Optimized LC-MS/MS quantification of tuberculosis drug candidate macozinone (PBTZ169), its dearomatized Meisenheimer Complex and other metabolites, in human plasma and urine

Tuberculosis, and especially multidrug-resistant tuberculosis (MDR-TB), is a major global health threat which emphasizes the need to develop new agents to improve and shorten treatment of this difficult-to-manage infectious disease. Among the new agents, macozinone (PBTZ169) is one of the most promising candidates, showing extraordinary potency in vitro and in murine models against drug-susceptible and drug-resistant Mycobacterium tuberculosis. A previous analytical method using liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) was developed by our group to support phase I clinical trials of PBTZ169. These plasma sample analyses revealed the presence of several additional metabolites among which the most prominent was H₂PBTZ, a reduced species obtained by dearomatization of macozinone, one of the first examples of Meisenheimer Complex (MC) metabolites identified in mammals. Identification of these new metabolites required the optimization of our original method for enhancing the selectivity between isobaric metabolites as well as for ensuring optimal stability for H₂PBTZ analyses. Sample preparation methods were also developed for plasma and urine, followed by extensive quantitative validation in accordance with international bioanalytical method recommendations, which include selectivity, linearity, qualitative and quantitative matrix effect, trueness, precision and the establishment of accuracy profiles using β-expectation tolerance intervals for known and newer analytes. The newly optimized methods have been applied in a subsequent Phase Ib clinical trial conducted in our University Hospital with healthy subjects. H₂PBTZ was found to be the most abundant species circulating in plasma, underscoring the importance of measuring accurately and precisely this unprecedented metabolite. Low concentrations were found in urine for all monitored analytes, suggesting extensive metabolism before renal excretion.

Psychosocial and behavioral characteristics of still smokers at 6 months after acute cerebro or cardiovascular events: preliminary findings from INEV@L, a prospective pilot study

Introduction

Considering the benefits of smoking cessation, and evolving new tobacco-product consumption, such as e-cigarettes (e-cig), contemporary behavioral and psychosocial factors (PSF) associated with smoking after acute stroke or myocardial infarction (MI) remain to be investigated.

Methods

From INEV@L, a prospective pilot study in 128 workers hospitalized for MI or stroke (MI/stroke: 199/57) <65 y, between 2016 and 2017 in CHU Dijon. Among them, 67 (52%) current smokers were analyzed. PSF (education level (EL), socioeconomic status (SES), perceived disease severity (PDS), anxiety/depression), and health behavior (adhesion to Mediterranean diet (AMD), BMI, physical activity (PA), smoking) were collected at the acute phase and at 6 Months Follow-Up. Patients who quit smoking were compared with non-quitting patients.

Results

Still smokers at 6-M FU were frequent (30 (45%)) and had similar risk factors including age (51±7 y) than quitters. Rate of overweight/obese patients and AMD were similar (52 vs 65%, p=0.281 and 29±6 vs 26±7, p=0.207). SES and EL were slightly higher in still smokers group. The level of anxiety or depression was as high in the 2 groups (63 vs 68%, and 19 vs 20%, p=0.717 and 0.911). Although similar at the acute phase (p=0.867), PDS at 6-M FU, trended to be lower in non-quitters (57 vs 78%, p=0.057). At FU, only few returned to work (57% for both groups). Overweight/obese who reduced their weight were more common in non-quitters (60 vs 38%, p=0.170). Patients who improved AMD or PA level were similar (62 vs 78%, p=0.166, and 67 vs 92%, p=0.317). The vast majority of non-quitters introduced the use of e-cig (80% vs 0%, p<0.001).

Conclusion

Our pilot study in young workers highlights the low rate of smoking cessation, and generalized dual use of electronic+conventional cigarette at mid-term after acute MI or stroke. Our findings further suggest specific PSF pattern of non-quitters, associated with loss of perceived disease severity.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): Conseil Régional de Bourgogne Franche Comté et CHU Dijon Bourgogne

Sport-related acute myocardial infarction. Contemporary data from IMACS survey

Background

Sport-related (SR) acute cardiovascular (CV) events are the main cause of sudden cardiac death in the setting of sport activities. However, data are very scarce regarding onset and follow-up of SR acute myocardial infarction (AMI).

Methods

From the prospective study IMACS (Infarctus du Myocarde et Arret Cardiaque au cours du Sport) patients admitted for a SR-AMI in our university hospital from April 2018 to March 2020 were included. A 12 months follow-up (FU) was achieved through telephone interview to address CV outcomes and sport practice information. Information was obtained from relatives in case of out of hospital sudden cardiac arrest (OH-SCA).

Results

Among the 55 patients included, all were male, with median (IQR) age at 62 (55–69) y. Most common sports were cycling (n=21), fitness (n=7), swimming (n=5) and hiking (n=5). The SR-AMI occurred during effort for 39 subjects and during recovery for 16. Most SR-AMI occurred in public area (n=24), at home (n=16), or in a specific sport location (n=14). An Automated External Defibrillator (AED) was available in the SR-AMI location in only 10, but was missing in 43 (unknown for 2). In 1 subject with OH-SCA, cardiopulmonary resuscitation (CPR), initiated by witnesses, using a public AED, was unsuccessful. The 4 other patients with OH-SCA underwent successful CPR. Among the 55 subjects, 4 were vapers, of whom 1 was a dual user, 17 were current tobacco smokers, 18 were ex-smokers and 2 experienced cannabis and cocaine use. Among the smokers, most smoked (n=10) or consumed cannabis (n=1) <2h before the event. Strikingly, CV history and/or recent symptoms were present in almost half (n=25). Only 10 felt symptoms exclusively during the sport session. Moreover, a medical advice for recent symptoms was found only for 3 subjects. Three patients who experienced prior AMI have neglected symptoms during the index event. Most were ST segment elevated MI (n=35). Only one patient (with OH-SCA) died <3 days after hospital admission. During hospitalization, most underwent revascularization with coronary stenting (n=44) (drug eluting stent in 43 patients), or coronary artery bypass graft (n=6) and no death nor significant CV event occurred. At 1-FU, most attended a rehabilitation program (n=41) and the majority of smokers quitted (14/17), with 3 persistent smokers starting to vape. Almost half patients (n=23) decreased their physical activity, and 21 increased it. A significant rate of patient (n=9) added fitness in their usual activity, and as a main sport for 4 of them.

Conclusions

In this on-going monocentric prospective survey in SR-AMI, a high proportion of subjects had prodromal symptoms, of whom only few led to sport cessation and medical advices, when requested, failed to prevent the AMI. Our findings highlight that public and medical education are urgently warranted for SR-AMI prevention.

Funding Acknowledgement

Type of funding sources: Public hospital(s). Main funding source(s): CHU Dijon Bourgogne Franche Comté et ARS Bourgogne Franche Comté

Development and validation of a multiplex UHPLC-MS/MS method for the determination of the investigational antibiotic against multi-resistant tuberculosis macozinone (PBTZ169) and five active metabolites in human plasma

The emergence of Mycobacterium tuberculosis strains resistant to current first-line antibiotic regimens constitutes a major global health threat. New treatments against multidrug-resistant tuberculosis (MDR-TB) are thus eagerly needed in particular in countries with a high MDR-TB prevalence. In this context, macozinone (PBTZ169), a promising drug candidate with an unique mode of action and highly potent in vitro tuberculocidal properties against MDR Mycobacterium strains, has now reached the clinical phase and has been notably tested in healthy male volunteers in Switzerland. To that endeavor, a multiplex UHPLC-MS/MS method has been developed for the sensitive and accurate human plasma levels determination of PBTZ169 along with five metabolites retaining in vitro anti-TB activity. Plasma protein precipitation with methanol was carried out as a simplified sample clean-up procedure followed by direct injection of the undiluted supernatant for the bioanalysis of the six analytes within 5 min, using 1.8 μm reversed-phase chromatography coupled to triple quadrupole mass spectrometry employing electrospray ionization in the positive mode. Stable isotopically-labelled PBTZ169 was used as internal standard (ISTD), while metabolites could be reliably quantified using two unlabeled chemical analogues selected as ISTD from a large in-house analogous compounds library. The overall methodology was fully validated according to current recommendations (FDA, EMEA) for bioanalytical methods, which include selectivity, carryover, qualitative and quantitative matrix effect, extraction recovery, process efficiency, trueness, precision, accuracy profiles, method and instrument detection limits, integrity to dilution, anticoagulant comparison and short- and long-term stabilities. Stability studies on the reduced metabolite H₂-PBTZ169 have shown no significant impact on the actual PBTZ169 concentrations determined with the proposed assay. This simplified, rapid, sensitive and robust methodology has been applied to the bioanalysis of human plasma samples collected within the frame of a phase I clinical study in healthy volunteers receiving PBTZ169.

Analysis of Riboflavin Compounds in the Rabbit Cornea In Vivo

PURPOSE

To investigate the composition and concentration of individual riboflavin compounds in the corneal stroma in vivo after soaking with various commercially available riboflavin formulations.

METHODS

Experiments were performed in 26 rabbit corneas in vivo: 24 corneas were soaked with riboflavin formulations for 30 minutes or with 0.9% NaCl for control (n = 2). After treatment, corneas were excised and prepared for ultra-high-pressure liquid chromatography (UHPLC) analysis. Additionally, computational chemical analysis of riboflavin compounds and keratan sulfate were performed.

RESULTS

The amount of riboflavin and riboflavin phosphate isomers in cornea decreased by a factor of 10 to 100, when compared to the amount in riboflavin formulations. In particular, we found an inverse relationship in the ratio of riboflavin to riboflavin phosphate isomer concentration between formulations and cornea. The electronegativity and ionization potential of riboflavin and phosphate isomers are different.

CONCLUSIONS

The inverse relationship observed might be explained by a stronger electronegativity of the phosphate isomers, leading to a stronger repulsion by corneal proteoglycans. Indicating the individual concentration of riboflavin compounds in formulations is more representative than the total riboflavin concentration. Riboflavin formulations and CXL protocols might be improved considering the differences in diffusion and ionization potentials of the different riboflavin compounds.

New prostaglandin analog formulation for glaucoma treatment containing cyclodextrins for improved stability, solubility and ocular tolerance

Latanoprost is a practically insoluble prostaglandin F2α analog considered a first-line agent for glaucoma treatment. From a pharmaceutical point of view, latanoprost is challenging to be formulated as an eye drop due to its poor water solubility and the presence of an ester bond that needs to be cleaved in vivo but maintained unchanged during storage. Cyclodextrins (CDs) are known to form complexes with hydrophobic drugs, influencing their stability, availability, solubility, and tolerance in a non-predictable manner. A variety of CDs including native α, β, and γCDs as well as substituted hydroxypropylβCD, hydroxypropylγCD, dimethylβCD, sulphatedβCD, and propylaminoβCD were screened and the most appropriate CD for the formulation of latanoprost for an ocular topical application was selected. Among the tested CDs, propylaminoβCD had the best trade-off between latanoprost stability and availability, which was confirmed by its complex constant value of 3129M(-1). Phase-solubility and NMR investigations demonstrated that the propylaminoβCD effectively formed a complex involving the ester group of latanoprost providing protection to its ester bond, while ensuring proper latanoprost solubilization. Furthermore, in vivo experiments demonstrated that the latanoprost-propylaminoβCD formulation led to lower ocular irritation than the commercial latanoprost formulation used as a reference. The latanoprost-propylaminoβCD formulation was demonstrated to successfully address the main stability, solubility, and tolerance limitations of topical ocular latanoprost therapy for glaucoma.

Identification of aggregation breakers for bevacizumab (Avastin®) self-association through similarity searching and interaction studies

Aggregation is a common challenge in the optimization of therapeutic antibody formulations. Since initial self-association of two monomers is typically a reversible process, the aim of this study is to identify different excipients that are able to shift this equilibrium to the monomeric state. The hypothesis is that a specific interaction between excipient and antibody may hinder two monomers from approaching each other, based on previous work in which dexamethasone phosphate showed the ability to partially reverse formed aggregates of the monoclonal IgG1 antibody bevacizumab back into monomers. The current study focuses on the selection of therapeutically inactive compounds with similar properties. Adenosine monophosphate, adenosine triphosphate, sucrose-6-phosphate and guanosine monophosphate were selected in silico through similarity searching and docking. All four compounds were predicted to bind to a protein-protein interaction hotspot on the Fc region of bevacizumab and thereby breaking dimer formation. The predictions were supported in vitro: An interaction between AMP and bevacizumab with a dissociation constant of 9.59±0.15 mM was observed by microscale thermophoresis. The stability of the antibody at elevated temperature (40 °C) in a 51 mM phosphate buffer pH 7 was investigated in presence and absence of the excipients. Quantification of the different aggregation species by asymmetrical flow field-flow fractionation and size exclusion chromatography demonstrates that all four excipients are able to partially overcome the initial self-association of bevacizumab monomers.

Glycoprofiling with micro-arrays of glycoconjugates and lectins

To facilitate deciphering the information content in the glycome, thin film-coated photoactivatable surfaces were applied for covalent immobilization of glycans, glycoconjugates, or lectins in microarray formats. Light-induced immobilization of a series of bacterial exopolysaccharides on photoactivatable dextran-coated analytical platforms allowed covalent binding of the exopolysaccharides. Their specific galactose decoration was detected with fluorescence-labeled lectins. Similarly, glycoconjugates were covalently immobilized and displayed glycans were profiled for fucose, sialic acid, galactose, and lactosamine epitopes. The applicability of such platforms for glycan profiling was further tested with extracts of Caco2 epithelial cells. Following spontaneous differentiation or on pretreatment with sialyllactose, Caco2 cells showed a reduction of specific glycan epitopes. The changed glycosylation phenotypes coincided with altered enteropathogenic E. coli adhesion to the cells. This microarray strategy was also suitable for the immobilization of lectins through biotin-neutravidin-biotin bridging on platforms functionalized with a biotin derivatized photoactivatable dextran. All immobilized glycans were specifically and differentially detected either on glycoconjugate or lectin arrays. The results demonstrate the feasibility and versatility of the novel platforms for glycan profiling.

Calcium supplementation of chocolate: effect on cocoa butter digestibility and blood lipids in humans

BACKGROUND

The digestibility of cocoa butter was reported in animal but not human studies to be low (60-70% and 89-94%, respectively). These differences could be due to the much higher ratio of calcium to fat (by wt) in the diet of rats (0.04-0.18) than in that of humans (0.01).

OBJECTIVE

We investigated whether supplementation of chocolate with 0.9% calcium (by wt), as an integral part of a Western diet, reduces absorption of cocoa butter and hence the digestible energy value of chocolate. We also assessed the effect of calcium supplementation on the blood lipid profile.

DESIGN

Ten men were fed control diets containing 98-101 g chocolate/d with or without a 0.9%-Ca supplement (0.9 g Ca/d) for 2 periods of 2 wk each. The study was conducted with use of a randomized, double-blind crossover design under free-living conditions but with strict control of food intake.

RESULTS

Calcium supplementation of chocolate increased fecal fat 2-fold (from 4.4 to 8.4 g/d; P < 0.0001) and reduced the absorption of cocoa butter by 13.0%. This was due mainly to an increase in the excretion of palmitic and stearic acids (3.4 g/d), which reduced the absorbable energy value of the chocolate by approximately 9%. This supplementation also reduced plasma LDL cholesterol by 15% (P < 0.02); HDL cholesterol was unchanged.

CONCLUSIONS

Calcium supplementation can be used as a means of reducing the absorbable energy value of chocolate. Supplementation with 2.25% CaCO3 had no effect on the taste of chocolate, was well tolerated by the subjects, and reduced LDL cholesterol in a short-term study.

Effect of dietary phytic acid on zinc absorption in the healthy elderly, as assessed by serum concentration curve tests

Zn absorption was investigated in healthy elderly subjects aged 71-78 years and in young subjects aged 23-43 years using serum concentration curve (SCC) tests. Both groups had similar Zn and protein status. The increase in serum Zn was monitored for 180 min after ingestion of 200 ml of soya milk enriched with 50 mg of Zn. Three levels of phytic acid were used: 0 g/200 ml (totally dephytinized soya milk), 0.13 g/200 ml (half dephytinized), and 0.26 g/200 ml (natural phytic acid content). In a first study the effect of 0 v. 0.26 g/200 ml phytic acid was compared in 10 elderly and 10 young subjects, each subject receiving both treatments. In a second study soya milks with 0 and 0.13 g/200 ml were tested in nine elderly and ten young subjects, again receiving both treatments. Mean areas under the curve of the SCC tests conducted with the 0 g/200 ml soya milk were found to be the same in both studies. Phytic acid strongly depressed Zn absorption in both studies (P < or = 0.05), but to a greater extent at the 0.26 g/200 ml level. No difference was found between the groups of young and elderly subjects. Therefore, no significant effect of aging on Zn absorption, as evaluated by the SCC test, or on the inhibitory effect of phytic acid was detected.

Influence of large intakes of trace elements on recovery after major burns

Because Cu, Se, and Zn are involved in immune and antioxidative defense mechanisms and tissue repair, deficiencies might aggravate complications classically observed with burns. After measuring massive cutaneous trace element losses in 10 burn patients, our aim in this study was to determine whether large intravenous intakes of Cu, Zn, and Se can modify serum trace element levels and recovery after major burns. Ten patients, aged 34 +/- 6 yr (mean +/- SD), admitted to the burns center of a Swiss university hospital with thermal burns on 41 +/- 9% of their body surface were studied prospectively, with trace element balance studies from day 1 (D1) to D7 postinjury. Urine and blood samples were also collected on D10, D15, D20, and D25. The patients were divided into two groups of five and received either standard (group 1, control) or greatly increased (group 2, treatment: 4.5 mg Cu, 190 micrograms Se, and 40 mg Zn/day) trace element intakes. Energy and protein intake and wound treatment were similar in both groups. The treatment group was characterized by improved Cu, Se, and Zn status (increase in serum levels and various protein indicators), a much larger leukocyte increase between D4 and D14 (mainly neutrophils), and shorter hospital stay (45 days) compared with the untreated group (57 days). Grafting requirements were more extensive in group 1. Although severity of injury and wound treatment were similar in the groups, the duration of hospitalization was lower in the treated group. Further studies are required to determine whether this is related to trace element supplementation.

Zinc absorption in healthy elderly humans and the effect of diet

Absorption of a zinc stable isotope was measured on two consecutive occasions in nine young and eight elderly healthy men aged 24-40 and 70-83 y, respectively. A zinc stable-isotope label (0.8 mg 70Zn) was added to a test meal of either high or low zinc bioavailability, depending mainly on phytic acid content. Zinc absorption from the high-bioavailability test meal was not significantly different (P > 0.05) in the young (38.9 +/- 9.8%, mean +/- SD) and elderly (35.0 +/- 10.9%) subjects. Zinc absorption from the low-bioavailability test meal was 40% and 43% lower, at 23.4 +/- 10.2% and 19.8 +/- 6.1% in these young and elderly men, respectively. Again, no significant effect of age was found. These results show that aging does not lead to nutritionally relevant changes in zinc absorption and in the effect of dietary inhibitors on zinc absorption. Thus, zinc absorption ability seems to be preserved in healthy elderly people, at least until the age of 80 y.

Cutaneous copper and zinc losses in burns

To measure the exudative cutaneous copper (Cu) and zinc (Zn) losses in burns, 10 patients, aged 36 +/- 9 years (mean +/- s.d.) with burns covering 33 +/- 10 per cent of the total body surface area, were studied from the first postburn day (D1) until D7. All intakes and losses were analysed for Cu, Zn and nitrogen (N) content. Cutaneous losses were extracted from textiles surrounding the patients. Urinary excretions were 0.12 +/- 0.06mg/24h for Cu, 0.9 +/- 0.6mg/24h for Zn, and 14.1 +/- 4.4g/24h for N. Mean daily exudative losses through wound seepage from D1 to D7 were 4.7 +/- 2.1mg/24h for Cu, 27.1 +/- 14.4mg/24h for Zn, and 8.7 +/- 3.8g/24h for N. The cumulated mean losses over 7 days were 37mg for Cu, and 212mg for Zn, representing respectively 20-40 per cent and 5-10 per cent of normal body content. Serum Cu and Zn levels were strongly depressed. The urinary Cu/N ratios correlated with clinical improvement. We conclude that the exudative Cu and Zn losses during the first week postburn contribute significantly to the increased nutrient requirements in burns.