Neuroprotective effect of liquiritin as an antioxidant via an increase in glucose-6-phosphate dehydrogenase expression on B65 neuroblastoma cells.

Glycyrrhiza (the roots and rhizomes of licorice) has been used worldwide as both an herbal nutraceutical and herbal medicine. In addition, it is well known that Glycyrrhiza contains various compounds with biological effects, such as anti-viral, anti-inflammatory, immunoregulatory, anti-tumor and neuroprotective effects. Among the various compounds in Glycyrrhiza, the active compounds that show biological activity are thought to include glycyrrhizin, glycyrrhetinic acid, glabridin, licochalcones and liquiritin. In the present study, we investigated the biological effects of three of these compounds (glycyrrhizin, liquiritin and isoliquiritin) on B65 neuroblastoma cells derived from serotonergic neurons. Among these three compounds, only liquiritin enhanced the proliferation of B65 neuroblastoma cells. In contrast, both glycyrrhizin and isoliquiritin, particularly at high concentrations had cytotoxic effects. Cells were treated with various cytotoxic agents and liquiritin could ameliorate the cytotoxicity induced by menadione sodium bisulfate in a dose-dependent manner. We also examined the effect of liquiritin on cell survival by evaluating the expression levels of phospho-p44/42 mitogen-activated protein kinase, cyclin-related proteins and glucose-6-phosphate dehydrogenase, which produces nicotinamide adenine dinucleotide phosphate. Under treatment with liquiritin, the protein expression level of glucose-6-phosphate dehydrogenase increased in a dose-dependent manner. In contrast, the protein expression level of cyclin-related proteins did not change at all under treatment with liquiritin. These results suggest that liquiritin, which is contained in Glycyrrhiza, may enhance cell survival by increasing the protein expression level of glucose-6 phosphate dehydrogenase.

Sinomenine and magnoflorine, major constituents of Sinomeni caulis et rhizoma, show potent protective effects against membrane damage induced by lysophosphatidylcholine in rat erythrocytes.

The effects of the water extract of Sinomeni Caulis et Rhizoma (SCR-WE) and its major constituents, sinomenine (SIN) and magnoflorine (MAG), on moderate hemolysis induced by lysophosphatidylcholine (LPC) were investigated in rat erythrocytes and compared with the anti-hemolytic effects of lidocaine (LID) and propranolol (PRO) as reference drugs. LPC caused hemolysis at concentrations above the critical micelle concentration (CMC), and the concentration of LPC producing moderate hemolysis (60 %) was approximately 10 µM. SCR-WE at 1 ng/mL-100 µg/mL significantly inhibited the hemolysis induced by LPC. SIN and MAG attenuated LPC-induced hemolysis in a concentration-dependent manner from very low to high concentrations (1 nM-100 µM and 10 nM-100 µM, respectively). In contrast, the inhibiting effects of LID and PRO on LPC-induced hemolysis were observed at higher concentrations (1-100 µM) but not at lower concentrations (1-100 nM). Neither SIN nor MAG affected micelle formation of LPC, nor, at concentrations of 1 nM-1 µM, did they attenuate the hemolysis induced by osmotic imbalance (hypotonic hemolysis). Similarly, SCR-WE also did not modify micelle formation or hypotonic hemolysis, except at the highest concentration. These results suggest that SIN and MAG potently protect the erythrocyte membrane from LPC-induced damage and contribute to the beneficial action of SCR-WE. The protective effects of SIN and MAG are mediated by some mechanism other than prevention of micelle formation or protection of the erythrocyte membrane against osmotic imbalance.

Effects of Saireito, a Japanese herbal medicine, on edema via antagonistic actions against aldosterone in anti-GBM nephritic rats.

BACKGROUND: In order to clarify the diuretic mechanisms of Saireito, a Japanese herbal medicine, the mineralcorticoid receptor antagonistic action of Saireito was evaluated in anti-glomerular basement membrane (GBM) nephritic rats. METHODS: Anti-GBM nephritis was induced in rats by the intravenous, injection of anti-GBM serum, and test drugs were administered 5 days after the induction of nephritis. In addition, we also investigated aldosterone-loaded mice to clarify the effects of test drugs on aldosterone signal transduction. In an in vitro study, a mineralocorticoid receptor binding assay of the components of Saireito was performed. RESULTS: Saireito and spironolactone inhibited the development of proteinuria and abdominal ascites in anti-GBM nephritic rats. Saireito and spironolactone increased the urine volume and decreased the abdominal saline content in aldosterone-loaded mice. Saikosaponin H, a component of Saireito, inhibited the receptor binding of aldosterone in the in vitro assay 50% inhibitory concentration ([IC(50)], 22 micromol/l). Saikosaponin H also inihibited the decrease in urine volume in aldosterone-loaded mice. CONCLUSIONS: These results suggest that the diuretic action of Saireito may be partly due to an antagonistic action on the mineralocorticoid receptor, exerted by saikosaponin H.

Suppressive effects of isorhynchophylline on 5-HT2A receptor function in the brain: behavioural and electrophysiological studies.

Isorhynchophylline is a major oxindole alkaloid found in Uncaria species which have long been used in traditional Chinese medicine. Here, we investigated the effects of isorhynchophylline and isorhynchophylline-related alkaloids on 5-hydroxytryptamine (5-HT) receptor-mediated behavioural responses in mice and 5-HT-evoked current responses in Xenopus oocytes expressing 5-HT2A or 5-HT2C receptors. Isorhynchophylline dose-dependently inhibited 5-HT2A receptor-mediated head-twitch but not 5-HT1A receptor-mediated head-weaving responses evoked by 5-methoxy-N,N-dimethyltryptamine. Pretreatment with reserpine, a monoamine-depleting agent, enhanced the head-twitching, but did not influence the effect of isorhynchophylline on the behavioural response. Isocorynoxeine, an isorhynchophylline-related alkaloid in which the configuration of the oxindole moiety is the same as in isorhynchophylline, also reduced the head-twitch response in reserpinized mice over the same dose range as isorhynchophylline, while both rhynchophylline and corynoxeine, stereoisomers of isorhynchophylline and isocorynoxeine, did not. None of the alkaloids tested had an effect on meta-chlorophenylpiperazine-induced hypolocomotion, a 5-HT2C receptor-mediated behavioural response. In experiments in vitro, isorhynchophylline and isocorynoxeine dose-dependently and competitively inhibited 5-HT-evoked currents in Xenopus oocytes expressing 5-HT2A receptors, but had less of a suppressive effect on those in oocytes expressing 5-HT2C receptors. These results indicate that isorhynchophylline and isocorynoxeine preferentially suppress 5-HT2A receptor function in the brain probably via a competitive antagonism at 5-HT2A receptor sites and that the configuration of the oxindole moiety of isorhynchophylline is essential for their antagonistic activity at the 5-HT2A receptor.

Effects of rikkunshi-to, a traditional Japanese medicine, on the delay of gastric emptying induced by N(G)-nitro-L-arginine.

We evaluated the effects of Rikkunshi-to and several of its ingredients on the delay of gastric emptying induced by a nitric oxide (NO) synthase inhibitor, N(G)-nitro-L-arginine (L-NNA). After oral administration of L-NNA to rats, the gastric emptying rate at 24 h was decreased from 82.8 +/- 2.4% to 53.3 +/- 5.7%. The decrease of the gastric emptying rate induced by L-NNA treatment was markedly ameliorated by administration of Rikkunshi-to (250 and 500 mg/kg, p.o.) in a dose-dependent manner. To identify the active ingredient of Rikkunshi-to, the components were separated according to polarity, and the effects of the respective fractions on gastric emptying were evaluated. Significant efficacy was found in the water and methanol fractions, but not in the 50% aqueous-methanol fraction. Furthermore, hesperidin (1 - 4.29 mg/kg, p.o.) contained in the methanol fraction and L-arginine (4.5 mg/kg, p.o.) contained in the water fraction ameliorated the decrease in the gastric emptying rate induced by L-NNA treatment. These results suggest that Rikkunshi-to ameliorated abnormalities of NO-mediated gastric functions such as delayed gastric emptying, and hesperidin and L-arginine were identified as two of the active ingredients contributing to the ability of Rikkunshi-to to facilitate gastric emptying.

Inhibitory effects of triterpenes isolated from Chuling (Polyporus umbellatus Fries) on free radical-induced lysis of red blood cells.

Chuling, sclerotia of Polyporus umbellatus FRIES, has long been used for urological disorders in traditional medicine. In this study, we demonstrated that Chuling in vitro protects red blood cells from 2,2-azo-bis(2-amidinopropane)dihydrochloride (AAPH)-induced hemolysis. The inhibitory effect was dose-dependent at concentrations of 50 to 1000 microg/ml. Moreover, tests were carried out to identify the main ingredient of Chuling with scavenging effect on free radicals. Triterpene carboxylic acids isolated from the methanol extract of Chuling, namely, polyporusterone A and polyporusterone B, were found to have inhibitory activities against AAPH-induced lysis of red blood cells. The anti-hemolytic effect was significantly stronger in polyporusterone B compared with polyporusterone A. Furthermore, the ingestion of 150 mg of Chuling was associated with a significant increase in free-radical scavenging effect of plasma in rats.

Inhibitory effects of Stephania tetrandra S. Moore on free radical-induced lysis of rat red blood cells.

Crude preparations of Stephania tetrandra S. MOORE (ST), a traditional herbal medicine, have been used safely for arthritis and silicosis in China. In this study, we demonstrated that ST in vitro protects red blood cells from 2,2-azo-bis (2-amidinopropane) dihydrochloride (AAPH)-induced hemolysis. The inhibitory effect was dose-dependent at concentrations of 10 to 1000 microg/ml. Moreover, tests were carried out to identify the main ingredient of ST that exerts a scavenging effect on free-radicals. Three representative alkaloids, tetrandrine, fangchinoline, and cyclanoline, isolated from ST, were found to have inhibitory activities against AAPH-induced lysis of red blood cells (RBC). Furthermore, the ingestion of 200 mg of ST extract was associated with a significant increase in free-radical scavenging effect of plasma in rats. These results suggest that ST as antioxidant inhibits AAPH-induced hemolysis of RBC both in vitro and in vivo.

Separation and isolation methods for analysis of the active principles of Sho-saiko-to (SST) oriental medicine.

Sho-saiko-to (SST) was introduced into Japan as an oriental classical medicine from China approximately 1500 years ago, and it is currently the most representative Kampo medicine (traditional Japanese medicine). SST is manufactured in Japan as an ethical drug on a modern industrial scale in which the quality of ingredients is standardized with Good Manufacturing Practices (GMP) regulation. SST is widely used for the treatment of chronic hepatitis. Experimental and clinical studies including multi-center, placebo-controlled, double-blind studies have demonstrated the various pharmacological effects of SST. SST is prepared from the hot water extraction of seven raw materials, therefore many kinds of constituents are included. Three-dimensional (3D) HPLC analysis is useful for obtaining many kinds of constituents, especially low molecular ultraviolet (UV) quenching compounds, contained in SST as well as its fractions. Fingerprint pattern provided by 3D HPLC analysis makes possible to identify the overall-viewing of SST. Databases of UV spectra of the components of medicinal herbs obtained by reversed-phase (RP) HPLC using a photodiode array (PDA) and fingerprint patterns of crude drugs made by 3D HPLC analysis facilitate the identification, analysis and quality of herbal drugs. Studies using both PDA HPLC and an amino acid analysis with a fluorometric detector have found that SST contains fifteen major low molecular compounds (i.e. baicalin, wogonin-7-O-glucuronide, liquiritin, their three aglycons, liquiritin apioside, glycyrrhizin, saikosaponin b1, saikosaponin b2, ginsenoside Rg1, ginsenoside Rb1, (6)-gingerol, (6)-shogaol and arginine). These compounds have various pharmacological actions, and are assumed to be responsible, at least partly, for the pharmacological effects of SST. Although there have only been a few investigations on high molecular compounds with pharmacological actions contained in SST, several kinds of polysaccharides have been isolated from constituent herbs of SST. This review paper summarizes analytical methods of separation, isolation and identification of compounds with biological activities from SST, which is a mixture drug of medicinal herbs. Accordingly, this paper would not focus on methods of separation, isolation and analysis of particular compounds from each constituent herb of SST.

Protective effects of Choto-san and hooks and stems of Uncaria sinensis against delayed neuronal death after transient forebrain ischemia in gerbil.

Previously, we revealed that Choto-san (Diao-teng-san in Chinese), a Kampo formula, is effective on vascular dementia clinically, and the hooks and stems of Uncaria sinensis (Oliv.) Havil., a medicinal plant comprising Chotosan, has a neuroprotective effect in vitro. In the present study, for the purpose of clarifying their effects in vivo, we investigated whether the oral administration of Choto-san extract (CSE) or U. sinensis extract (USE) reduces delayed neuronal death following ischemia/reperfusion (i/rp) in gerbils. Transient forebrain ischemia was induced by bilateral carotid artery occlusion for 4 min, and two doses (1.0% and 3.0%) of CSE or USE were dissolved in drinking water and provided to the gerbils ad libitum from 7 days prior to i/rp until 7 days after i/rp. It was found that 1.0% and 3.0% CSE treatments significantly reduced pyramidal cell death in the hippocampal CA1 region at 7 days post i/rp. Three percent USE treatment also inhibited pyramidal cell death significantly at 7 days after i/rp. Superoxide anion and hydroxyl radical scavenging activities of the homogenized hippocampus at 7 days after i/rp in the 1.0% CSE- and 3.0% USE-treated groups were significantly enhanced compared to those of control. Further, lipid peroxide and NO2-/NO3- levels of the homogenized hippocampus at 48h after i/rp in the 1.0% CSE- and 3.0% USE-treated groups were significantly lower than those of control. These results suggest that the oral administration of CSE or USE provides a protective effect against transient ischemia-induced delayed neuronal death by reducing oxidative damage to neurons.

Pharmacological evidence for antidementia effect of Choto-san (Gouteng-san), a traditional Kampo medicine.

To clarify the clinical efficacy of one of the traditional medicines in the treatment of patients with vascular dementia, we investigated the pharmacological activities of Choto-san in animal models. Pretreatment with Choto-san (0.75-6.0 g/kg po), a component herb, Chotoko (75-600 mg/kg po), and indole alkaloids and phenolic fractions of Chotoko prevented ischemia-induced impairment of spatial learning behaviour in water maze performance of mice. A single administration of Choto-san (0.5 to 6.0 g/kg po) or Chotoko (Uncaria genus) produced a dose-dependent antihypertensive effect in spontaneously hypertensive rats (SHR) and partly inhibited the induction of the apoplexy in stroke-prone SHR (SHR-SP). Choto-san, Chotoko, and its phenolic constituents, (-)epicatechin and caffeic acid, significantly protected NG108-15 cells from injury induced by H(2)O(2) exposure in vitro and also inhibited lipid peroxidation in the brain homogenate. Indole alkaloids, rhynchophylline and isorhynchophylline (1-100 microM), reversibly reduced N-methyl-D-aspartate (NMDA)-induced current concentration dependently in NMDA receptor-expressed Xenopus oocytes. These results suggest that antidementia effects of Choto-san are due to antihypertensive, free radical scavenging and antiexcitotoxic effects, which are attributed at least partly to phenolic compounds and indole alkaloids contained in Chotoko.

Effects of goshajinkigan on corneal sensitivity, superficial punctate keratopathy and tear secretion in patients with insulin-dependent diabetes mellitus.

Goshajinkigan (niu-che-shen-qi-wan in Chinese), a traditional herbal medicine, has been used in Japan to treat clinical symptoms of diabetic neuropathy. A double-masked study was performed to evaluate its effects on corneal sensitivity, superficial punctate keratopathy and tear production in patients with insulin-dependent diabetes mellitus. Fifty diabetic patients were randomized into two groups: Group A, in which 25 patients received goshajinkigan orally, 7.5 g/day for 3 months; Group B, in which 25 patients were orally administered placebo, 6.0 g/day for 3 months; and in Group C, 25 non-diabetic subjects were orally administered goshajinkigan, 7.5 g/day for 3 months. Corneal sensitivity was measured with an aesthesiometer. The area of superficial punctate keratopathy was expressed as a fluorescein staining score. Reflex tearing was determined with a Schirmer test without anesthesia goshajinkigan was analyzed by high-performance liquid chromatography. Corneal thresholds after treatment with goshajinkigan (2.03 g/mm2) in Group A were significantly lower than those before treatment (2.47 g/mm2). Those in Groups B and C did not change after treatment. Fluorescein staining scores after administration of Goshajinkigan (0.64) in Group A were significantly lower than those before treatment (1.32). Those in Groups B and C did not change after treatment. Schirmer test results after goshajinkigan administration (11.0 mm/5 min) in Group A were significantly higher than those before treatment (9.3 mm/5 min). Those in Groups B and C did not change after treatment. Hemoglobin A1c levels in Groups A, B,and C did not change after treatment. Several components in goshajinkigan were found on high performance liquid chromatography. In conclusion, goshajinkigan improved ocular surface disorders in patients with insulin-dependent diabetes mellitus.

Inhibitory effects of Oren-Gedoku-To (Huanglian-Jie-Du-Tang) on free radical-induced lysis of human red blood cells.

Oren-gedoku-to (Huanglian-Jie-Du-Tang, OGT) has been used for the treatment of cerebrovascular disease, hypertension, gastritis and liver disease in Japan. The present study was to test our hypothesis that ingestion of Oren-gedoku-to extract (TJ-15) would protect red blood cell (RBC) membrane from free radical-induced oxidation if antioxidants in OGT could be absorbed and circulated in blood. When incubated with RBC suspension, OGT and its four constituting herbs provided strong protection for RBC membrane to hemolysis induced by 2,2-azo-bis (2-amidinopropane) dihydrochloride (AAPH), an azo free radical initiator. The inhibitory effect was in a dose-dependent manner at concentrations of 5 microgram/ml to 500 microgram/ml. Furthermore, the ingestion of 7.5 g of OGT (daily dose) was associated with a significant decrease in susceptibility of RBC to hemolysis in humans. The direct protection of RBC membrane from free-radical attack as observed in the present study could provide an important pathophysiological basis for making use of the favorable hemorheological effect of OGT.

Inhibitory effects of triterpenes isolated from Hoelen on free radical-induced lysis of red blood cells.

Hoelen, sclederma of Poria cocos Wolf, has long been used as a sedative and diuretic in traditional medicine. Formerly, we demonstrated that Hoelen in vitro protects red blood cells from AAPH-induced hemolysis. In this study, tests were carried out to identify the main ingredient of Hoelen that has the scavenging effect on free-radicals. Triterpene carboxylic acids isolated from the methanol extract of Hoelen, i.e. pachymic acid, polyporenic acid, 3-epidehydrotumulosic acid, 3beta-hydroxylanosta-7,9(11), 24-trien-21-oic acid and 3-o-acetyl-16 alpha -hydroxytrametenolic acid, were found to have inhibitory activities against AAPH-induced lysis of red blood cells.

Effect of the rhizomes of Atractylodes lancea and its constituents on the delay of gastric emptying.

The effect of rhizomes of Atractylodes lancea on gastric disorders, in particular, the delay in gastric emptying induced by N(G)-nitro-L-arginine in rats, was investigated. Intragastric treatment with an aqueous extract (250 mg/kg) and its lipophilic fractions (4 mg/kg) significantly improved delayed gastric emptying. The major constituents of the lipophilic fraction were two sesquiterpens, hinesol and beta-eudesmol, and four known polyacetylenic compounds, atractylodin, atractylodinol, acetylatractylodinol and 4,6,12-tetradecatriene-8,10-diyne-1,3,14-triol. The activity was found in the four polyacetylenic compounds at a similar potency, but not in the two sesquiterpens. To clarify the effect of the four polyacetylenic compounds in this extract, we attempted to evaluate the activity of atractylodin, as representative, at a dose of 0.2 mg/kg based on the total amounts (0.2 mg/250 mg aqueous extract) of the four polyacetylenic compounds. In addition, atractylodin improved the delay in gastric emptying at between 0.1 and 0.3 mg/kg in a dose-dependent manner. These results suggest that the aqueous extract improved the delayed gastric emptying, and polyacetylenic compounds contributed to its activity.

Components of Panax ginseng that improve accelerated small intestinal transit.

We previously clarified that Dai-kenchu-to, a Chinese prescription, was useful for improving carbachol-induced hyperperistalsis of the small intestine in vivo, and the efficacy of Ginseng Radix, a crude drug component of Dai-kenchu-to, was also confirmed. Ginseng Radix, the root of Panax ginseng C.A. Meyer, showed significant ameliorative effects on both the carbachol-induced and the BaCl(2)-induced accelerated small intestinal transit model in mice, suggesting that both an inhibitory effect on the cholinergic nervous system and direct suppressive effect on muscles were involved in the ameliorative effect of Ginseng Radix on the accelerated small intestinal transit. Ginsenoside Rb1 (4) and ginsenoside Rd (7), major components of Ginseng Radix, improved both animal models. These results suggest that ginsenoside Rb1 (4) and ginsenoside Rd (7) were representative compounds of Ginseng Radix for improving the accelerated movement of the small intestine and that these compounds partly contribute to the action of Dai-kenchu-to on small intestinal transit.

Component of Zingiber officinale that improves the enhancement of small intestinal transport.

6-Shogaol, a constituent of Zingiber officinale, improved carbachol-induced accelerated small intestinal transit in vivo, as well as improving longitudinal muscle contraction induced by low-frequency electrical stimulation of the isolated guinea pig small intestine in vitro. In addition, 6-shogaol ameliorated BaCl(2) -induced hyperperistalsis of the small intestine in vivo.

Pharmacological evaluation of Shokyo and Kankyo (1).

Zingiberis Rhizoma (Shokyo, [Japanese characters: see text]) showed significant ameliorative effect on the BaCl2-induced delay of gastric emptying in rat. Bioassay-guided fractionation of the aqueous extract of Shokyo resulted in isolation of 6-gingesulfonic acid (1) and shogasulfonic acid A (3). These compounds significantly improved the delay of gastric emptying on both BaCl2-induced and N(G)-nitro-L-arginine (L-NNA)-induced model in rat. Zingiberis Siccatum Rhizoma (Kankyo, [Japanese characters: see text]) had significant efficacy against castor oil-induced diarrhea. In addition, Kankyo showed the activity increasing intestinal blood flow in normal rat.

Suppressive effect of hochu-ekki-to on collagen induced arthritis in DBA1J mice.

OBJECTIVE: To investigate the effect of hochu-ekki-to (HET) decoction on the development of collagen-induced arthritis (CIA) in mice. METHODS: CIA was induced in male DBA/IJ mice by immunization with 2 injections of bovine type II collagen (CII). HET was orally administered at different doses and with different schedules. The incidence of arthritis, arthritis index, levels of anti-CII antibody, interleukin 6 (IL-6), and tumor necrosis factor-alpha (TNF-alpha) and lymphocyte subsets were examined. RESULTS: HET caused suppression of CIA development in a dose dependent fashion and exerted a suppressive effect on CIA when administered from the first CII immunization or from the onset of CIA, but not when administered for 2 weeks before CII immunization. HET inhibited the production of specific anti-CII antibody, IL-6, and TNF-alpha, and tended to normalize the proportions of cells in lymphocyte subsets. CONCLUSION: HET suppresses the development of CIA, and HET redistributes the population of lymphocytes in lymph node and blood and inhibits IL-6 and TNF-alpha secretion in CIA mice.

Geissoschizine methyl ether, an indole alkaloid extracted from Uncariae Ramulus et Uncus, is a potent vasorelaxant of isolated rat aorta.

Effects of geissoschizine methyl ether, an indole alkaloid isolated from the hook of Uncariae Ramulus et Uncus, on vascular responses were examined using isolated strips of rat aorta. Geissoschizine methyl ether (10(-7)-10(-4) M) relaxed norepinephrine (5x10(-8) M)-induced contraction in a dose-dependent manner. The potency (50% efficacy concentration, EC(50)=0.744 microM) was approximately 14 times greater than that (EC(50)=10.6 microM) of hirsutine, one of the indole alkaloids isolated from Uncariae Ramulus et Uncus that demonstrates a vasorelaxant effect by Ca(2+)-channel blocking. The vasorelaxant effect of geissoschizine methyl ether found at the lower concentrations (10(-7)-3x10(-6) M) on the norepinephrine-induced contraction was abolished by pretreatment with N(G)-nitro-L-arginine (10(-4) M), an inhibitor of nitric oxide synthesis, or by denuding aortas of endothelium, while the effects at the higher concentrations (10(-5)-10(-4) M) were not completely prevented by either N(G)-nitro-L-arginine and deendothelialization. Furthermore, geissoschizine methyl ether did not relax high K(+)-, Ca(2+)- and a Ca(2+)-channel agonist Bay K8644-induced contractions at the lower concentrations that markedly relaxed the norepinephrine-induced contractions, while the higher concentrations of geissoschizine methyl ether relaxed the high K(+)-, Ca(2+)- and Bay K8644-induced contractions. These results suggest that the vasorelaxant effect of geissoschizine methyl ether is composed of two different mechanisms: endothelial dependency with nitric oxide and endothelial independency with voltage-dependent Ca(2+)-channel blocking.