Ceftizoxime sodium is a parenteral beta-lactamic antibacterial drug. In the synthesis of ceftizoxime sodium, eight process related impurities were detected in HPLC analysis. Pure impurities obtained by both synthesis and preparative HPLC were co-injected with ceftizoxime sample to confirm the retention times in HPLC. The impurities were characterized as, (6R,7R)-7-amino-3-cephem-4-carboxylic acid (impurity I); (6R,7R)-7-[(Z)-2-(2-amino-4-thiazolyl)-2-(methoxyimino)acetamido]-3-cephem-1-oxo-4-carboxylic acid (impurity II); (4RS,6R,7R)-7-[(Z)-2-(2-amino-4-thiazolyl)-2-(methoxyimino) acetamido]-3,4-dihydro-3-cephem-4-carboxylic acid (impurity III); (6R,7R)-7-[(E)-2-(2-amino-4-thiazolyl)-2-(methoxyimino)acetamido]-3-cephem-4-carboxylic acid (impurity IV); (6R,7R)-7-[(Z)-2-(2-amino-4-thiazolyl)-2-(methoxyimino)acetamido]-3-cephem-N-(3-cephem-4-carboxy-7-yl)-4-carboxamide (impurity V); (6R,7R)-7-[(Z)-2-[[(Z)-2-(2-amino-4-thiazolyl)-2-(methoxyimino)acetylamino]thiazol-4-yl]-2-methoxyiminoacetamido]-3-cephem-4-carboxylic acid (impurity VI); 2-mercaptobenzothiazole (impurity VII) and 2-mercapto benzothiazolyl [(Z)-2-(2-amino-4-thiazolyl)-2-methoxyimino] acetate (impurity VIII). Structural elucidation of all impurities by spectral data ((1)H NMR, (13)C NMR, MS and IR) has been discussed. 相似文献
Atmospheric pressure chemical ionization mass spectrometry (APCI-MS) was operated in positive mode (PI) to characterize polymethoxylated flavonoids (PMFs) through its specific radical cations by collision-induced dissociation (CID). The fragments of [M + H − n × 15]+ produced by loss of one or more methyl group from the protonated molecule, as well as [M + H − 29]+, [M + H − 31]+, [M + H − 33]+, [M + H − 43]+, [M + H − 46]+, and [M + H − 61]+ fragment ions were detected, which were diagnostic for the polymethoxylated species, and could be adopted to form the multiple MS (MSn) “fingerprint” of PMFs. Based on this “fingerprint”, 29 PMFs were screened out from extracts of Fructus aurantii, among which two of them were identified as sinensetin and tangeretin. It was proved that the PI was suitable for structural characterization of PMFs by APCI-MSn. 相似文献
A method coupling high-performance liquid chromatography (HPLC) with diode-array detector (DAD) and electrospray ionization mass spectrometry (ESI) was established for the separation and characterization of flavonoids in Sophora flavescens Ait. Based on the chromatographic separation of most flavonoids present in S. flavescens Ait., a total of 24 flavonoids were identified. Fourteen compounds were unambiguously identified comparing experimental data for retention time (t(R)), UV and MS spectra with those of the authentic compounds: 3',7-dihydroxy-4'-methoxy-isoflavone (13), trifolirhizin (14), kurarinol (18), formononetin (19), 7,4'-dihydroxy-5-methoxy-8-(gamma,gamma-dimethylallyl)-flavanone (22), maackiain (21), isoxanthohumol (23), kuraridine (26), kuraridinol (27), sophoraflavanone G (30), xanthohumol (31), isokurarinone (33), kurarinone (35) and kushenol D (38), and additional 10 compounds were tentatively identified as kushenol O (10), trifolirhizin-6'-malonate (15), sophoraisoflavanone A (20), norkurarinol/kosamol Q (24), kushenol I/N (25), kushenol C (28), 2'-methoxykurarinone (29), kosamol R (32), kushecarpin A (34) and kushenol A (37) by comparing experimental data for UV and MS spectra with those of literature. Furthermore, fragmentation pathways in positive ions mode of 24 flavonoid compounds of types of flavanone, flavanonol, flavonol, chalcone, isoflavone, isoflavanone and ptercocarpane were summarized. Some common features, such as CH(3)., H(2)O, CO, CO(2), C(3)O(2) and C(2)H(2)O losses, together with Retro-Diels-Alder fragmentations were observed in the prenylated flavonoids in S. flavescens Ait. The loss of the lanandulyl chain was their characteristic fragmentation, which might help deducing the structure of unknown flavonoid compounds. The present study provided an approach to rapidly characterize bioactive constituents in S. flavescens Ait. 相似文献
Didanosine is an antiviral drug. During the preparation of didanosine in our lab, six process related known impurities and one unknown impurity were detected in HPLC analysis at levels ranging from 0.05 to 0.8%. The same unknown impurity was also observed in commercial batches. This new impurity was isolated by preparative HPLC and co-injected with didanosine sample to confirm the retention times in HPLC. This impurity was characterized as, 9-(2,3,5-trideoxy-beta-D-glycero-pentofuranosyl)-9H-purin-6-one (2',3',5'-trideoxyinosine). Structural elucidation of this impurity by spectral data (1H NMR, 13C NMR, MS and IR) has been discussed. 相似文献
Sophisticated delivery systems, such as nanoparticles, represent a growing area in biomedical research. Nanoparticles (Np) were prepared using a solvent emulsion evaporation method (SEEM) to load zinc(II) phthalocyanine (ZnPc). Np were obtained using poly (d,l latic-co-glycolic acid) (PLGA). ZnPc is a second generation of photoactive agents used in photodynamic therapy.
ZnPc loaded PLGA nanoparticles were prepared by SEEM, characterized and available in cellular culture. The process yield and encapsulation efficiency were 80 and 70%, respectively. The nanoparticles have a mean diameter of 285 nm, a narrow size distribution with polydispersive index of 0.12, smooth surface and spherical shape. ZnPc loaded nanoparticles maintains its photophysical behavior after encapsulation. Photosensitizer release from nanoparticles was sustained with a moderate and burst effect of 15% for 3 days. The photocytotoxicity of ZnPc loaded PLGA Np was evaluated on P388-D1 cells what were incubated with ZnPc loaded Np (5 μM) by 6 h and exposed to red light (675 nm) for 120 s, and light dose of 30 J/cm2. After 24 h of incubation, the cellular viability was determined, obtaining 61% of cellular death. All the physical–chemical, photophysical and photobiological measurements performed allow us conclude that ZnPc loaded PLGA nanoparticles is a promising drug delivery system for photodynamic therapy. 相似文献
In the synthesis of Moxifloxacin four prominent impurities were detected in HPLC analysis. These impurities were detected in gradient HPLC method. They were isolated from enriched mother liquors and were characterized as 1-cyclopropyl-6-fluoro-1,4-dihydro-8-methoxy-7-[(S,S)-N-methyl-2,8-diazabicyclo (4,3,0) non-8yl]-4-oxo-3-quinoline carboxylic acid (Impurity-1), methyl-1-cyclopropyl-6-fluoro-1,4-dihydro-8-methoxy-7-[(S,S)-2,8-diazabicyclo(4,3,0)non-8-yl]-4-oxo-3-quinoline carboxylate (impurity-2), and 1-cyclopropyl-6-fluoro-1,4 dihydro-8-hydroxy-7-[(S,S)-2,8-diazobicyclo(4,3,0)non-8-yl]-4-oxo-3-quinoline carboxylicacid (impurity-3), 1-cyclopropyl-6,7-difluoro-8-hydroxy-4-oxo-1,4 dihydro-3-quinoline carboxylicacid (impurity-4) by means of 1H, 13C NMR, DEPT, IR and mass spectral data. Structural elucidation by spectral data was discussed. 相似文献