Enantiomeric separation and quantitative determination of propranolol enantiomers in pharmaceutical preparations by chiral liquid chromatography

Neste trabalho é descrito um método validado empregando a cromatografia líquida de alta eficiência com fase estacionária quiral para a separação e determinação quantitativa dos enantiômeros do propranolol em formulações farmacêuticas. A separação foi obtida em meio orgânico polar empregando a coluna ±-Burke 2® como fase estacionária quiral (250 x 4,6 mm, 5 µm) e fase móvel constituída por diclorometano: metanol (90:10 v/v) juntamente com 12 mM de acetato de amônio e vazão de 0,9 mL/min. A detecção foi efetuada por absorção no ultravioleta a 280 nm. Em todos casos o tempo de corrida foi menor do que 10 min. O coeficiente de correlação obtido pelo método de regressão linear foi de 0,9995 para o R-prop e de 0,9998 para o S-prop. A precisão intra-dia, expressa como desvio padrão relativo, foi menor do que 2%. A exatidão, determinada pela recuperação média de R- e S-prop nas amostras foi de 97,3% e 100,1% para a amostra comercial e de 99,5% e 100,4% para a amostra simulada, respectivamente. Excelentes níveis para os limites de detecção (1,34 ng) e de quantificação (4,47 ng), além do tempo rápido de eluição dos enantiômeros do propranolol, confirmam a aplicabilidade do método no controle de qualidade de preparações farmacêuticas contendo este fármaco.This paper describes validated direct liquid chromatographic chiral methods for enantiomeric separation and quantitative determination of clinically significant ²-blocking agent, propranolol. A liquid chromatographic method was validated and applied for enantiomeric determination of propranolol enantiomers in pharmaceutical formulations. Separation were obtained in polar organic mode on a ±-Burke 2® chiral stationary phase (250 x 4.6 mm, 5µm) with mobile phase composed of dichloromethane:methanol (90:10 v/v), along with 12 mM of ammonium acetate, at a flow rate of 0.9 mL/min. Detection was made by ultraviolet absorption at 280 nm. In all cases the run time was less than 10 min. The correlation coefficient for linear regression curves of R-propranolol and S-propranolol were 0.9995 and 0.9998 respectively. The intra-day precision, expressed as RSD was less than 2%. The accuracy determined by average recovery of R-propranolol and S-propranolol from sample matrices were 97.3% and 100.1% in commercial sample and 99.5% and 100.4% in simulated samples, respectively. Excellent levels of limit of detection (mean value = 1.34 ng) and limit of quantitation (mean value = 4.47 ng), along with rapid elution time of both enantiomers, makes the method useful for routine enantiomeric quality control applications

Non-invasive tool to assess heart rhythm in Zebrafish embryos

In the last years the zebrafish (Danio rerio) has emerged as model organism for cardiac research, in spite of the morphological differences with the human heart. In consequence of the similarity to humans in the early function, the zebrafish embryo has been suggested as an ideal model i) to study the molecular mechanism of cardiac development, and ii) to identify genes related to congenital cardiac defects in human [1]. The overall similarity of zebrafish embryos and human, in responses to human cardiotoxic drugs, was demonstrated, for example, in drug-induced cardiac arrhythmia [2]. For this reason, several methods have been developed to assess cardiac functions in zebrafish embryos [3,4]. Unfortunately, all these techniques suffer from drawbacks (time consuming, skillful operator are ended to perform the experiments) which limit their applications for large scale studies. The development in digital imaging has recently made analysis of cardiac functions in genetically modified transparent zebrafish embryos easier. This allowed to assess non-invasively heart rate variability in zebrafish embryos from videos of beating heart, but without measuring heartbeat rhythm, an important indicator of the cardiac function (heartbeat regularity is associated with cardiotoxicity in humans [1]), from power spectrum of heart signal. In the present study, we present a simple, non-invasive method that, by video-recording embryo images using confocal microscopy, and integrating image processing and power spectral analysis, allows to measure the heartbeat rhythm in zebrafish embryos heart chambers (atrium, ventricle, bulb) (Figure 1). The reliability of the herein proposed method was verified. Some embryos undergone treatment by tricaine, a cardiac anaesthetizing drug, in consequence of which a decrease of the heart rate is expected: the heartbeat regularity in tricaine- treated embryos determined from power spectral analysis decreased as compared to no-treated embryos. The results demonstrated that our method is able to assess the cardiac physiology, in term of heart rhythm, in zebrafish embryos

Long Covid: where we stand and challenges ahead

Post-acute sequelae of SARS-CoV-2 (PASC), also known as Post-Covid Syndrome, and colloquially as Long Covid, has been defined as a constellation of signs and symptoms which persist for weeks or months after the initial SARS-CoV-2 infection. PASC affects a wide range of diverse organs and systems, with manifestations involving lungs, brain, the cardiovascular system and other organs such as kidney and the neuromuscular system. The pathogenesis of PASC is complex and multifactorial. Evidence suggests that seeding and persistence of SARS-CoV-2 in different organs, reactivation, and response to unrelated viruses such as EBV, autoimmunity, and uncontrolled inflammation are major drivers of PASC. The relative importance of pathogenetic pathways may differ in different tissue and organ contexts. Evidence suggests that vaccination, in addition to protecting against disease, reduces PASC after breakthrough infection although its actual impact remains to be defined. PASC represents a formidable challenge for health care systems and dissecting pathogenetic mechanisms may pave the way to targeted preventive and therapeutic approaches

po 8580 treatment response among cameroonian adolescents receiving antiretroviral therapy in urban and rural settings preliminary findings from the ready study

BackgroundTransitioning from paediatric to adult healthcare requires successful antiretroviral treatment (ART) for adolescents living with HIV (ADLHIV). Implementing such a policy implies monitoring ART response and selecting for therapeutic options for ADLHIV in resource-limited settings (RLS) like Cameroon.MethodsThe Ready study (EDCTP-CDF-1027) is conducted amongst ART-experienced ADLHIV (10–19 years old) in the Centre region, Cameroon. WHO-clinical staging, CD4-counts and viraemia were determined; in case of virological failure [VF] (viraemia ≥1000 copies/ml), HIV drug resistance (HIVDR) and subtyping were performed, and p<0.05 considered significant.ResultsOut of 279 ADLHIV (212 urban vs 67 rural), the gender distribution was similar (54.5% female); median age was higher in urban (15 [IQR: 13–17] years) compared to rural (13 [IQR: 11–17] years), as well as the median duration on ART (7 [IQR: 3–10] years compared to 4 [IQR: 2–7] years, respectively); and the majority was on first-line ART (79.4% [162/204] urban vs 98.5% [66/67] rural, p<0.0004). Following treatment response, clinical failure (WHO-stage 3/4) was similarly low in both urban (5.7% [12/210]) and rural (4.5% [3/67]), p=0.938; CD4 increased similarly (p=0.298) from ART-initiation (370 cells/mm3[urban] vs 332 cells/mm3[rural]) to 6 years after initiation (938 cells/mm3[urban] vs 548 cells/mm3[rural]) and rate of immunodeficiency (<500 CD4 cells/mm3) was 41.0% (87/208) in urban vs 47.5% (29/61) in rural, p=0.428. VF was 43.2% (41/95) in urban vs 60.9% (14/23) in rural, p=0.126. Among nine (9) sequences available from those experiencing VF, overall HIVDR was found in 88.8%, with 77.7% NNRTI, 55.6% NRTI and 22.2% PI/r. All were HIV-1 group M, with 55.6% CRF02_AG, 22.0% F1 and 22.4% others.ConclusionADLHIV appear clinically asymptomatic, with considerable immune recovery overtime. Despite differences in ART duration between urban and rural settings, VF was similarly high, associated with HIVDR mainly to NNRTI-based regimens. Thus, NNRTI-sparing regimens might be highly convenient when transitioning ADLHIV to adult ART-regimens in RLS like Cameroon

Silybins inhibit human IAPP amyloid growth and toxicity through stereospecific interactions

Type 2 Diabetes is a major public health threat, and its prevalence is increasing worldwide. The abnormal accumulation of islet amyloid polypeptide (IAPP) in pancreatic β-cells is associated with the onset of the disease. Therefore, the design of small molecules able to inhibit IAPP aggregation represents a promising strategy in the development of new therapies. Here we employ in vitro, biophysical, and computational methods to inspect the ability of Silybin A and Silybin B, two natural diastereoisomers extracted from milk thistle, to interfere with the toxic self-assembly of human IAPP (hIAPP). We show that Silybin B inhibits amyloid aggregation and protects INS-1 cells from hIAPP toxicity more than Silybin A. Molecular dynamics simulations revealed that the higher efficiency of Silybin B is ascribable to its interactions with precise hIAPP regions that are notoriously involved in hIAPP self-assembly i.e., the S20-S29 amyloidogenic core, H18, the N-terminal domain, and N35. These results highlight the importance of stereospecific ligand-peptide interactions in regulating amyloid aggregation and provide a blueprint for future studies aimed at designing Silybin derivatives with enhanced drug-like properties. Keywords: Aggregation; Diabetes; Inhibitors; Molecular dynamics; Peptid

New rapid Derivative spectrophotometric and chromatographic methods for assay of loratadine in tablets and syrups

New rapid first-derivative spectrophotometric (UVDS) and a stability-indicating high performance liquid chromatographic (HPLC) methods were developed, validated and successfully applied in the analysis of loratadine (LT) in tablets and syrups. In the UVDS method, 0.1 M HCl was used as solvent. The measurements were made at 312.4 nm in the first order derivative spectra. The HPLC method was carried out on a RP-18 column with a mobile phase composed of methanol-water-tetrahydrofuran (50:30:20, v/v/v). UV detection was made at 247 nm. For HPLC methods the total analysis time was <3min, adequate for routine quality control of tablets and syrups containing loratadine.Colegio de Farmacéuticos de la Provincia de Buenos Aire

N-type inactivation of the potassium channel KcsA by the Shaker B "ball" Peptide: Mapping the inactivating peptide-binding epitope

10 pags, 6 figsThe effects of the inactivating peptide from the eukaryotic Shaker B K + channel (the ShB peptide) on the prokaryotic KcsA channel have been studied using patch clamp methods. The data show that the peptide induces rapid, N-type inactivation in KcsA through a process that includes functional uncoupling of channel gating. We have also employed saturation transfer difference (STD) NMR methods to map the molecular interactions between the inactivating peptide and its channel target. The results indicate that binding of the ShB peptide to KcsA involves the ortho and meta protons of Tyr 8, which exhibit the strongest STD effects; the C4H in the imidazole ring of His16; the methyl protons of Val4, Leu 7, and Leu10 and the side chain amine protons of one, if not both, the Lys18 and Lys19 residues. When a noninactivating ShB-L7E mutant is used in the studies, binding to KcsA is still observed but involves different amino acids. Thus, the strongest STD effects are now seen on the methyl protons of Val4 and Leu10, whereas His16 seems similarly affected as before. Conversely, STD effects on Tyr8 are strongly diminished, and those on Lys18 and/or Lys19 are abolished. Additionally, Fourier transform infrared spectroscopy of KcsA in presence of 13C-labeled peptide derivatives suggests that the ShB peptide, but not the ShB-L7E mutant, adopts a β-hairpin structure when bound to the KcsA channel. Indeed, docking such a β-hairpin structure into an open pore model for K+ channels to simulate the inactivating peptide/channel complex predicts interactions well in agreement with the experimental observations. © 2008 by The American Society for Biochemistry and Molecular Biology, Inc.This work was supported by Spanish Ministerio de Educación y Ciencia Grants CTQ2005-00360/BQU (to J. L. N.) and BFU2005-00749 (to J. M. G.-R.);FIPSE Experiment 36557/06 (to J. L. N.) and Grant BANCAJA-UMH IP/UR/01;and Consellería de Empresa, Universidad y Ciencia de la Generalitat Valenciana Grant GV07/017 (to J. A. E.)