Structure of a highly acidic O-specific polysaccharide of lipopolysaccharide of Pseudoalteromonas haloplanktis KMM 223 (44-1) containing L-iduronic acid and D-QuiNHb4NHb

An acidic O-specific polysaccharide was obtained by mild acid degradation of the lipopolysaccharide isolated by phenol-water extraction of Pseudoalteromonas haloplanktis strain KMM 223 (44-1). L-Iduronic acid (IdoA) was found to be a component of the polysaccharide and identified by NMR spectroscopy and after carboxyl-reduction followed by acid hydrolysis and acetylation, by GLC-MS as 2,3,4-tri-O-acetyl-1,6-anhydroidose. On the basis of 1H and 13C NMR spectroscopic studies, including 1D NOE, 2D NOESY, HSQC and HMBC experiments, the following structure of the branched pentasaccharide repeating unit of the polysaccharide was established: -->4)-beta-D-GlcpAI-(1-->4)-beta-D-GlcpAII-(1-->3)-beta-D-++ +QuipNHb4NHbII- (1-->2)-alpha-L-IdopA-(-->4 increases 1 alpha-D-QuipNAc4NAcI where QuiNAc4NAc and QuiNHb4NHb are 2,4-diacetamido-2,4,6-trideoxyglucose and 2,4,6-tri-deoxy-2,4- di[(S)-3-hydroxybutyramido]glucose, respectively. This is the first report of L-iduronic acid in a lipopolysaccharide and of D-QuiNHb4NHb in nature.     

Structure of a neutral O-specific polysaccharide of the bacterium Proteus mirabilis O24

Lipopolysaccharide of the bacterium Proteus mirabilis O24 was found to have a neutral O-specific polysaccharide chain containing D-galactose, 2-acetamido-2-deoxy-D-glucose, and 2-acetamido-2-deoxy-D-galactose in ratios 1:2:1. On the basis of 1H- and 13C-NMR spectroscopy, including two-dimensional correlation spectroscopy (COSY), H-detected 1H, 13C heteronuclear multiple-quantum coherence (HMQC), and nuclear Overhauser effect spectroscopy (NOESY), the following structure of the branched tetrasaccharide repeating unit of the O-specific polysaccharide was established: -->3)-beta-D-GlcpNAc-(1-->4)-beta-D-GalpNAc-(1-->4)-beta-D-GlcpNAc-(1--> [formula: see text] beta-D-Galp.     

NMR spectroscopic elucidation of the structure of a glycerol teichoic acid-like O-specific polysaccharide of the bacterium Hafnia alvei strain PCM 1199

The structure of the acidic O-specific polysaccharide of a Gram-negative bacterium, H. alvei strain PCM 1199, was studied by NMR spectroscopy including two-dimensional correlation spectroscopy (COSY), total correlation spectroscopy (TOCSY), nuclear Overhauser effect spectroscopy (NOESY), 1H, 13C heteronuclear single-quantum coherence (HSQC), 1H, 13C heteronuclear multiple-bond correlation (HMBC), and one-dimensional 1H, 31P heteronuclear multiple-quantum coherence (HMQC) experiments. It was found that the polysaccharide contains D-galactose, 2-acetamido-2-deoxy-D-glucose, 4-acetamido-4,6-dideoxy-D-glucose, glycerol, and phosphate in the ratios 1:2:1:1:1, as well as O-acetyl groups in non-stoichiometric amounts. The polysaccharide is similar in structure to teichoic acids of Gram-positive bacteria and has the following structure of the repeating unit: 3)-beta-D-Galp-(1-->3)-alpha-D-GlcpNAc-(1-->3)-beta-D-Quip4NAc-(1- ->1)-Gro- 3-P-(O--> [formula: see text] beta-D-GlcpNAc [formula: see text] The O-specific polysaccharide of H. alvei PCM 1199 is structurally related to another teichoic acid-like O-specific polysaccharide of H. alvei PCM 1205 studied by us earlier.     

Structure of O-specific polysaccharide from Proteus mirabilis O10, containing a new component of O-antigens--L-altruronic acid

An acidic O-specific polysaccharide was obtained by mild acid degradation of the lipopolysaccharide of Proteus mirabilis O10 and studied after full acid hydrolysis and carboxyl reduction by 1H- and 13C-NMR spectroscopy, including two-dimensional correlation spectroscopy (COSY), H-detected heteronuclear 1H,13C multi-quantum coherence (HMQC), and rotating-frame nuclear Overhauser effect spectroscopy (ROESY). It was found that the polysaccharide contains 2-acetamido-2-deoxy-D-glucose, 2-acetamido-2-deoxy-D-galactose, D-galacturonic acid, and L-altruronic acid, and the following structure of the branched tetrasaccharide repeating unit of the polysaccharide was established: [sequence: see text]     

Studies on the constituents of Calliandra anomala (Kunth) Macbr. I. Structure elucidation of two acylated triterpenoidal saponins

Two novel triterpenoidal saponins, called calliandra saponins A and E, were isolated from the branches of Calliandra anomala (Kunth) Macbr. On the basis of the chemical and physiocochemical evidence, their structures were defined as 3-O-alpha-L-arabinopyranosyl-(1-->2)-alpha-L-arabinopyranosyl++ +-(1-->6)-2- acetamido-2-deoxy-beta-D-glucopyranosyl echinocystic acid 28-O-(beta-D-glucopyranosyl-(1-->3)-[beta-D-xylopyranosyl-(1-->3)-beta-D - xylopyranosyl-(1-->4)]-alpha-L-rhamnopyranosyl-(1-->2)-[(6S)-2-trans- 2,6-dimethyl-6-O-beta-D-xylopyranosyl-2,7-octadienoyl-(1-->6)]-bet a-D- glucopyranosyl) ester (4) and 3-O-alpha-L-arabinopyranosyl-(1-->2)-alpha-L-arabinopyranosyl++ +-(1-->6)-2- acetamido-2-deoxy-beta-D-glucopyranosyl echinocystic acid 28-O-[beta-D-glucopyranosyl-(1-->3)-[beta-D-xylopyranosyl-(1-->3)-beta-D - xylopyranosyl-(1-->4)]-alpha-L-rhamnopyranosyl-(1-->2)-[(6'S)-2'-trans- 2',6'-dimethyl-6'-O-(2-O-(6S)-2-trans-2,6-dimethyl-6-hydroxy-2,7-octa dienoyl)- beta-D-xylopyranosyl-2',7'-octadienoyl-(1-->6)]-beta-D-glucopyr ano syl] ester (5), respectively.     

Steroidal glycosides from Allium albopilosum and A. ostrowskianum

Chemical studies of the bulbs of Allium albopilosum and A. ostrowskianum have led to the isolation of two new steroidal saponins and four new cholestane glycosides together with several known compounds. The structures of the new compounds were established by the spectroscopic data, hydrolysis and chemical correlations as (25 R and S)-5 alpha-spirostane-2 alpha,3 beta,6 beta-triol 3-O-(O-beta-D-glucopyranosyl-(1-->2)-O-[3-O-acetyl-beta-D-xylopyranosyl- (1-->3)]-O-beta-D-glucopyranosyl-(1-->4)-beta-D-galactopyranoside), (25R)-2-O-[(S)-3-hydroxy-3-methylglutaroyl]-5 alpha-spirostane-2 alpha, 3 beta, 6 beta-triol 3-O-(O-beta-D-glucopyranosyl-(1-->2)-O-[beta-D-xylopyranosyl-(1-->3)]-O- beta-D-glucopyranosyl-(1-->4)-beta-D-galactopyranoside), (22S)-cholest-5-ene-1 beta,3 beta,16 beta,22-tetraol 1-O-alpha-L-rhamnopyranoside 16-O-(O-alpha-L-rhamnopyranosyl-(1-->3)-beta-D-glucopyranoside), 1 beta,3 beta,16 beta-trihydroxycholest-5-en-22-one 1-O-alpha-L-rhamnopyranoside 16-O-(O-alpha-L-rhamnopyranosyl-(1-->3)-beta-D-glucopyranoside), 1 beta,3 beta,16 beta-trihydroxy-5 alpha-cholestan-22-one 1-O-alpha-L-rhamnopyranoside 16-O-(O-alpha-L-rhamnopyranosyl-(1-->3)-beta-D-glucopyranoside) and (22S)-cholest-5-ene-1 beta,3 beta,16 beta,22-tetraol 16-O-(O-beta-D-glucopyranosyl-(1-->3)-beta-D-glucopyranoside).     

Chemoenzymatic synthesis of a 3IV,6III-disulfated Lewis(x) pentasaccharide, a candidate ligand for human L-selectin

The disulfated pentasaccharide 3-O-SO3(-)-beta-D-Galp-(1-->4)-[alpha-L-Fucp-(1-->3)]-6-O-SO3(-)- beta-D-GlcpNAc-(1-->3)-beta-D-Galp-(1-->4)-D-Glcp was prepared according to a chemoenzymatic approach, starting from 4-methoxybenzyl O-(4-O-acetyl-2,6-di-O-benzyl-beta- D-galactopyranosyl)-(1-->4)-O-2,3,6-tri-O-benzyl-beta-D-glucopyranoside, obtained in six steps from hepta-O-acetyl lactosyl bromide. Coupling of this lactose derivative with O-(3,4,6-tri-O-acetyl-2-deoxy-2-phthalimido-beta-D-glucopyranosyl) trichloracetimidate afforded, after dephthaloylation and re-N-acetylation, 4-methoxybenzyl O-(2-acetamido-2-deoxy-beta-D- glucopyranosyl)-(1-->3)-O-(2,6-di-O-benzyl-beta-D-galactopyranosyl)-(1-- >4)- O-2,3,6-tri-O-benzyl-beta-D-glucopyranoside. Regioselective sulfation at the primary position of the glucosamine residue was then successfully achieved and the benzyl groups were removed. Enzymatic galactosylation of 4-methoxybenzyl O-(2-acetamido-2-deoxy-6-O-sulfo-beta-D- glucopyranosyl)-(1-->3)-O-beta-D-galactopyranosyl-(1-->4)-O-beta-D- glucopyranoside sodium salt, and subsequent regioselective sulfation at position 3 of the outer galactose residue through the stannylene procedure, led then to 4-methoxybenzyl O-(3-sulfo-beta-D- galactopyranosyl)-(1-->4)-O-(2-acetamido-2-deoxy-6-sulfo-beta-D- glucopyranosyl)-(1-->3)-O-beta-D-galactopyranosyl)-(1-->4)-O-beta-D- glucopyranoside disodium salt, which was finally fucosylated using human milk alpha-(1-->3/4)-fucosyltransferase affording, after anomeric deprotection, the target pentasaccharide.     

Structure of the O-specific polysaccharide of an Aeromonas trota strain cross-reactive with Vibrio cholerae O139 Bengal

The O-specific polysaccharide of an Aeromonas trota strain was isolated by hydrolysis of the lipopolysaccharide at pH 4.5 followed by gel-permeation chromatography and found to consist of hexasaccharide repeating units containing D-galactose, L-rhamnose, 3,6-dideoxy-L-xylo-hexose (colitose, Col), 2-acetamido-2-deoxy-D-glucose and 2-acetamido-2-deoxy-D-galactose in the ratios 1:1:2:1:1. Partial hydrolysis of the polysaccharide with 48% hydrofluoric acid resulted in selective removal of colitose to give a modified polysaccharide containing the other four sugar constituents. On the basis of methylation analysis and NMR spectroscopic studies of the initial and modified, colitose-free polysaccharide, it was concluded that the repeating unit of the O-specific polysaccharide has the following structure [sequence: see text] The known cross-reactivity between the strain studied and Vibrio cholerae O139 Bengal is substantiated by the presence of a common colitose-containing epitope shared by the O-specific polysaccharide of A. trota and the capsular polysaccharide of V. cholerae, which is thought to carry determinants of O-specificity.     

Effects of non-REM sleep on ventilation and respiratory mechanics in adults with cystic fibrosis

A polysaccharide containing 2-acetamido-2-deoxy-D-glucose (GlcNAc), 2-acetamido-2-deoxy-L-fucose (FucNAc), and 2-acetamido-2-deoxy-D-galacturonic acid (GalNAcA) was isolated from an aqueous phenol extract of lipid-free, isolated cell walls of the reference strain for Acinetobacter baumannii serogroup O5, by mild acid hydrolysis of the extract and chromatography of the water-soluble products on Sephadex G-50. By means of NMR studies, methylation analysis, carboxyl reduction and chemical degradations, the repeating unit of the polymer was identified as a branched tetrasaccharide of the structure shown. The serologically active polymer is believed to correspond to the side chain of the O5 lipopolysaccharide: [table: see text]     

Structure and epitope characterisation of the O-specific polysaccharide of Proteus mirabilis O28 containing amides of D-galacturonic acid with L-serine and L-lysine

The O-specific polysaccharide of Proteus mirabilis O28 was found to contain D-galactose, D-galacturonic acid (GalA), 2-acetamido-2-deoxy-D-glucose, L-serine, L-lysine, and O-acetyl groups in molar ratios 1:2:1:1:1:1, the amino acids being linked via their alpha-amino group to the carboxyl group of GalA. The polysaccharide was studied using 1H- and 13C-NMR spectroscopy, including selective spin-decoupling, one-dimensional total correlation spectroscopy, two-dimensional homonuclear correlation spectroscopy (COSY), heteronuclear 13C,1H COSY, one-dimensional NOE, and two-dimensional rotating-frame NOE spectroscopy and partial acid hydrolysis followed by borohydride reduction, methylation, and GLC/MS analysis of the derived glycosyl alditols. The following structure of the repeating unit was established: [formula: see text] Epitope specificity of the P. mirabilis O28 polysaccharide was analysed using a homologous rabbit polyclonal antiserum in quantitative precipitation, passive immunohemolysis, and inhibition of passive immunohemolysis. Study with related synthetic glycopolymers (2-acrylamidoethyl glycosides of amides of alpha-D-GalA with amino acids copolymerised with acrylamide) showed the importance of D-GalA(L-Lys) for manifesting serological specificity of the O-antigen. Serological cross-reactions between P. mirabilis O28, S1959, and R14/S1959 (a transient-like form) are discussed.     

Pharmacological characterization of metabotropic glutamate receptors coupled to phospholipase D in the rat hippocampus

1. Phospholipase D (PLD) is the key enzyme in a signal transduction pathway leading to the formation of the second messengers phosphatidic acid and diacylglycerol. In order to define the pharmacological profile of PLD-coupled metabotropic glutamate receptors (mGluRs), PLD activity was measured in slices of adult rat brain in the presence of mGluR agonists or antagonists. Activation of the phospholipase C (PLC) pathway by the same agents was also examined. 2. The mGluR-selective agonist (1S,3R)-l-aminocyclopentane-1,3-dicarboxylic acid [(1S,3R)-ACPD] induced a concentration-dependent (10-300 microM) activation of PLD in the hippocampus, neocortex, and striatum, but not in the cerebellum. The effect was particularly evident in hippocampal slices, which were thus used for all subsequent experiments. 3. The rank order of potencies for agonists stimulating the PLD response was: quisqualate > ibotenate > (2S,3S,4S)-alpha-(carboxycyclopropyl)-glycine > (1S,3R)-ACPD > L-cysteine sulphinic acid > L-aspartate > L-glutamate. L-(+)-2-Amino-4-phosphonobutyric acid and the ionotropic glutamate receptor agonists N-methyl-D-aspartate, alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid, and kainate failed to activate PLD. (RS)-3,5-dihydroxyphenylglycine (100300 microM), an agonist of mGluRs of the first group, stimulated PLC but inhibited the PLD response elicited by 100 microM (1S,3R)-ACPD. 4. (+)-alpha-Methyl-4-carboxyphenylglycine (0.1-1 mM), a competitive antagonist of mGluRs of the first and second group, elicited a significant PLD response. L-(+)-2-Amino-3-phosphonopropionic acid (1 mM), an antagonist of mGluRs of the first group, inhibited the 100 microM (1S,3R)-ACPD-induced PLC response but produced a robust stimulation of PLD. 5. 12-O-Tetradecanoylphorbol 13-acetic acid and phorbol 12,13-dibutyrate (PDBu), activators of protein kinase C, at 1 microM had a stimulatory effect on mGluRs linked to PLD but depressed (1S,3R)-ACPD-induced phosphoinositide hydrolysis. The protein kinase C inhibitor, staurosporine (1 and 10 microM) reduced PLD activation induced by 1 microM PDBu but not by 100 microM (1S,3R)-ACPD. 6. Our results suggest that PLD-linked mGluRs in rat hippocampus may be distinct from any known mGluR subtype coupled to PLC or adenylyl cyclase. Moreover, they indicate that independent mGluRs coupled to the PLC and PLD pathways exist and that mGluR agonists can stimulate PLD through a PKC-independent mechanism.     

The O-specific polysaccharide chain of Campylobacter fetus serotype A lipopolysaccharide is a partially O-acetylated 1,3-linked alpha-D-mannan

A polysaccharide fraction liberated from Campylobacter fetus subsp. fetus serotype A lipopolysaccharide by mild acid hydrolysis followed by gel-permeation chromatography contained a partially O-acetylated D-mannan chain, as an O-specific polysaccharide, with a core oligosaccharide attached. The structure of the polysaccharide was studied by O-deacetylation, methylation, and 1H- and 13C-NMR spectroscopy, including computer-assisted analysis of the 13C-NMR spectrum. A structure of -->3)-alpha-D-Manp2Ac-(1--> was established as the structure of the O-specific polysaccharide, the degree of O-acetylation of the mannose residues at position 2 being estimated as 80-90%. As judged by the ratio of mannose to core constituents, the D-mannan chain consists on average of 10-12 monosaccharide units.     

Structural characterization of the galactoxylomannan of Cryptococcus neoformans Cap67

The galactoxylomannan (GalXM) obtained from the culture supernatant of an acapsular mutant of Cryptococcus neoformans Cap67 was purified by Concanavalin A affinity, ion-exchange, and gel-filtration chromatographies. The structure of GalXM was determined by methylation analysis and by 1D and 2D NMR spectroscopic studies of the intact polysaccharide and of the oligosaccharide fragments generated by Smith degradation and by acetolysis. GalXM is a complex polysaccharide with an alpha-(1-->6) -galactan backbone. The polysaccharide is branched at c-3 of alternate Gal units of the backbone. C-3 is the point of attachment of the oligosaccharide side chains comprised of alpha-D-Man- (1-->3)-alpha-D-Man-(1-->4)- beta-D-Gal-substituted with zero to three terminal beta-Xyl residues as shown in the following structure: [formula: see text].     

Preparation of optically active succinic acid derivatives. III. Regioselective condensation reactions of optically active 2-substituted succinic acids with diimidazolide

We investigated the large scale synthesis of monocalcium bis [(2S)-2-benzyl-3-(cis-hexahydroisoindolin-2-ylcarbonyl) propionate] dihydrate (KAD-1229), which has a potent hypoglycemic effect, in a single reaction vessel. (2S)-2-Benzyl-3-(cis-hexahydroisoindolin-2-ylcarbonyl) propionic acid (7) was directly obtainable from (S)-2-benzylsuccinic acid (2) and cis-hexahydroisoindoline (4), without the isolation of intermediates by the method using thionyldiimidazole (9) and/or diimidazolide of the acid 2. Sequential reaction of imidazole with thionyl chloride, 2, and 4, followed by acid catalyzed hydrolysis gave amidecarboxylic acid 7 in 86% overall yield. The acid 7 was treated with 2 N NaOH, followed by the treatment with calcium chloride to give KAD-1229 in 91% yield.     

Design and synthesis of potent, selective inhibitors of endothelin-converting enzyme

Endothelin-1 is the most potent peptidic vasoconstrictor discovered to date. The final step of posttranslational processing of this peptide is the conversion of its precursor by endothelin-converting enzyme-1 (ECE-1), a metalloprotease which displays high amino acid sequence identity with neutral endopeptidase 24.11 (NEP) especially at the catalytic center. A series of potent and selective arylacetylene-containing ECE-1 inhibitors have been prepared. (S, S)-3-Cyclohexyl-2-[[5-(2, 4-difluorophenyl)-2-[(phosphonomethyl)amino]pent-4-ynoyl]amino] propio nic acid (47), an arylacetylene amino phosphonate dipeptide, was found to inhibit ECE-1 and NEP with IC50 values of 14 nM and 2 microM, respectively. Similarly, (S)-[[1-[(2-biphenyl-4-ylethyl)carbamoyl]-4-(2-fluorophenyl)but-3- yny l]amino]methyl]phosphonic acid (56), an arylacetylene amino phosphonate amide, had IC50's of 33 nM and 6.5 microM for ECE-1 and NEP, respectively. Slight modification of the aryl moiety was found to have dramatic effects on ECE-1/NEP selectivity. The 2-fluoro dipeptide analogue, (S, S)-2-[[5-(2-fluorophenyl)-2-[(phosphonomethyl)amino]pent-4-ynoyl]+ ++amin o]-4-methylpentanoic acid (40), showed a 72-fold selectivity for ECE-1 over NEP, while the 3-fluoro dipeptide analogue, (S, S)-2-[[5-(3-fluorophenyl)-2-[(phosphonomethyl)amino]pent-4-ynoyl]+ ++amin o]-4-methylpentanoic acid (22), was equipotent for ECE-1 and NEP. Several of these inhibitors were shown to be potent in blocking ET-1 production in vivo as demonstrated by the big ET-1-induced pressor response in rats. These potent inhibitors are the most selective for ECE-1 reported to date and are envisaged to have a variety of therapeutic applications.     

Control of tissue progastrin concentrations in the rat

An acidic capsular and an O-specific polysaccharide were isolated from the marine microorganism Alteromonas haloplanktis KMM 156. Both polysaccharides have the identical structure and are built up of tetrasaccharide repeating units, containing two residues of L-rhamnose as well as a 2-acetamido-2-deoxy-D-glucose and a 3-O-[(R)-1-carboxyethyl]-D-glucose (Glc3Lac) residue. On the basis of methylation studies, 1H- and 13C-NMR-spectroscopy including nuclear Overhauser effect and two-dimensional heteronuclear 13C/1H correlation spectroscopy, the following structure was suggested for the polysaccharide repeating unit: [formula: see text]     

Lack of association between the alpha-adducin locus and essential hypertension in the Japanese population

A neutral O-specific polysaccharide obtained from the lipopolysaccharide of Proteus penneri strain 26 was studied using sugar analysis and 1H and 13C NMR spectroscopy, including two-dimensional NMR techniques. The following structure of the trisaccharide repeating unit was established: -->6)-alpha-D-GlcpNAc-(1-->3)-alpha-L-QuipNAc-(1-->3)-alpha-D-Glcp NAc-(1--> where L-QuiNAc is 2-acetamido-2,6-dideoxy-L-glucose (N-acetyl-L-quinovosamine). Cross-reactivity of the Proteus penneri 26 anti-O serum with other strains of P. penneri isolated in Poland and USA and one strain of P. vulgaris is discussed.     

Structure of the O-specific polysaccharide of Citrobacter freundii O3a,3b,1c

The following structure of the O-specific polysaccharide of Citrobacter freundii O3a,3b,1c containing D-mannose and D-rhamnose was established using sugar analysis and NMR spectroscopy, including computer-assisted analysis of the 13C NMR spectrum, 2D COSY, H,H-relayed COSY, heteronuclear 13C, 1H correlation (HETCOR), and rotating-frame NOE spectroscopy (ROESY):-->4)-alpha-D-Manp-(1-->3)-beta-D-Rhap-(1-->4) -beta-D-Rhap-(1-->.     

Structure of an acidic exopolysaccharide of Burkholderia pseudomallei

A recently described water-soluble exopolysaccharide of Burkholderia pseudomallei recognized by the IgG 1 monoclonal antibody 3015 [Steinmetz, I., Rohde, M. & Brenneke, B. (1995) Infect. Immun. 63, 3959-3965] was isolated by repetitive ethanol-precipitation steps and by anion-exchange chromatography. The structure of the polysaccharide was determined by a combination of chemical-derivatization and mass-spectrometric techniques (compositional and methylation analysis, GC/MS, and electrospray-ionization-MS/MS of reduced and permethylated hydrolytic fragments), and two-dimensional 1H-NMR methods (COSY, TOCSY and NOESY) and confirmed by isolation and structural characterization of the depolymerized repeating unit of the polysaccharide. The combined structural data established a linear tetrasaccharide repeating unit consisting of three galactose residues, one bearing a 2-linked O-acetyl group, and a 3-deoxy-D-manno-2-octulosonic acid residue. [-->3)-beta-D-Galp2Ac-(1-->4)-alpha-D-Galp-(1-->3)-beta-D-Galp-(1- ->5)-beta-Kdo-(2-->]n     

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.