromol/L increased HO-1 expression by 259% compared with control. The antiproliferative effect of neferine was significantly attenuated by coapplication of zinc protoporphyrin IX (ZnPP IX, an HO-1 inhibitor) with neferine. Ang II-enhanced ERK1/2 phosphorylation was markedly reversed by neferine. By inhibiting HO-1 activity with ZnPP IX, the inhibitive effect of neferine on ERK1/2 phosphorylation was significantly attenuated. Cobalt-protoporphyrin (CoPP), an HO-1 inducer, significantly decreased Ang II-induced ERK1/2 phosphorylation and inhibited Ang II-induced cell proliferation. The ERK1/2 pathway inhibitor PD98059 significantly blocked Ang II-enhanced ERK1/2 phosphorylation and inhibited cell proliferation.

CONCLUSION

These findings suggest that neferine can inhibit Ang II-induced HUVSMC proliferation by upregulating HO-1, leading to the at least partial downregulation of ERK1/2 phosphorylation.

The relaxation mechanisms of tetrandrine on the rabbit corpus cavernosum tissue in vitro

The relaxation mechanisms of tetrandrine (Tet) on the rabbit corpus cavernosum tissue in vitro were investigated. Strips of rabbit corpus cavernosum were mounted in organ chambers. The effects of Tet were examined on isolated muscle strips pre-contracted with phenylephrine (PE) alone, in the presence of N(W)-nitro-L-arginine (LNNA, a nitric oxide synthase inhibitor), 1-H-[1,2,4]oxadiazolo[4,3-alpha]quinoxalin-1-one(ODQ, a guanylyl cyclase inhibitor), indomethacin (cyclooxygenase inhibitor), tetraethylammonium (TEA, 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 Tet on KCl-induced contraction of isolated muscle strips were also investigated. The procedure of calcium absence-calcium addition was designed to observe the effect of Tet on the two components of the contractile responses to PE based on the source of Ca(2+) (extracellular vs. intracellular). Corpus cavernosum strips showed relaxation in response to Tet (10(-8) approximately 10(-3) mol L(-1)) in a concentration-dependent manner with an IC(50) of 3.73 x 10(-5) mol L(-1). However, they were not affected by LNNA, ODQ, indomethacin and K(+)-channel blockers. Tet (10 micromol L(-1), 30 micromol L(-1)) concentration dependently reduced the maximal contraction response of isolated strips induced by KCl to (73.0 +/- 3.8) and (41.5 +/- 3.4)%, respectively (p < 0.01). In the procedure of calcium absence-calcium addition, Tet 100 micromol L(-1) inhibited both intracellular calcium-dependent and extracellular calcium-dependent contraction induced by PE (20 micromol L(-1)) (p < 0.05). The inhibition ratios were (23.8 +/- 7.1) and (40.7 +/- 11.2)%, respectively. The results of the present study suggest that Tet possesses a relaxant effect on rabbit corpus cavernosum 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.

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 (Nef), 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 E1 (PGE1, 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.