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).

Characterization and Expression of Chicken Selenoprotein U.

Selenoprotein U (SelU) may regulate a myriad of biological processes through its redox function. In chicks, neither the nucleotide sequence nor the amino acid sequence is known. The main objectives of this study were to clone and characterize the chicken Selu gene and investigate Selu messenger RNA (mRNA) and protein expression in chicken tissues. The coding sequence (CDS) of Selu contained 387 bases with a typical mammalian selenocysteine insertion sequence (SECIS) located in the 3'-untranslated region. The deduced amino acid sequence of chicken SelU contains 224 amino acids with UAA as the stop codon. Like all SelU genes identified in different species, chicken SelU contains one well-conserved selenocysteine (Sec) at the 85th position encoded by the UGA codon. The SECIS element was with the conserved denosine (--AAA--) rather than the motif cytidine (--CC--) motif. Moreover, the expression pattern of Selu mRNA in muscle, liver, kidney, heart, spleen, lung, testis, and brain was analyzed with real-time quantitative PCR in young male chickens fed a Se-deficient corn-soybean meal basal diet supplemented with 0.0 and 0.3 mg Se/kg in the form of sodium selenite. We found that the abundance of Selu mRNA in muscle, liver, kidney, heart, spleen, and lung was downregulated (P < 0.05) by Se deficiency. However, it was not affected by dietary Se concentrations in testis and brain. Furthermore, protein abundance of SelU in these seven tissues was consistent with the mRNA abundance. Hence, we suggest that Selu might play an important role in the biochemical function of Se in birds.

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.

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.

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.

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 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.

[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.

[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.

Synthesis and in vitro antibacterial activity of a series of novel gatifloxacin derivatives.

A series of novel gatifloxacin (GTFX) derivatives were designed, synthesized and characterized by (1)H NMR, (13)C NMR, MS and HRMS. These derivatives were evaluated for in vitro antibacterial activity against representative Gram-positive and Gram-negative strains. Our results reveal that most of the target compounds show good potency in inhibiting the growth of Staphylococcus aureus including MRSA and Staphylococcus epidermidis including MRSE. Compounds 8, 14 and 20 have useful activity against all of the tested Gram-positive and Gram-negative strains (MICs: 0.06-4 µg/mL). In particular, 20 possessing a broad antimicrobial spectrum (MICs: 0.06-1 µg/mL) was found to be 2-32-folds more potent than the reference drug levofloxacin and parent GTFX against Pseudomonas aeruginosa.

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-alkoxyimino-4-amino-4-methylpiperidin-1-yl) fluoroquinolone derivatives.

A series of novel 7-(3-alkoxyimino-4-amino-4-methylpiperidin-1-yl)fluoroquinolone derivatives were designed, synthesized and evaluated for their in vitro antibacterial activity and cytotoxicity. All of the target compounds have potent antibacterial activity against the tested Gram-positive and Gram-negative strains, and exhibit good potency in inhibiting the growth of Staphylococcus aureus including MRSA, Staphylococcus epidermidis including MRSE and Streptococcus pneumoniae (MICs: 0.125-4 µg/mL). Compound 22, with the best activity against Gram-positive strains, is 4-16 fold more potent than gemifloxacin, gatifloxacin and levofloxacin against Enterococcus faecalis, and 16- and 4-fold more potent than levofloxacin against S. epidermidis 09-6 and S. pneumoniae 08-4, respectively.

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.

Synthesis and in vitro antimycobacterial activity of 8-OCH(3) ciprofloxacin methylene and ethylene isatin derivatives.

A series of novel 8-OCH(3) ciprofloxacin methylene and ethylene isatin derivatives with remarkable improvement in lipophilicity were synthesized in this study. These derivatives were evaluated for their in vitro activity against some mycobacteria. All of the synthesized compounds were less active than the parent 8-OCH(3) ciprofloxacin against Mycobacteriumsmegmatis CMCC 93202, but most of the methylene isatin derivatives were more active than 8-OCH(3) ciprofloxacin, ciprofloxacin, isoniazid and rifampin against MTB H37Rv ATCC 27294. It was noted that compound 3b (MIC: 0.074 µM) was 2-13 fold more potent than the reference compounds against MTB H37Rv ATCC 27294, and compounds 3f and 3i-k (MIC: 6.72-7.05 µM) were around 1.6 fold more potent than the parent 8-OCH(3) ciprofloxacin, 3.5 fold more potent than ciprofloxacin against MDR-MTB 09710.

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.