Pyridonecarboxylic acids as antibacterial agents. 4. Synthesis and antibacterial activity of 7-(3-amino-1-pyrrolidinyl)-1-ethyl-6-fluoro-1,4 -dihydro-4-oxo-1,8-naphthyridine-3-carboxylic acid and its analogues

The title compounds (28-56) with an amino- and/or hydroxy-substituted cyclic amino group at C-7 were prepared with 1-substituted 7-chloro-, 7-(ethylsulfonyl)-, and 7-(tosyloxy)-6-fluoro-1,4-dihydro-4-oxo-1,8-naphthyridine-3- carboxylic acids and their ethyl esters (3-7) with cyclic amines such as 3-aminopyrrolidine. The N-1 substituent includes ethyl, vinyl, and 2-fluoroethyl groups. As a result of in vitro and in vivo antibacterial screenings, three compounds, 1-ethyl- and 1-vinyl-7-(3-amino-1-pyrrolidinyl)-6-fluoro- 1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxylic acids (33a and 33b) and 1-vinyl-7-[3-(methylamino)-1-pyrrolidinyl] analogue 34b, were found to be more active than enoxacin (2) and to be worthy of further biological study. Structure-activity relationships are discussed.     

Chiral DNA gyrase inhibitors. 1. Synthesis and antimicrobial activity of the enantiomers of 6-fluoro-7-(1-piperazinyl)-1-(2'-trans-phenyl-1'-cyclopropyl)-1, 4-dihydro-4-oxoquinoline-3-carboxylic acid

New quinolone antimicrobial agents (racemic, (1'S,2'R)- and (1'R,2'S)-6-fluoro-7-(1-piperazinyl)-1-(2'-trans-phenyl-1'-cyclopropyl)- 1, 4-dihydro-4-oxoquinoline-3-carboxylic acids) were synthesized, and their in vitro antimicrobial potencies and spectra were determined. As compared to their conceptual parents, these agents retained a considerable amount of the antimicrobial potency and spectra of ciprofloxacin and of 6-fluoro-1-phenyl-7-(1-piperazinyl)-1,4-dihydro-4-oxoquinoline-3-carboxy lic acid against Gram-positives. Gram-negatives were considerably less sensitive. The (-)-(1'S,2'R) analogue was the more potent of the enantiomers, but the degree of chiral discrimination by most bacteria was only 4-fold. The 4-fold chiral discrimination was observed also using purified DNA gyrase obtained from Micrococcus luteus, whereas the two enantiomers were essentially equiactive against the enzyme derived from Escherichia coli. These results confirm that there is a substantial degree of bulk tolerance available at N-1 of quinolone antimicrobial agents and suggest that electronic factors controlled by substitution at that site are of considerable importance. On the other hand, chiral recognition brought about by attachment of optically active groups to the N-1 position in these derivatives is relatively small.     

Pyridonecarboxylic acids as antibacterial agents. 2. Synthesis and structure-activity relationships of 1,6,7-trisubstituted 1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxylic acids, including enoxacin, a new antibacterial agent

The title compounds having nitro, amino, cyano, chloro, or fluoro as the C-6 substituent were prepared. Introduction of the chloro and cyano groups at C-6 was accomplished by the Sandmeyer reaction of 6-amino-1,8-naphthyridine derivatives 9 via their 6-diazonium salts. The reaction was extended to the synthesis of the 6-fluoro analogues, involving the Balz-Schiemann reaction of the diazonium tetrafluoroborate. Furthermore, a series of the 1-ethyl, 1-vinyl, 1-(2-fluoroethyl), and 1-(difluoromethyl) analogues of 7-substituted 6-fluoro-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxylic acids was prepared. 1-Pyrrolidinyl and, particularly, N-substituted or unsubstituted 1-piperazinyl groups were introduced as the C-7 variants. As a result of this study, 1-ethyl-6-fluoro-1,4-dihydro-4-oxo-7-(1-piperazinyl)-1, 8-naphthyridine-3-carboxylic acid (named enoxacin, originally AT-2266) was found to show the most broad and potent in vitro antibacterial activity, an excellent in vivo efficacy on systemic infections, and a weak acute toxicity. Structure-activity relationships of compounds with variations of substituents at C-1, C-6, and C-7 are also discussed.     

Studies on quinolone antibacterials. I. Synthesis and antibacterial activity of 7-(2-aminoethoxy)-, 7-(2-aminoethylthio)-, and 7-(2-aminoethylamino)-1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo qui noline -3-carboxylic acids and their derivatives

7-(2-Aminoethoxy)-, 7-(2-aminoethylthio)-, and 7-(2-aminoethylamino)-1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxoq uin oline-3- carboxylic acids and their derivatives (11a--f, h, j, k, 12a--f, and 13a--f) were synthesized and their antibacterial activities were tested. Among them, compounds (13a, d) having a primary amino group at the terminal position of alkoxy and alkylthio groups were found to have excellent in vitro and in vivo antibacterial activity comparable to those of ciprofloxacin (5). Structure-activity relationship of these compounds was also stated.     

Synthesis and structure-activity relationships of novel 7-substituted 1,4-dihydro-4-oxo-1-(2-thiazolyl)-1,8-naphthyridine-3-carboxylic acids as antitumor agents. Part 1

In an attempt to search for clinically useful antitumor agents, we have discovered that a series of 1,7-disubstituted-6-fluoro-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxylic acids possessed moderate cytotoxic activity. We investigated the structure-activity relationships in this series of compounds by changing N-1 and C-7 positions and the core ring structure itself and evaluated the synthesized compounds against several murine and human tumor cell lines. These modifications led us to the following findings. (1) The 2-thiazolyl group at the N-1 position of the naphthyridine structure is the best substituent for antitumor activity. (2) Regarding core ring structure, the naphthyridine derivative is the most active followed by pyridopyrimidine analogue. (3) At the C-7 position, aminopyrrolidine derivatives are more effective than other amines or thioether derivatives. Finally, the trans-3-amino-4-methoxypyrrolidinyl derivative (43j) and the 3-amino-3-methylpyrrolidinyl derivative (43f) as well as 3-aminopyrrolidinyl derivative (AT-3639, 1) were determined to be effective in in vitro and in vivo antitumor assays, and their activity was comparable to that of etoposide.     

Synthesis and structure-activity relationships of novel 7-substituted 1,4-dihydro-4-oxo-1-(2-thiazolyl)-1,8-naphthyridine-3-carboxylic acids as antitumor agents. Part 2

We have previously reported that a series of 7-substituted 6-fluoro-1,4-dihydro-4-oxo-1-(2-thiazolyl)-1,8-naphthyridine-3-carboxylic acids possess moderate cytotoxic activity. In a further attempt to find clinically useful antitumor agents, we investigated the structure-activity relationships (SARs) of a new series of compounds obtained by changing the C-6 position of the fluorine atom in addition to the C-5 and C-7 positions and evaluating their cytotoxic activity against several murine and human tumor cell lines. Our results showed that the 6-unsubstituted 1,8-naphthyridine structure had the most potent cytotoxic activity against murine P388 leukemia twice that of the 6-fluoro analogue. In addition, introduction of an amino group at the C-5 position did not have any substantial effect on the cytotoxic activity, while both the 5-chloro and 5-trifluoromethyl groups decreased the cytotoxic activity by 5- to 10-fold. Moreover, aminopyrrolidine derivatives at the C-7 position showed more potent cytotoxic activity than other amines or carbon derivatives. Among the 7-(3-aminopyrrolidinyl) derivatives, the trans-3-methoxy-4-methylaminopyrrolidinyl derivative (27l) was determined to have potent cytotoxic activity in both in vitro and in vivo assays and high water solubility. Finally, the (S,S)-isomer (AG-7352, 3) of 27l, with a cytotoxic activity against human tumor cell lines more potent than that of etoposide, was selected for further development.     

Study on metabolism of pyridonecarboxylic acid. I. Isolation and identification of metabolites of (+-)-7-(3-amino-1-pyrrolidinyl)-6-fluoro-1- (2,4-difluorophenyl)-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxylic acid p-toluenesulfonate hydrate (T-3262) in urine

Metabolism of (+-)-7-(3-amino-1-pyrrolidinyl)-6-fluoro-1-(2,4-difluorophenyl)-1,4- dihydro-4- oxo-1,8-naphthyridine-3-carboxylic acid p-toluenesulfonate hydrate (T-3262) was studied. Metabolites were isolated from urine of mouse, rat, rabbit, dog and monkey following oral administration of T-3262, and identified using high performance liquid chromatography and mass spectrometry. Two metabolites, other than unchanged (+-)-7-(3-amino-1-pyrrolidinyl)-6-fluoro-1-(2,4-difluorophenyl)-1,4- dihydro-4-oxo-1,8-naphthyridine-3-carboxylic acid (T-3262 base), in which 3-aminopyrrolidinyl ring of T-3262 was metabolized, were identified as: (+-)-7-(3-acetyl-amino-1-pyrrolidinyl)-1-(2,4-difluorophenyl)-6-fluoro- 1,4- dihydro-4-oxo-1, 8-naphthyridine-3-carboxylic acid (T-3262A) in all animals: (+-)-1-(2,4-difluorophenyl)-6-fluoro-7-(3-hydroxy-1-pyrrolidinyl)-1,4- dihydro- 4-oxo-1,8-naphthyridine-3-carboxylic acid (T-3262B) in monkey. The glucuronide of T-3262 was detected in mouse, dog and monkey, the glucuronides of T-3262A and T-3262B were detected in monkey. M-I, unidentified metabolite, was detected only in mouse.     

硫酸二乙酯作乙基化剂制备-7氯-1-乙基-6-氟1,4-二氢-4-氧喹啉-3-羧酸的工艺改进

本文采用硫酸二乙酯与7-氯-6-氟-4-羟基喹啉-3-羧酸乙酯反应,然后用氢氧化钠液水解得7-氯-1-乙基-6-氟-1,4-二氢-4-氧喹啉-3-羧酸。其总收率为80％,此法降低了原料成本,简化了工艺,适合工业生产。     

Isolation and identification of metabolites of ofloxacin in rats, dogs and monkeys

Metabolites of (+/-)-9-fluoro-2,3-dihydro-3-methyl-10-(4-methyl-1-piperazinyl)-7-oxo-7H -pyrido [1,2,3-de][1,4]benzoxazine-6-carboxylic acid (ofloxacin) in excreta of rats, dogs and monkeys after oral administration of 14C-ofloxacin (20 mg/kg) were isolated and identified. Three metabolites of ofloxacin were detected in the excreta of all three species, and identified by t.l.c., u.v., n.m.r. and mass spectrometry as follows: M-1, ester glucuronide of ofloxacin; M-2, unchanged ofloxacin; M-3, (+/-)-9-fluoro-2,3-dihydro-3-methyl-10-(1-piperazinyl)-7-oxo-7H-pyrido [1,2,3-de][1,4]benzoxazine-6-carboxylic acid (desmethyl ofloxacin); M-4, (+/-)-9-fluoro-2,3-dihydro-3-methyl-10-(4-methyl-1-piperazinyl)-7-oxo-7H -pyrido [1,2,3-de][1,4]-benzoxazine-6-carboxylic acid piperazine-4-oxide (ofloxacin N-oxide). It is concluded that ofloxacin is metabolized by O-acyl glucuronidation, N-demethylation and N-oxidation.     

Anti-inflammatory activity of a naphthyridine derivative (7-chloro-6-fluoro-N-(2-hydroxy-3-oxo-1-phenyl-3-(phenylamino)propyl)-4-oxo-1-(prop-2-yn-1-yl)-1,4-dihydro-1,8-naphthyridine-3-carboxamide) possessing in vitro anticancer potential

We have previously synthesized a series of 1,8-naphthyridine-3-carboxamide derivatives to identify potential anti-cancer/anti-inflammatory compounds. Three derivatives, 7-chloro-N-(3-(cyclopentylamino)-3-oxo-1-phenylpropyl)-6-fluoro-4-oxo-1-(prop-2-yn-1-yl)-1,4-dihydro-1,8-naphthyridine-3-carboxamide (C-22), 7-chloro-N-(2-hydroxy-3-oxo-1-phenyl-3-(phenylamino)propyl)-4-oxo-1-(prop-2-yn-1-yl)-1,4-dihydro-1,8-naphthyridine-3-carboxamide (C-31) and 7-chloro-6-fluoro-N-(2-hydroxy-3-oxo-1-phenyl-3-(phenylamino)propyl)-4-oxo-1-(prop-2-yn-1-yl)-1,4-dihydro-1,8-naphthyridine-3-carboxamide (C-34) demonstrated high cytotoxicity against a number of cancer cell lines and inhibited secretion of IL-1-β and IL-6. In the present study, C-22, C-31 and C-34 were assessed for modulation of pro-inflammatory cytokines, TNF-α and IL-8, chemokine RANTES and NO produced by lipopolysaccharide (LPS)-treated mouse Dendritic cells (DCs). Among the 3 compounds, C-34 showed the most potent inhibition of inflammatory markers in DC model at 0.2 and 2 μM. C-34 also significantly downregulated the secretion of TNF-α, IL-1-β and IL-6 by murine splenocytes and THP-1 cells against LPS induced levels. In vitro effects of C-34 on bone marrow toxicity were assessed in CFU-GM assay. Human CFU-GM population was comparatively more sensitive to C-34 (0.1–10 μM) than murine CFU-GM. IC₅₀ values for murine and human CFU-GM were not attained. C-34 was further examined for in vivo suppression of LPS induced cytokines in a mice model. At doses ranging from 1.25 to 5 mg/kg, C-34 led to significant inhibition of TNF-α, IL-1-β, IL-6 and MIP-1-α. At the highest dose of 5 mg/kg, C-34 also protected LPS-treated mice against endotoxin-induced lethality. In conclusion, C-34 demonstrates anti-inflammatory activity in vitro and in vivo in addition to cytotoxic properties. This finding suggests its potential for further development as a synthetic naphthyridine derivative with dual anti-cancer and anti-inflammatory (cytokine inhibition) properties.     

Studies on quinolone antibiotics. III. Synthesis and antibacterial activity of 5-amino-7-(2-aminoalkoxy)-1-cyclopropyl-6-fluoro-1,4- dihydro-4-oxoquinoline-3-carboxylic acid and their derivatives]

5-Amino-7-(2-aminoalkoxy)-1-cyclopropyl-6-fluoro-1,4-dihydro-4- oxoquinoline-3-carboxylic acid and their derivatives (10, 11) were prepared and their antibacterial activities were evaluated. As a result of in vitro antibacterial screening, the compounds having mono- or di-methyl (11d, e) group at alpha-position of amino group were most effective among the 7-aminoalkoxy derivatives. Structure-activity relationship of these compounds is also discussed.     

Isolation and structural elucidation of urinary metabolites of ciprofloxacin

After oral administration of 1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-7-piperazine-1-ylquinoline++ +-3-carboxylic acid (ciprofloxacin, Bay o 9867; designated trademark: Ciprobay) four metabolites M1-M4 were isolated from human urine by Craig counter current distribution and semipreparative high-performance liquid chromatography. Their molecular structures were elucidated by nuclear magnetic resonance and mass spectrometry and confirmed by comparing their spectra with those of authentic synthetic reference compounds.     

Isolation and identification of metabolites of ofloxacin in rats,dogs and monkeys

1. Metabolites of (±)-9-fluoro-2,3-dihydro-3-methyl-10-(4-methyl-1-piperazinyl)-7-oxo-7H-pyrido[1,2,3-de][1,4]benzoxazine-6-carboxylic acid (ofloxacin) in excreta of rats, dogs and monkeys after oral administration of ¹⁴C-ofloxacin (20?mg/kg) were isolated and identified.

2. Three metabolites of ofloxacin were detected in the excreta of all three species, and identified by t.l.c., u.v., n.m.r. and mass spectrometry as follows: M-1, ester glucuronide of ofloxacin; M-2, unchanged ofloxacin; M-3, (±)-9-fluoro-2,3-dihydro-3-methyl-10-(1-piperazinyl)-7-oxo-7H-pyrido[1,2,3-de][1,4]benzoxazine-6-carboxylic acid (desmethyl ofloxacin); M-4, (±)-9-fluoro-2,3-dihydro-3-methyl-10-(4-methyl-1-piperazinyl)-7-oxo-7H-pyrido[1,2,3-de][1,4]-benzoxazine-6-carboxylic acid piperazine-4-oxide (ofloxacin N-oxide).

3. It is concluded that ofloxacin is metabolized by O-acyl glucuronidation, N-demethylation and N-oxidation.     

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.     

Antibacterial and antifungal agents. VI. Pirfloxacin and related compounds: synthetic and microbiological studies

A new route to pirfloxacin, a fluorinated pyrrylquinolone with high broad-spectrum antibacterial activities, is described starting from 7-amino-1-ethyl-6-fluoro-1,4-dihydro-4-oxoquinoline-3-carboxylic acid and 2,5-dimethoxytetrahydrofuran. When the reaction with the latter compound was carried out using the ethyl ester of the above acid the related pyrryl ester formed, which on alkaline hydrolysis gave pirfloxacin. The synthesis and antibacterial activities of the 1-allyl analogue of pirfloxacin and of 7-[2-(1-pyrrolidinomethyl)-1-pyrryl]-1-ethyl-1, 4-dihydro-4-oxoquinoline-3-carboxylic acid and its 6-fluoroderivative are also reported.     

Fluoronaphthyridines as antibacterial agents. 4. Synthesis and structure-activity relationships of 5-substituted-6-fluoro-7-(cycloalkylamino)-1,4-dihydro-4-oxo-1,8- naphthyridine-3-carboxylic acids.

A series of 5-substituted-6-fluoro-7-(cycloalkylamino)-1,4-dihydro-4-oxo-1,8- naphthyridine-3-carboxylic acids have been prepared and tested for their in vitro and in vivo antibacterial activities. The 5-methyl group gave better in vitro activity with the 1-cyclopropyl appendage, but poorer activity with the 1-tert-butyl moiety. With the 1-(2,4-difluorophenyl) substitution, the influence of the 7-cycloalkylamino group was determinant: a (3S)-3-amino-pyrrolidine was shown to enhance greatly the in vitro and in vivo activity of the 5-methyl derivative. Compound 33 (BMY 43748) was selected as a promising candidate for an improved therapeutic agent.     

In vitro activity of the new quinoline derivative ciprofloxacin alone and in combination against various Mycobacterium-, Salmonella- and Escherichia coli strains

The antibacterial effect of 1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-7-piperazine-1-ylquinoline++ + 3-carboxylic acid (ciprofloxacin, Bay o 9867) has been tested using different test systems and various strains, especially of Escherichia coli, Mycobacterium and Salmonella. Ciprofloxacin shows low MIC's against most of the tested strains. The high in vitro and in vivo activity against Salmonella is most promising for cure of salmonellosis.     

6-氟喹诺酮类衍生物的合成及抗菌活性

报道一系列7,8-双取代的1-环丙基和1-乙基-6-氟-1,4-二氢-4-氧-3-喹啉羧酸衍生物的合成和体外抗菌活性。其中,1-环丙基-6-氟-7-(4-乙酰氧基哌啶)-8-氯-1,4-氢-4-氧-3-喹啉羧酸(11c)和1-环丙基-6-氟-7-(4-羟基哌啶)-8-氯-1,4-二氢-4-氧-3-喹啉羧酸(11b)同环丙沙星相比有更强的体外活性,尤其对金黄色葡萄球菌、耐甲氧青霉素金葡菌(MRSA)和绿脓杆菌。     

Quinolone antibacterial agents. Synthesis and structure-activity relationships of a series of amino acid prodrugs of racemic and chiral 7-(3-amino-1-pyrrolidinyl)quinolones. Highly soluble quinolone prodrugs with in vivo pseudomonas activity.

A series of amino acid prodrugs of racemic and chiral 7-(3-amino-1-pyrrolidinyl)-6-fluoro-1,8-naphthyridine-3-carboxylic acids, 1-cyclopropyl-6,8-difluoro-3-quinolinecarboxylic acids, 1-cyclopropyl-6-fluoro-3-quinolinecarboxylic acids, and 5-amino-1-cyclopropyl-6,8-difluoro-3-quinolinecarboxylic acids have been prepared and evaluated for comparative antibacterial activity. Compounds were prepared by acylation of the 3-amino group of the pyrrolidine with common amino acids using standard peptide chemistry. This series has been compared with the parent compounds for antibacterial activity in vitro and in vivo as well as for comparative solubility. The amino acid analogues were less active in vitro, but had equal or increased efficacy in vivo. Indeed, it was proven that these compounds, which were stable to acid and base under the reaction conditions for their preparation, were rapidly cleaved in serum to give the parent quinolones. The amino acid derivatives showed a 3-70 times improved solubility when compared to the parent compounds. The most active compound of the series was [S-(R*,R*)]-7-[3-[(2-amino-1-oxopropyl)-amino]-1-pyrrolidinyl]-1- cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxylic acid (PD 131112).     

5-氨基-8-甲氧基-喹诺酮类的合成及其体外抗菌作用

以1-环丙基-6，7-二氟-8-甲氧基-1，4-二氢-4-氧代喹啉-3-羧酸乙酯为起始原料依次经过硝化、还原和水解三步反应制得5-氨基-1-环丙基-6，7-二氟-8-甲氧基-1，4-二氢-4-氧代喹啉-3-羧酸，然后分别与2（R）-（-）／2（S）-（＋）或2（R，S）-甲基哌嗪缩合，得到3种目标化合物（5a、5b和5c）。测定它们对20株临床分离和标准革兰阴性菌和标准革兰阳性菌的最低抑菌浓度。结果表明，5a和5b的体外抗菌活性与外消旋体5c基本相当。