The concentrations of 15 priority PAHs were determined in the atmospheric gaseous and particulate phases from nine sites across Assiut City, Egypt. While naphthalene, acenaphthene, and fluorene were the most abundant in the gaseous phase with average concentrations of 377, 184, and 181 ng/m3, benzo[b]fluoranthene, chrysene, and benzo[g,h,i]perylene showed the highest levels in the particulate phase with average concentrations of 76, 6, and 52 ng/m3. The average total atmospheric concentration of target PAHs (1,590 ng/m3) indicates that Assiut is one of the highest PAH-contaminated areas in the world. Statistical analysis revealed a significant difference between the levels of PAHs in the atmosphere of urban and suburban sites (P= 0.029 and 0.043 for gaseous and particulate phases, respectively). Investigation of diagnostic PAH concentration ratios revealed vehicular combustion and traffic exhaust emissions as the major sources of PAHs with a higher contribution of gasoline rather than diesel vehicles in the sampled areas. Benzo[a]pyrene has the highest contribution (average= 32, 4% for gaseous and particulate phases) to the total carcinogenic activity (TCA) of atmospheric PAHs. While particulate phase PAHs have higher contribution to the TCA, gaseous phase PAHs present at higher concentrations in the atmosphere are more capable of undergoing atmospheric reactions to form more toxic derivatives.

The concentrations of 15 priority PAHs were determined in the atmospheric gaseous and particulate phases from nine sites across Assiut City, Egypt. While naphthalene, acenaphthene, and fluorene were the most abundant in the gaseous phase with average concentrations of 377, 184, and 181 ng/m3, benzo[b]fluoranthene, chrysene, and benzo[g,h,i]perylene showed the highest levels in the particulate phase with average concentrations of 76, 6, and 52 ng/m3. The average total atmospheric concentration of target PAHs (1,590 ng/m3) indicates that Assiut is one of the highest PAH-contaminated areas in the world. Statistical analysis revealed a significant difference between the levels of PAHs in the atmosphere of urban and suburban sites (P= 0.029 and 0.043 for gaseous and particulate phases, respectively). Investigation of diagnostic PAH concentration ratios revealed vehicular combustion and traffic exhaust emissions as the major sources of PAHs with a higher contribution of gasoline rather than diesel vehicles in the sampled areas. Benzo[a]pyrene has the highest contribution (average= 32, 4% for gaseous and particulate phases) to the total carcinogenic activity (TCA) of atmospheric PAHs. While particulate phase PAHs have higher contribution to the TCA, gaseous phase PAHs present at higher concentrations in the atmosphere are more capable of undergoing atmospheric reactions to form more toxic derivatives.

The trisubstituted enolate- and C–C bond-forming capacities of engineered carboxymethylproline synthases CMPSs are coupled with the malonyl-CoA synthetase MatB to enable stereoselective preparation of 5- and 6-membered N-heterocycles functionalised with alkyl-substituted carboxymethyl side chains, starting from achiral alkyl-substituted malonic acids and L-amino acid semialdehydes. The results illustrate the biocatalytic utility of crotonases in tandem enzyme-catalysed reactions for stereoselective synthesis.

The beta-lactam antibiotics and related -lactamase inhibitors are amongst the most important small molecules in clinical use. Most, but not all, -lactams including penicillins, cephalosporins, and clavulanic acid are produced via fermentation or via modification of fermented intermediates, with important exceptions being the carbapenems and aztreonam. The desire for more efficient routes to existing antibiotics and for access to new and synthetically challenging ones stimulates continued interest in -lactam biosynthesis. We review knowledge of the pathways leading to -lactam antibiotics focusing on the mechanisms, structures and biocatalytic applications of the enzymes involved.

A new, simple, rapid and sensitive batch chemiluminescence (CL) method for determination of six fluoroquinolones (ciprofloxacin, gatifloxacin, levofloxacin, lomefloxacin HCl, ofloxacin and sparfloxacin) is proposd. The method is based on the CL generated during the oxidation of luminol by N-bromosuccinimide (NBS) in alkaline medium. The determination of the studied drugs is based on their inhibiting effect on the emission intensity of NBS-luminol chemiluminescent reaction. The effect of analytical variables on this CL system is discussed. The study was validated according to ICH guidelines. Under the optimum experimental conditions, the linear range is 50 to 400 ng/ml for ciprofloxacin, 50 to 600 ng/ml for gatifloxacin, lomefloxacin HCl and sparfloxacin and 25 to 400 ng/ml for levofloxacin and ofloxacin and the detection and quantitation limits for the studied drugs were not more than 4.88 and 14.80 ng/ml, respectively. The proposed method has been applied to detect the studied drugs in their pure forms and in different pharmaceutical formulations. The possible mechanism of the CL reaction was discussed.

A new, simple, rapid and sensitive batch chemiluminescence (CL) method for determination of six fluoroquinolones (ciprofloxacin, gatifloxacin, levofloxacin, lomefloxacin HCl, ofloxacin and sparfloxacin) is proposd. The method is based on the CL generated during the oxidation of luminol by N-bromosuccinimide (NBS) in alkaline medium. The determination of the studied drugs is based on their inhibiting effect on the emission intensity of NBS-luminol chemiluminescent reaction. The effect of analytical variables on this CL system is discussed. The study was validated according to ICH guidelines. Under the optimum experimental conditions, the linear range is 50 to 400 ng/ml for ciprofloxacin, 50 to 600 ng/ml for gatifloxacin, lomefloxacin HCl and sparfloxacin and 25 to 400 ng/ml for levofloxacin and ofloxacin and the detection and quantitation limits for the studied drugs were not more than 4.88 and 14.80 ng/ml, respectively. The proposed method has been applied to detect the studied drugs in their pure forms and in different pharmaceutical formulations. The possible mechanism of the CL reaction was discussed.

A new, simple, rapid and sensitive batch chemiluminescence (CL) method for determination of six fluoroquinolones (ciprofloxacin, gatifloxacin, levofloxacin, lomefloxacin HCl, ofloxacin and sparfloxacin) is proposd. The method is based on the CL generated during the oxidation of luminol by N-bromosuccinimide (NBS) in alkaline medium. The determination of the studied drugs is based on their inhibiting effect on the emission intensity of NBS-luminol chemiluminescent reaction. The effect of analytical variables on this CL system is discussed. The study was validated according to ICH guidelines. Under the optimum experimental conditions, the linear range is 50 to 400 ng/ml for ciprofloxacin, 50 to 600 ng/ml for gatifloxacin, lomefloxacin HCl and sparfloxacin and 25 to 400 ng/ml for levofloxacin and ofloxacin and the detection and quantitation limits for the studied drugs were not more than 4.88 and 14.80 ng/ml, respectively. The proposed method has been applied to detect the studied drugs in their pure forms and in different pharmaceutical formulations. The possible mechanism of the CL reaction was discussed.

A new, simple, rapid and sensitive batch chemiluminescence (CL) method for determination of six fluoroquinolones (ciprofloxacin, gatifloxacin, levofloxacin, lomefloxacin HCl, ofloxacin and sparfloxacin) is proposd. The method is based on the CL generated during the oxidation of luminol by N-bromosuccinimide (NBS) in alkaline medium. The determination of the studied drugs is based on their inhibiting effect on the emission intensity of NBS-luminol chemiluminescent reaction. The effect of analytical variables on this CL system is discussed. The study was validated according to ICH guidelines. Under the optimum experimental conditions, the linear range is 50 to 400 ng/ml for ciprofloxacin, 50 to 600 ng/ml for gatifloxacin, lomefloxacin HCl and sparfloxacin and 25 to 400 ng/ml for levofloxacin and ofloxacin and the detection and quantitation limits for the studied drugs were not more than 4.88 and 14.80 ng/ml, respectively. The proposed method has been applied to detect the studied drugs in their pure forms and in different pharmaceutical formulations. The possible mechanism of the CL reaction was discussed.

This study describes, for the first, the development and validation of a novel high-throughput micorwell spectrophotometric assay for determination of the quinolone antibiotic rosoxacin (ROS) in its bulk and capsules. The assay involved the reaction between ROS and sodium nitroprusside (SNP) forming a red-colored product exhibiting maximum absorption peak (λmax) at 455 nm. The reaction was carried out in 96-microwell plate and the absorbance of the colored-product was measured by microwell plate absorbance reader at 455 nm. The variables affecting the reaction were carefully investigated using the microwell format and the optimum conditions under were established. Under the optimized conditions, a linear relationship with good correlation coefficient (0.9992) was found between the absorbance of the ROS-SNP chromogen and ROS concentration in the range of 15-150 μg/mL. The limits of detection and quantification were 3.5 and 11.6 μg/mL, respectively. The assay showed high precision as the values of relative standard deviations (RSD) did not exceed 2%. The proposed assay was successfully applied to the determination of ROS in its capsules; the label claim percentages were 102.81±1.43%. The results were compared favorably with those of a reference pre-validated method. The proposed assay is practical and valuable in terms of its routine application in determination of ROS in its bulk and capsules in pharmaceutical quality control laboratories.

This study describes, for the first, the development and validation of a novel high-throughput micorwell spectrophotometric assay for determination of the quinolone antibiotic rosoxacin (ROS) in its bulk and capsules. The assay involved the reaction between ROS and sodium nitroprusside (SNP) forming a red-colored product exhibiting maximum absorption peak (λmax) at 455 nm. The reaction was carried out in 96-microwell plate and the absorbance of the colored-product was measured by microwell plate absorbance reader at 455 nm. The variables affecting the reaction were carefully investigated using the microwell format and the optimum conditions under were established. Under the optimized conditions, a linear relationship with good correlation coefficient (0.9992) was found between the absorbance of the ROS-SNP chromogen and ROS concentration in the range of 15-150 μg/mL. The limits of detection and quantification were 3.5 and 11.6 μg/mL, respectively. The assay showed high precision as the values of relative standard deviations (RSD) did not exceed 2%. The proposed assay was successfully applied to the determination of ROS in its capsules; the label claim percentages were 102.81±1.43%. The results were compared favorably with those of a reference pre-validated method. The proposed assay is practical and valuable in terms of its routine application in determination of ROS in its bulk and capsules in pharmaceutical quality control laboratories.