Apocynum venetum leaf extract, an antihypertensive herb, inhibits rat aortic contraction induced by angiotensin II: a nitric oxide and superoxide connection.

ETHNOPHARMACOLOGICAL RELEVANCE: The leaves extract of Apocynum venetum (AVLE), also known as "luobuma", have long been used in traditional Chinese medicine to treat hypertension and depression in parts of China and it has been shown to possess anti-oxidant and anti-lipid peroxidation effects. AVLE (10 µg/ml) has been reported to have a long-lasting endothelium-dependent relaxant effect and this effect has been proposed to be due to its nitric oxide(NO)-releasing and superoxide anion(SOA)-scavenging properties. AIM OF THE STUDY: The present study seeks to evaluate the differential actions of AVLE extract between Ang II- and PE-induced vasoconstriction and the involvement of superoxide anions. MATERIALS AND METHODS: Single dose of Ang II (100 nM and 1 nM)- or PE (0.1 µM)-induced contraction were assessed in both endothelium-intact and -denuded aortic rings after pre-incubation of AVLE (10 µg/ml) for 15 min. The experiment was repeated in either the presence of NO synthase inhibitor, L-NAME (300 µM) or selective AT(1) receptor inhibitor, losartan (0.1 nM), or superoxide scavenger, tiron (1 mM) or a combination of L-NAME and AVLE. Superoxide production was measured by using enhanced-chemiluminescence assay. RESULTS: We have demonstrated that AVLE (10 µg/ml) effectively suppressed the Ang II-induced contraction (100 nM and 1 nM) of both endothelium-intact and -denuded rat aortic rings. In endothelium-intact rings, L-NAME, reversed AVLE-induced inhibition of Ang II-contraction. PE-induced contraction was significantly inhibited by AVLE in endothelium-intact rings, but not in endothelium-denuded rings. The inhibition by AVLE of PE-induced contraction was totally abolished in the presence of L-NAME. Ang II-induced SOA production concentration dependently with the optimal effect seen at 100 nM of Ang II, and AVLE (0.3, 1, 10 µg/ml) reduced this effect. SOA production in Ang II-stimulated rings was significantly higher than unstimulated control rings, while PE did not stimulate SOA production at all. SOA formation in the presence of Ang II was also inhibited in the presence of SOD (superoxide scavenger), DPI (NADPH inhibitor) and losartan (specific AT(1) receptor antagonist). CONCLUSION: These results collectively suggest that the ability of AVLE in inhibiting Ang II-induced contraction via its SOA scavenging properties and nitric oxide releasing effect may account for its usage as an antihypertensive treatment in traditional folk medicine.

Apocynum venetum leaf aqueous extract inhibits voltage-gated sodium channels of mouse neuroblastoma N2A cells.

ETHNOPHARMACOLOGICAL RELEVANCE: Apocynum venetum Linn. (Apocynaceae family), also called Luobuma, is a shrub which grows widely in the Xinjiang Autonomous Region of China. Its leaves are used in herbal tea for the treatment of hypertension, anxiety and depression. Animal studies have also shown that Apocynum venetum leaf extract (AVLE) also exerts anti-depressant and anti-anxiety activities. The effects of AVLE on neuronal tissues in vitro are not fully understood. MATERIALS AND METHODS: Using the whole-cell voltage-clamp method, we studied the effects of AVLE on ion channels in cultured mouse neuroblastoma N2A cells. RESULTS: AVLE inhibited voltage-gated inward Na(+) current in a reversible and concentration-dependent manner (half-inhibitory concentration was 18 µg/ml and maximum inhibition at 100 µg/ml). AVLE specifically promoted steady-state inactivation of Na(+) channels but did not affect voltage-dependence of activation. The inhibitory effect was not use-dependent and was not affected by 300µM L-NAME, suggesting that NO was not involved in the action of AVLE in neuronal cells. AVLE also had a mild inhibitory effect on voltage-gated K(+) channels, but did not affect ATP-sensitive K(+) channels. CONCLUSIONS: Since voltage-gated Na(+) and K(+) channels are associated with neuronal excitability and therefore affect neurotransmission, the modulation of neuronal ion channels by AVLE may exert neuropharmacological effects. In particular, the inhibition of voltage-gated Na(+) currents by AVLE may in part account for the psychopharmacological effects of this herbal remedy.

Constituents and pharmacological effects of Eucommia and Siberian ginseng.

The bark and leaves of Eucommia ulmoides Oliv (Eucommiaceae) and "Siberian ginseng" (Ezoukogi in Japanese) prepared from the root bark or stem bark of Eleutherococcus senticosus Maxim (Acanthopanax senticosus Harms) have been used as tonic and anti-stress drug. The extracts of Eucommia showed anti-hypertensive, anti-complementary, anti-oxidative, and anti-gastric ulcer effects, and promoting collagen synthesis, accelating granuloma formation, and other pharmacological effects. The Siberian ginseng exhibited anti-fatigue, anti-stress, immuno-enhancing effect, CNS activity, and anti-depressive effect. By now, 40, 28, and 10 compounds have been isolated from Eucommia ulmoides bark, Eucommia ulmoides leaves, and Siberian ginseng, respectively, and their structures were elucidated. Their pharmacological activities were mainly due to lignans and iridoid glycosides.

Flavonol glycosides from the stems of Trigonella foenum-graecum.

Two kaempferol glycosides [kaempferol 3-O-beta-D-glucosyl(1-->2)-beta-D-galactoside 7-O-beta-D-glucoside and kaempferol 3-O-beta-D-glucosyl(1-->2)-(6"-O-acetyl)-beta-D-galactoside 7-O-beta-D-glucoside] as well as the quercetin glycoside [quercetin 3-O-beta-D-glucosyl(1-->2)-beta-D-galactoside 7-O-beta-D-glucoside] were isolated from the stems of Trigonella foenum-graecum L. (Leguminosae) along with a known kaempferol glycoside, lilyn [kaempferol 3-O-beta-D-glucosyl(1-->2)-beta-D-galactoside]. Their structures were established by analysis of chemical and spectral evidence.

Antidepressant effects of apocynum venetum leaves in a forced swimming test.

An extract of the leaves of Apocynum venetum L. (Apocynaceae) markedly shortened the immobility time of male rats in a forced swimming test (FST) in a dose range of 30-125 mg/kg, indicating a possible antidepressant activity. This effect was comparable to that of the tricyclic antidepressant imipramine (20 mg/kg). Neither imipramine (20 mg/kg) nor the Apocynum extract in various doses (30, 60, 125 mg/kg) produced any overt behavioural change or motor dysfunction in the open field test. This result confirms the assumption that the antidepressant effect of an Apocynum extract in the FST is specific. Further, it can be speculated that this effect might be related to hyperoside and isoquercitrin which are major flavonoids in the extract.

In vitro metabolism of plant lignans: new precursors of mammalian lignans enterolactone and enterodiol.

The metabolism of the plant lignans matairesinol, secoisolariciresinol, pinoresinol, syringaresinol, arctigenin, 7-hydroxymatairesinol, isolariciresinol, and lariciresinol by human fecal microflora was investigated to study their properties as mammalian lignan precursors. The quantitative analyses of lignan precursors and the mammalian lignans enterolactone and enterodiol were performed by HPLC with coulometric electrode array detector. The metabolic products, including mammalian lignans, were characterized as trimethylsilyl derivatives by gas chromatography-mass spectrometry. Matairesinol, secoisolariciresinol, lariciresinol, and pinoresinol were converted to mammalian lignans only. Several metabolites were isolated and tentatively identified as for syringaresinol and arctigenin in addition to the mammalian lignans. Metabolites of 7-hydroxymatairesinol were characterized as enterolactone and 7-hydroxyenterolactone by comparison with authentic reference compounds. A metabolic scheme describing the conversion of the most abundant new mammalian lignan precursors, pinoresinol and lariciresinol, is presented.

Induction of apoptosis by Acanthopanax senticosus HARMS and its component, sesamin in human stomach cancer KATO III cells.

Antitumor effect of the stem bark of Acanthopanax senticosus HARMS (ASH) from Hokkaido (Japanese name: Ezoukogi) on human stomach cancer KATO III cells was investigated. The extract of the stem bark of ASH prepared with hot water was dissolved in distilled water and used for the assay of antitumor effect on the KATO III cells. The exposure of KATO III cells to ASH led to both growth inhibition and induction of apoptosis. Morphological change showing apoptotic bodies was observed in the cells treated with ASH. The fragmentation by ASH of DNA to oligonucleosomal-sized fragments that are characteristics of apoptosis was observed to be concentration- and time-dependent. We have investigated which component in ASH is effective on the induction of apoptosis. Among chlorogenic acid, syringaresinol di-o-beta-D glucoside, syringin, and sesamin, components of the n-butanol extract prepared from ASH, sesamin suppressed the growth and induced apoptosis in the cells. These findings suggest that growth inhibition by ASH results from the apoptosis induced by sesamin, a component of ASH.

Effects of arctiin on PhIP-induced mammary, colon and pancreatic carcinogenesis in female Sprague-Dawley rats and MeIQx-induced hepatocarcinogenesis in male F344 rats.

Chemopreventive effects of arctiin, a lignan isolated from Arctium lappa (burdock) seeds, on the initiation or post initiation period of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) induced mammary carcinogenesis in female rats and on 2-amino-3, 8-dimethylimidazo[4,5-f]quinoxaline (MeIQx)-associated hepatocarcinogenesis in male rats were examined. In experiment 1, female Sprague-Dawley (SD) rats were given intragastric doses of 100 mg/kg body wt of PhIP once a week for 8 weeks as initiation. Groups of 20 rats each were treated with 0.2 or 0.02% arctiin during or after PhIP initiation. Control rats were fed 0.2 or 0.02% arctiin, or basal diet alone during the experimental period. Animals were killed at the end of week 48. Although the incidence of mammary carcinomas did not significantly differ among the PhIP-treated groups, multiplicity was significantly decreased in rats given 0.2 (0.7+/-0.7, P<0.05) or 0.02% (1.0+/-1.1, P<0.05) arctiin after PhIP initiation as compared with the PhIP alone controls (2.1+/-2.5). The average number of colon aberrant crypt foci was also significantly decreased in these two groups. Pancreas acidophilic foci were induced in PhIP treated animals with slight decrease in the multiplicity with arctiin during the initiation phase. For liver carcinogenesis, groups of 15 male F344 rats were given a single intraperitoneal injection of diethylnitrosamine (DEN) and starting 2 weeks later, they were administered 0.03% MeIQx in the diet, MeIQx together with 0.5% arctiin, 0.1% arctiin or basal diet for 6 weeks. They were subjected to two-third partial hepatectomy 3 weeks after DEN initiation and killed at the end of week 8 for glutathione S-transferase placental form (GST-P) immunohistochemistry. The numbers and areas of preneoplastic GST-P positive foci were elevated by the treatment with MeIQx, and further increased by the simultaneous treatment with arctiin. These results indicate that arctiin has a protective effect on PhIP-induced carcinogenesis particularly in the mammary gland in the promotion period. On the other hand, it may have a weak co-carcinogenic influence on MeIQx-induced hepatocarcinogenesis. In addition, the results suggested that PhIP is a weak pancreatic carcinogen in female SD rats, targeting acinar cells.

[Anesthetic management of patients with tracheal stenosis for endoscopic treatment: usefulness of laryngeal mask airway].

We report two cases of tracheal stenosis for endoscopic treatment under general anesthesia with laryngeal mask airway. The tracheal stenosis of the two patients was so close to the glottis that endotracheal tube could not be inserted, and laryngeal mask airway was beneficial for maintaining airway and obtaining operating field. During the procedure, patients breathed spontaneously and we could support their ventilation easily and sufficiently. Endoscopic treatment of the airway obstruction by Nd-YAG laser associated with balloon dilatation and stent is an effective method of relieving the distressing symptom of asphylaxia, and laryngeal mask airway is considered to be useful for performing successful endoscopic procedure.

Synthesis and antifungal activity of coumarins and angular furanocoumarins.

Angelicin, a naturally occurring furanocoumarin, that showed antifungal activity, was considered as a lead structure for a group of synthetic coumarins. Antifungal activities of the synthesized coumarins and angelicin derivatives were reported against Candida albicans, Cryptococcus neoformans, Saccharomyces cerevisiae and Aspergillus niger. Human cell line cytotoxicity of several coumarins was evaluated against KB cells. Angelicin and several potent antifungals showed to be non-toxic in this assay.

Effects of the lignan, arctiin, on 17-beta ethinyl estradiol promotion of preneoplastic liver cell foci development in rats.

Anti-promotional effects of arctiin, a lignan with antiestrogenic action, against 17-beta ethinyl estradiol (EE) and 2-acetylaminofluorene (2-AAF) were examined using a medium-term liver bioassay based upon the induction of glutathione S-transferase placental form (GST-P) positive foci in rat liver. Male F344 rats were initially injected with diethylnitrosamine (DEN, 200 mg/kg body weight) intraperitoneally and two weeks later were treated with arctiin (1%), EE (1.5 ppm or 5 ppm), 2-AAF (20 ppm), arctiin + EE (1.5 ppm or 5 ppm), or arctiin + 2-AAF (20 ppm) in the diet for 6 weeks and then killed, all rats being subjected to partial hepatectomy at week 3. EE and 2-AAF clearly increased the development of GST-P foci. Antipromotional effects of arctiin were observed only for 2-AAF. These findings provide experimental evidence that arctiin exerts weak-protective potential against hepatocarcinogenesis in rats.

Protective effects of Acanthopanax senticosus Harms from Hokkaido and its components on gastric ulcer in restrained cold water stressed rats.

The aim of this study is to investigate the pharmacological effect of the stem bark of Acanthopanax senticosus Harms from Hokkaido (Japanese name: Ezoukogi) in place of the root bark as a restorative tonic on the stress-induced gastric ulcer. In the test, the extract of the stem bark of A. senticosus prepared with hot water was dissolved in water and used for the assay of the protective effect of gastric ulcer (erosion) on stressed rats that were restrained on cold water. The result from a single oral administration of the stem bark of A. senticosus-extract (50, 100 and 500 mg/kg, per day) dissolved in 1 ml distilled water did not show any protective effect on gastric ulcer, but the protective effect was observed in a dose-dependent manner from the oral administration of the extract (50, 100 and 500 mg/kg, per day) for 2 weeks. Pre-administration of the stem bark of A. senticosus-extract in a dose of 500 mg/kg showed the most potent inhibition without affecting either body or adrenal glands weights. Among ether, chloroform, n-butanol and aqueous residue extracts from the stem bark of A. senticosus-extract, the n-butanol extract used for oral administration for 2 weeks showed an obvious inhibition of 61.1% on gastric ulcer, compared with the control group which was treated with distilled water in the same way. Chlorogenic acid and syringaresinol di-o-beta-D-glucoside, as the major components of the n-butanol extract, showed a significantly inhibitory effect on gastric ulcer, at 21.4% and 51.3%, respectively. We suggested that the protective effect of the stem bark of A. senticosus on gastric ulcer may be partially due to those of chlorogenic acid and syringaresinol di-o-beta-D-glucoside.

Phenylethanoids in the herb of Plantago lanceolata and inhibitory effect on arachidonic acid-induced mouse ear edema.

The five phenylethanoids, acteoside (1), cistanoside F (2), lavandulifolioside (3), plantamajoside (4) and isoacteoside (5) were isolated from the herb of Plantago lanceolata L. (Plantaginaceae). Compounds 1, the major phenylethanoid in the herb of P. lanceolata L., and 4, the major phenylethanoid in the herb of P. asiatica L., showed inhibitory effects on arachidonic acid-induced mouse ear edema.

Search for naturally occurring substances to prevent the complications of diabetes. II. Inhibitory effect of coumarin and flavonoid derivatives on bovine lens aldose reductase and rabbit platelet aggregation.

An EtOAc extract of Artemisiae Capillari Spica inhibited both bovine lens aldose reductase (bovine-LAR) and rabbit platelet aggregation. Two simple coumarins, scoparone (1) and scopoletin (2), and three flavonoids, capillarisin (21), cirsimaritin (22) and rhamnocitrin (23), were isolated from this extract. Scoparone (1) and scopoletin (2) exhibit a potent inhibitory effect on rabbit platelet aggregation induced by four types of agent, ADP, PAF, sodium arachidonate and/or collagen. Capillarisin (21) exhibits a potent inhibitory effect on bovine-LAR. In addition, thirteen simple coumarins, five coumarin glycosides and two flavonoids were tested for their inhibitory effect against bovine-LAR and rabbit platelet aggregation.

A phenylethanoid glycoside from Plantago asiatica.

A new phenylethanoid glycoside, plantasioside, was isolated from the aerial parts of Plantago asiatica. The structure of plantasioside was deduced from chemical and spectral evidence to be 1',2'-[beta(3,4-dihydroxyphenyl)-alpha,beta-dioxoethanol]-6'-O- caffeoyl- O-beta-D-glucopyranoside. In addition, the structure of orobanchoside from P. depressa and P. camtschatica was revised to be 1',2'-[beta(3,4-dihydroxyphenyl)- alpha,beta-dioxoethanol]-4'-O-caffeoyl-O-alpha-L-rham- nopyranosyl-(1-->3)-O- beta-D-glucopyranoside from beta-hydroxy-[beta(3,4-dihydroxyphenyl)-ethyl]-4'-O-caffeoyl-O-alp ha-L- rhamnopyranosyl-(1-->2)-O-beta-D-glucopyranoside.

Structural transformation of lignan compounds in rat gastrointestinal tract; II. Serum concentration of lignans and their metabolites.

Serum concentrations of arctiin, tracheloside, and their metabolites formed in the gastrointestinal tract were investigated in the rat. Arctiin or tracheloside was not detected in the serum after oral administration (200 mg/kg). In regard to their metabolites, each metabolite 1 (AM1, TM1), their genuine genins, appeared in the serum, and the serum concentration of arctiin metabolite 1 (AM1) reached its peak at 4 h and that of tracheloside metabolite 1 (TM1) reached its peak at 8 h. On the other hand, both metabolites 2 (AM2, TM2), which each possess a catechol moiety as reported previously, were not found in the serum. Now, we have studied the detection of their metabolites in the rat large intestinal contents after oral administration. It was revealed that all metabolites reported previously were certainly formed in rat gastrointestinal tract in vivo. Thus, we presumed a possibility that metabolite 2 was converted into metabolite 1 through C-3" methylation by catechol-O-methyltransferase (COMT) in rat liver. Each metabolite 2 was incubated with rat liver cytosol in the presence of S-adenosyl-L-methionine. It was proved that metabolite 2 was rapidly converted into metabolite 1 within 3 min. We suggest that arctiin or tracheloside was transformed to at least two metabolites in the gastrointestinal tract, and after absorption from the intestine, metabolite 2 was converted into metabolite 1 through methylation by COMT in the liver, and arctiin and tracheloside existed as metabolite 1, the genuine genin, in the blood stream.

Structural transformation of lignan compounds in rat gastrointestinal tract.

Structural transformation of arctiin and tracheloside, major components of seeds of Arctium lappa and Carthamus tinctorius, were investigated using rat gastric juice (pH 1.2-1.5) and rat large intestinal flora in vitro. Quantitative analysis of lignans and their metabolites was carried out by high performance liquid chromatography. Both lignans were stable in rat gastric juice and arctiin was rapidly transformed to arctigenin in rat large intestinal flora, followed by conversion to the major metabolite, 2-(3",4"-dihydroxybenzyl)-3-(3',4'-dimethoxybenzyl)-butyrolactone. On the other hand, tracheloside also decreased dependently with time and was converted to trachelogenin and its major metabolite, 2-(3",4"-dihydroxybenzyl)-3-(3',4'-dimethoxybenzyl)-2-hydroxybutyrola ctone. These experiments suggest that in the course of metabolism of lignans, firstly a cleavage of the glycosidic bond occurred and then demethylation of the phenolic methoxy group in the alimentary tract followed.

Growth factor stimulation of phospholipase C-gamma 1 activity. Comparative properties of control and activated enzymes.

We demonstrated previously tyrosine phosphorylation-dependent modulation of phospholipase C-gamma 1 (PLC-gamma 1) catalytic activity (Nishibe, S., Wahl, M. I., Hernandez-Sotomayor, S. M. T., Tonks, N. K., Rhee, S. G., and Carpenter, G. (1990) Science 250, 1253-1256). The increase in PLC-gamma 1 catalytic activity in A-431 cells occurs rapidly, with maximal activation 5 min after epidermal growth factor (EGF) stimulation. Certain other growth factors (fibroblast growth factor, platelet-derived growth factor) also stimulate PLC-gamma 1 catalytic activity, whereas insulin does not. A similar increase in PLC-gamma 1 specific activity (2-3-fold) was observed in both soluble (cytosol) and particulate (membrane) preparations from EGF-treated cells. Tyrosine-phosphorylated PLC-gamma 1 was detected in both cytosol and membrane fractions in lysates from EGF-treated A-431 cells, but the proportion of tyrosine-phosphorylated PLC-gamma 1 was higher in the cytosol (approximately 50%) than in the membrane (approximately 20%). Because a micellar concentration of the non-ionic detergent Triton X-100 allows detection of the tyrosine phosphorylation-dependent increase in PLC-gamma 1 catalytic activity in this assay, we evaluated the kinetic properties of PLC-gamma 1, immunoprecipitated from cytosol of control or EGF-treated cells, using substrate, phosphatidylinositol 4,5-bisphosphate (PtdIns 4,5-P2), solubilized in Triton X-100 at various molar ratios. The behavior of the control enzyme differed from the EGF-activated enzyme with respect to both Ks and Km. The control enzyme has a 7.5-fold higher Ks value than the activated enzyme (1.5 mM as compared with 0.22 mM). Activation by EGF is also a positive allosteric modifier of PLC-gamma 1-catalyzed PtdIns 4,5-P2 hydrolysis, i.e. the activated enzyme displayed apparent Michalis-Menton kinetics, with a Km of 0.6 mol fraction PtdIns 4,5-P2, whereas the control enzyme displayed sigmoidal kinetics with respect to PtdIns 4,5-P2 hydrolysis. At low substrate mol fractions (e.g. 0.07), the reaction velocity of the control enzyme was 4-fold lower than the activated enzyme. However, at a high substrate mol fraction (e.g. 0.33), the estimated maximal reaction velocities (Vmax) for both forms of PLC-gamma 1 were equivalent. PLC-gamma 1 activity from both control and EGF-treated cells was stimulated by increasing nanomolar Ca2+ concentrations. Although the catalytic activity of PLC-gamma 1 from EGF-treated cells was greater than control PLC-gamma 1 at every Ca2+ concentration tested, the relative stimulation of activity was markedly greater at Ca2+ concentrations above approximately 300 nM.