Cytotoxic and leishmanicidal aminoglycosteroids and aminosteroids from Holarrhena curtisii

The EtOH extract of the leaves of Holarrhena curtisii yielded five new steroidal alkaloids: 17-epi-holacurtine (3), 17-epi-N-demethylholacurtine (4), holacurtinol (5), 3alpha-amino-14beta-hydroxypregnan-20-one (7), and 15alpha-hydroxyholamine (8), in addition to the known compounds, holacurtine (1), N-demethylholacurtine (2), and holamine (6). All eight compounds showed significant cytotoxic and leishmanicidal activities.     

Intestinal immune system modulating polysaccharides from rhizomes of Atractylodes lancea

Hot water extract (ALR-0) of rhizomes of Atractylodes lanceo DC. was fractionated into MeOH-soluble fraction (ALR-1), supernatant fraction of EtOH precipitation (ALR-3 + 4), and crude polysaccharide fraction (ALR-5). Among these fractions, only ALR-5 showed potent stimulating activity for proliferation of bone marrow cells mediated by Peyer's patch cells. ALR-5 gave three potently active carbohydrate-rich fractions (ALR-5IIa, 5IIb, and 5IIc) by anion-exchange chromatography on DEAE-Sepharose CL-6B, and three active polysaccharides (ALR-5IIa-1-1, ALR-5IIb-2-2, and ALR-5IIc-3-1) were further purified from the respective fractions. The order of activity was revealed to be ALR-5IIb-2-2 > or = ALR-5IIa-1-1 > ALR-5IIc-3-1, ALR-5IIa-1-1, 5IIb-2-2, and 5IIc-3-1 each was eluted as a single peak on HPLC and their molecular weights were estimated to be 74,000, 3,100, 16,000, respectively. ALR-5IIa-1-1 consisted mainly of Ara and Gal (molar ratio; 0.6: 1.0) in addition to a trace amount of uronic acid whereas ALR-5IIb-2-2 and ALR-5IIc-3-1 mainly comprised Ara, Gal, GlcA, and GalA (molar ratio; 0.2: 1.0: 0.2: 0.8, and 0.5: 1.0: 0.7: 1.5, respectively). Methylation analysis indicated that ALR-5IIa-1-1 consisted mainly of terminal Araf, 4- or 5-linked Ara, 3.4- or 3.5-branched Ara, and 3-linked, 4-linked, and 3,6-branched Gal. ALR-5IIb-2-2 and ALR-5IIc-3-1 were composed mainly of terminal Araf, 4- or 5-linked Ara, 4-linked Gal, 4-linked GalA, and terminal GlcA. In addition, ALR-5IIb-2-2 mainly comprised 4-linked Xyl whereas ALR-5IIc-3-1 consisted mainly of 2,4-branched Rha. Single radial gel diffusion indicated that ALR-5IIa-1-1 showed a strong reactivity with beta-glucosyl-Yariv antigen, whereas ALR-5IIb-2-2 and ALR-5IIc-3-1 did not show the reactivity with the antigen. Treatments of ALR-5IIa with NalO4, NaClO2 and pronase did not reduce the stimulating activity for Peyer's patch cells, however combination of exo-alpha-L-arabinofuranosidase and exo-beta-D-(1-->3)-galactanase digestions of ALR-5IIa-1-1 significantly decreased its activity.     

Phenylethanoid glycosides from Digitalis purpurea and Penstemon linarioides with PKCalpha-inhibitory activity

In a continuation of our search for potential tumor inhibitors from plants, it was found that the CH2Cl2-MeOH (1:1) extracts from Digitalis purpurea and Penstemon linarioides both showed PKCalpha-inhibitory bioactivity. Bioassay-directed fractionation of the extract from D. purpurea yielded the new, weakly active phenylethanoid glycoside 2-(3-hydroxy-4-methoxy-phenyl)-ethyl-O-(alpha-L-rhamnosyl)-(1-->3) -O- (alpha-L-rhamnosyl)-(1-->6)-4-O-E-feruloyl-beta-D-glucopy ran oside (1) together with the four known compounds calceolarioside A (2), calceolarioside B (3), forsythiaside (4), and plantainoside D (5). The extract from P. linarioides yielded the three known glycosides leucosceptoside A (6), acteoside (7), and poliumoside (8), together with the iridoid plantarenaloside (9). All of the isolated compounds, except compound 9, showed inhibitory activity against PKCalpha with IC50 values (in microM) of 125 (1), 0.6 (2), 4.6 (3), 1.9 (4), 14.8 (5), 19.0 (6), 9.3 (7), and 24.4 (8).     

Effects of the benzodiazepine inverse agonist RO19-4603 alone and in combination with the benzodiazepine receptor antagonists flumazenil, ZK 93426 and CGS 8216, on ethanol intake in alcohol-preferring (P) rats

The present study investigated dose dependence and time course effects of the benzodiazepine (BDZ) partial inverse agonist, RO19-4603 (0.005-0.30 mg/kg) alone, and in combination with the BDZ receptor antagonists flumazenil, ZK 93426, and CGS 8216 (20 mg/kg) in selectively bred alcohol-preferring (P) rats provided a two-bottle choice test between ethanol (EtOH) (10% v/v), and a palatable saccharin (0.0125% g/v) solution. A single dose of RO19-4603 as low as 0.009 mg/kg selectively reduced EtOH drinking during the initial 15 min of a 4 h access to 19-0% of control levels on day 1. The 0.08, 0.15 and 0.30 mg/kg doses of RO19-4603 significantly reduced total EtOH intake in the 4 h access period to 57-45% of controls on day 1. On day 2, no RO19-4603 injections were given; however, six of the seven doses of RO19-4603 (0.009, 0.02, 0.04, 0.08, 0.15, and 0.30 mg/kg) continued to reduce EtOH intake to 42-3% of control levels at the initial 15 min interval, while the 0.005, 0.009, 0.08, and 0.30 mg/kg doses reduced total 4 h EtOH intake to 60-42% of controls. Saccharin intake was either not altered by RO19-4603 or showed increases during the initial 15 min intervals and the total 4 h sessions on days 1 and 2. Food intake was also unaffected by RO19-4603. The CGS 8216, but neither flumazenil nor ZK 93426, reliably reversed the RO19-4603-induced suppression of EtOH intake on days 1 and 2. That certain BDZ inverse agonists can attenuate motivated behavior for EtOH reinforcement over a prolonged time course may provide a possible therapeutic approach to reducing EtOH consumption associated with alcoholism.     

Aldose reductase inhibitory constituents of the root of Salvia miltiorhiza Bunge

The constituents of the MeOH extract of Salvia miltiorhiza BUNGE, which showed strong aldose reductase (AR) inhibitory activity, were examined, and two new abietane-type diterpenoids, danshenol A (1) and danshenol B (2), were isolated together with six known ones: dihydrotanshimme I (3), cryptotanshinone (4), tanshinone I (5), tanshinone IIA (6), (-)-danshexinkun A (7), and sugiol (8). Among them, 4, 5, and 8 were weak AR inhibitors with IC50 from 4.80 to > 10.0 microM, while 1, 2, 3, 6, and 7 were strong inhibitors (IC50 from 0.10 to 1.75 microM). Danshenol A (1), the strongest inhibitor, had IC50 of 0.10 microM which is comparable to that of epalrestat in clinical use. Moreover, from a consideration of IC50, and yield of each compound, it was concluded that tanshinone IIA (6) is the major active constituent of the MeOH extract and danshenol A (I) and (-)danshexinkun A(7) are the minor ones.     

Fatty acyl desaturation in isolated hepatocytes from Atlantic salmon (Salmo salar): stimulation by dietary borage oil containing gamma-linolenic acid

The effects of different dietary oils on the fatty acid compositions of liver phospholipids and the desaturation and elongation or [1-14C]18:3n-3 and [1-14C]18:2n-6 were investigated in isolated hepatocytes from Atlantic salmon. Atlantic salmon smolts were fed diets containing either a standard fish oil (FO) as a control diet, a 1:1 blend of Southern Hemisphere marine oil and tuna orbital oil (MO/TO), sunflower oil (SO), borage oil (BO), or olive oil (OO) for 12 wk. The SO and BO diets significantly increased the percentages of 18:2n-6, 18:3n-6, 20:2n-6, 20:3n-6, and total n-6 polyunsaturated fatty acids (PUFA) in salmon liver lipids in comparison with the FO diet. The BO diet also increased the percentage of 20:4n-6. Both the SO and BO diets significantly reduced the percentages of all n-3 PUFA in comparison with the FO diet. The OO diet significantly increased the percentages of 18:1n-3, 18:2n-6, total monoenes, and total n-6 PUFA in liver lipids compared to the FO diet, and the percentages of all n-3 PUFA were significantly reduced. With [1-14C]18:3n-3, the recovery of radioactivity in the products of delta 6 desaturation was significantly greater in the hepatocytes from salmon fed SO, BO, and OO in comparison with the FO diet. The BO diet also increased the recovery of radioactivity in the products of delta 5 desaturation. Only the BO diet significantly affected the desaturation of [1-14C]18:2n-6, increasing recovery of radioactivity in both delta 6- and delta 5-desaturation products. In conclusion, dietary BO, enriched in gamma-linolenic acid (18:3n-6), significantly increased the proportions of both 20:3n-6 and 20:4n-6 in salmon liver phospholipids and also significantly increased the desaturation of both 18:2n-6 and 18:3n-3 in salmon hepatocytes. The possible relationships between dietary fatty acid composition, tissue phospholipid fatty acid composition, and desaturation/elongation activities are discussed.     

MR angiography of aneurysms in Beh?et disease: a report of four cases

Two new pregnane-type steroidal alkaloids, saligcinnamide [(20S,2'E)-20-(N,N-dimethylamino)-3beta-(3'-phenyl-2'-propenyl-N-meth ylamido)pregnane](1) and N(a)-methyl epipachysamine-D [(20S)-20-(N,N-dimethylamino)-3beta-(N-methylbenzamido)pregnane](2 ), along with a known base, epipachysamine D [(20S)-20-(N,N-dimethylamino)-3beta-(benzamido)pregnane] (3), were isolated from the EtOH extracts of the roots and stems of Sarcococca saligna. The new bases exhibited antibacterial activity against several human pathogenic bacteria. Two derivatives of 1, dihydrosaligcinnarnide [(20S)-20-(N,N-dimethylamino)-3beta-(3'-phenylpropionoyl-N-meth ylamido)pregnane](4) and dihydrosaligcinnamine [(20S)-20-(N,N-dimethylamino)-3beta-N-(3'-phenylpropyl-N-methylamino)pre gnane](5), and a derivative of 2, N(a)-methyl epipachysamine [(20S)-20-(N,N-dimethylamino)-3beta-(N-benzyl,N-methylamino)pregnane](6) were prepared and their antibacterial activity determined.     

Hepatoprotective, superoxide scavenging, and antioxidative activities of aromatic constituents from the bark of Betula platyphylla var. japonica

The 50% aqueous methanolic extract from the bark of Betula platyphylla SUKATCHEV var. japonica (MIQ). HARA was found to show potent inhibitory activity on the liver-injury induced by CCl4 or D-galactosamine (D-GalN)/lipopolysaccharide as well as O2- scavenging and antioxidative activities. From the 50% aqueous methanolic extract, two new diarylheptanoids named betulaplatosides Ia (1) and Ib (2) and a new arylbutanoid named betulaplatoside II (3) were isolated together with seventeen known aromatic constituents. 1, 2, and two known diarylheptanoids [(5S)-5-hydroxy-1,7-bis-(4-hydroxyphenyl)-3-heptanone 5-O-beta-D-apiofurano-syl-(1-->6)-beta-D-glucopyranoside (6) and aceroside VIII (7)] showed protective activity against D-GalN-induced cytotoxicity in primary cultured rat hepatocytes. Furthermore, several aromatic constituents exhibited potent O2- scavenging and antioxidative activities.     

Effects of tannins from Geum japonicum on the catalytic activity of thrombin and factor Xa of blood coagulation cascade

Bioassay-guided fractionation of the MeOH extract of the whole plant of Geum japonicum led to the isolation of seven known tannins. They were identified by spectroscopic methods as penta-O-galloyl-beta-glucoside (1), pedunculagin (2), 2, 3-(S)-hexahydroxydiphenoyl-D-glucose (3), tellimagrandin II (4), 2, 6-di-O-galloyl-D-glucose (5), casuariin (6), and 5-desgalloylstachyurin (7). Compounds 1, 2, 4, 6, and 7 showed potent anticoagulant activity by significantly prolonging the clotting of rabbit plasma. The inhibitory effect of 2 was competitively directed against thrombin. Its IC50 values for inhibition of the enzymatic activity of thrombin on synthetic substrate and fibrinogen were 0.18 and 0.15 microM, respectively. On the other hand, compounds 1, 4, 6, and 7 are mixed noncompetitive inhibitors of thrombin. Their IC50 values for inhibition of fibrinogen hydrolysis were twofold to sevenfold lower than those for the inhibition of synthetic substrate hydrolysis. Factor Xa was competitively inhibited by compounds 1, 2, 4, 6, and 7. The phenolic hydroxyl groups of the active tannins appear to play an important role in their inhibitory effect on the enzymes.     

New p-terphenyl and polyketide metabolites from the sclerotia of Penicillium raistrickii

Three new p-terphenyls (1-3), a new xanthone derivative (4), and two known fungal metabolites (5 and 6) have been isolated from the sclerotia of Penicillium raistrickii (NRRL 2039). The structures for 3,3"-dihydroxy-6'-desmethylterphenyllin (1); 3'-demethoxy-6'-desmethyl-5'-methoxycandidusin B (2); 6'-desmethylcandidusin B (3); and 1,3,5, 6-tetrahydroxy-8-methylxanthone (4) were determined on the basis of HRMS and NMR data. Although compounds 1 and 4 exhibited mild antiinsectan and antibacterial activity, griseofulvin (5) was responsible for most of the activity of the sclerotial extract in dietary assays against the corn earworm Helicoverpa zea.     

Determinants of left ventricular mass in early hypertension

Four modified cyclic hexapeptides, tenuecyclamides A-D (1-4), were isolated along with the known antibiotic, borophycin (5), from the methanol extract of Nostoc spongiaeforme var. tenue (TAU strain IL-184-6). The planar structure of tenuecyclamides A-D (1-4) was determined by homonuclear and inverse-heteronuclear 2D-NMR techniques as well as by high-resolution mass spectrometry measurements. The absolute configuration of the asymmetric centers was studied by Marfey's method for HPLC. The stereochemistry of the asymmetric centers in tenuecyclamides A and B (1 and 2) could not be fully determined, while that of tenuecyclamides C and D (3 and 4) was unambiguously determined.     

Novel cytotoxic acylated oligorhamnosides from Mezzettia leptopoda

Activity-guided fractionation of a stem extract of Mezzettia leptopoda using human oral epidermoid carcinoma (KB) cells led to the isolation of seven highly acylated oligorhamnosides. Four of these constituents are novel, namely, n-octyl 2-O-acetyl-alpha-L-rhamnopyranosyl-(1-->3)-2, 4-di-O-acetyl-alpha-L-rhamnopyranosyl-(1-->3)-4-O-hexanoyl-alpha-L-rh amnopyranoside (mezzettiaside 8) (1); n-octyl 2, 3-di-O-acetyl-alpha-L-rhamnopyranosyl-(1-->3)-4-O-hexanoyl-alpha-L-rh amnopyranoside (mezzettiaside 9) (2); n-octyl 2, 4-di-O-acetyl-alpha-L-rhamnopyranosyl-(1-->3)-4-O-hexanoyl-alpha-L-rh amnopyranoside (mezzettiaside 10) (3); and n-octyl 2,3, 4-tri-O-acetyl-alpha-L-rhamnopyranosyl-(1-->3)-4-O-hexanoyl-alpha-L-r hamnopyranoside (mezzettiaside 11) (4). Three known compounds were identified as mezzettiasides 2 (5), 3 (6), and 4 (7), respectively, previously isolated from this same plant. The structures of novel compounds 1-4 were determined by spectroscopic methods. All the isolates were evaluated against a panel of human cancer cell lines in this study, and compounds 1-2 and 4-7 were found to be weakly cytotoxic toward KB and/or human colon and lung cancer cell lines.     

Chronic ethanol administration down-regulates cannabinoid receptors in mouse brain synaptic plasma membrane

The effects of chronic ethanol (EtOH) consumption on the central nervous system may be related in part to its action on biological membranes by altering various receptor functions. In the current study, we examined the effects of chronic EtOH (4 day inhalation) on cannabinoid receptors (CB1) labeled with [3H]CP55,940 in synaptic plasma membranes (SPM) isolated from mouse brain. Our results indicate the presence of a high level of CB1 receptors in controls (Bmax=12.0+/-0.3 pmol mg-1 protein) which decreased significantly (-58%) in SPM from mouse brain chronically exposed to EtOH. This effect occurs without any changes in the receptor affinity (Kd=2. 3+/-0.3 nM for control and 2.9+/-0.3 nM for EtOH group, P>0.05). Dissociation kinetic results showed a dissociation rate constant (K-1) of 0.09+/-0.01 min-1 for control and this dissociation rate constant decreased significantly in the chronic EtOH treated mice brain (0.05+/-0.01 min-1, P<0.05). The competition studies with anandamide resulted in a substantial decrease in [3H]CP55,940 binding in both the control and EtOH group, with a decrease (P<0.05) in the Ki values in the SPM of chronic EtOH exposed mice. Hill transformation analysis showed an nH close to one in control (0. 92+/-0.01). This did not change significantly after chronic EtOH (0. 95+/-0.01) administration, which indicates the existence of a single class of receptor for [3H]CP55,940 binding in SPM from control and EtOH treated mice. The observed down-regulation of CB1 receptors by chronic EtOH may indicate the involvement of cannabinoid receptors in EtOH tolerance and dependence.     

Effects of gavage versus dosed feed administration on the toxicokinetics of benzyl acetate in rats and mice

8-epi-prostaglandin F2 alpha stimulated contraction of human myometrial strips obtained from five different donors at the time of hysterectomy with a pEC50 value of 6.3 +/- 0.5. In paired strips from the same donors the pEC50 value for the selective TP receptor agonist U46619 ([1R-[1a,4a,5b(Z),6a(1E,3S*)]]-7-[6-(3- hydroxy-1-octenyl)-2-oxabicyclo[2.2.1]hept-5-yl]-5-heptenoic acid) was 8.3 +/- 0.4. In strips from four other donors 8-epi-prostaglandin F2 alpha was ineffective whereas the pEC50 for U46619 was 6.9 +/- 0.3. Responses to 8-epi-prostaglandin F2 alpha were unaffected by the selective DP receptor antagonist BW A868C (3-benzyl-5-(6-carboxyhexyl)-1-(2- cyclohexyl-2-hydroxyethylamino)hydantoin) at 50 nM but were blocked by the selective TP receptor antagonist L670596 ((-)6,8-difluoro-9-p-methylsulfonyl benzyl-1,2,3,4- tetrahydrocarbazol-1-yl-acetic acid) at 50 nM. The pIC50 values obtained when the TP receptor antagonists GR 32191 ([1R- [1 alpha(Z),2 beta,3 beta,5 alpha]]-(+)-7-[5-[[(1,1'-biphenyl)-4- yl]methoxy]-3-hydroxy-2-(1-piperidinyl)cyclopentyl]-4-heptenoic acid), ICI D1542 ((4(Z)-6-[(2S,4S,5R)-2-[1-methyl-1-(2-nitro-4-tolyloxy)ethyl]- 4-(3-pyridyl)-1,3-dioxan-5-yl]hex-4-enoic acid), ICI 192605 (4(Z)-6-[(2,4,5-cis)-2-(2-chlorophenyl)-4-(2-hydroxyphenyl)-1,3- dioxan-5-yl]hexenoic acid), L670596 and SQ 29548 ([1S-(1 alpha,2 beta(5Z),3 beta,4 alpha]]-7- [3-[[2-[(phenylamino)carbonyl]hydrazino]methyl]-7- oxabicyclo[2.2.1]hept-2-yl]-5-heptenoic acid) were added cumulatively to strips pre-contracted with an EC80 concentration of 8-epi-prostaglandin F2 alpha were not significantly different from those obtained when an EC80 concentration of U46619 was used. The effects of 8-epi-prostaglandin F2 alpha on strips pre-contracted with an EC80 concentration of U46619 were not different from those of U46619 itself. It is concluded that in the non-pregnant human myometrium 8-epi-prostaglandin F2 alpha is a medium potency contractile agonist acting predominantly at the TP receptor.     

The Orc4p and Orc5p subunits of the Xenopus and human origin recognition complex are related to Orc1p and Cdc6p

The location of origins of DNA replication within the Saccharomyces cerevisiae genome is primarily determined by the origin recognition complex (ORC) interacting with specific DNA sequences. The analogous situation in vertebrate cells is far less clear, although ORC subunits have been identified in several vertebrate organisms including Xenopus laevis. Monoclonal antibodies were raised against Xenopus Orc1p and used for single-step immunoaffinity purification of the entire ORC from an egg extract. Six polypeptides ( approximately 110, 68, 64, 48, 43, and 27 kDa) copurified with Xenopus Orc1p. Protein sequencing also showed the 64-kDa protein to be the previously identified Xenopus Orc2p. Microsequencing of the 43- and 48-kDa proteins that copurified with Orc1p and Orc2p led to their identification as the Orc4p and Orc5p subunits, respectively. Peptide sequences from the 43-kDa protein also allowed the isolation of cDNAs encoding the Xenopus, mouse, and human ORC4 subunits. Human ORC5 was also cloned; its sequence displayed extensive homology to both Drosophila and yeast ORC5. Surprisingly, comparison of the amino acid sequences of Orc1p, Orc4p, and Orc5p suggests that they are structurally related to each other and to the replication initiation protein, Cdc6p. Finally, we present the sequence of the putative Xenopus and human Orc3p.     

Time-dependent alteration of epidermal growth factor receptor in rat stomach by ethanol feeding

This study investigated the time-dependent effects of ethanol (EtOH) feeding on epidermal growth factor binding and epidermal growth factor-mediated functions in the stomach. Adult male rats were fed either an isocaloric control or EtOH-containing liquid diet (36% total calories as EtOH) for 2, 4 and 6 weeks. At the end of each feeding period, animals were sacrificed and the stomach was dissected for the sample preparation. EtOH caused a time-dependent alteration (r = 0.89) of the 125I-epidermal growth factor binding to the gastric mucosal membrane (% control: week 2, 114%; week 4, 64%* and week 6, 45%*, n = 5, *P < 0.05). Protein kinase analysis also showed that EtOH caused a time-dependent decrease of epidermal growth factor-stimulated autophosphorylation of epidermal growth factor receptor protein (180 kDa) during three feeding periods. Western blot analysis, using anti-tyrosine phosphorylated epidermal growth factor receptor (active form) antibody, revealed a major immunoreactive protein band (180 kDa) in all samples pre-incubated with 1 microM epidermal growth factor. Consistent with data from kinase analysis, treatment of EtOH decreased the immunoreactivity of the active form of epidermal growth factor receptor (180 kDa) in the stomach. In conclusion, EtOH feeding caused a time-dependent alteration of epidermal growth factor receptor in the stomach, which may be one of the mechanisms underlying the gastric pathology associated with alcohol abuse.     

Some pharmacologic and toxicologic studies on Rhazya stricta decne in rats, mice and rabbits

1. This work examines some in vivo and in vitro pharmacologic and toxicologic effects of extracts of Rhazya stricta, a medicinal plant in the United Arab Emirates. 2. R. stricta extracts at doses of 0.1-10 mg reduced the mean arterial blood pressure (MBP) of anesthetized rats in a dose-dependent manner. The depressor effect was partially sensitive to atropine (5 microM). Although the MBP was reduced by 50% by both doses of extracts, the normal electrocardiogram pattern and the heart rate remained unaltered. 3. Acute treatment of rats with the lyophilized extract at doses of 4 g/kg produced a significant rise in insulin concentration. In streptozotocin-diabetic rats loaded orally with glucose (1 g/kg), R. stricta at doses of 8 g/kg produced significant decreases in plasma glucose concentration at 0.5 and 1 h after treatment. 4. Chronic treatment of rats and mice for 28 days with the lyophilized extract of R. stricta did not affect the plasma glucose or insulin concentration or any of the hematological or biochemical indices measured. 5. The extracts of R. stricta (0.5-4 g/kg) dose-dependently decreased the gastrointestinal transit time in mice by 4-50%. 6. The butanolic extract of R. stricta (1 and 2 g/kg) significantly reduced the carrageenan-induced increase in raw paw edema 3 and 4 h after the extract administration. 7. The rectal temperatures of normothermic and pyrexic rats were reduced significantly 0.5 and 1 h after administration of butanolic R. stricta at doses of 1 and 2 g/kg. 8. The butanolic extract of R. stricta at doses of 1 and 2 g/kg significantly increased the reaction time on the hot plate 30 and 60 min after administration to rats. 9. At concentration < 0.05 mg/ml (bath concentration), lyophilized water and butanol extracts of R. stricta potentiated the twitch responses induced by indirect electrical stimulation in the rat phrenic nerve diaphragm preparation. The responses were inhibited by concentrations > 0.05 mg/ml. Neostigmine (2 x 10(-4)M) did not alter these effects of the extracts. 10. R. stricta extracts dose-dependently decreased the force of contraction and heart rate of the isolated rabbit heart. Atropine (1 x 10(-5)M) had no effect on the inhibitory activity of these extracts. The lyophilized water extract (> 10 mg) and butanol extract (> 5 mg) produced irreversible inhibition and disturbances in the force of contraction and heart rate.     

Platelets enhance contractility in perfused rat mesenteric arteries: involvement of endothelin-1

We investigated the effects of platelet supernatant on pressor responses to norepinephrine in isolated perfused rat mesenteric arteries. Perfusion of the arteries with platelet supernatant for 2 h markedly enhanced the pressor responses to norepinephrine (10(-6) and 3 x 10(-6) M). This enhancement was significantly inhibited by phosphoramidon (10(-4) M), an endothelin converting enzyme inhibitor. Both BQ788 [N-cis-2,6-dimethylpiperidinocarbonyl-L-gamma-methylleucyl-D -1-methoxycarbonyltryptophanyl-D-norleucine] (10(-6) M), an endothelin ET(B) receptor antagonist, and bosentan (Ro47-0203, 4-tert-butyl-N-[6-(2-hydroxy-ethoxy)-5-(2-methoxy-phenoxy)-2,2-bipyri midin-4-yl]-benzenesulfonamide) (10(-5) M), a nonselective endothelin receptor antagonist, also prevented the potentiation of responses to norepinephrine evoked by platelet supernatant, but FR 139317 ((R)2-[(R)-2-[(S)-2-[[1-(hexahydro-1H-azepinyl)]carbonyl]amino-4-+ ++methylpentanoyl] amino-3-[3-(1-methyl-1H-indoyl)]propionyl]amino-3-(2-pyridyl) propionic acid) (10-6 M), an endothelin ET(A) receptor antagonist, had little effect. Suppressor doses of endothelin-1 (3 x 10(-10) M) or sarafotoxin S6c (S6c) (3 x 10(-10) M) potentiated significantly the norepinephrine-induced vasoconstriction, in the same preparation. Moreover, supernatant-induced enhancement of pressor responses to norepinephrine was markedly suppressed by TGF-beta1 neutralizing antibody. Transforming growth factor-beta1 (TGF-beta1) (40 pM) also significantly enhanced the pressor responses to norepinephrine (10(-6) M) and this enhancement was significantly inhibited by phosphoramidon. These results suggest that platelet-derived TGF-beta1 stimulates the vascular production of endothelin-1 and thereby enhances vasoconstrictor responses to norepinephrine. Platelet-induced enhancement of vasoconstrictor responses to norepinephrine seems to be mainly mediated by endothelin ET(B) receptor, in rat mesenteric arteries.     

Selective protective effect of an extract from Fumaria parviflora on paracetamol-induced hepatotoxicity

1. The hepatoprotective activity of an aqueous-methanolic extract of Fumaria parviflora was investigated against paracetamol- and CCI4-induced hepatic damage. 2. Paracetamol (1 g/kg; orally) produced 100% mortality in mice; pretreatment of animals with the plant extract (500 mg/kg; orally) reduced the death rate to 50%. 3. Pretreatment of rats with plant extract (500 mg/kg, orally twice daily for 2 days) prevented (P < 0.001) the paracetamol (640 mg/kg)-induced rise in serum enzymes alkaline phosphatase (ALP) and transaminases (GOT and GPT), whereas the same dose of the extract was unable to prevent (P > 0.05) the CCI4-induced rise in serum enzyme levels. 4. Posttreatment with 3 successive doses of the extract (500 mg/kg, 6 hourly) also restricted the paracetamol-induced hepatic damage. 5. The plant extract (500 mg/kg; orally) caused significant prolongation in pentobarbital (75 mg/ kg)-induced sleep as well as increased strychnine-induced lethality in mice (P < 0.05), suggestive of an inhibitory effect on microsomal drug metabolizing enzymes (MDME). 6. It is conceivable therefore, that Fumaria parviflora extract exhibits a selective protective effect against paracetamol-induced hepatotoxicity, probably mediated through MDME inhibition.