Effects of neferine on cytosolic free calcium concentration in corpus cavernosum smooth muscle cells of rabbits

Alkaloids from lotus (Nelumbo nucifera): recent advances in biosynthesis, pharmacokinetics, bioactivity, safety, and industrial applications

Different parts of lotus (Nelumbo nucifera Gaertn.) including the seeds, rhizomes, leaves, and flowers, are used for medicinal purposes with health promoting and illness preventing benefits. The presence of active chemicals such as alkaloids, phenolic acids, flavonoids, and terpenoids (particularly alkaloids) may account for this plant's pharmacological effects. In this review, we provide a comprehensive overview and summarize up-to-date research on the biosynthesis, pharmacokinetics, and bioactivity of lotus alkaloids as well as their safety. Moreover, the potential uses of lotus alkaloids in the food, pharmaceutical, and cosmetic sectors are explored. Current evidence shows that alkaloids, mainly consisting of aporphines, 1-benzylisoquinolines, and bisbenzylisoquinolines, are present in different parts of lotus. The bioavailability of these alkaloids is relatively low in vivo but can be enhanced by technological modification using nanoliposomes, liposomes, microcapsules, and emulsions. Available data highlights their therapeutic and preventive effects on obesity, diabetes, neurodegeneration, cancer, cardiovascular disease, etc. Additionally, industrial applications of lotus alkaloids include their use as food, medical, and cosmetic ingredients in tea, other beverages, and healthcare products; as lipid-lowering, anticancer, and antipsychotic drugs; and in facial masks, toothpastes, and shower gels. However, their clinical efficacy and safety remains unclear; hence, larger and longer human trials are needed to achieve their safe and effective use with minimal side effects.

Neferine alleviates P2X3 receptor in rat dorsal root ganglia mediated neuropathic pain

Chronic neuropathic pain is caused by tissue damage or nervous system inflammation and is characterized by sensitivity to painful stimuli. P2X3 receptors play an important role in facilitating pain transmission. Neferine is a bisbenzylisoquinline alkaloid isolated from seed embryos of lotus, which has anti-inflammatory and anti-oxidation pharmacological functions. The present research investigated whether neferine relieves neuropathic pain related to the P2X3 receptor in rat dorsal root ganglia (DRGs). Chronic contraction injury (CCI) in rats was used as a model for neuropathic pain. The results indicated that the expression of P2X3 receptor was significantly increased in the DRGs of CCI rats and that mechanical allodynia and thermal hyperalgesia were also enhanced in CCI rats. Neferine markedly lowered the upregulated P2X3 receptor and interleukin-1beta, inhibited the phosphorylation and activation of ERK1/2 in the DRGs of CCI rats, and relieved neuropathic pain. Therefore, neferine alleviates neuropathic pain by downregulating the expression of P2X3 receptor.

Neferine induces autophagy-dependent cell death in apoptosis-resistant cancers via ryanodine receptor and Ca2+-dependent mechanism

Resistance of cancer cells to chemotherapy is a significant clinical concern and mechanisms regulating cell death in cancer therapy, including apoptosis, autophagy or necrosis, have been extensively investigated over the last decade. Accordingly, the identification of medicinal compounds against chemoresistant cancer cells via new mechanism of action is highly desired. Autophagy is important in inducing cell death or survival in cancer therapy. Recently, novel autophagy activators isolated from natural products were shown to induce autophagic cell death in apoptosis-resistant cancer cells in a calcium-dependent manner. Therefore, enhancement of autophagy may serve as additional therapeutic strategy against these resistant cancers. By computational docking analysis, biochemical assays, and advanced live-cell imaging, we identified that neferine, a natural alkaloid from Nelumbo nucifera, induces autophagy by activating the ryanodine receptor and calcium release. With well-known apoptotic agents, such as staurosporine, taxol, doxorubicin, cisplatin and etoposide, utilized as controls, neferine was shown to induce autophagic cell death in a panel of cancer cells, including apoptosis-defective and -resistant cancer cells or isogenic cancer cells, via calcium mobilization through the activation of ryanodine receptor and Ulk-1-PERK and AMPK-mTOR signaling cascades. Taken together, this study provides insights into the cytotoxic mechanism of neferine-induced autophagy through ryanodine receptor activation in resistant cancers.

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.

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.

Relaxant action of plumula nelumbinis extract on mouse airway smooth muscle

The traditional herb Plumula Nelumbinis is widely used in the world because it has many biological activities, such as anti-inflammation, antioxidant, antihypertension, and butyrylcholinesterase inhibition. However, the action of Plumula Nelumbinis on airway smooth muscle (ASM) relaxation has not been investigated. A chloroform extract of Plumula Nelumbinis (CEPN) was prepared, which completely inhibited precontraction induced by high K⁺ in a concentration-dependent manner in mouse tracheal rings, but it had no effect on resting tension. CEPN also blocked voltage-dependent L-type Ca²⁺ channel- (VDCC-) mediated currents. In addition, ACh-induced precontraction was also completely blocked by CEPN and partially inhibited by nifedipine or pyrazole 3. Besides, CEPN partially reduced ACh-activated nonselective cation channel (NSCC) currents. Taken together, our data demonstrate that CEPN blocked VDCC and NSCC to inhibit Ca²⁺ influx, resulting in relaxation of precontracted ASM. This finding indicates that CEPN would be a candidate of new potent bronchodilators.

The interaction between human breast cancer resistance protein (BCRP) and five bisbenzylisoquinoline alkaloids

BCRP is one of the key factors to drug absorption, distribution and elimination. Bisbenzylisoquinoline alkaloids are a large family of natural phytochemicals with great potential for clinical use. In this study, the interaction between BCRP and five bisbenzylisoquinoline alkaloids (neferine, isoliensinine, liensinine, dauricine and tetrandrine) were evaluated using LLC-PK1/BCRP cell model. The intracellular accumulation and bi-directional transport studies were conducted, and then molecular docking analysis was carried out employing a homology model of BCRP. Our study revealed that the permeability of these five alkaloids was not high, the Papp values were all less than 6.5 × 10(-6)cm/s. Liensinine and dauricine were substrates of BCRP: at lower concentration (10 μM), the net efflux ratios were 2.87 and 1.64 respectively. And their cellular accumulation was lower in LLC-PK1/BCRP cells than in LLC-PK1 cells. On the other hand, tetrandrine, isoliensinine and neferine were not substrates of BCRP. On the basis of docking studies, a direct hydrogen bond was formed between liensinine and arginine 482 which is a hot spot of BCRP for substrate specificity; and dauricine had hydrophobic interaction with BCRP. In conclusion, our study indicated that BCRP could mediate the excretion of liensinine and dauricine, thus influence their pharmacological activity and disposition.

Neferine, an alkaloid ingredient in lotus seed embryo, inhibits proliferation of human osteosarcoma cells by promoting p38 MAPK-mediated p21 stabilization

Identification of natural products that have antitumor activity is invaluable to the chemoprevention and therapy of cancer. The embryos of lotus (Nelumbo nucifera) seeds are consumed in beverage in some parts of the world for their presumed health-benefiting effects. In this report we studied the effects of neferine, a major alkaloid component in lotus embryos, on human osteosarcoma cells and the underlying mechanisms. We found that neferine possessed a potent growth-inhibitory effect on human osteosarcoma cells, but not on non-neoplastic human osteoblast cells. The inhibitory effect of neferine on human osteosarcoma cells was largely attributed to cell cycle arrest at G1. The induction of G1 arrest was p21(WAF1/CIP1)-dependent, but was independent of p53 or RB (retinoblastoma-associated protein). The up-regulation of p21 by neferine was due to an increase in the half-life of p21 protein. We examined four kinases that are known to affect the stabilization of p21, and found that p38 MAPK and JNK were activated by neferine. However, only SB203580 (an inhibitor of p38), but not SP600125 (the inhibitor of JNK), can attenuate the up-regulation of p21 in response to neferine. Furthermore, the p21-stabilizing effect of neferine was abolished when p38 was silenced by RNA interference. Finally, we showed that neferine treatment led to an increased phosphorylation of p21 at Ser130 that was dependent on p38. Our results for the first time showed a direct antitumor effect of neferine, suggesting that consumption of neferine may have cancer-preventive and cancer-therapeutic benefit.

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.

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.