Publications by authors named "E Gil-Martins"

5 Publications

  • Page 1 of 1

Quality by design (QbD) optimization of diazepam-loaded nanostructured lipid carriers (NLC) for nose-to-brain delivery: Toxicological effect of surface charge on human neuronal cells.

Int J Pharm 2021 Jul 27;607:120933. Epub 2021 Jul 27.

UCIBIO/REQUIMTE, MEDTECH, Laboratory of Pharmaceutical Technology, Department of Drug Sciences, Faculty of Pharmacy, University of Porto, 4050-313 Porto, Portugal; FP-ENAS (UFP Energy, Environment and Health Research Unit), CEBIMED (Biomedical Research Centre), Faculty of Health Sciences, University Fernando Pessoa, 4249-004 Porto, Portugal. Electronic address:

Diazepam is commonly used in the management of epileptic seizures, although it has limitations that can be overcome by using formulations that are easier to administer and capable of directing the drug to the brain. In this field, it has been reported that the use of nanostructured lipid carriers (NLC) via intranasal (or via nose-to-brain) promotes the targeting of drugs to the brain, improving the effectiveness of therapy. The aim of this work was to optimize two diazepam-loaded NLC formulations for nose-to-brain delivery, one with positive surface charge and one with negative surface charge. The quality by design (QbD) approach was used to design the experiments, where the quality target product profile (QTPP), the risk assessment and the critical quality attributes (CQAs) were defined to ensure safety, efficacy and quality of the final formulations. The experiments started with the optimization of critical material attributes (CMAs), related to the ratios of lipids and emulsifiers, followed by the selection of critical process parameters (CPPs), related to the production methods of the diazepam-loaded NLC formulation (ultrasound technique and high-pressure homogenization - HPH). Afterwards, the positive surface charge of the diazepam-loaded NLC was optimized. Finally, the biocompatibility with human neuronal cells of the formulation with a negative surface charge and of the formulation with a positive surface charge was evaluated. The results of the optimization of the CMAs showed that the ratios of lipids and emulsifiers more adequate were 6.7:2.9 and 4.2:0.3 (% w,w), respectively. Regarding the CPPs, HPH was considered the most suitable production method, resulting in an optimized diazepam-loaded NLC formulation (F1C15) with negative surface charge, showing particle size of 69.59 ± 0.22 nm, polydispersity index (PDI) of 0.19 ± 0.00, zeta potential (ZP) of -23.50 ± 0.24 mV and encapsulation efficiency (EE) of 96.60 ± 0.03 %. The optimized diazepam-loaded NLC formulation (F2A8) with positive surface charge had particle size of 124.40 ± 0.84 nm, PDI of 0.17 ± 0.01, ZP of 32.60 ± 1.13 mV and EE of 95.76 ± 0.24 %. In addition, the incorporation of diazepam in NLC resulted in a sustained release of the drug. No significant changes in particle size, PDI, ZP and EE were observed for the formulation F1C15, after 3 months of storage, whereas for formulation F2A8, particle size increased significantly. Biocompatibility studies showed that the formulation F2A8 was more cytotoxic than the formulation F1C15. Thereby, we conclude that the formulation F1C15 is more suitable for targeting the brain, when compared with the formulation F2A8. From the results of these studies, it can be confirmed that the QbD approach is an adequate and central tool to optimize NLC formulations.
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http://dx.doi.org/10.1016/j.ijpharm.2021.120933DOI Listing
July 2021

Mapping Chromone-3-Phenylcarboxamide Pharmacophore: ?

J Med Chem 2021 Aug 16;64(15):11169-11182. Epub 2021 Jul 16.

CIQUP/Department of Chemistry and Biochemistry, Faculty of Sciences, University of Porto, Porto 4169-007, Portugal.

Chromone-3-phenylcarboxamides ( and ) were identified as potent, selective, and reversible inhibitors of human monoamine oxidase B (MAO-B). Since they exhibit some absorption, distribution, metabolism, and excretion (ADME)-toxicity liabilities, new derivatives were synthesized to map the chemical structural features that compose the pharmacophore, a process vital for lead optimization. Structure-activity relationship data, supported by molecular docking studies, provided a rationale for the contribution of the heterocycle's rigidity, the carbonyl group, and the benzopyran heteroatom for MAO-B inhibitory activity. From the study, -(3-chlorophenyl)-4-thiochromone-3-carboxamide () (MAO-B IC = 1.52 ± 0.15 nM) emerged as a reversible tight binding inhibitor with an improved pharmacological profile. In ADME-toxicity studies, compound showed a safe cytotoxicity profile in Caco-2, SH-SY5Y, HUVEC, HEK-293, and MCF-7 cells, did not present cardiotoxic effects, and did not affect P-gp transport activity. Compound also protected SH-SY5Y cells from iron(III)-induced damage. Collectively, these studies highlighted compound as the first-in-class and a suitable candidate for preclinical investigation.
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http://dx.doi.org/10.1021/acs.jmedchem.1c00510DOI Listing
August 2021

Xanthones as P-glycoprotein modulators and their impact on drug bioavailability.

Expert Opin Drug Metab Toxicol 2021 Apr 20;17(4):441-482. Epub 2021 Apr 20.

UCIBIO-REQUIMTE, Laboratório de Toxicologia, Departamento de Ciências Biológicas, Faculdade de Farmácia, Universidade do Porto, Porto, Portugal.

: P-glycoprotein (P-gp) is an important efflux pump responsible for the extruding of many endogenous and exogenous substances out of the cells. P-gp can be modulated by different molecules - including xanthone derivatives - to surpass the multidrug resistance (MDR) phenomenon through P-gp inhibition, or to serve as an antidotal strategy in intoxication scenarios through P-gp induction/activation.: This review provides a perspective on P-gp modulators, with particular focus on xanthonic derivatives, highlighting their ability to modulate P-gp expression and/or activity, and the potential impact of these effects on the pharmacokinetics, pharmacodynamics and toxicity of P-gp substrates.: Xanthones, of natural or synthetic origin, are able to modulate P-gp, interfering with its protein synthesis or with its mechanism of action, by decreasing or increasing its efflux capacity. These modulatory effects make the xanthonic scaffold a promising source of new derivatives with therapeutic potential. However, the mechanisms beyond the xanthones-mediated P-gp modulation and the chemical characteristics that make them more potent P-gp inhibitors or inducers/activators are still understudied. Furthermore, a new window of opportunity exists in the neuropathologies field, where xanthonic derivatives with potential to modulate P-gp should be further explored to optimize the prevention/treatment of brain pathologies.
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http://dx.doi.org/10.1080/17425255.2021.1861247DOI Listing
April 2021

Dysfunction of ABC transporters at the blood-brain barrier: Role in neurological disorders.

Pharmacol Ther 2020 09 19;213:107554. Epub 2020 Apr 19.

UCIBIO-REQUIMTE, Laboratório de Toxicologia, Departamento de Ciências Biológicas, Faculdade de Farmácia, Universidade do Porto, Rua de Jorge Viterbo Ferreira, 228, 4050-313 Porto, Portugal. Electronic address:

ABC (ATP-binding cassette) transporters represent one of the largest and most diverse superfamily of proteins in living species, playing an important role in many biological processes such as cell homeostasis, cell signaling, drug metabolism and nutrient uptake. Moreover, using the energy generated from ATP hydrolysis, they mediate the efflux of endogenous and exogenous substrates from inside the cells, thereby reducing their intracellular accumulation. At present, 48 ABC transporters have been identified in humans, which were classified into 7 different subfamilies (A to G) according to their phylogenetic analysis. Nevertheless, the most studied members with importance in drug therapeutic efficacy and toxicity include P-glycoprotein (P-gp), a member of the ABCB subfamily, the multidrug-associated proteins (MPRs), members of the ABCC subfamily, and breast cancer resistance protein (BCRP), a member of the ABCG subfamily. They exhibit ubiquitous expression throughout the human body, with a special relevance in barrier tissues like the blood-brain barrier (BBB). At this level, they play a physiological function in tissue protection by reducing or limiting the brain accumulation of neurotoxins. Furthermore, dysfunction of ABC transporters, at expression and/or activity level, has been associated with many neurological diseases, including epilepsy, multiple sclerosis, Alzheimer's disease, and amyotrophic lateral sclerosis. Additionally, these transporters are strikingly associated with the pharmacoresistance to central nervous system (CNS) acting drugs, because they contribute to the decrease in drug bioavailability. This article reviews the signaling pathways that regulate the expression and activity of P-gp, BCRP and MRPs subfamilies of transporters, with particular attention at the BBB level, and their mis-regulation in neurological disorders.
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http://dx.doi.org/10.1016/j.pharmthera.2020.107554DOI Listing
September 2020

Design of novel monoamine oxidase-B inhibitors based on piperine scaffold: Structure-activity-toxicity, drug-likeness and efflux transport studies.

Eur J Med Chem 2020 Jan 16;185:111770. Epub 2019 Oct 16.

CIQUP/Department of Chemistry and Biochemistry, Faculty of Sciences, University of Porto, Porto, Portugal. Electronic address:

Piperine has been associated with neuroprotective effects and monoamine oxidase (MAO) inhibition, thus being an attractive scaffold to develop new antiparkinsonian agents. Accordingly, we prepared a small library of piperine derivatives and screened the inhibitory activities towards human MAO isoforms (hMAO-A and hMAO-B). Structure-activity relationship (SAR) studies pointed out that the combination of α-cyano and benzyl ester groups increased both potency and selectivity towards hMAO-B. Kinetic experiments with compounds 7, 10 and 15 indicated a competitive hMAO-B inhibition mechanism. Compounds 15 and 16, at 10 μM, caused a small but significant decrease in P-gp efflux activity in Caco-2 cells. Compound 15 stands out as the most potent piperine-based hMAO-B inhibitor (IC = 47.4 nM), displaying favourable drug-like properties and a broad safety window. Compound 15 is thus a suitable candidate for lead optimization and the development of multitarget-directed ligands.
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http://dx.doi.org/10.1016/j.ejmech.2019.111770DOI Listing
January 2020
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