A new bisabolane sesquiterpenoid from Euphorbia chrysocoma

The new sesquiterpenoid (6R)-2-chloro-6-[(1S)-1,5-dimethylhex-4-en-1-yl]-3-methylcyclohex-2-en-1-one (1), together with ten known compounds, (6R)-6-[(1S)-1,5-dimethylhex-4-en-1-yl]-3-methylcyclohex-2-en-1-one (2), bauerenol acetate (3), lupenone (4), α-amyrenone (5), β-sitosterol (6), stigmasterol (7), β-amyrin (8), ursolic acid (9), betulinic acid (10), scopolin (11), have been isolated from the roots of Euphorbia chrysocoma Lévl. et Vant. Their structures have been elucidated by spectroscopic data.     

Specific anticancer activity of a new bisabolane sesquiterpene against human leukemia cells inducing differentiation in vitro

A bisabolane sesquiterpene, rel-(1S,4R,5S,6R)-4,5-diacetoxy-6- [(R)-5-hydroxy-1,5-dimethylhex-3-enyl]- 3-methylcyclohex-2-enyl (Z)-2-methylbut-2 -enoate, which was newly isolated from the roots of Leontopodium longifolium, presented specific anticancer activity against human leukemia HL-60 cells, but did not inhibit proliferation of human hepatoma SMMC-7721 cells and human normal hepatocytes L02 cells. Nitroblue tetrazolium (NBT) reduction, phagocytosis of latex beads, and cell electrophoresis all demonstrated that this bisabolane sesquiterpene presented its anticancer activity against human leukemia HL-60 cells in vitro via inducing cell differentiation. Our results may have implications for treatment of human leukemia with the sesquiterpene.     

Norsesquiterpenoid glucosides and a rhamnoside of pyrrolizidine alkaloid from Tephroseris kirilowii

Four new glycosylated compounds have been isolated from the whole plant of Tephroseris kirilowii, including (-)-(1R,5R,6S,7R,8S)-8-O-beta-D-glucopyranosyloxy-7-hydroxy-6-(2-hydroxypropan-2-yl)-9-methylenebicyclo[4.3.0]non-3-one (tephroside A, 1), (-)-(1R,5R,6R,8R)-6-(2-O-beta-D-glucopyranosyloxypropan-2-yl)-8-hydroxy-9-methylenebicyclo[4.3.0]non-3-one (tephroside B, 2), thesinine-4'-O-alpha-L-rhamnoside (3), and p-coumaric acid 4-O-alpha-L-rhamnoside (4), together with the known roseoside. The structures of the new compounds were established by means of spectroscopic analysis.     

A new antipseudomonal cephalosporin CP6162 and its congeners

The synthesis and biological activity of a series of 3-[2-(5-hydroxy-4-pyridon-2-yl)ethenyl]cephalosporin derivatives are described. They showed very potent activity against Gram-negative bacteria, especially Pseudomonas aeruginosa. (6R, 7R)-7-[(Z)-2-(2-Aminothiazol-4-yl)-2 -(1-carboxy-1-methyl)-ethoxyiminoacetamido]-3-[(Z)-2-(1,5-dihydrox y-4- pyridon-2-yl)ethenyl]ceph-3-em-4-carboxylic acid, CP6162 (8e), was selected for further evaluation as antipseudomonal chemotherapeutic agent.     

Patent Evaluation: Highly Potent Carbapenems Resistant to DHP-I

Summary

Novelty: 7-Oxo-1-aza-bicyclo[3.2.0]hept-2-en-2-carboxylic acids (carbapenems) with novel 2-(2-alicyclic heterocyclic (alkyl)pyrrolidin-4-ylthio) substituents are disclosed. The compounds have good antibacterial activity against Gram-positive bacteria such as Staphylococcus aureus and Gram-negative bacteria including Pseudomonas aeruginosa and additionally exhibit excellent DHP-I stability.

Biology: Antibacterial activity (MIC or relative potency) against MRSA and Ps. aeruginosa is compared to meropenem and imipenem for selected compounds. The preferred compounds are significantly more active than the reference compounds with MIC values of 0.1–1.56 μg/ml compared to 1.56–6.25 for imipenem against Pseudomonas strains.

Chemistry: Representative experimental procedures for the synthesis of the C-2 substituent thio precursor and subsequent elaboration to the required carbapenems are fully documented (forty-four detailed examples; one thousand thirty-three compounds claimed). Preferred compounds are (1R,5S,6S)-6-[(R)-1-hydroxyethyl]-1-methyl-2-[(2S,4S)-2-(pyrrolidin-3-yl)pyrrolidin-4-ylthio]-1-carbapen-2-em-3-carboxylic acid and (1R,5S,6S)-6-[(R)-1-hydroxyethyl]-1-methyl-2-[(2S,4S)-2-(piperidin-4-yl)pyrrolidin-4-ylthio]-1-carbepen-2-em-3-carboxylic acid.     

New constituents of Leontopodium alpinum and their in vitro leukotriene biosynthesis inhibitory activity

Phytochemical investigations of the roots of Leontopodium alpinum Cass. resulted in the isolation and structure elucidation of six novel compounds and two known compounds. Novel constituents could be identified as the polyacetylenes 1-acetoxy-3-angeloyloxy-(4 E,6 E)-tetradeca-4,6-diene-8,10,12-triyne and its (6 Z)-isomer, the kaurenic acid derivative methyl ent-7alpha,9alpha-dihydroxy-15beta-[(2 Z)-2-methyl-but-2-enoyloxy]kaur-16-en-19-oate, the bisabolane derivative (1 R*,3 S*,4 R*,6 S*)-9-(acetoxy)-4-hydroxy-1-[(2Z)-2-methylbut-2-enoyloxy]bisabol-10(11)-ene and the lignans [(2 S,3 R,4 R)-4-(3,4-dimethoxybenzyl)-2-(3,4,5-trimethoxyphenyl)-tetrahydrofuran-3-yl]-methyl-(2 Z)-2-methylbut-2-enoate and its 3,4,5-trimethoxybenzyl derivative. Known compounds, reported here for the first time for the genus Leontopodium, were identified as ent-kaur-16-en-19-oic acid and T-cadinol. The obtained compounds were tested together with 15 previously described compounds of L. alpinum in an ex vivo leukotriene biosynthesis inhibition assay. The highest activities were determined for the bisabolane derivates (IC50: 7.7 to 11.4 microM), one lignan (IC50: 10.7 microM) and the ent-kaurenoate (IC50: 10.4 microM).     

Structure-based optimization of novel azepane derivatives as PKB inhibitors

Novel azepane derivatives were prepared and evaluated for protein kinase B (PKB-alpha) and protein kinase A (PKA) inhibition. The original (-)-balanol-derived lead structure (4R)-4-(2-fluoro-6-hydroxy-3-methoxy-benzoyl)-benzoic acid (3R)-3-[(pyridine-4-carbonyl)amino]-azepan-4-yl ester (1) (IC(50) (PKB-alpha) = 5 nM) which contains an ester moiety was found to be plasma unstable and therefore unsuitable as a drug. Based upon molecular modeling studies using the crystal structure of the complex between PKA and 1, the five compounds N-[(3R,4R)-4-[4-(2-fluoro-6-hydroxy-3-methoxy-benzoyl)-benzoylamino]-azepan-3-yl]-isonicotinamide (4), (3R,4R)-N-[4-[4-(2-fluoro-6-hydroxy-3-methoxy-benzoyl)-benzyloxy]-azepan-3-yl]-isonicotinamide (5), N-[(3R,4S)-4-[4-(2-fluoro-6-hydroxy-3-methoxy-benzoyl)-phenylamino]-methyl]-azepan-3-yl)-isonicotinamide (6), N-[(3R,4R)-4-[4-(2-fluoro-6-hydroxy-3-methoxy-benzoyl)-benzylamino]-azepan-3-yl]-isonicotinamide (7), and N-[(3R,4S)-4-(4-[trans-2-[4-(2-fluoro-6-hydroxy-3-methoxy-benzoyl)-phenyl]-vinyl]-azepan-3-yl)-isonicotinamide (8) with linkers isosteric to the ester were designed, synthesized, and tested for in vitro inhibitory activity against PKA and PKB-alpha and for plasma stability in mouse plasma.(1) Compound 4 was found to be plasma stable and highly active (IC(50) (PKB-alpha) = 4 nM). Cocrystals with PKA were obtained for 4, 5, and 8 and analyzed for binding interactions and conformational changes in the ligands and protein in order to rationalize the different activities of the molecules.     

Isolation, structural elucidation and characterization of impurities in Cefdinir

Three unknown impurities in Cefdinir bulk drug at levels below 0.2% (ranging from 0.05 to 0.2%) have been detected by high performance liquid chromatography (HPLC). These impurities were isolated from crude sample of Cefdinir using preparative HPLC. Based on the spectral data (NMR, IR and MS) the structures of these impurities were characterized as (6R, 7R)-7-[(z)-2-(2-aminothiazol-4-yl)-2-hydroxyiminoacetamido]-8-oxo-3-vinyl-5-thia-1-azabicyclo [4.2.0] oct-2-ene-2-carboxylic acid-5-oxide (I). (6R, 7R)-7-[(z)-2-(2-aminothiazol-4-yl)-2-hydroxyiminoacetamido]-8-oxo-3-vinyl-5-thia-1-azabi-cyclo [4.2.0] oct-3-ene-2-carboxylic acid (II). (6R, 7R)-7-[(z)-2-(2-aminothiazol-4-yl)-2-hydroxyiminoacetamido]-8-oxo-3-methyl-5-thia-1-azabicyclo-[4.2.0]oct-2-ene-2-carboxylic acid (III), respectively. The origin and structural elucidation of all impurities have been discussed.     

New aminothiazolylglycylcephalosporins with a 1,5-dihydroxy-4-pyridone-2-carbonyl group. I. Synthesis and biological activity of cephalosporin derivatives leading to MT0703

A series of new aminothiazolylglycylcephalosporins with a mono- or dihydroxypyridonecarbonyl group at the alpha-amino group of the C-7 substituent have been prepared and antibacterial activity of these compounds was investigated. Among them, the compounds having a 1,5-dihydroxy-4-pyridone-2-carbonyl group showed excellent anti-pseudomonal activity. In particular, (6R,7R)-7-[(RS)-2-(2-aminothiazol-4-yl)-2-(1,5-dihydroxy-4- pyridone-2-carboxamido)- acetamido]-3-[[1-(2-hydroxyethyl)pyridinium-4-yl]thiomethyl]ceph-3 -em- 4-carboxylate (MT0703, 7g) was found to be a well balanced compound with respect to antibacterial activity.     

Face-washing behavior induced by the group I metabotropic glutamate receptor agonist (S)-3,5-DHPG in mice is mediated by mGlu1 receptor

It is known for the non-selective group I metabotropic glutamate (mGlu) receptors agonist (S)-3,5-dihydroxyphenylglycine (S-3,5-DHPG) to cause convulsions, which are mediated by mGlu1 receptor. However, the behavioral changes other than convulsions caused by (S)-3,5-DHPG have not been well studied. The purpose of the present study was to explore the behavioral changes elicited by activation of group I mGlu receptors with (S)-3,5-DHPG and to clarify which, mGlu1 receptor or mGlu5 receptor, is responsible for such behavior. (S)-3,5-DHPG at doses of 3-30 nmol caused characteristic face-washing behavior. This behavioral change was inhibited by both the competitive mGlu1 receptor antagonists (RS)-1-aminoindan-1,5-dicarboxylic acid (AIDA) and (S)-4-carboxyphenylglycine (S-4CPG) and the non-competitive mGlu1 receptor antagonist, 4-[1-(2-fluoropyridin-3-yl)-5-methyl-1H-1,2,3-triazol-4-yl]-N-isopropyl-N-methyl-3,6-dihydropyridine-1(2H)-carboxamide (FTIDC), but not by the mGlu5 receptor antagonist 2-Methyl-6-(phenylethynyl)pyridine hydrochloride (MPEP), the mGlu2/3 receptor agonist (-)-2-oxa-4-aminobicyclo[3.1.0]hexane-4,6-dicarboxylate (LY379268), the mGlu2/3 receptor antagonist (2S)-2-amino-2-[(1S,2S)-2-carboxycycloprop-1-yl]-3-(xanth-9-yl) propanoic acid (LY341495), the N-methyl-d-asparate (NMDA) receptor antagonist 5R,10S-(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine hydrogen maleate (MK-801), or the competitive non-NMDA receptor antagonist 2,3-dioxo-6-nitro-1,2,3,4-tetrahydrobenzo[f]quinoxaline-7-sulfonamide (NBQX). These findings indicate that face-washing behavior is due to selective activation of mGlu1 receptor by (S)-3,5-DHPG, and that the face-washing behavior induced by (S)-3,5-DHPG in mice can be used for in vivo testing of the antagonistic potency of both competitive and non-competitive mGlu1 receptor antagonists.     

New monoterpenes from Mentha microphylla

Four new monoterpenes, (1 R*,2 S*)-1,2-dihydroxy- p-menth-4(8)-en-3-one ( 1), (4 S*)-4-hydroxy- p-mentha-1,8-dien-3-one ( 2), (4 S*)-4-methoxy- p-mentha-1,8-dien-3-one ( 3), and (3 R*,4 R*,6 S*)-3-acetoxy-6-hydroxy- p-mentha-1,8-diene ( 4) together with four known compounds have been isolated from the aerial parts of Mentha microphylla. The structures were determined using spectroscopic methods particularly high resolution (1)H-, (13)C-NMR as well as 2D (1)H- (1)H COSY, HMQC and HMBC analysis.     

Photodimerization of heteroaryl chalcones: comparative antimicrobial activities of chalcones and their photoproducts

The heterocyclic analogues of chalcones were synthesized by Claisen Schmidt reaction of (a) benzaldehyde with 2-acetylfurane, 2-acetylpyrrole and 2-acetylthiophene and (b) acetophenone with furfural, thiophene-2-carbaldehyde and pyrrole-2-carbaldehyde. The photolysis of class (a) and (b) chalcones under UV lamp gave different products. The stereoselective photodimerization of 1-(furane-2-yl)-3-phenylprop-2-en-1-one (1), 3-phenyl-1-(1H-pyrrole-2-yl)-prop-2-en-1-one (2) gave β-truxinic type dimers, (3,4-diphenylcyclobutane-1,2-diyl)bis (furane-2-yl methanone) (7), (3,4-diphenylcyclobutane-1,2-diyl)bis ((1H-pyrrol-2-yl) methanone) (8) by syn head-to-head coupling whereas 3-phenyl-1-(thiophen-2-yl)-prop-2-en-1-one (3) gave δ-truxinic type dimers, (3,4-diphenylcyclobutane-1,2-diyl)bis (thiophen-2-yl methanone) (9) by anti head-to-head coupling. The photolytic products of 3-(furane-2-yl)-1-phenylprop-2-en-1-one (4), 1-phenyl-3-(thiophen-2-yl)-prop-2-en-1-one (5) and 1-phenyl-3-(1H-pyrrole-2-yl)- prop-2-en-1-one (6) were identified as corresponding 1,6-di(furane-2-yl)-3,4-diphenylhexa-1,5-diene-3,4-diol (10), 3,4-diphenyl-1,6-di(thiophen-2-yl)hexa-1,5-diene-3,4-diol (11) and 3,4-diphenyl-1,6-di(1H-pyrrol-2-yl)hexa-1,5-diene-3,4-diol (12) pinacol dimers. The antibacterial and antifungal activity of the precursor chalcones and the dimeric products showed antimicrobial activities of different extents with respect to individual compounds. In general, photolysis of heteroaryl chalcones causes the depletion of antimicrobial activity.     

Duration of action of a broad range of selective κ-opioid receptor antagonists is positively correlated with c-Jun N-terminal kinase-1 activation

The κ-opioid receptor is a widely expressed G-protein-coupled receptor that has been implicated in biological responses to pain, stress, anxiety, and depression, and its potential as a therapeutic target in these syndromes is becoming increasingly apparent. However, the prototypical selective κ-opioid antagonists have very long durations of action that have been attributed to c-Jun N-terminal kinase (JNK) 1 activation in vivo. To test generality of this proposed noncompetitive mechanism, we used C57BL/6 wild type mice to determine the durations of antagonist action of novel κ-opioid receptor ligands and examined their efficacies for JNK1 activation compared with conventional competitive antagonists. Of the 12 compounds tested, 5 had long durations of action that positively correlated with JNK activation: RTI-5989-97 [(3S)-7-hydroxy-N-[(1S)-1-[(3R,4R)-4-(3-hydroxyphenyl)-3,4-dimethyl-1-piperidinyl]methyl}-(2-methylpropyl]-2-methyl-1,2,3,4-tetrahydro-3-isoquinolinecarboxamide], RTI-5989-194 [(3R)-7-hydroxy-N-[(1S)-1-[(3R,4R)-4-(3-hydroxyphenyl)-3,4-dimethyl-1-piperidinyl]methyl}-(2-methylbutyl]-1,2,3,4-tetrahydro-3-isoquinolinecarboxamide], RTI-5989-241 [(3R)-7-hydroxy-N-[(1S)-1-{[(3R,4R)-4-(3-methoxyphenyl)-3,4-dimethyl-1-piperidinyl]methyl}-2-methylpropyl]-1,2,3,4-tetrahydroisoquinoline-3-carboxamide)], nor-binaltorphimine (nor-BNI); and (3R)-7-hydroxy-N-((1S)-1-{[(3R,4R)-4-(3-hydroxyphenyl)-3,4-dimethyl-1-piperidinyl]methyl}-2-methylpropyl)-1,2,3,4-tetrahydro-3-isoquinolinecarboxamide (JDTic). Seven had short durations of action and did not increase phospho-JNK-ir: RTI-5989-212[(3R)-N-[(1S)-1-[(3R,4R)-4-(3-hydroxyphenyl)-3,4-dimethyl-1-piperidinyl]methyl}-(2-methylpropyl]-7-methoxy-1,2,3,4-tetrahydroisoquinoline-3-carboxamide], RTI-5989-240 [(3R)-7-hydroxy-N-[(1S)-1-[(3R,4R)-4-(3-hydroxyphenyl)-3,4-dimethylpiperidin-1-yl]methyl}-(2-methylpropyl]-3-methyl-1,2,3,4-tetrahydroisoquinoline-3-carboxamide], JSPA0658 [(S)-3-fluoro-4-(4-((2-(3,5-dimethylphenyl)pyrrolidin-1-yl)methyl)phenoxy)benzamide], JSPA071B [(S)-3-fluoro-4-(4-((2-(3,5-bis(trifluoromethyl)phenyl)pyrrolidin-1-yl)methyl)phenoxy)benzamide]. PF-4455242 [2-methyl-N-((2'-(pyrrolidin-1-ylsulfonyl)biphenyl-4-yl)methyl)propan-1-amine], PF-4455242 [2-methyl-N-((2'-(pyrrolidin-1-ylsulfonyl)biphenyl-4-yl)methyl)propan-1-amine], FP3FBZ [(S)-3-fluoro-4-(4-((2-(3-fluorophenyl)pyrrolidin-1-yl)methyl)phenoxy)benzamide], and naloxone. After long-acting antagonist treatment, pJNK-ir did not increase in mice lacking the κ-opioid receptor; increased pJNK-ir returned to baseline by 48 h after treatment; and a second challenge with nor-BNI 72 h after the first did not increase pJNK-ir. Long-lasting antagonism and increased phospho-JNK-ir were not seen in animals lacking the JNK1 isoform. These results support the hypothesis that the duration of action of small molecule κ-opioid receptor antagonists in vivo is determined by their efficacy in activating JNK1 and that persistent inactivation of the κ-receptor does not require sustained JNK activation.     

New dammaranes, esterified with malonic acid, from leaves of Betula pendula

Three known and five new dammarane triterpenes, esterified with malonic acid at C-3 with hemolytic activity were identified from the ethanol-water extract of leaves of Betula pendula Roth: 12-O-acetyl-3alpha,12beta,20(S),24(R)-tetrahydroxydammar-25-en-3-yl hydrogen propanedioate, 12-O-acetyl-3alpha,12beta20(S),24(S)-tetrahydroxydammar-25-en-3-yl hydrogen propanedionate, 12-O-acetyl-3alpha,12beta,17alpha,20(S),24(R)-pentahydroxydammar-25-en-3-yl hydrogen propanedioate, [12beta-acetoxy-4,4,8,10,14-pentamethyl-17-(2-methyl-5-oxotetrahydrofuran2(S)-yl)-hexadecahydrocyclopenta[A]phenanthren-3alpha-yl] hydrogen propanedioate, 12- O-acetyl-3alpha,12beta,20(S),25-pentahydroxydammar-23(E)-en-3-yl hydrogen propanedioate, and one which was new for Betula pendula but found in other Betula species: 12-O-acetyl-20,24-epoxy-3alpha,12beta,20(S),24(R),25-pentahydroxydammar-3-yl hydrogen propanedioate. The structures were elucidated by MS, (1)H-NMR, (13)C-NMR, (1)H-(1)H-COSY, DEPT, (1)H-(13)C-NMR (HMQC, HMBC) experiments.     

Two new metabolites with cytotoxicities from deep-sea fungus,aspergillus sydowi YH11-2

Two new compounds, 2, 3, 5-trimethyl-6-(3-oxobutan-2-yl)-4H-pyran-4-one (1) and (2R)-2, 3- dihydro-7-hydroxy-6, 8-dimethyl-2-[(E)-prop-1-enyl] chromen-4-one (2), together with six known compounds (3-8), were isolated from a deep-sea fungus, identified as Aspergillus sydowi, by a bioassay-guided method. Their structures were elucidated by spectroscopic methods and the cytotoxicities were evaluated by SRB method.     

Absolute configurations of the dihydrodiol metabolites of 5,5-diphenylhydantoin (phenytoin) from rat, dog, and human urine

Dihydrodiol metabolites (DHD) of phenytoin (PHT) have been extracted from the urine of rats and dogs, and from that of a patient on chronic PHT therapy. The crystalline rat DHD was dehydrated to give a mixture of (S)-5-(4-hydroxyphenyl)-5-phenylhydantoin and (S)-5-(3-hydroxyphenyl)-5-phenylhydantoin. The absolute configuration of C5 of the hydantoin ring of the DHD can accordingly be assigned as (S). Circular dichroism studies allowed further assignment of absolute configuration to the crystalline rat DHD, the metabolite being identified as (5S)-5-[(3R,4R)-3,4-dihydroxy-1,5-cyclohexadien-1-yl]-5-phenylhydantoin, (5S)-DHD. The human DHD metabolite was identical with the (5S)-DHD. The DHD from dog urine was found to be a mixture of diastereoisomers; the major component was identified as (5R)-5-[(3R,4R)-3,4-dihydroxy-1,5-cyclohexadien-1-yl]-5-phenylhydantoin, (5R)-DHD, and the minor diastereoisomer was identified as (5S)-DHD. The ratio (5R)-DHD/(5S)-DHD was approximately 2. A comparison of the absolute configurations of phenolic metabolites of PHT and of the DHD's offered a basis for speculation as to stereochemical aspects of PHT metabolism in the rat, dog, and man.     

Synthesis and characterization of nucleosides and oligonucleotides bearing adducts of butadiene epoxides on adenine n(6) and guanine n(2)

Butadiene is a major industrial chemical whose genotoxic effects are attributed to the reaction of its oxidized metabolites, butadiene monoepoxide (BDO) and butadiene diepoxide (BDO2), with DNA. Nucleosides and oligonucleotides containing regio- and stereochemically specific adducts of BDO and the BDO2-related compound, butene 3,4-diol 1,2-epoxide (BDE), on guanine [(2R)- and (2S)-N(2)-(1-hydroxy-3-buten-2-yl) and (2R,3R)- and (2S,3S)-N(2)-(2,3,4-trihydroxybut-1-yl), respectively] and on adenine [(2R)- and (2S)-N(6)-(1-hydroxy-3-buten-2-yl) and (2R,3R)- and (2S,3S)-N(6)-(2,3,4-trihydroxybut-1-yl), respectively] have been prepared by nonbiomimetic routes. For guanine adducts, 2-fluoro-O(6)-(trimethylsilylethyl)-2'-deoxyinosine was treated with (2R)- and (2S)-2-amino-3-buten-1-ol to give the BDO adducts and with (2R,3R)- and (2S,3S)-1-amino-2,3,4-butanetriol to produce the BDE adducts; the adducted oligonucleotides were prepared from 11-mer oligonucleotides containing the halopurine. Adenine adducts were prepared in a similar fashion using 6-chloropurine 2'-deoxyriboside as the reactive purine component.     

(S)-2-Amino-3-(3-hydroxy-7,8-dihydro-6H-cyclohepta[d]isoxazol-4-yl)propionic acid,a potent and selective agonist at the GluR5 subtype of ionotropic glutamate receptors. Synthesis,modeling, and molecular pharmacology

We have previously described (RS)-2-amino-3-(3-hydroxy-7,8-dihydro-6H-cyclohepta[d]isoxazol-4-yl)propionic acid (4-AHCP) as a highly effective agonist at non-N-methyl-d-aspartate (non-NMDA) glutamate (Glu) receptors in vivo, which is more potent than (RS)-2-amino-3-(3-hydroxy-5-methylisoxazol-4-yl)propionic acid (AMPA) but inactive at NMDA receptors. However, 4-AHCP was found to be much weaker than AMPA as an inhibitor of [(3)H]AMPA binding and to have limited effect in a [(3)H]kainic acid binding assay using rat cortical membranes. To shed light on the mechanism(s) underlying this quite enigmatic pharmacological profile of 4-AHCP, we have now developed a synthesis of (S)-4-AHCP (6) and (R)-4-AHCP (7). At cloned metabotropic Glu receptors mGluR1alpha (group I), mGluR2 (group II), and mGluR4a (group III), neither 6 nor 7 showed significant agonist or antagonist effects. The stereoisomer 6, but not 7, activated cloned AMPA receptor subunits GluR1o, GluR3o, and GluR4o with EC(50) values in the range 4.5-15 microM and the coexpressed kainate-preferring subunits GluR6 + KA2 (EC(50) = 6.4 microM). Compound 6, but not 7, proved to be a very potent agonist (EC(50) = 0.13 microM) at the kainate-preferring GluR5 subunit, equipotent with (S)-2-amino-3-(5-tert-butyl-3-hydroxyisothiazol-4-yl)propionic acid [(S)-Thio-ATPA, 4] and almost 4 times more potent than (S)-2-amino-3-(5-tert-butyl-3-hydroxyisoxazol-4-yl)propionic acid [(S)-ATPA, 3]. Compound 6 thus represents a new structural class of GluR5 agonists. Molecular modeling and docking to a crystal structure of the extracellular binding domain of the AMPA subunit GluR2 has enabled identification of the probable active conformation and binding mode of 6. We are able to rationalize the observed selectivities by comparing the docking of 4 and 6 to subtype constructs, i.e., a crystal structure of the extracellular binding domain of GluR2 and a homology model of GluR5.     

Structural identification and characterization of impurities in ceftizoxime sodium

Ceftizoxime sodium is a parenteral beta-lactamic antibacterial drug. In the synthesis of ceftizoxime sodium, eight process related impurities were detected in HPLC analysis. Pure impurities obtained by both synthesis and preparative HPLC were co-injected with ceftizoxime sample to confirm the retention times in HPLC. The impurities were characterized as, (6R,7R)-7-amino-3-cephem-4-carboxylic acid (impurity I); (6R,7R)-7-[(Z)-2-(2-amino-4-thiazolyl)-2-(methoxyimino)acetamido]-3-cephem-1-oxo-4-carboxylic acid (impurity II); (4RS,6R,7R)-7-[(Z)-2-(2-amino-4-thiazolyl)-2-(methoxyimino) acetamido]-3,4-dihydro-3-cephem-4-carboxylic acid (impurity III); (6R,7R)-7-[(E)-2-(2-amino-4-thiazolyl)-2-(methoxyimino)acetamido]-3-cephem-4-carboxylic acid (impurity IV); (6R,7R)-7-[(Z)-2-(2-amino-4-thiazolyl)-2-(methoxyimino)acetamido]-3-cephem-N-(3-cephem-4-carboxy-7-yl)-4-carboxamide (impurity V); (6R,7R)-7-[(Z)-2-[[(Z)-2-(2-amino-4-thiazolyl)-2-(methoxyimino)acetylamino]thiazol-4-yl]-2-methoxyiminoacetamido]-3-cephem-4-carboxylic acid (impurity VI); 2-mercaptobenzothiazole (impurity VII) and 2-mercapto benzothiazolyl [(Z)-2-(2-amino-4-thiazolyl)-2-methoxyimino] acetate (impurity VIII). Structural elucidation of all impurities by spectral data ((1)H NMR, (13)C NMR, MS and IR) has been discussed.     

Synthesis and structure-activity relationships of 5-amino-6-fluoro-1-[(1R,2S)-2-fluorocyclopropan-1-yl]-8-methylquinolonecarboxylic acid antibacterials having fluorinated 7-[(3R)-3-(1-aminocyclopropan-1-yl)pyrrolidin-1-yl] substituents

A series of novel 5-amino-6-fluoro-1-[(1R,2S)-2-fluorocyclopropan-1-yl]-8-methylquinolones bearing fluorinated (3R)-3-(1-aminocyclopropan-1-yl)pyrrolidin-1-yl substituents at the C-7 position (2-4) was synthesized to obtain potent drugs for infections caused by Gram-positive pathogens, which include resistant strains such as methicillin-resistant Staphylococcus aureus (MRSA), penicillin-resistant Streptococcus pneumoniae (PRSP), and vancomycin-resistant enterococci (VRE). These fluorinated compounds 2-4 exhibited potent antibacterial activity comparable with that of a compound bearing a non-fluorinated (3R)-3-(1-aminocyclopropan-1-yl)pyrrolidine moiety at the C-7 position (1) and had at least 4 times more potent activity against representative Gram-positive bacteria than ciprofloxacin (CPFX), gatifloxacin (GFLX), or moxifloxacin (MFLX). Among them, the 7-[(3S,4R)-4-(1-aminocyclopropan-1-yl)-3-fluoropyrrolidin-1-yl] derivative 3 (=DQ-113), which showed favorable profiles in preliminary toxicological and nonclinical pharmcokinetic studies, exhibited potent antibacterial activity against clinically isolated resistant Gram-positive pathogens.