Simultaneous Estimation and Validation of Four Antiepileptic Drugs from Bulk and Formulations Using Reverse Phase HPLC

Abstract Epilepsy is a disorder of the central nervous system, in which the nerve cell activity in the brain is disturbed causing seizures. The objective was to develop an RP-HPLC method for consistent simultaneous quantitation of four antiepileptic drugs Levetiracetam (LVT), Lamotrigine (LTG), Phenobarbital (PBT) and Phenytoin (PTY). An isocratic method was developed on C18 column in JASCO HPLC using 5 mM potassium phosphate buffer (pH 6) and acetonitrile as the mobile phase at a flow rate of 1ml/min and detected at 230 nm using UV detector. The mean retention time for LVT, LTG, PBT and PTY were found as 2.55, 3.55, 4.65 and 5.99 minutes respectively. The method was validated as per ICH guidelines and was found to be acceptable. The %RSD value was <2.0 % thus stating the developed method was precise for the drugs in the given range. The accuracy values were within 85-115% of the recovery range. The specificity of the method was evaluated by an assay of marketed formulation, and it showed a percent content between 90-110% w/w for all the four drugs. The proposed analytical method was simple, accurate and robust and was precisely able to resolve the four major antiepileptic drugs. Hence, the current method can be applied successfully for routine examination of these drugs

Development and validation of a reversed-phase HPLC method for quantification of 1'-acetoxychavicol acetate content in a nanostructured lipid carrier formulation

Abstract 1'-acetoxychavicol acetate (ACA)-loaded nanostructured lipid carriers (NLCs) were formulated for prostate cancer therapy and to determine the optimal therapeutic dose, we developed a rapid, specific, and accurate reversed-phase high-performance liquid chromatography (RP-HPLC) method to quantify the ACA content in NLCs. The method was validated according to International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH) guidelines. Chromatographic separation of ACA from the lipid components was performed with an Agilent 1220 Infinity LC system and ultraviolet detector using an Agilent Poroshell C18 column (4.6 x 250.0 mm). The mobile phase consisted of acetonitrile and water (80:20 [v/v]) with a flow rate of 0.8 mL/min in isocratic mode. Linearity of the standard curve was assessed at an ACA concentration range of 5-200 µg/mL, and a 1/x weighted linear regression was adopted for the calibration curve. The calculated limits of detection and quantification were 0.59 µg/mL and 1.79 µg/mL, respectively. The mean percent recovery of ACA was 100.02% (relative SD, 2%), and the coefficients of variation for intraday and interday assays were within the values required by the ICH. We also demonstrated robustness of the method by altering the mobile phase ratio and flow rate. Furthermore, we proved specificity of the method for ACA by comparing chromatograms of the blank NLC and ACA-NLC. Hence, we effectively used this validated method to determine the drug-loading capacity and entrapment efficiency of the NLCs.

Separation and determination of D-malic acid enantiomer by reversed-phase liquid chromatography after derivatization with (R)-1-(1-naphthyl) ethylamine

Abstract L-Malic acid is the Active Pharmaceutical Ingredient of the latest generation of compound electrolyte injection (STEROFUNDIN ISO, Germany) and plays a very important role in the rescue of critically ill patients. The optical purity of L-malic acid is a Critical Quality Attributes. A new reversed-phase high performance liquid chromatography (RP-HPLC) method for pre-column derivatization of D-malic acid enantiomer impurity in L-malic acid bulk drug was established. The derivatization reaction was carried out using (R)-1-(1-naphthyl)ethylamine ((R)-NEA) as a chiral derivatization reagent. The Kromasil C18 column was used with a detection wavelength of 225 nm, a flow rate of 1.0 mL·min-1, and a column temperature of 30 °C. The mobile phase was acetonitrile-0.01 mol·L-1 potassium dihydrogen phosphate solution (containing 20 mmol·L-1 sodium heptanesulfonate, adjusted to pH 2.80 with phosphoric acid) (at a ratio of 45:55) and the resolution of D-malic acid and L-malic acid derivatization products reached 1.7. The proposed method possesses the advantages of simple operation, mild conditions, stable derivatization products and low cost. Also it gave better separation and was more accurate than previous methods

Chemical constituents from Clausena excavata and their inhibitory activities against proliferation of synoviocytes / 中国中药杂志

The chemical constituents from the stems and leaves of Clausena excavata were isolated and purified by column chromatography with silica gel, ODS, Sephadex LH-20 and RP-HPLC. The chemical structures of the isolated compounds were identified on the basis of physicochemical properties, spectroscopic analysis, as well as the comparisons with the data reported in literature. Nineteen compounds were isolated from the 90% ethanol extract of the stems and leaves of C. excavata, which were identified as methyl orsellinate(1), syringaresinol(2), lenisin A(3), scopoletin(4), osthenol(5), N-benzoyltyrarnine methyl ether(6), N-p-coumaroyltyramine(7), aurantiamide acetate(8), 1H-indole-3-carboxaldehyde(9), furostifoline(10), clausenalansine E(11), 3-formylcarbazole(12), clausine L(13), clausine E(14), methyl carbazole-3-carboxylate(15), glycosinin(16), murrayafoline A(17), clausine H(18) and 2,7-dihydroxy-3-formyl-1-(3'-methyl-2'-butenyl)carbazole(19). Among these isolated compounds, compounds 1-11 were isolated from C. excavata for the first time, and compounds 1, 2 and 10 were isolated from the genus Clausena for the first time. In addition, this study evaluated the anti-rheumatoid arthritis activities of compounds 1-19 by measuring their anti-proliferative effects on synoviocytes in vitro according to MTS method. Compounds 10-19 displayed remarkable anti-rheumatoid arthritis activities, which exhibited the inhibitory effects on the proliferation of MH7 A synovial fibroblast cells with the IC_(50) values ranging from(27.63±0.18) to(235.67±2.16) μmol·L~(-1).

A novel alkaloid from Corydalis tomentella / 中国中药杂志

The chemical constituents in the ethyl acetate extract of Corydalis tomentella was isolated and purified with normal and reversed phase silica gel column chromatography, Sephadex LH-20, MCI, and semi-preparative HPLC. The compound structures were identified based on spectroscopic experiments and reported papers. Finally, eighteen compounds(1-18) were obtained from C. tomentella, including 17 alkaloids and 1 terpenoid. Among them, compound 1(tomentellaine A) was a novel alkaloid. Compounds 2-5, 7-14, and 16-18 were isolated from this plant for the first time.

Purification and identification of novel cytotoxic oligopeptides from soft coral Sarcophyton glaucum / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

Globally, peptide-based anticancer therapies have drawn much attention. Marine organisms are a reservoir of anticancer peptides that await discovery. In this study, we aimed to identify cytotoxic oligopeptides from Sarcophyton glaucum. Peptides were purified from among the S. glaucum hydrolysates produced by alcalase, chymotrypsin, papain, and trypsin, guided by a methylthiazolyldiphenyl-tetrazolium bromide (MTT) assay on the human cervical cancer (HeLa) cell line for cytotoxicity evaluation. Purification techniques adopted were membrane ultrafiltration, gel filtration chromatography, solid phase extraction (SPE), and reversed-phase high-performance liquid chromatography (RP-HPLC). Purified peptides were identified by de novo peptide sequencing. From papain hydrolysate, three peptide sequences were identified: AGAPGG, AERQ, and RDTQ (428.45, 502.53, and 518.53 Da, respectively). Peptides synthesized from these sequences exhibited cytotoxicity on HeLa cells with median effect concentration (EC50) values of 8.6, 4.9, and 5.6 mmol/L, respectively, up to 5.8-fold stronger than the anticancer drug 5-fluorouracil. When tested at their respective EC50, AGAPGG, AERQ, and RDTQ showed only 16%, 25%, and 11% cytotoxicity to non-cancerous Hek293 cells, respectively. In conclusion, AERQ, AGAPGG, and RDTQ are promising candidates for future development as peptide-based anticancer drugs.

Rapid chemical profiling of Artemisiae Scopariae Herba using reversed phase liquid chromatography-hydrophilic interaction liquid chromatography-predictive multiple reaction monitoring / 中国中药杂志

Chemical profiling of a given herbal medicine( HM) is the prerequisite for clarifying the effective material basis and therapeutic mechanisms,and it is an important integral part of traditional Chinese medicine chemical biology( TCMCB). In current study,we aimed to propose a new strategy for fast chemical characterization of HM by using reversed phase liquid chromatography-hydrophilic interaction chromatography-predictive multiple reaction monitoring( RPLC-HILIC-p MRM),and Artemisiae Scopariae Herba was employed in this study to illustrate the entire strategy. In response to wide polarity spanning of the diverse chemical clusters in Artemisiae Scopariae Herba,RPLC and HILIC were coupled in series to retain and separate hydrophilic and hydrophobic components simultaneously by identifying the characteristics of chromatographic separation. Most of the chemical constituents in traditional Chinese medicine can be predicted by summarizing the results of chemical constituents of the same genera and introducing primary metabolites and possible substitution reaction types. Therefore,we constructed predictive ion pairs to rapidly identify the chemical constituents of Artemisiae Scopariae Herba. After comparison with control products,discussion on fragmentation pattern,and access to relevant information from literature and databases,a total of 139 components were detected and structurally annotated by matching the obtained spectral data with the information of authentic compounds. Above all,RPLC-HILIC-p MRM could be used as an eligible analytical tool for the chemical profiling of HMs.

LC-UV method to assay raloxifene hydrochloride in rat plasma and its application to a pharmacokinetic study

A specific, precise, and accurate LC-UV method was developed and validated to assay raloxifene hydrochloride in rat plasma. Raloxifene was analyzed after liquid-liquid extraction and quantified by reversed phase liquid chromatography (C18 column) using acetonitrile and ammonium acetate buffer 0.05 M (pH 4.0) as mobile phase at a flow rate of 1 mL.min-1 and UV detection at 287 nm. Retention times of raloxifene and internal standard (dexamethasone) were approximately 11 min and 14 min, respectively. Linearity was checked for a concentration range between 25 ng.mL-1 and 1000 ng.mL-1. Intra- and inter-day precision had relative standard deviation lower than 10% and 15%, respectively. Recovery from plasma was higher than 90%. Accuracy values were 98.21%, 99.70%, and 102.70% for lower, medium, and upper limits of quantification, respectively. Limit of quantification was 25 ng.mL-1. Drug stability was analyzed at room temperature using plasma kept in a freezer at -80 °C for 45 days after processing for 6 h and three freeze-thaw cycles. The advantages of the method developed include stability under different conditions and low limit of quantification. Its applicability was confirmed by the analysis of raloxifene levels in plasma samples in a designed pharmacokinetic study in rats after intravenous administration (5 mg.kg-1).

Evaluation of recombinant human interferon beta 1b by liquid chromatography methods and bioassay

Recombinant human interferon beta 1b (rhIFNß-1b) is clinically used to treat multiple sclerosis. A reversed-phase liquid chromatography (RP-LC) method was carried out on a Jupiter C4 column (250 mm × 4.6 mm i.d.). The mobile phase A consisted of 0.1% trifluoroacetic acid (TFA) in water, and the mobile phase B was acetonitrile with 0.1% TFA run at a flow rate of 1.0 mL/min. A size exclusion liquid chromatography (SE-LC) method was carried out on a BioSep-SEC-S 2000 column (300 mm × 7.8 mm i.d.). The mobile phase consisted of 1 mM monobasic potassium phosphate, 8 mM sodium phosphate dibasic and 200 mM sodium chloride buffer pH 7.4, run isocratically at a flow rate of 0.8 mL/min. Retention times were 31.87 and 17.78 min, and calibration curves were linear over the concentration range of 1-200 µg/mL (r2 = 0.9998) and 0.50-200 µg/mL (r2 = 0.9999), respectively, for RP-LC and SE-LC, with detection at 214 nm. Liquid chromatography (LC) methods were validated and employed in conjunction with the in vitro bioassay to assess the content/potency of rhIFNß-1b, contributing to improve the quality control and to ensure the efficacy of the biotherapeutic

Biochemical characterization of a phospholipase A2 homologue from the venom of the social wasp Polybia occidentalis

Wasp venoms constitute a molecular reservoir of new pharmacological substances such as peptides and proteins, biological property holders, many of which are yet to be identified. Exploring these sources may lead to the discovery of molecules hitherto unknown. This study describes, for the first time in hymenopteran venoms, the identification of an enzymatically inactive phospholipase A2 (PLA2) from the venom of the social wasp Polybia occidentalis. Methods: P. occidentalis venom was fractioned by molecular exclusion and reverse phase chromatography. For the biochemical characterization of the protein, 1D and 2D SDS-PAGE were performed, along with phospholipase activity assays on synthetic substrates, MALDI-TOF mass spectrometry and sequencing by Edman degradation. Results: The protein, called PocTX, was isolated using two chromatographic steps. Based on the phospholipase activity assay, electrophoresis and mass spectrometry, the protein presented a high degree of purity, with a mass of 13,896. 47 Da and a basic pI. After sequencing by the Edman degradation method, it was found that the protein showed a high identity with snake venom PLA2 homologues. Conclusion: This is the first report of an enzymatically inactive PLA2 isolated from wasp venom, similar to snake PLA2 homologues.(AU)

A quantitative analytical method for valienone and its application in the evaluation of valienone production by a breakthrough microbial process / 中国天然药物

Valienone is a significant natural carbasugar member of the C7-cyclitol family as a valuable precursor for glycosidase inhibitor drugs. It is an intermediate of validamycin A biosynthesis pathway and exhibits minimal accumulation in the fermentation broth of the natural Streptomyces producer. A quantitative analytical method is crucial for the development of a breakthrough microbial process overcoming the consumption of the natural metabolic flux. The present study was designed to develop a pre-column derivatization high-performance liquid chromatography method for quantification of valienone and to help establish a straightforward fermentation process for valienone production by metabolically engineered Streptomyces hygroscopicus 5008. Valienone was derivatized by 2, 4-dinitrophenylhydrazine (DNPH) in 10 mmol·L HPO at 37 °C for 45 min and the derivatives were separated on Eclipse XDB-C (5 μm, 4.6 mm × 150 mm) column at 30 °C eluted with 50% acetonitrile for 18 min. The derivatives were detected by diode array detector at 380 nm and the configurations of the derivatives were determined by computational studies. The method was shown to be effective, sensitive, and reliable. Good linearity was found in the range of 5-2 000 μg·mL. The intra- and inter-day precisions were 1.1%-2.7% and 1.7%-2.2%, respectively. The absolute recovery of the spiked samples was 97.2%-102.6%. To date, this is the first reversed-phase high-performance liquid chromatography detection method for valienone in microbial culture medium. This method successfully helped evaluate the valienone production capability of the engineered Streptomyces hygroscopicus 5008 and could be promising for C7-cyclitol profiling of different engineered mutants combined with the metabonomics methods.

Modificações em proteínas induzidas por compostos eletrofílicos. possível papel em esclerose lateral amiotrófica / Modifications in proteins induced by electrophilic compounds. Possible role in amyotrophic lateral

Danos em biomoléculas podem ocorrer a partir de uma interação direta entre as biomoléculas e espécies reativas de oxigênio e nitrogênio como também, pela reação de produtos secundários dessas espécies como eletrófilos gerados na peroxidação lipídica. Alguns desses produtos secundários possuem estabilidade química maior que as espécies reativas das quais foram derivadas e podem se ligar covalentemente as biomoléculas comprometendo o funcionamento normal das mesmas. Portanto, modificações em proteínas por aldeídos gerados na lipoperoxidação têm sido investigadas por suas implicações com desordens patológicas relacionadas à agregação proteica, e modificações em diversas vias de sinalização amplificando os efeitos deletérios em sistemas biológicos. Os objetivos desse trabalho foi contribuir na elucidação dos mecanismos moleculares associados ao desenvolvimento da esclerose lateral amiotrófica (ELA) através da identificação, caracterização e quantificação de modificações póstraducionais em proteínas pelos aldeídos 4-hidroxi-2-hexenal (HHE) e trans-4-hidroxi-2-nonenal (HNE) in vitro (citocromo c) e in vivo (modelo ELA) a partir de técnicas de Western blot, imunoprecipitação e espectrometria de massa com abordagem proteômica de "shotgun" em ratosSOD1G93A modelo de esclerose lateral amiotrófica (ELA). Estudos com citocromo c mostraram a ligação dos aldeídos ao citocromo c e mecanismos de reação foram propostos. Foram encontrados seis peptídeos modificados por HHE e um para o HNE, e o peptídeo TGPNLHGLFGR se mostrou modificado pelos dois aldeídos paralelamente. Foi demonstrado que a histidina 33 é um "hot spot" frente as adições pelos aldeídos. Nas análises por western blot das proteínas ligadas a aldeídos foi possível observar uma tendência de aumento na concentração de proteínas ligadas ao HNE nos animais ELA, mais acentuada nas amostras de 70 dias comparadas ao controle. Com relação aos resultados obtidos com HHE tanto os animais pré-sintomáticos quanto os sintomáticos não apresentaram diferenças de HHE-proteína, tantonos controles quanto nos animais ELA. Nas amostras dos animais sintomáticos não detectamos diferença significativa na concentração de aldeído-proteína entre os grupos. Já as análises proteômicas revelaram 24 proteínas diferencialmente expressas, com destaque para proteínas com os maiores valores de significância (p-value), como a ubiquitina no grupo dos pré- sintomáticos e a neurogranina, no grupo dos animais sintomáticos e várias proteínas de metabolismo energético, de neurofilamentos, proteínas de processos redox e proteínas ligadas o metabolismo de cálcio (fundamentais na fisiopatologia em ELA). Algumas proteínas importantes foram encontradas com exclusividades nos grupos pré-sintomáticos e sintomáticos pelo diagrama de Venn. Com relação a proteínas modificadas pelos aldeídos, foram encontradas algumas relevantes como a proteína 2 de interação com a polimerase delta que foi modificada por HNE via adição de Michael encontrada nos animais ELA pré-sintomáticos e sintomáticos, a catalase que foi encontrada modificada por HNE via base de Schiff apenas nos ELA pré- sintomáticos, e a tiol redutase induzível por interferon gama no grupo dos animais ELA sintomáticos. Com relação a proteínas modificadas por HHE, foram encontradas a Janus quinase e proteína 3 de interação com microtúbulo, modificadas tanto por adição de Michael quanto via base de Schiff nos animais ELA sintomáticos. É interessante ressaltar que algumas modificações encontradas em proteínas não caracterizadas podem indicar proteínas novas ainda não descritas como modificadas por esses aldeídos. Os resultados mostram que algumas das proteínas modificadas por HNE e HHE encontradas neste trabalho, estão relacionadas ao estresse redox, vias metabólicas energéticas, proteínas envolvidas na resposta a danos oxidativos, e processos inflamatórios. Tais modificações ocorrem não só no modelo de neurodegeneração, mas foram previamente descritas em outros processos patológicos, como doença cardiovascular, lesão hepática por uso crônico de álcool

Damage to biomolecules can occur from a direct interaction between biomolecules and reactive of oxygen and nitrogen species as well as from the reaction of secondary products of these species as electrophiles generated in lipid peroxidation. Some of these by-products have greater chemical stability than the derived reactive species and can bind to biomolecules compromising their normal function. Therefore, protein modifications by aldehydes generated during lipoperoxidation have been investigated for their implications with pathological disorders related to protein aggregation and modifications in signaling pathways amplifying the deleterious effects in biological systems. The aim of this work was to contribute to the elucidation of the molecular mechanisms associated with the development of amyotrophic lateral sclerosis (ALS) through the identification, characterization and quantification of posttranslational modifications in proteins by 4-hydroxy-2-hexenal (HHE) and trans-4-hydroxy-2- nonenal (HNE) in vitro, cytochrome c, and in vivo, rat model (SOD1G93A) of amyotrophic lateral sclerosis (ALS), throught Western blot techniques, and mass spectrometry with shotgun proteomics approach. The results showed the binding of aldehydes to cytochrome c. Six peptides were modified by HHE and one by HNE. The peptide TGPNLHGLFGR was modified by the two aldehydes. Histidine 33 has been shown to be a hot spot against aldehydes additions. By western blot analysis of the aldehyde-bound proteins, it was possible to observe a tendency of increase in the concentration of HNE-bound proteins in the ALS animals, more pronounced in the samples of 70 days compared to control samples. Regarding the results obtained with HHE, both pre-symptomatic and symptomatic animals did not show HHE-protein differences, both in controls and in ALS animals. We did not detect a significant difference in the aldehyde-protein concentration between the groups in the samples of the symptomatic animals. Proteomic analysis revealed 24 differentially expressed proteins, with emphasis on proteins with thehighest values of significance (p-value), such as the ubiquitin in the pre-symptomatic group and neurogranin in the group of the symptomatic animals and several proteins of the energetic metabolism pathways, neurofilaments, proteins of redox processes and proteins linked to calcium metabolism (fundamental in the pathophysiology of ALS). Some important proteins were found exclusivity in the pre-symptomatic and symptomatic groups by the Venn diagram. With regard to aldehyde-modified proteins, some relevant ones such as Delta-2 polymerase interaction protein, that was modified by HNE via the addition of Michael found in presymptomatic and symptomatic ELA animals, catalase that was found to be modified by HNE via Schiff's base only in pre-symptomatic ALS, and gamma interferon-inducible thiol reductase in the group of symptomatic ALS animals. Janus kinase and microtubule interaction protein 3, were found to be modified by Michael addition and Schiff base pathway respectively in symptomatic ALS animals. It is interesting to note that some modifications found in uncharacterized proteins may indicate new proteins not yet described as modified by these aldehydes. The results show that some of the proteins modified by HNE and HHE found in this work are related to redox stress, energetic metabolic pathways, proteins involved in the response to oxidative damage, and inflammatory processes. Such modifications occur not only in the neurodegeneration model, but were previously described in other pathological processes, such as cardiovascular disease, liver injury due to chronic alcohol use

Development and validation of stability indicating liquid chromatographic (RP-HPLC) method for estimation of ubidecarenone in bulk drug and formulations using quality by design (QBD) approach

ABSTRACT A novel, accurate, precise and economical stability indicating Reverse Phase-High Performance Liquid Chromatography (RP-HPLC) method, was developed and validated for the quantitative determination of ubidecarenone (UDC) in bulk drug, UDC marketed formulation and UDC loaded cubosomes (CBMs) nanocarriers through Response surface methodology (RSM) design with three factors and three levels was performed to optimize the chromatographic variables followed by forced degradation studies of UDC were performed to detect degradation peak. RP-HPLC separation was achieved using mobile phase consisting of Acetonitrile:Tetrahydrofuran:Deionised water in the ratio 55:42:3 and a flow rate of 1.0 mL/min was optimized with a standard retention time (Rt) of 2.15 min, through experiment. The method was found linear in the concentration range of 5-100 µg/mL with a regression coefficient of 0.999. The limit of detection (LOD) and limit of quantification (LOQ) were found to be 3.04 µg/mL and 9.11 µg/mL, respectively.

Stability indicating RP-HPLC method for simultaneous determination of gatifloxacin and dexamethasone in binary combination

Abstract In this study, conditions were optimized for development of a simple RP-HPLC method for simultaneous analysis of gatifloxacin and dexamethasone in different matrices like pharmaceuticals, human serum and urine. Good separation of gatifloxacin and dexamethasone from the induced degradation products was accomplished using C8 as stationary phase; 0.02 M phosphate buffer (pH 3.0) and methanol (42:58 v/v) as mobile phase. The concentration was measured with DAD at 270 nm. Linearity was observed in the range of 0.000040-0.000280 mol/L for gatifloxacin (r2≥0.999) and 0.000013-0.000091 mol/L for dexamethasone (r2≥0.999). Both the analyte peaks were completely separated from the peaks of induced degradation products as indicated by the peak purity index (≥0.9999 for both analytes). The optimized method is recommended to be used for concurrent analysis of gatifloxacin and dexamethasone in different matrices.

Patient age does not affect mefloquine concentrations in erythrocytes and plasma during the acute phase of falciparum malaria

Abstract Objective To evaluate whether patient age has a significant impact on mefloquine concentrations in the plasma and erythrocytes over the course of treatment for uncomplicated falciparum malaria. Methods A total of 20 children aged between 8 and 11 years and 20 adult males aged between 22 and 41 years with uncomplicated falciparum malaria were enrolled in the study. Mefloquine was administered to patients in both age groups at a dose of 20 mg kg−1. The steady-state drug concentrations were measured by reversed-phase high performance liquid chromatography. Results All patients had an undetectable mefloquine concentration on day 0. In adults, the plasma mefloquine concentrations ranged from 770 to 2930 ng mL−1 and the erythrocyte concentrations ranged from 2000 to 6030 ng mL−1. In children, plasma mefloquine concentrations ranged from 881 to 3300 ng mL−1 and erythrocyte concentrations ranged from 3000 to 4920 ng mL−1. There was no significant correlation between mefloquine concentrations in the plasma and erythrocytes in either adults or children. Conclusion In the present study, we observed no effect of patient age on the steady-state concentrations of mefloquine in the plasma and erythrocytes. We found that the mefloquine concentration in the erythrocytes was approximately 2.8-times higher than in the plasma. There were no significant correlations between mefloquine concentrations in the erythrocytes and plasma for either age group.

Stability-indicating RP-LC method for quantification of fusidic acid in cream

ABSTRACT Fusidic acid is an antibiotic steroid indicated for the treatment of infections caused by the genus Staphylococcus, including methicillin resistant Staphylococcus aureus strains, and other Gram-positive bacteria. In the present study, a stability-indicating reversed-phase liquid chromatography (RP-LC) method was developed and validated for the determination of fusidic acid in dermatological cream as an alternative to existing methods. Analyses were performed using a C18 column and guard column at room temperature, eluting with an isocratic mobile phase of acetonitrile and water (72:28, v/v), adjusted to pH 3.5 with acetic acid, pumped at a flow rate of 1.0 mL min-1, detection at 210 nm and 20 µL of injection volume. The forced degradation study was conducted under acidic, alkaline, neutral, photolytic, and oxidative stress conditions. The method was validated according to ICH and FDA guidelines; it was linear, precise, accurate, selective, and robust over concentrations of 5-95 µg mL-1, with detection and quantification limits of 0.43 and 1.31 μg mL-1, respectively. Therefore, we conclude that this method is suitable for quantifying fusidic acid in pharmaceutical dermatological creams and determining its stability, representing a more economical and practical alternative for routine analysis in quality control.

Antifungal activity of extracts from Atacama Desert fungi againstParacoccidioides brasiliensis and identification ofAspergillus felis as a promising source of natural bioactive compounds

Fungi of the genus Paracoccidioides are responsible for paracoccidioidomycosis. The occurrence of drug toxicity and relapse in this disease justify the development of new antifungal agents. Compounds extracted from fungal extract have showing antifungal activity. Extracts of 78 fungi isolated from rocks of the Atacama Desert were tested in a microdilution assay against Paracoccidioides brasiliensis Pb18. Approximately 18% (5) of the extracts showed minimum inhibitory concentration (MIC) values≤ 125.0 µg/mL. Among these, extract from the fungus UFMGCB 8030 demonstrated the best results, with an MIC of 15.6 µg/mL. This isolate was identified as Aspergillus felis (by macro and micromorphologies, and internal transcribed spacer, β-tubulin, and ribosomal polymerase II gene analyses) and was grown in five different culture media and extracted with various solvents to optimise its antifungal activity. Potato dextrose agar culture and dichloromethane extraction resulted in an MIC of 1.9 µg/mL against P. brasiliensis and did not show cytotoxicity at the concentrations tested in normal mammalian cell (Vero). This extract was subjected to bioassay-guided fractionation using analytical C18RP-high-performance liquid chromatography (HPLC) and an antifungal assay using P. brasiliensis. Analysis of the active fractions by HPLC-high resolution mass spectrometry allowed us to identify the antifungal agents present in the A. felis extracts cytochalasins. These results reveal the potential of A. felis as a producer of bioactive compounds with antifungal activity.

Simultaneous determination of diosmin and hesperidin in pharmaceuticals by RPLC using ionic liquids as mobile phase modifiers

Diosmin and hesperidin are natural flavonoid glycosides found in various plant materials, mainly in citrus fruits in different concentrations. Diosmin for pharmaceutical use is obtained mainly semi-synthetically from hesperidin. Hesperidin often accompanies diosmin as a natural impurity in different pharmaceutical formulations; therefore, a simple, fast and precise method for the simultaneous assay of diosmin and hesperidin in pharmaceutical formulations has been developed to control their contents. Chromatographic resolution was performed using a column with C-18 packing and the following mobile phase: methanol/water [45: 55, v/v] with 0.025% added didecyldimethylammonium lactate, which significantly affects retention, shortening analysis time and having a positive impact on the symmetry of resulting chromatographic peaks. The method shows linearity between 2.5 and 100 microg/mL, high repeatability [0.39 and 0.42% for diosmin and hesperidin, respectively] and accuracy of 96 to 102% for both the assayed compounds. Intraday and interday precision of the new method were less than RSD% 1, 2. The limit of detection of the assayed compounds is 2.5 and 1.2 microg/mL for diosmin and hesperidin, respectively. The method was tested on several pharmaceutical products available in Poland

Establishment and reliability evaluation of the design space for HPLC analysis of six alkaloids in Coptis chinensis (Huanglian) using Bayesian approach / 中国天然药物

Coptis chinensis (Huanglian) is a commonly used traditional Chinese medicine (TCM) herb and alkaloids are the most important chemical constituents in it. In the present study, an isocratic reverse phase high performance liquid chromatography (RP-HPLC) method allowing the separation of six alkaloids in Huanglian was for the first time developed under the quality by design (QbD) principles. First, five chromatographic parameters were identified to construct a Plackett-Burman experimental design. The critical resolution, analysis time, and peak width were responses modeled by multivariate linear regression. The results showed that the percentage of acetonitrile, concentration of sodium dodecyl sulfate, and concentration of potassium phosphate monobasic were statistically significant parameters (P < 0.05). Then, the Box-Behnken experimental design was applied to further evaluate the interactions between the three parameters on selected responses. Full quadratic models were built and used to establish the analytical design space. Moreover, the reliability of design space was estimated by the Bayesian posterior predictive distribution. The optimal separation was predicted at 40% acetonitrile, 1.7 g·mL(-1) of sodium dodecyl sulfate and 0.03 mol·mL(-1) of potassium phosphate monobasic. Finally, the accuracy profile methodology was used to validate the established HPLC method. The results demonstrated that the QbD concept could be efficiently used to develop a robust RP-HPLC analytical method for Huanglian.

Stability-indicating RP-HPLC method for determination of beclomethasone dipropionate in nanocapsule suspensions

abstract A simple stability-indicating RP-HPLC/UV method was validated for determination of beclomethasone dipropionate (BD) in nanocapsule suspensions. Chromatographic conditions consisted of a RP C18column (250 mm x 4.60 mm, 5 µm, 110 Å), using methanol and water (85:15 v/v) as mobile phase at 1.0 mL/min with UV detection at 254 nm. The calibration curve was found to be linear in the concentration range of 5.0-25.0 µg/mL with a correlation coefficient > 0.999. Precision was demonstrated by a relative standard deviation lower than 2.0%. Accuracy was assessed by the recovery test of BD from nanocapsules (98.03% to 100.35%). Specificity showed no interference from the components of nanocapsules or from the degradation products derived from acid, basic and photolytic conditions. In conclusion, the method is suitable to be applied to assay BD in bulk drug and in nanocapsules, and it can be employed to study stability and degradation kinetics.

resumo Um método simples de CLAE-FR/UV indicativo de estabilidade foi validado para a determinação do dipropionato de beclometasona (BD) em suspensões de nanocápsulas. As condições cromatográficas foram: coluna C18 fase reversa (250 mm x 4,60 mm, 5 µm, 110 Å), usando como fase móvel metanol e água (85:15 v/v) a 1,0 mL/min, com detecção UV a 254 nm. A curva de calibração foi linear no intervalo de 5,0-25,0 µg/mL com coeficiente de correlação >0,999. A precisão foi demonstrada por um desvio padrão relativo menor que 2,0%. A exatidão foi avaliada pelo teste de recuperação do BD a partir das nanocápsulas (98,03% a 100,35%). O teste de especificidade não mostrou interferência dos componentes das nanocápsulas e nem dos produtos de degradação derivados de condições ácidas, básicas e fotolíticas. Em conclusão, o método é adequado para ser aplicado na avaliação do BD puro e em nanocápsulas e pode ser empregado para o estudo de estabilidade e degradação cinética.