Laboratory of BioChemistry

Polyelectrolytes with ionic domains screened by bulkyhydrophobicsegments form processable, hydrophobic complexes called “compleximers”.Ionic liquids, which are chemically similar, further plasticize compleximers,yet the mechanisms behind their plasticization effects and distributionwithin the complexes remain unclear. This study examines the relaxationdynamics of plasticized compleximers across multiple length scalesusing rheology, fluorescence recovery after photobleaching (FRAP),and broadband dielectric spectroscopy (BDS). The incorporation ofionic liquids into compleximers reduces their glass transition temperature(Tg), accelerates diffusive processes,increases segmental motion, and leads to a small decrease in activationenergy associated with these relaxation processes. However, the activationenergies vary substantially between techniques, probing differentphysical processes: approximately 200 kJ/mol in rheology, 50 kJ/molin FRAP, and 90 kJ/mol in BDS. These variations suggest that collectivedynamics strongly influence the compleximer rheology, making the mobilization(and activation) of polymer chains distinct from the local movementof ionic segments.

BackgroundLetrozole, an aromatase inhibitor metabolised via CYP2A6 and CYP3A4/5 enzymes, is used as adjuvant therapy for women with hormone receptor (HR)-positive early breast cancer. The objective of this study was to quantify the impact of CYP2A6 genotype on letrozole pharmacokinetics (PK), to identify non-adherent patients using a population approach and explore the possibility of a relationship between non-adherence and early relapse. MethodsBreast cancer patients enrolled in the prospective PHACS study (ClinicalTrials.gov NCT01127295) and treated with adjuvant letrozole 2.5 mg/day were included. Trough letrozole concentrations (Css,trough) were measured every 6 months for 3 years by a validated LC-MS/MS method. Concentration-time data were analysed using non-linear mixed effects modelling. Three methods were evaluated for identification of non-adherent subjects using the base PK model. Results617 patients contributing 2534 plasma concentrations were included and led to a one-compartment PK model with linear absorption and elimination. Model-based methods identified 28 % of patients as non-adherent based on high fluctuations of their Css,trough compared to 3 % based on patient declarations. The covariate analysis performed in adherent subjects revealed that CYP2A6 intermediate (IM) and slow metabolisers (SM) had 21 % (CI95 % = 12 – 30 %) and 46 % (CI95 % = 41 – 51 %) lower apparent clearance, respectively, compared to normal and ultrarapid metabolisers (NM+UM). Early relapse (19 patients) was not associated with model-estimated, concentration-based or declared adherence in the total population (p = 0.41, p = 0.37 and p = 0.45, respectively). ConclusionsThese findings will help future investigations focusing on the exposure-efficacy relationship for letrozole in adjuvant setting.

The open reading frame 8 (ORF8) protein, encoded by the SARS-CoV-2 virus after infection, stimulates monocytes/macro-phages to produce pro-inflammatory cytokines. We hypothesized that a positive ex vivo monocyte response to ORF8 protein pre-COVID-19 would be associated with subsequent severe Coronavirus disease 2019 (COVID-19). We tested ORF8 ex vivo on peripheral blood mononuclear cells from 26 anonymous healthy blood donors and measured intracellular cytokine/ chemokine levels in monocytes by flow cytometry. The percentage of positive monocyte staining in the sample and change in mean fluorescence intensity (∆MFI) after ORF8 were used to calculate the adjusted MFI for each cytokine. We then tested pre-COVID-19 peripheral blood mononuclear cell samples from 60 chronic lymphocytic leukemia (CLL) patients who subsequently developed COVID-19 infection. Severe COVID-19 was defined as hospitalization due to COVID-19. In the 26 normal donor samples, the adjusted MFI for interleukin (IL)-1β, IL-6, IL-8, and CCL-2 were significantly different with ORF8 stimulation versus controls. We next analyzed monocytes from pre-COVID-19 PBMC samples from 60 CLL patients. The adjusted MFI to ORF8 stimulation of monocyte intracellular IL-1β was associated with severe COVID-19 and a reactive ORF8 monocyte response was defined as an IL-1β adjusted MFI ≥0.18 (sensitivity 67%, specificity 75%). The median time to hospitalization after infection in CLL patients with a reactive ORF8 response was 12 days versus not reached for patients with a non-reactive ORF8 response with a hazard ratio of 7.7 (95% confidence interval: 2.4-132; P=0.005). These results provide new insight on the monocyte inflammatory response to virus with implications in a broad range of disorders involving monocytes.

This study aimed to enhance the production of the intracellular L-asparaginase bacterial enzyme, which is known to impede the growth of cancer cells, by optimizing the culture conditions. In the present study, we exploited the ability of a new Actinomycete strain isolated from a food byproduct, wheat bran, to produce the desired enzyme. Streptomyces paulus CA01 was identified following morphological, biochemical, and molecular testing, and its total L-asparaginase activity was evaluated using ADS agar. Intracellular L-asparaginase activity was measured on the same medium using the well-diffusion method and was quantified by Nesslerization. A Box-Behnken design was employed to optimize the production of the enzyme by analyzing the effect of three factors: temperature, L-Asparagine concentration and glucose concentration. The ADS base medium, which was previously optimized and consisted of starch, K2HPO4, and MgSO4, was also included in the analysis. The optimal conditions for intracellular L-asparaginase production were temperature of 27.5 °C, L-Asparagine concentration of 1.19%, glucose concentration of 0.26% and ADS base medium composition, with which we achieved an incrase in enzymatic activity from 3.20 IU/mL to 8.39 IU/mL. This study indicates that Algerian wheat bran is a potential source of Streptomyces paulus CA01, which produces the bacterial intracellular L-asparaginase enzyme and also opens up prospects for the exploitation of agricultural by-products as sources of interesting micro-organisms. Despite the complex process of cell lysis required for its production, intracellular L-asparaginase is important and depends on culture conditions, making its optimization and increased yield feasible.

Symmetrical and dissymmetrical bolaforms were prepared with good to high yields from unsaturated L-rhamnosides and phenolic esters (ferulic, phloretic, coumaric, sinapic and caffeic) using two eco-compatible synthetic strategies involving glycosylation, enzymatic synthesis and cross-metathesis under microwave activation. The plant-eliciting activity of these new compounds was investigated in Arabidopsis model plants. We found that the monocatenar rhamnosides and bolaforms activate the plant immune system with a response depending on the carbon chain length and the nature of the hydrophilic heads. Their respective antioxidant activities were also evaluated, as well as their cytotoxic properties on dermal cells for cosmetic uses. We showed that phenolic ester-based compounds present good antioxidant activities and that their cytotoxicity is low. These properties are also dependent on the carbon chains used.

In Côte d'Ivoire, the non-alcoholic beverage industry is gradually turning to fruits from local wild species. More and more products from the latter are entering the market. Black plum, fruit of <em>Vitex doniana</em>, very pleasant and rich in bioactive compounds, has been transformed into nectar without the addition of preservatives. As a result, this product remains subject to a possible alteration of its nutritional quality and to reduction of its shelf life. Monitoring of the evolution of certain biochemical parameters of traditional nectar of black plums stored at different temperatures, for three (3) months, was carried out with the aim of highlighting the influence of temperature and storage duration on its nutritional quality but also to be able to determine its best use-by date, in order to guarantee best preservation of nutritional qualities. Black plum nectar used for this work was made from fruits, harvested in three (3) regions of northern Côte d'Ivoire and using a process modeled on traditional technique. Biochemical analyzes was carried out using the classic methods analysis. At the end of this study, we note an increase in acidity and soluble dry extract of traditional nectar linked to the rise in storage temperature. Vitamin C losses are minimal when this storage temperature is low. The longer the shelf life of nectar, the more it registers a decline in its nutritional value. Temperature that allows better nutritional preservation of black plum traditional nectar remains that of refrigeration (4 °C). However, at this temperature, its shelf life cannot exceed ten (10) weeks if you want to enjoy its benefits.

Extracellular matrixes (ECMs) are intricate 3-dimensional macromolecular networks of unique architectures with regulatory roles in cell morphology and functionality. As a dynamic native biomaterial, ECM undergoes constant but tightly controlled remodeling that is crucial for the maintenance of normal cellular behavior. Under pathological conditions like cancer, ECM remodeling ceases to be subjected to control resulting in disease initiation and progression. ECM is comprised of a staggering number of molecules that interact not only with one another, but also with neighboring cells via cell surface receptors. Such interactions, too many to tally, are of paramount importance for the identification of novel disease biomarkers and more personalized therapeutic intervention. Recent advances in big data analytics have allowed the development of online databases where researchers can take advantage of a stochastic evaluation of all the possible interactions and narrow them down to only those of interest for their study, respectively. This novel approach addresses the limitations that currently exist in studies, expands our understanding on ECM interactions, and has the potential to advance the development of targeted therapies. In this article we present the current trends in ECM biology research and highlight its importance in tissue integrity, the main interaction networks, ECM-mediated cell functional properties and issues related to pharmacological targeting.

Background: Some ergogenic medicinal plants are used in exercise and sport in Africa in order to increase sport performance. However, data on their composition and their possible impacts on health are limited. This study was initiated to provide ethnobotanical data on plants traditionally used to optimize physical performance and to perform a qualitative characterization of their main chemical groups. Methods: Ethnobotanical surveys in two communes (Dedougou and Nouna), of the region of Boucle du Mouhoun, Burkina Faso and phytochemical analyses of the most interesting plants were conducted. Results: A total of 50 respondents including traditional hunters dozo, farmers, healers, herbalists, marabouts, etc., were interviewed. Fifty-two species used in the optimization of exercise and sports have been identified. The most cited species were Cassia sieberiana, Tamarindus indica, Annona senegalensis, Gardenia sokotensis, Securidaca longepedunculata, and Ficus tonningii. These plants are known to prevent muscle and skeletal disorders, aches and pains, and mental disorders. The study identified several types of plants including those displaying stimulation, anxiolytic, sedative, adaptogenic, or erythropoietic activities. Phytochemical screening revealed the presence of phenolic compounds, alkaloids, terpenes, and steroids, which are similar molecules families of those of doping molecules. Additionally, TLC screening allowed the characterization of numerous terpene and flavonoid compounds including rutin. Conclusions: The possible structural similarity of the characterized chemical groups of these species with those of doping families raise concerns about the consequences of their consumption. However, the identification of the active molecules of these species remains to be performed in order to predict the real risks associated with their consumption.

Syncope without prodromes in subjects with normal heart and normal electrocardiogram (ECG) is classified as non-classical neurally mediated syncope and is characterized by low adenosine plasma levels (APLs) and frequent asystolic syncope. We assessed the efficacy of theophylline, a non-selective adenosine receptor antagonist, in preventing syncopal events. Participants received an implantable cardiac monitor, underwent APL measurement, and received oral theophylline at maximum tolerated dose (starting dose 300 mg b.i.d.). They were compared with a historical cohort of untreated patients with implantable cardiac monitor who had the same inclusion criteria and were balanced with the propensity score (PS) method as regard age, sex, lifetime syncopal episodes, APL, and antihypertensive drugs. Primary endpoint was time to first syncopal recurrence at 24 months. There were 76 patients in the theophylline group and 58 in the control group. Syncope recurred in 25 (33%) patients in the theophylline group and in 27 (47%) patients in the control group, with an estimated 2-year recurrence rate of 33% and 60%, respectively, and a hazard ratio of 0.53 [95% confidence interval (CI), 0.30-0.95; P = 0.034]. Most of the benefit of theophylline is derived from reduction of syncope due to asystolic atrioventricular (AV) block (hazard ratio of 0.13; 95% CI, 0.03-0.58; P = 0.008). Thirty (39%) patients discontinued theophylline after a median of 6.4 (interquartile range 1.7-13.8) months due to side effects. Theophylline was effective in preventing recurrences in patients with syncope without prodromes, normal heart, and normal ECG. The benefit was greater in patients with syncope due to asystolic AV block. NCT03803215.