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P Bitha

Publications and source records attributed to P Bitha.

12 recordsLinked to original sources
PubMed1999

6-(1-Hydroxyalkyl)penam sulfone derivatives as inhibitors of class A and class C beta-lactamases I.

Five 6-(1-hydroxyalkyl)penam sulfone derivatives and two 6-(hydroxymethyl)penams were synthesized for beta-lactamase inhibitor screens. The substituent effects and stereochemical requirements of 6alpha- and 6beta-(1-hydroxyalkyl) groups for the biological activity of penam sulfone derivatives were investigated. Of these substituents, only the 6beta-hydroxymethyl group of 15 improved the activity of sulbactam against both TEM-1 and AmpC beta-lactamases. The sulfone moiety is required for the enhancement of the beta-lactamase inhibitory activity. 6Beta-hydroxymethylsulbactam (15) was able to restore the activity of piperacillin in vitro and in vivo against various beta-lactamase producing microorganisms.

Animals↗
PubMed1999

6-(1-Hydroxyalkyl))penam sulfone derivatives as inhibitors of class A and class C beta-lactamases II.

Two stereoselective processes for the synthesis of novel 3,6-disubstituted penam sulfone derivatives were developed. One 6beta-(1-hydroxyethyl) and four 6beta-hydroxymethyl penam sulfone derivatives were synthesized. All four 6beta-(hydroxymethyl)penam sulfone derivatives demonstrated good IC50 against both TEM-1 and AmpC beta-lactamases. Of these, 6beta-hydroxymethyl penam sulfone derivative 25 was the most active inhibitor which was able to restore the activity of piperacillin in vitro and in vivo against both TEM-1 and AmpC beta-lactamases producing organisms.

Enzyme Inhibitors↗
PubMed1999

In vitro activities of aminomethyl-substituted analogs of novel tetrahydrofuranyl carbapenems.

CL 188,624, CL 190,294, and CL 191,121 are novel aminomethyl tetrahydrofuranyl (THF)-1 beta-methylcarbapenems. The in vitro antibacterial activities of these THF carbapenems were evaluated and compared with those of biapenem, imipenem, and meropenem against 554 recent clinical isolates obtained from geographically distinct medical centers across North America. The antibacterial activities of the THF carbapenems were equivalent to that of biapenem, and the THF carbapenems were slightly more active than imipenem and less active than meropenem against most of the members of the family Enterobacteriaceae but lacked significant activity against Pseudomonas isolates. In general, CL 191,121 was two- to fourfold more active than CL 188,624 and CL 190,294 against the staphylococcal and enterococcal isolates tested. CL 191,121 was twofold less active than imipenem against methicillin-susceptible staphylococci and was as activity as imipenem against Enterococcus faecalis isolates. Biapenem and meropenem were two- and fourfold less active than CL 191,121, respectively, against the methicillin-susceptible staphylococci and E. faecalis. All the carbapenems displayed equivalent good activities against the streptococci. Biapenem was slightly more active than the other carbapenems against Bacteroides fragilis isolates. Time-kill curve studies demonstrated that the THF carbapenems were bactericidal in 6 h against Escherichia coli and Staphylococcus aureus isolates. The postantibiotic effect exerted by CL 191,121 was comparable to or slightly longer than that of imipenem against isolates of S. aureus, E. coli, and Klebsiella pneumoniae.

Bacteria↗
PubMed1999

In vivo activities of peptidic prodrugs of novel aminomethyl tetrahydrofuranyl-1 beta-methylcarbapenems.

A series of novel aminomethyl tetrahydrofuranyl (THF)-1 beta-methylcarbapenems which have excellent broad-spectrum antibacterial activities exhibit modest efficacies against acute lethal infections (3.8 mg/kg of body weight against Escherichia coli and 0.9 mg/kg against Staphylococcus aureus) in mice when they are administered orally. In an effort to improve the efficacies of orally administered drugs through enhanced absorption by making use of a peptide-mediated transport system, several different amino acids were added at the aminomethyl THF side chains of the carbapenem molecules. The resulting peptidic prodrugs with L-amino acids demonstrated improved efficacy after oral administration, while the D forms were less active than the parent molecules. After oral administration increased (3 to 10 times) efficacy was exhibited with the alanine-, valine-, isoleucine-, and phenylalanine-substituted prodrugs against acute lethal infections in mice. Median effective doses (ED50s) of < 1 mg/kg against infections caused by S. aureus, E. coli, Enterobacter cloacae, or penicillin-susceptible Streptococcus pneumoniae were obtained after the administration of single oral doses. Several of the peptidic prodrugs were efficacious against Morganella morganii, Serratia marcescens, penicillin-resistant S. pneumoniae, extended-spectrum beta-lactamase-producing Klebsiella pneumoniae, and E. coli infections, with ED50s of 1 to 14 mg/kg by oral administration compared with ED50s of 14 to > 32 mg/kg for the parent molecules. In general, the parent molecules demonstrated greater efficacy than the prodrugs against these same infections when the drugs were administered by the subcutaneous route. The parent molecule was detectable in the sera of mice after oral administration of the peptidic prodrugs.

Administration, Oral↗
PubMed1999

Convergent syntheses of oral THF 1beta-methylcarbapenems.

Convergent syntheses of oral THF 1beta-methylcarbapenems 4 (OCA-983) and 5 starting from M2-phosphate 1 were developed. Reaction of the M2-phosphate 1 with THF thiols containing a requisite prodrug side chain, 9 and 10, gave the desired oral THF 1beta-methylcarbapenems 4 and 5, respectively, in 46% and 42% overall yields.

Animals↗
PubMed1990

Synthesis and structure-activity relationships of new 7-[3-(fluoromethyl)piperazinyl]- and -(fluorohomopiperazinyl)quinolone antibacterials.

Some novel 6-fluoro-7-substituted-1,4-dihydro-4-oxoquinoline-3-carboxylic acids have been prepared. At the N-1 position "standard" substitution was employed with the ethyl, cyclopropyl, and p-fluorophenyl groups being used. At C-7 the introduction of some novel piperazines was made. Most notably, 2-(fluoromethyl)piperazine (10) and hexahydro-6-fluoro-1H-1,4-diazepine (16, fluorohomopiperazine) at the quinolone C-7 position produced products with similar in vitro antibacterial activity as the ciprofloxacin reference. The in vivo efficacy of 1-cyclopropyl-6-fluoro-7-[3-(fluoromethyl)piperazinyl]-1,4-dihydro-4- oxoquinoline-3-carboxylic acid (20) was excellent with better oral absorption than ciprofloxacin (2).

4-Quinolones↗
PubMed1989

Water-soluble third generation antitumor platinum complexes, [2,2-bis (aminomethyl)-1,3-propanediol-N,N']-[1,1-cyclobutanedicarboxylato (2-)-O,O']platinum(II) and [1,1-cyclobutanedicarboxylato(2-)-O,O'] [tetrahydro-4H-pyran-4,4-dimethanamine-N,N']platinum(II).

The synthesis, stability, and antitumor activity of a series of water-soluble third generation platinum(II) complexes have been described. Among these complexes, [2,2-bis(aminomethyl)-1,3- propanediol-N,N'] [1,1-cyclobutanedicarboxylato(2-)-O,O']platinum(II) and [1,1-cyclobutanedicarboxylate(2-)-O,O'](tetrahydro-4H-pyran-4,4- dimethanamine-N,N'-)platinum(II) have shown the greatest promise for further investigation and are currently under clinical evaluation.

Animals↗
PubMed1989

A new family of water-soluble, third generation antitumor platinum complexes.

[1,1-Cyclobutanedicarboxylato(2)-O,O'](1,3-dioxane-5,5-dimethan amine- N,N')platinum(II), 3a, a third generation, very water-soluble platinum complex, has been synthesized along with several of its analogues. All members of the new family contain a 1,3-dioxane or 1,3-dioxolane-1,3-diamine as their basic ligand, a moiety which contributes to their increased water solubility, and a bidentate acid ligand, which is responsible for their good stability. They were all easily crystallized and characterized by 1H NMR and elemental analysis, and the parent complex 3a was further characterized by 13C NMR. Their very desirable physical properties combined with their broad spectrum of antitumor activity and reduced toxicity make them good candidates of further development.

Animals↗
PubMed1986

Fast atom bombardment mass spectrometry of cisplatin analogs.

Cisplatin analogs of the type PtLACl2 and PtLALB are thermally unstable, non-volatile and highly insoluble. For these platinum coordination complexes, LA is a bidentate amine ligand and LB is a bidentate carboxylate ligand. Mass spectral data for structural elucidation of these compounds are absent in the literature because they are difficult to ionize. Nevertheless, a routine fast atom bombardment mass spectroscopic method has been developed utilizing the mixed solvent system of dimethyl sulfoxide:thioglycerol in a ratio of about 1:3 v/v. Using both positive and negative ionization modes, structurally significant ions were observed from representative molecules of the two named classes of compounds. [M-H]- ions were observed in both structural classes while [M + H]+ ions were observed only in the PtLALB class of compounds. Additional ions observed are rationalized in terms of the condensed-phase solution chemistry of the cisplatin analogs and the mixed solvent system when exposed to the fast atom beam. The two mechanisms causing ionization of the cisplatin analogs in the condensed phase appear to be: displacement of the ligands with dimethyl-sulfoxide and addition of chloride and the ionized solvents [dimentyl sulfoxide + H]+ and [thioglycerol - H]- to the cisplatin analogs. It is hypothesized that the addition reactions of the ionized solvents occur because of the differences in the basicity of the solvents and their reactivity in forming platinum(II)-sulfur bonds.

Cisplatin↗