Synthesis and antifungal activity of pradimicin derivatives. Modifications on the aglycone part.

Synthesis and antifungal activity of pradimicin analogs modified on the aglycone part is described. Upon modification studies at various sites of the aglycone part using pradimicin A (PRM A), C-11 position was found to be the sole site to be modified without loosing antifungal activity. Further modification studies at C-11 position were carried out with 11-OH derivative of pradimicin T1 (PRM T1) because of its easy availability. Among the compounds prepared, 11-demethoxy derivative of PRM A (12) and 11-O-ethyl (13) and 11-O-fluoroethyl (14) derivatives of PRM T1 showed promising antifungal activity comparable to that of PRM A.

Antifungal activities of pradimicin derivatives modified at C4'-amino group.

In order to explore potent derivatives of pradimicins (PRMs), modification of their C4'-amino group was carried out. 4'-N-Cyano (1,2), 4'-deamino-4'-nitroguanidino (4), 4'-deamino-4'-ureido (7-9) and 4'-deamino-4'-thioureido (10) derivatives were synthesized by trimethylsilylation of PRMs A and C, followed by condensation with appropriate reagents. 4'-Deamino-4'-guanidino (5) and 4'-deamino-4'-amidino (6) derivatives were synthesized by catalytic hydrogenation of 4 and 2, respectively. 4'-N-Nitroso derivative 3 was prepared by treatment of PRM A with nitrous acid. Among these compounds, the 4'-N-cyano derivative of PRM C (2) exhibited in vitro and in vivo antifungal activities comparable to the parent compounds together with good water-solubility.

BU-4794F, a new beta-1,3-glucan synthase inhibitor.

New beta-1,3-glucan synthase inhibitor (BU-4794F) was isolated from the culture broth of Gilmaniella sp. FA4459. Structural studies indicated that it was a novel member of the papulacandin group of antibiotics.

Synthesis and antibacterial activity of cephalosporins having a catechol in the C3 side chain.

Cephalosporins having a catechol through a variety of linkages to the C3 position and a different C7 side chain were prepared. Among them, 3-(catechol-4- ylcarbonyloxy)methylcephalosporin (14) and 3-[(E)-3-(catechol-4-ylcarbonyloxy)-1-propen-1-yl]cephalospo rin (10) showed excellent activity against Gram-negative activity including ceftazidime-resistant Escherichia coli, Pseudomonas aeruginosa, Xanthomonas maltophilia and Pseudomonas cepacia.

Synthesis and antifungal activity of pradimicin derivatives. Modifications of the sugar part.

Modifications at the sugar part of pradimicins were carried out by glycosidations of the aglycones or chemical transformations of natural pradimicins and their antifungal activity was evaluated. Among them, some of the D-xylose-modified derivatives (14, 17, 24) showed activity comparable to that of pradimicin A. The structure-activity relationships obtained through there studies clarified the role of the sugar part in the manifestation of antifungal activity: The 5-O-(6-deoxy-beta-D-sugar) is essential for activity and 2'-epi, 3'-oxo and 4'-deoxy sugar derivatives retain activity against yeasts.

In vitro and in vivo antifungal activities of BMY-28864, a water-soluble pradimicin derivative.

BMY-28864, a water-soluble pradimicin derivative, had potent in vitro activity against a wide variety of fungi, including those associated with deep-seated mycosis; it inhibited the growth of standard strains and clinical isolates at concentrations of 12.5 micrograms/ml or less. At the MIC or higher concentrations, BMY-28864 was fungicidal for Candida albicans under both growing and nongrowing conditions. BMY-28864 expressed fungicidal activity only in the presence of Ca2+, and its activity was totally diminished when ethylene glycol-bis(2-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA), a Ca2+ chelator, was added to the test medium. The effectiveness of intravenously administered BMY-28864 in vivo was examined and compared with that of amphotericin B in mouse models of fungal infections. Both normal and cyclophosphamide-treated immunosuppressed mice infected with C. albicans, Cryptococcus neoformans, or Aspergillus fumigatus responded to therapy with BMY-28864 (50% protective doses of 17, 18, and 37 mg/kg of body weight in normal mice and of 32, 35, and 51 mg/kg in cyclophosphamide-treated mice, respectively). Lethal lung infections were also established with C. albicans or A. fumigatus in cyclophosphamide-treated mice. The 50% protective doses of BMY-28864 were 15 and 23 mg/kg per dose against C. albicans and A. fumigatus, respectively. The immunosuppression induced by intraperitoneal administration of 200 mg of cyclophosphamide per kg lasted for 5 days, and total recovery was observed by day 7.

Synthesis and activity of butirosin derivatives with 5''-amidino and 5''-guanidino substituents.

The preparation and antibacterial activity of the 5''-guanidino (6) and 5''-amidino (7) derivatives of 4'-deoxybutirosin A (1) as well as the 5''-guanidino derivative (8) of butirosin A are described. The key intermediates, tetra-N-benzyloxycarbonyl-5''-azido derivatives were selectively reduced with NiCl2-NaBH4 to give the corresponding 5'-amino derivatives. Subsequent guanidination or amidination followed by deblocking afforded the final compounds 6, 7 and 8. The 5''-guanidino derivatives (6 and 8) were more active against Gram-positive and Gram-negative bacteria than the corresponding 5''-hydroxy derivatives (1 and butirosin A). Compound 6 was also active against a variety of methicillin-resistant Staphylococcus aureus (MRSA).

In vitro and in vivo evaluations of a new broad-spectrum oral cephalosporin, BMY-28232, and its prodrug esters.

The in vitro activity of a new cephalosporin, BMY-28232 (7-[(Z)-2-(2-aminothiazol-4-yl)-2-hydroxyiminoacetamido]-3-[ (Z)-1- propenyl]-3-cephem-4-carboxylic acid), was compared with those of cefuroxime and BMY-28488, the 3-vinyl congener of BMY-28232, against 899 bacteria including strains resistant to newer cephalosporins. BMY-28232 displayed potent, broad-spectrum antibacterial activity with high stability to various types of beta-lactamase. Its acetoxyethyl ester (BMY-28271) and pivaloyloxymethyl ester (BMY-28257) were well absorbed after oral administration to mice and rats. Both esters were metabolized to BMY-28232 and mainly excreted in urine. Oral bioavailability of both prodrug esters (60 to 70%) was better than that of cefuroxime axetil (46%) and gave excellent therapeutic efficacy against gram-positive- and gram-negative-bacterial infections in mice. Oral 50% protective doses (in milligrams per kilogram of body weight) of 0.65 and 0.72 for Staphylococcus aureus Smith, 0.9 and 1.2 for Escherichia coli Juhl, 1.6 and 1.6 for Proteus vulgaris, and 18.9 and 14.3 for Enterobacter cloacae were obtained for BMY-28271 and BMY-28257, respectively.

Comparison of the in vitro and in vivo antibacterial activities of cefepime (BMY-28142) with ceftazidime, cefuzonam, cefotaxime and cefmenoxime.

Cefepime (BMY-28142), a new semisynthetic cephalosporin, was evaluated for in vitro and in vivo antibacterial activities in comparison with ceftazidime, cefuzonam, cefotaxime and cefmenoxime. Cefepime showed a well-balanced, broad spectrum of activity against a number of clinical isolates collected in Japan. The activity of cefepime against Gram-positive bacteria was several times greater than that of ceftazidime, nearly comparable to cefotaxime and cefmenoxime, and slightly weaker than cefuzonam. Against Enterobacteriaceae, cefepime showed superior activity to the reference cephalosporins against Proteus inconstans, Providencia rettgeri, Morganella morganii, Citrobacter freundii and Enterobacter cloacae. The activity of cefepime against Pseudomonas aeruginosa was nearly comparable to that of ceftazidime. Cefotaxime, cefuzonam and cefmenoxime were substantially less active against P. aeruginosa. Cefepime was more stable than cefuzonam, cefotaxime and cefmenoxime to various types of beta-lactamases from Gram-negative bacteria. The high in vitro activity of cefepime was reflected in its in vivo efficacy against experimental infections in normal and immuno-suppressed mice. Cefepime was the most effective among the cephalosporins tested against four Gram-negative bacterial infections.

Purification and some properties of a chloramphenicol acetyltransferase mediated by plasmids from Vibrio anguillarum.

Vibrio anguillarum strains were isolated from chloramphenicol-resistant bacteria in diseased fish. Plasmid Rms418, which confers chloramphenicol resistance, was transferred from V. anguillarum GN11379 to Escherichia coli K12 by conjugation. The Rms418-encoded chloramphenicol acetyltransferase (CAT) [EC 2.3.1.99] was isolated and purified to homogeneity using affinity chromatography on immobilized p-amino-chloramphenicol or ATP. The general CAT could be adsorbed by a matrix with a chloramphenicol base ligand (Zaidenzaig, Y. & Shaw, W.V. (1976) FEBS Lett. 62,266-271), but the Rms418-encoded CAT was not bound under these conditions. The specific activity of the enzyme, when measured by the spectrophotometric assay, was 71.4 units/mg protein at 37 degrees C. The molecular weight of the enzyme treated with SDS and 2-mercaptoethanol was shown to be approximately 22,000. The molecular weight of the native enzyme, as determined by gel filtration, was approximately 69,000, and the optimal pH was 7.8. The Km values for chloramphenicol and CoASAc were 34.5 and 150 microM, respectively. Enzyme activity was inhibited by HgCl2, p-chloromercuribenzoate (p-CMB), 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB), and ethylendiaminotetraacetic acid (EDTA). The half life at 53 degrees C was approximately 100 min.

Cephalosporinase interactions and antimicrobial activity of BMY-28142, ceftazidime and cefotaxime.

Cephalosporinases of Enterobacter cloacae and Citrobacter freundii were responsible for resistance to newer cephalosporins such as cefotaxime and ceftazidime but not BMY-28142. Interaction of these cephalosporins including hydrolysis, binding, inhibition, and inactivation with cephalosporinases from E. cloacae GN7471 and C. freundii GN7391 were studied. BMY-28142 was much more stable against the both enzymes than cephalothin, but more hydrolyzable than cefotaxime and ceftazidime at higher concentration such as 100 microM. Because of low affinity for the enzymes, i.e. large Km and Ki, the calculated hydrolysis rate of BMY-28142 at 0.1 microM was smaller than those of cefotaxime and ceftazidime, that explained the difference in activity against cephalosporinase-producing strains between BMY-28142 and cefotaxime or ceftazidime. The effects of cephalosporinase production on susceptibility of Escherichia coli omp mutants were examined using a plasmid having cephalosporinase gene of C. freundii GN346. Decrease in susceptibility of E. coli by cephalosporinase production was larger in the strain lacking outer membrane proteins (Omp) F and C, and smaller in the strain producing OmpF constitutively.

In vitro activity and beta-lactamase stability of the oral cephalosporin BMY-28100.

BMY-28100 was compared with cephalexin, cefaclor, cefixime, and cefteram and found to be more active than the reference cephalosporins against Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus faecalis, and Clostridium difficile. BMY-28100 was the next most active, after cefteram, against Streptococcus pyogenes and Streptococcus pneumoniae. Against gram-negative bacteria, BMY-28100 showed similar activity to that of cefaclor. The antimicrobial activity of BMY-28100, including bactericidal activity, against Staphylococcus aureus was less affected by penicillinase-production than was that of cefaclor. BMY-28100 was more stable than cefaclor against various types of penicillinases, especially against the penicillinase from Staphylococcus aureus.

In vitro and in vivo evaluations of BMY-28100, a new oral cephalosporin.

A new semisynthetic oral cephalosporin, BMY-28100, was evaluated for in vitro and in vivo antibacterial activities in comparison with cefaclor and cephalexin. BMY-28100 showed in vitro activity 3- and 10-fold more potent than that of cefaclor against Staphylococcus aureus and Streptococcus pneumoniae, respectively. BMY-28100 was slightly better than cefaclor and about 4 times more active than cephalexin against Haemophilus influenzae and Neisseria gonorrhoeae. Escherichia coli, Klebsiella pneumoniae and Proteus mirabilis were comparably susceptible to BMY-28100 and cefaclor. The bactericidal activity of BMY-28100 against S. aureus, E. coli and P. mirabilis was equal to or twice as high as MIC value, which was similar to that of cefaclor. The stability of BMY-28100 against penicillinases was nearly comparable to that of cefaclor, whereas cefaclor was somewhat unstable to cephalosporinases. BMY-28100 was about twice as active as cefaclor against three Gram-positive bacterial infections. BMY-28100 was also more potent against infections of H. influenzae and P. mirabilis, but slightly less active against E. coli Juhl than cefaclor. Blood level parameters of BMY-28100 were significantly superior to those of cefaclor and slightly better than cephalexin in mice and rats. The urinary recovery of BMY-28100 was somewhat higher and comparable to that of cefaclor and cephalexin, respectively. BMY-28100 was more stable than cefaclor in human and calf sera at 37 degrees C.

Distribution of cefodizime to exudate in the croton oil-induced rat granuloma pouch and its therapeutic effects on experimental infections in the pouch.

Cefodizime was compared with cefotaxime (CTX) in regard to its distribution to an inflammatory site (exudate in croton oil-induced granuloma pouch) of rats and its therapeutic effects on experimental infections in such pouches after intravenous injection. Cefodizime levels in rat serum and pouch exudate were higher than those of CTX, and the former compound disappeared from the serum and pouch exudate far more slowly than the latter. In the tests for therapeutic effects, cefodizime showed almost the same degree of inhibitory activity as CTX against growth in pouch exudate of Escherichia coli Ec-7, Proteus mirabilis Pm-428, and Serratia marcescens Sm-390 for which the minimum inhibitory concentrations (MICs) of cefodizime were equal to or greater than the CTX values, and such activity of cefodizime lasted for a longer period than that of CTX. These results suggest that the above pharmacokinetic features of cefodizime compensate for its MICs against organisms displaying lower values for CTX.

Antibacterial activity of BMY-28142, a novel broad-spectrum cephalosporin.

BMY-28142, 7-[(Z)-2-(2-aminothiazol-4-yl)-2-methoxyiminoacetamido]-3- (1-methylpyrrolidinio)methyl-3-cephem-4-carboxylate, exhibited a well-balanced, extended-spectrum of antibacterial activity both in vitro and in vivo. Against Staphylococci and Streptococci, BMY-28142 was about four to ten times more active than ceftazidime and comparable to cefotaxime. Most Enterobacteriaceae were more susceptible to BMY-28142 than to ceftazidime, though strains of Pseudomonas aeruginosa were slightly more sensitive to ceftazidime. BMY-28142 showed potent activity against Gram-negative bacteria resistant to ceftazidime and/or cefotaxime. Bactericidal activity of BMY-28142 against 10 strains of P. aeruginosa was superior to that of ceftazidime. In bacterial infection models in mice, BMY-28142 was more effective than ceftazidime against three Gram-positive and three Gram-negative pathogens. The anti-pseudomonal in vivo activity of BMY-28142 was nearly comparable to that of ceftazidime. The blood levels and urinary excretion rates of BMY-28142 in mice were similar to those of ceftazidime.

In vitro antibacterial activity and beta-lactamase stability of cefodizime, a new cephalosporin antibiotic.

The in vitro activity and beta-lactamase stability of cefodizime (HR 221), a new cephalosporin, were compared with those of other cephem antibiotics. HR 221 was highly active against Gram-negative bacteria. The compound inhibited growth of all tested Haemophilus influenzae strains at 0.10 microgram/ml and showed strong activity even against penicillin-resistant Neisseria gonorrhoeae strains, but it was less effective against Pseudomonas aeruginosa than the other antibiotics tested. Against Gram-positive bacteria, HR 221 showed 100% inhibition of growth of Streptococcus pneumoniae at 0.39 microgram/ml, and it was slightly less active against Staphylococcus aureus (MIC90:12.5 micrograms/ml) than other antibiotics such as cefotaxime (CTX). The bactericidal activity of HR 221 against E. coli was dose-related and comparable to that of CTX, cefoperazone and latamoxef. The bactericidal activity of the compound at medium concentrations simulating human serum levels was higher than that of CTX and cefmetazole, and no cell regrowth was noted after beta-lactamase-induced inactivation of the compound. HR 221 was stable to most drug-inactivating enzyme preparations from various bacterial species.

In vivo antibacterial activity of cefodizime, a new cephalosporin antibiotic.

The in vivo activity of cefodizime (HR 221) was compared with that of cefotaxime (CTX), cefmenoxime, latamoxef, cefazolin and cefmetazole (CMZ). The protective effects of HR 221 on experimental infections in mice caused by Staphylococcus aureus Smith, Escherichia coli C-11, Proteus vulgaris GN-76 and Serratia marcescens No. 2 were directly related to its in vitro activity against these strains. In contrast, the compound showed the smallest ED50 values, among the 5 antibiotics tested (not including CMZ), for Klebsiella pneumoniae 3K-25 and Pseudomonas aeruginosa PI 67 against which it had relatively low in vitro activity, and its ED50 for Citrobacter freundii GN-346 was as small as 1.821 mg/mouse in spite of its MIC of greater than 100 micrograms/ml. HR 221 exerted potent bactericidal activity against Streptococcus pneumoniae Sp-1 inoculated into the mouse lung; the duration of action was prolonged. When tested against the E. coli Ec-89 infection induced in the rat uterus, the activity of HR 221 given to rats once daily was equal to that of CTX or CMZ given at the same dose twice daily.

[Study of cefotaxime on stability to beta-lactamases and affinity to penicillin-binding proteins].

Cefotaxime (CTX) was compared with other cephems concerning stability to beta-lactamases and affinity to penicillin-binding proteins of Escherichia coli JE1011. The results are summarized as follows. 1. CTX showed potent activity against bacteria whose resistance is mediated by plasmids on chromosomal genes. 2. The antibacterial activity of CTX was not influenced by the transfer of 25 different plasmids to E. coli ML1410. 3. CTX was stable to typical cephalosporinases (CSases). This compound was slightly hydrolyzed by cefuroximases (CXases). 4. There was no difference between CTX and other cephems in the affinity to beta-lactamases. 5. CTX showed high affinity to the 1A, 1Bs and 3 fractions of penicillin-binding proteins of E. coli JE1011.