Design, Synthesis and Antibacterial Evaluation of 1-[(1R,2S)-2-Fluorocyclopropyl]ciprofloxacin-1,2,4-triazole-5(4H)-thione Hybrids.

A new class of 1-[(1R,2S)-2-fluorocyclopropyl]ciprofloxacin (CPFX)-1,2,4-triazole-5(4H)-thione hybrids 6a - 6o was designed, synthesized and evaluated for their in vitro antibacterial activities against a panel of clinically important drug-sensitive and drug-resistant Gram-positive and Gram-negative pathogens. Our results revealed that all hybrids 6a - 6o had great potency against the tested strains, especially Gram-negative pathogens. The synthesized hybrids were more potent than the parent 1-[(1R,2S)-2-fluorocyclopropyl]CPFX (1) and comparable to CPFX and levofloxacin against the majority of the tested pathogens, worth to be further investigated.

Synthesis and In Vitro Antimycobacterial and Antibacterial Activity of 8-OMe Ciprofloxacin-Hydrozone/Azole Hybrids.

A series of novel 8-OMe ciprofloxacin (CPFX)-hydrazone/azole hybrids were designed, synthesized, and evaluated for their in vitro biological activities. Our results reveal that all of the hydrozone-containing hybrids (except for 7) show potency against Mycobacterium tuberculosis (MTB) H37Rv (minimum inhibitory concentration (MIC): <0.5 µM), which is better than the parent drug CPFX, and comparable to moxifloxacin and isoniazid, some of the tested Gram-positive strains (MIC: 0.06-4 µg/mL), and most Gram-negative strains (MIC: ≤0.03-4 µg/mL).

Bovine lactoferrin binds oleic acid to form an anti-tumor complex similar to HAMLET.

α-Lactalbumin (α-LA) can bind oleic acid (OA) to form HAMLET-like complexes, which exhibited highly selective anti-tumor activity in vitro and in vivo. Considering the structural similarity to α-LA, we conjectured that lactoferrin (LF) could also bind OA to obtain a complex with anti-tumor activity. In this study, LF-OA was prepared and its activity and structural changes were compared with α-LA-OA. The anti-tumor activity was evaluated by methylene blue assay, while the apoptosis mechanism was analyzed using flow cytometry and Western blot. Structural changes of LF-OA were measured by fluorescence spectroscopy and circular dichroism. The interactions of OA with LF and α-LA were evaluated by isothermal titration calorimetry (ITC). LF-OA was obtained by heat-treatment at pH8.0 with LD50 of 4.88, 4.95 and 4.62µM for HepG2, HT29, and MCF-7 cells, respectively, all of which were 10 times higher than those of α-LA-OA. Similar to HAMLET, LF-OA induced apoptosis in tumor cells through both death receptor- and mitochondrial-mediated pathways. Exposure of tryptophan residues and the hydrophobic regions as well as the loss of tertiary structure were observed in LF-OA. Besides these similarities, LF showed different secondary structure changes when compared with α-LA, with a decrease of α-helix and ß-turn and an increase of ß-sheet and random coil. ITC results showed that there was a higher binding number of OA to LF than to α-LA, while both of the proteins interacted with OA through van der Waals forces and hydrogen bonds. This study provides a theoretical basis for further exploration of protein-OA complexes.

Spectroscopic investigation of the influence of calcium ion on the structures of casein micelles.

The effects of calcium ion on the structural properties of casein micelles in the course of heat treatment were synthetically examined by non-structure-invasive spectrometry. The hydrophobicity, reflected by extrinsic fluorescence (ANS fluorescence), was positively correlated with the concentration of the calcium ion, within the range of 0 to 12 mmol x L(-1). Meanwhile, the turbidity and stability of casein micelles also increased with the growth of calcium concentrations. However, opposite results were observed for hydrodynamic diameter and polydispersity index. Compared with the calcium ion, the calcium-chelator (citrate) has an opposite effect on the structural characteristics of casein micelles. Within the calcium concentrations range of 0 to 12 mmol x L(-1), the hydrophobicity, stability and turbidity were negatively correlated with the concentration of the calcium ion, nevertheless, opposite results were observed for hydrodynamic diameter and polydispersity index. All the results indicate that the calcium ion could be used to modify the structures of casein micelles during heat heatment.

In vivo antibacterial activity of chinfloxacin, a new fluoroquinolone antibiotic.

OBJECTIVES: To evaluate the in vivo antibacterial efficacy of chinfloxacin, a novel fluoroquinolone, in murine systemic and local infection models. METHODS: The efficacy of chinfloxacin in systemic infection was evaluated in a mouse peritonitis model using isolates of methicillin-susceptible Staphylococcus aureus (MSSA, n = 3), methicillin-resistant Staphylococcus aureus (MRSA; n = 1), penicillin-intermediate Streptococcus pneumoniae (PISP; n = 1), penicillin-resistant S. pneumoniae (PRSP; n = 2), vancomycin-susceptible Enterococcus faecalis (VSE; n = 1), vancomycin-resistant E. faecalis (VRE; n = 2), Escherichia coli (n = 3) and Klebsiella pneumoniae (n = 2). The local infections included mouse pulmonary infections caused by penicillin-susceptible S. pneumoniae (PSSP; n = 1), PRSP (n = 1) and K. pneumoniae (n = 2). RESULTS: In the mouse systemic infection model, chinfloxacin demonstrated potent activity against MSSA [50% effective dose (ED(50)) 2.28-4.15 mg/kg], MRSA (ED(50) 14.75 mg/kg), PISP (ED(50) 6.20 mg/kg), PRSP (ED(50) 3.51-5.03 mg/kg), VSE (ED(50) 25.02 mg/kg), VRE (ED(50) 5.18-15.39 mg/kg), E. coli (ED(50) 1.25-1.90 mg/kg) and K. pneumoniae (ED(50) 2.92-8.28 mg/kg). The therapeutic efficacy of chinfloxacin was generally similar to (P > 0.05) that of moxifloxacin, significantly higher (P < 0.01 or P < 0.05) than that of levofloxacin in Gram-positive isolate infections (MSSA, MRSA, PISP, PRSP, VSE and VRE), and less than that of levofloxacin against E. coli and K. pneumoniae infections (P < 0.01). In the mouse pulmonary infection model, chinfloxacin showed potent activity towards S. pneumoniae (higher than levofloxacin and ciprofloxacin) and K. pneumoniae (lower than levofloxacin and similar to or higher than ciprofloxacin) infections. CONCLUSIONS: The results validated the potent efficacy of chinfloxacin in vivo. The high efficacy of chinfloxacin in murine systemic and local infections warrants investigation of its clinical use.

Synthesis, antimycobacterial and antibacterial activity of ciprofloxacin derivatives containing a N-substituted benzyl moiety.

We report herein the design and synthesis of a series of novel ciprofloxacin (CPFX) derivatives with remarkable improvement in lipophilicity by introducing a substituted benzyl moiety to the N atom on the C-7 piperazine ring of CPFX. Antimycobacterial and antibacterial activity of the newly synthesized compounds was evaluated. Results reveal that compound 4f has good in vitro activity against all of the tested Gram-positive strains including MRSA and MRSE (MICs: 0.06-32 µg/mL) which is two to eightfold more potent than or comparable to the parent drug CPFX (MICs: 0.25-128 µg/mL), Gram-negative bacteria P. aeruginosa (MICs: 0.5-4 µg/mL) and M. tuberculosis H37Rv ATCC 27294 (MIC: 1 µg/mL).

In vitro antibacterial activity of chinfloxacin, a new fluoroquinolone antibiotic.

BACKGROUND: Chinfloxacin is a novel synthetic fluoroquinolone with a structure similar to moxifloxacin. The in vitro activity of chinfloxacin was evaluated in the current study. METHOD: Chinfloxacin was tested against a total of 1,739 clinical isolates representing 23 species using the agar dilution method. Studies of bactericidal activity, including minimum bactericidal concentrations (MBC) and time-kill curve determinations, were conducted according to the recommendations of the Clinical and Laboratory Standards Institute. RESULTS: Minimum inhibitory concentrations (MIC)(50)s and MIC(90)s of chinfloxacin were found to be the same or 2-fold lower than those of moxifloxacin against gram-positive isolates except for Streptococcus pyogenes (against which chinfloxacin showed similar MIC(50) as moxifloxacin but 2-fold higher MIC(90)), and the same as or 2-fold higher than those of moxifloxacin against gram-negative isolates. Chinfloxacin showed potent bactericidal activity with MBC/MIC ratios in the range of 1-2 for almost all the isolates tested. Time-kill curves further demonstrated chinfloxacin as a concentration-dependent bactericidal agent usually effective at concentrations of 2 MIC or higher. CONCLUSION: Chinfloxacin showed similar in vitro activity as moxifloxacin.

[Spectral properties of interaction between caffeic acid and milk protein and the change in antioxidant capacity].

The interaction between caffeic acid and milk protein (alpha-casein, beta-casein, kappa-casein, alpha-lactalbumin, beta-lactoglobulin) were studied in this work. The binding constant K(A), binding force, binding distance r(0) and transfer efficiency E were evaluated by UV-absorption and fluorescence spectroscopy. The antioxidant capacity of the combination was determined using both 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay and ferric reducing antioxidant power (FRAP) assay. The results showed that the interaction between milk protein and caffeic acid resulted in the endogenous fluorescence quenching of milk protein, which belongs to a static quenching mechanism. The negative sign of free energy meant that the interaction process was spontaneous. The strength between caffeic acid and alpha-casein was electrostatic attraction (deltaH < 0, deltaS > 0), and that between beta-casein and alpha-Lactalbumin was hydrogen bonding (deltaH < 0, deltaS < 0). In addition, the strength of caffeic acid interacting with kappa-casein and beta-lactoglobulin was hydrophobic interaction (deltaH > 0, deltaS > 0). The binding distance (r(0) < 7 nm) proved that caffeic acid lead to a static quenching mechanism of milk protein. The antioxidant capacity of caffeic acid was inhibited by milk protein to different degrees.

[A comparison of different treatment conditions on the conformation changes of bovine lactoferrin].

In this study, the tertiary, secondary structures and disulfide bond changes of bovine lactoferrin (bLF) under 6 differents physico-chemical treatments were investigated by fluorescence, circular dichroism(CD) and UV-Vis absorption. A red shift from 333 to 354 nm in the fluorescence emission maximum (lambda(max)) was observed in the bLF treated by 6 mol x L(-1) GdnHCl, 8 mol x L(-1) Urea and 50 mmol x L(-1) DTT simultaneously, meanwhile a large number of exposed hydrophobic groups were detected. However, there was no marked shift in lambda(max) of bLF treated by heating (100 degrees C, 5 min), Ultrosonic(450 W, 5 s, 6 pulses) or beta-ME (1%), of which fluorescence intensity decreased significantly compared with the untreated bLF. The results indicated that the mechanism of changes in tertiary structure of the former three methods were different from the latter three. The detection by CD showed that the alpha- helix structure vanished completely in the bLF treated by GdnHCl. However, there was no remarkable change in the secondary structure of the bLF treated by the other five methods. In addition, UV-Vis absorption suggested that disulfide bond was seriously destructed in the bLF treated by DTT and Ultrosonict, but GdnHCl, beta-ME and heating induced a little damage merely. This study is instructive and meaningful to the further research on relationship between structure and activity of bLF.

Synthesis and in-vitro antimycobacterial activity of fluoroquinolone derivatives containing a coumarin moiety.

A series of gatifloxacin, ciprofloxacin, and 8-OCH(3) ciprofloxacin coumarin derivatives with remarkable improvement in lipophilicity as compared to the parent fluoroquinolones was designed, synthesized, and characterized by (1) H-NMR, MS, and HRMS. These derivatives were evaluated for their in-vitro activity against Mycobacterium smegmatis CMCC 93202 and MTB H37Rv ATCC 27294. All of the synthesized compounds were less active than the parent compounds against M. smegmatis CMCC 93202, but the activity of compound 6 was found to be 2-8-fold more potent than ciprofloxacin, 8-OCH(3) ciprofloxacin, moxifloxacin, and rifampin, and comparable to gatifloxacin against MTB H37Rv ATCC 27294. These results indicated that the lipophilicity of the tested compounds is not the sole parameter affecting antimycobacterial activity.

Synthesis and in-vitro antibacterial activity of 7-(3-aminopyrrolo[3,4-c]pyrazol-5(2H,4H,6H)-yl)-6-fluoro-4-oxo-1,4-dihydroquinoline-3-carboxylic acid derivatives.

A series of novel 7-(3-aminopyrrolo[3,4-c]pyrazol-5(2H,4H,6H)-yl)-6-fluoro-4-oxo-1,4-dihydroquinoline-3-carboxylic acid derivatives was designed, synthesized and characterized by (1)H-NMR, MS and HRMS. These fluoroquinolones were evaluated for their in-vitro antibacterial activity against representative Gram-positive and Gram-negative strains. Generally, all of the target compounds display rather weak potency against the tested Gram-negative strains, but most of them exhibit good potency in inhibiting the growth of S. aureus including methicillin-resistant Staphylococcus aureus (MRSA) and Staphylococcus epidermidis including methicillin-resistant S. epidermidis (MRSE) (MIC: 0.125-8 µg/mL). In particular, the compound 9g is 2 to 32 fold more potent than gemifloxacin (GM), moxifloxacin (MX), gatifloxacin (GT), and levofloxacin (LV) against S. pneumoniae 08-3, K. pneumoniae 09-23, and P. aeruginosa ATCC27853, 4 to 32 fold more potent than MX, GM, and LV against K. pneumoniae 09-21, and more active than or comparable to the four reference drugs against P. aeruginosa 09-32.

Synthesis and in vitro antibacterial activity of 7-(3-amino-6,7-dihydro-2-methyl-2H-pyrazolo[4,3-c] pyridin-5(4H)-yl)fluoroquinolone derivatives.

A series of novel 7-(3-amino-6,7-dihydro-2-methyl-2H-pyrazolo[4,3-c]pyridin- 5(4H)-yl)fluoroquinolone derivatives were designed, synthesized and characterized by 1H-NMR, MS and HRMS. These fluoroquinolones were evaluated for their in vitro antibacterial activity against representative Gram-positive and Gram-negative strains. Results reveal that most of the target compounds exhibit good growth inhibitory potency against methicillin-resistant Staphylococcus epidermidis (MRSE) (MIC: 0.25-4 µg/mL) and Streptococcus pneumoniae (MIC: 0.25-1 µg/mL). In addition, compound 8f is 8-128 fold more potent than the reference drugs gemifloxacin (GM), moxifloxacin (MX), ciprofloxacin (CP) and levofloxacin (LV) against methicillin-resistant Staphylococcus aureus 10-05 and Streptococcus hemolyticus 1002 and 2-64 fold more active against methicillin-sensitive Staphylococcus aureus 10-03 and 10-04.

[Interaction of lactoferrin and its peptides with DPPC and DPPG liposomes studied by Raman spectroscopy].

Interaction of lactoferrin and its peptides LfcinB4-14 and LfampinB with dipalmitoylglycero-phosphocholine (DPPC) and dipalmitoylglycero-phosphoglycerol (DPPG) liposomes were studied by means of Raman spectroscopy. In our study, conformational changes in the phospholipid molecules were investigated by measuring the intensities of 2 847 and 2 882 cm(-1) Raman bands which are assigned to acyl chains' symmetric and asymmetric C-H stretching vibrations. The addition of lactoferrin and its peptides LfcinB4-14 and LfampinB caused a decrease in the 2 882 cm(-1) intensity of DPPG liposomes, thus the order parameter for the lateral interactions between chains S(lat) decreased from 0.19 to 0.17, 0.14 and 0.12 respectively. On the contrary, the intensities at 2 847 and 2 882 cm(-1) of DPPC liposomes were poorly affected by lactoferrin and its peptides. The results show that lactoferrin and its peptides present a stronger effect on the molecular structure and order degree of anionic lipid DPPG than that of zwitterionic lipid DPPC. This suggests that lactoferrin, LfcinB4-14 and LfampinB can interact and combine with the negatively charged DPPG liposomes by electrostatic interaction and perform its antibacterial activity. Besides, LfcinB4-14 and LfampinB can affect the lipid more strongly than lactoferrin.

[FTIR analysis of cosrelation between emulsifying properties and the secondary structure of the proteins in modified egg yolk powder ].

Spray drying is an important processing of producing modificatied yolk powder (MEYP). To investigate the correlation between the secondary structure and emulsifying property of MEYP made at different spray-drying-temperatures, Fourier transform infrared spectroscopy (FTIR) was applied in the present study. The result indicated that emulsifiability and the percentage of alpha-helix were both significantly increased firstly and then remarkably decreased with rising of spray-drying-temperature, and the emulsifying property of MEYP was relative to the percentage of alpha-helix. After heat-treating, the percentage of alpha-helix was significantly decreased and the percentage of p-sheet was remarkably increased, however, the total percentage of the two structures was maintained. The stable total percentage of alpha-helix and beta-sheet would be a good explanation for the great heat stability of emulsion presented in the MEYP made at different spray-drying temperature.

FTIR analysis of protein secondary structure in cheddar cheese during ripening.

Proteolysis is one of the most important biochemical reactions during cheese ripening. Studies on the secondary structure of proteins during ripening would be helpful for characterizing protein changes for assessing cheese quality. Fourier transform infrared spectroscopy (FTIR), with self-deconvolution, second derivative analysis and band curve-fitting, was used to characterize the secondary structure of proteins in Cheddar cheese during ripening. The spectra of the amide I region showed great similarity, while the relative contents of the secondary structures underwent a series of changes. As ripening progressed, the alpha-helix content decreased and the beta-sheet content increased. This structural shift was attributed to the strengthening of hydrogen bonds that resulted from hydrolysis of caseins. In summary, FTIR could provide the basis for rapid characterization of cheese that is undergoing ripening.

The secondary structure of heated whey protein and its hydrolysates antigenicity.

Fourier transform infrared spectroscopy (FTIR) and circular dichroism (CD) were used to investigate the conformational changes of heated whey protein (WP) and the corresponding changes in the hydrolysates immunoreactivity were determined by competitive enzyme-linked immunosorbent assay (ELISA). Results showed that the contents of alpha- helix and beta-sheet of WP did not decrease much under mild heating conditions and the antigenicity was relatively high; when the heating intensity increased (70 degrees for 25 min or 75 degrees C for 20 min), the content of alpha- helix and beta-sheet decreased to the minimum, so was the antigenicity; However, when the WP was heated at even higher temperature and for a longer time, the beta-sheet associated with protein aggregation begun to increase and the antigenicity increased correspondingly. It was concluded that the conformations of heated WP and the antigenicity of its hydrolysates are related and the optimum structure for decreasing the hydrolysates antigeniity is the least content of alpha-helix and beta-sheet. Establishing the relationship between the WP secondary structure and WP hydrolysates antigenicity is significant to supply the reference for antigenicity reduction by enzymolysis.

Synthesis and in vitro antibacterial activity of 7-(3-alkoxyimino-4-methyl-4-methylaminopiperidin-1-yl)-fluoroquinolone derivatives.

A series of novel 7-(3-alkoxyimino-4-methyl-4-methylaminopiperidin-1-yl)fluoroquinolone derivatives were designed, synthesized, and characterized by 1H-NMR, MS, and HRMS. These fluoroquinolones were evaluated for their in-vitro antibacterial activity against representative Gram-positive and Gram-negative strains. Generally, all of the target compounds have considerable antibacterial activity against the tested forty strains, and exhibit exceptional potency in inhibiting the growth of methicillin-sensitive Staphylococcus aureus (MSSA) and methicillin-resistant S. aureus (MRSA) ATCC33591 (MICs: 0.06 to 2 microg/mL). In particular, compounds 14, 19, 28, and 29 are fourfold more potent than ciprofloxacin against MSSA 08-49. Compounds 23, 26, and 27 are twofold more potent than ciprofloxacin against MRSA ATCC33591 and MSSA ATCC29213. In addition, compound 14 exhibits excellent activity (MIC: 0.06 microg/mL) against Acinetobactes calcoaceticus, which is two- to 16-fold more potent than the reference drugs gemifloxacin, levofloxacin, and ciprofloxacin.

Synthesis and in vitro antibacterial activity of 7-(4-alkoxyimino-3-methyl-3-methylaminopiperidin-1-yl)quinolones.

To explore new agents of quinolone derivatives with high antibacterial activity, 7-(4-alkoxyimino-3-methyl-3-methylaminopiperidin-1-yl)quinolones were designed and synthesized, and their activity against gram-positive and gram-negative strains was tested in vitro. Sixteen target compounds were obtained. Their structures were established by 1H NMR, HRMS and X-ray crystallographic analysis. Compounds 14k and 14m-14o show good antibacterial activity against the tested five gram-positive strains and five gram-negative strains (MIC: 0.25-16 micromg x mL(-1)), of which the most active compound 14o is 8-fold more potent than levofloxacin against S. pneumoniae (MIC: 4 microg x mL(-1)), and comparable to levofloxacin against S. aureus, S. epidermidis, E. faecalis and E. coli (MIC: 0.25-1 microg x mL(-1)), but generally less potent than gemifloxacin.

Orally administered lactoferrin preserves bone mass and microarchitecture in ovariectomized rats.

Lactoferrin (LF) is reported to stimulate osteoblast proliferation and inhibit osteoclast activity in bone cell culture. However, the effect of oral LF on bone in osteoporosis needs to be explored. Three-month-old female Sprague-Dawley rats (n = 70) were assigned to the following groups: sham-operated, ovariectomized (OVX) untreated, OVX + bovine serum albumin (BSA; 85 mg/kg body weight), OVX + LF (0.85 mg/kg, 8.5 mg/kg, and 85 mg/kg body weight), and OVX + 17beta-estradiol (E(2); 10 microg/kg body weight). After 3 mo of treatment, E(2) completely prevented the OVX-induced bone loss. OVX rats treated with LF were protected against the OVX-induced reduction of bone volume, trabecular number, and thickness, and the elevation of trabecular separation was prevented. LF also increased bone mineral density and increased the parameters of mechanical strength at 8.5- and 85-mg/kg doses. Greater bone formation and reduced bone resorption, as assessed by biochemical markers of bone remodeling, occurred in rats administered LF. LF at 8.5- and 85-mg/kg concentrations caused a significant decrease in serum calcium, but this reduction did not occur in rats fed 0.85 mg/kg LF. In addition, serum tumor necrosis factor-alpha and interleukin-6 production were suppressed and serum calcitonin was elevated significantly in LF-fed rats at all 3 doses. These findings indicated that oral LF not only preserved bone mass but also improved bone microarchitecture. The absorption of LF peptides and their effects on bone cells could to some extent account for the osteogenic function of oral LF.

tert-Butyl 3-carbamoyl-4-methoxy-imino-3-methyl-piperidine-1-carboxyl-ate.

In the title compound, C(13)H(23)N(3)O(4), the piperidine ring adopts a chair conformation. An intra-molecular N-H⋯O hydrogen bond is observed between the carbamoyl and carboxyl-ate groups. In the crystal structure, mol-ecules form inversion dimers linked by pairs of N-H⋯O hydrogen bonds.