| 1. |
- Bonito, Catia A., et al.
(författare)
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Theoretical insights on helix repacking as the origin of P-glycoprotein promiscuity
- 2020
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Ingår i: Scientific Reports. - : NATURE PUBLISHING GROUP. - 2045-2322. ; 10:1
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Tidskriftsartikel (refereegranskat)abstract
- P-glycoprotein (P-gp, ABCB1) overexpression is, currently, one of the most important multidrug resistance (MDR) mechanisms in tumor cells. Thus, modulating drug efflux by P-gp has become one of the most promising approaches to overcome MDR in cancer. Yet, more insights on the molecular basis of drug specificity and efflux-related signal transmission mechanism between the transmembrane domains (TMDs) and the nucleotide binding domains (NBDs) are needed to develop molecules with higher selectivity and efficacy. Starting from a murine P-gp crystallographic structure at the inward-facing conformation (PDB ID: 4Q9H), we evaluated the structural quality of the herein generated human P-gp homology model. This initial human P-gp model, in the presence of the "linker" and inserted in a suitable lipid bilayer, was refined through molecular dynamics simulations and thoroughly validated. The best human P-gp model was further used to study the effect of four single-point mutations located at the TMDs, experimentally related with changes in substrate specificity and drug-stimulated ATPase activity. Remarkably, each P-gp mutation is able to induce transmembrane alpha-helices (TMHs) repacking, affecting the drug-binding pocket volume and the drug-binding sites properties (e.g. volume, shape and polarity) finally compromising drug binding at the substrate binding sites. Furthermore, intracellular coupling helices (ICH) also play an important role since changes in the TMHs rearrangement are shown to have an impact in residue interactions at the ICH-NBD interfaces, suggesting that identified TMHs repacking affect TMD-NBD contacts and interfere with signal transmission from the TMDs to the NBDs.
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| 2. |
- Isca, Vera M. S., et al.
(författare)
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Molecular Docking Studies of Royleanone Diterpenoids from Plectranthus spp. as P-Glycoprotein Inhibitors
- 2020
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Ingår i: ACS Medicinal Chemistry Letters. - : American Chemical Society (ACS). - 1948-5875. ; 11:5, s. 839-845
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Tidskriftsartikel (refereegranskat)abstract
- The development of multidrug resistance (MDR) is a major cause of failure in cancer chemotherapy. Several abietane diterpenes with antitumoral activities have been isolated from Plectranthus spp. such as 6,7-dehydroroyleanone (DHR, 1) and 7 alpha-acetoxy-6 beta-hydroxyroyleanone (AHR, 2). Several royleanone derivatives were prepared through hemisynthesis from natural compounds 1 and 2 to achieve a small library of products with enhanced anti-P-glycoprotein activity. Nonetheless, some derivatives tend to be unstable. Therefore, to reason such lack of stability, the electron density based local reactivity descriptors condensed Fukui functions and dual descriptor were calculated for several derivatives of DHR. Additionally, molecular docking and molecular dynamics studies were performed on several other derivatives to clarify the molecular mechanisms by which they may exert their inhibitory effect in P-gp activity. The analysis on local reactivity descriptors was important to understand possible degradation pathways and to guide further synthetic approaches toward new royleanone derivatives. A molecular docking study suggested that the presence of aromatic moieties increases the binding affinity of royleanone derivatives toward P-gp. It further suggests that one royleanone benzoylated derivative may act as a noncompetitive efflux modulator when bound to the M-site. The future generation of novel royleanone derivatives will involve (i) a selective modification of position C-12 with chemical moieties smaller than unsubstituted benzoyl rings and (ii) the modification of the substitution pattern of the benzoyloxy moiety at position C-6.
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| 3. |
- Reis, Mariana Alves, et al.
(författare)
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Epoxylathyrane Derivatives as MDR-Selective Compounds for Disabling Multidrug Resistance in Cancer
- 2020
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Ingår i: Frontiers in Pharmacology. - : Frontiers Media SA. - 1663-9812. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- Background: Multidrug resistance (MDR) has been regarded as one of the major hurdles for the successful outcome of cancer chemotherapy. The collateral sensitivity (CS) effect is one the most auspicious anti-MDR strategies. Epoxylathyrane derivatives 1-16 were obtained by derivatization of the macrocyclic diterpene epoxyboetirane A (17), a lathyrane-type macrocyclic diterpene isolated from Euphorbia boetica. Some of these compounds were found to strongly modulate P-glycoprotein (P-gp/ABCB1) efflux.Purpose: The main goal was to develop lathyrane-type macrocyclic diterpenes with improved MDR-modifying activity, by targeting more than one anti-MDR mechanism.Study design/methods: In this study, the potential CS effect of compounds 1-16 was evaluated against gastric (EPG85-257), pancreatic (EPP85-181), and colon (HT-29) human cancer cells and their drug-resistant counterparts, respectively selected against mitoxantrone (EPG85-257RNOV; EPP85-181RNOV; HT-RNOV) or daunorubicin (EPG85-257RDB; EPP85-181RDB; HT-RDB). The most promising compounds (8, 15, and 16) were investigated as apoptosis inducers, using the assays annexin V/PI and active caspase-3.Results: The compounds were more effective against the resistant gastric cell lines, being the CS effect more significant in EPG85-257RDB cells. Taking together the IC50 values and the CS effect, compounds 8, 15, and 16 exhibited the best results. Epoxyboetirane P (8), with the strongest MDR-selective antiproliferative activity against gastric carcinoma EPG85-257RDB cells (IC50 of 0.72 mu M), being 10-fold more active against this resistant subline than in sensitive gastric carcinoma cells. The CS effect elicited by compounds 15 and 16 appeared to be by inducing apoptosis via caspase-3 activation. Structure-activity relationships of the compounds were additionally obtained through regression models to clarify the structural determinants associated to the CS effect.Conclusions: This study reinforces the importance of lathyrane-type diterpenes as lead molecules for the research of MDR-modifying agents.
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| 4. |
- Ferreira, Ricardo J., PhD, 1980-, et al.
(författare)
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Antibiotic Uptake Across Gram-Negative Outer Membranes : Better Predictions Towards Better Antibiotics
- 2019
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Ingår i: ACS - Infectious Diseases. - : AMER CHEMICAL SOC. - 2373-8227. ; 5:12, s. 2096-2104
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Tidskriftsartikel (refereegranskat)abstract
- Crossing the Gram-negative bacterial membrane poses a major barrier to antibiotic development, as many small molecules that can biochemically inhibit key bacterial processes are rendered microbiologically ineffective by their poor cellular uptake. The outer membrane is the major permeability barrier for many drug-like molecules, and the chemical properties that enable efficient uptake into mammalian cells fail to predict bacterial uptake. We have developed a computational method for accurate prospective prediction of outer membrane uptake of drug-like molecules, which we combine with a new medium-throughput experimental assay of outer membrane vesicle swelling. Parallel molecular dynamics simulations of compound uptake through Escherichia coli (E. coli) OmpF are used to successfully and quantitatively predict experimental permeabilities measured via either outer membrane swelling or prior liposome-swelling measurements. These simulations are analyzed using an inhomogeneous solubility-diffusion model to yield predictions of permeability. For most polar molecules we test, outer membrane permeability also correlates well with whole-cell uptake. The ability to accurately predict and measure outer membrane uptake of a wide variety of small molecules will enable simpler determination of which molecular scaffolds and which derivatives are most promising prior to extensive chemical synthesis. It will also assist in formulating a more systematic understanding of the chemical determinants of outer membrane permeability.
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| 5. |
- Garcia, Catarina, et al.
(författare)
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Royleanone Derivatives From Plectranthus spp. as a Novel Class of P-Glycoprotein Inhibitors
- 2020
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Ingår i: Frontiers in Pharmacology. - : Frontiers Media SA. - 1663-9812. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- Cancer is among the leading causes of death worldwide. One of the most challenging obstacles in cancer treatment is multidrug resistance (MDR). Overexpression of P-glycoprotein (P-gp) is associated with MDR. The growing incidence of cancer and the development of MDR drive the search for novel and more effective anticancer drugs to overcome the MDR problem. Royleanones are natural bioactive compounds frequently found in Plectranthus spp. The cytotoxic diterpene 6,7-dehydroroyleanone (1) is the main component of the P. madagascariensis (Pers.) Benth. essential oil, while 7α-acetoxy-6β-hydroxyroyleanone (2) can be isolated from acetonic extracts of P. grandidentatus Gürke. The reactivity of the natural royleanones 1 and 2 was explored to obtain a small library of new P-gp inhibitors. Four new derivatives (6,7-dehydro-12-O-tert-butyl-carbonate-royleanone (20), 6,7-dehydro-12-O-methylroyleanone (21), 6,7-dehydro-12-O-benzoylroyleanone (22), and 7α-acetoxy-6β-hydroxy-12-O-benzoylroyleanone (23) were obtained as pure with overall modest to excellent yields (21–97%). P-gp inhibition potential of the derivatives 20–23 was evaluated in human non-small cell lung carcinoma NCI-H460 and its MDR counterpart NCI-H460/R with the P-gp overexpression, through MTT assay. Previously prepared diterpene 7α-acetoxy-6β-benzoyloxy-12-O-(4-chloro)benzoylroyleanone (4), has also been tested. The P-gp inhibiting effects of compounds 1–4 were also assessed through a Rhodamine 123 accumulation assay. Derivatives 4 and 23 have significant P-gp inhibitory potential. Regarding stability and P-gp inhibition potential, results suggest that the formation of benzoyl esters is a more convenient approach for future derivatives with enhanced effect on the cell viability decrease. Compound 4 presented higher anti-P-gp potential than the natural diterpenes 1, 2, and 3, with comparable inhibitory potential to Dexverapamil. Moreover, derivative 4 showed the ability to sensitize the resistant NCI-H460/R cells to doxorubicin.
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| 6. |
- Mollazadeh, Shirin, et al.
(författare)
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Theoretical studies on 1,4-dihydropyridine derivatives as P-glycoprotein allosteric inhibitors : insights on symmetry and stereochemistry
- 2021
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Ingår i: Journal of Biomolecular Structure and Dynamics. - : Taylor & Francis. - 0739-1102 .- 1538-0254. ; 39:13, s. 4752-4763
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Tidskriftsartikel (refereegranskat)abstract
- P-glycoprotein (P-gp) is a key efflux pump involved in cellular multidrug resistance (MDR), lowering the concentration of many anticancer drugs in tumor cells by pumping them into the extracellular milieu. While previous studies identified 1,4-dihydropyridines (DHP) as putative P-gp allosteric inhibitors, none reported the effect of stereochemistry on the ability of DHPs to bind P-gp. In the present study both symmetric (1) and asymmetric (2 R,S) DHPs were designed as P-gp inhibitors and, after biological evaluation, molecular docking and molecular dynamics simulation (MD) studies were performed to gain insights on how both scaffolds interact with P-gp. The results were thoroughly analyzed i) to evaluate the role of the different substituents and ii) to assess how stereochemistry may affect binding of DHPs to P-gp. Our results suggest that both the substitution pattern and stereochemistry may have a significant impact not only in drug binding but also on membrane permeation/accumulation, thus compromising in which site the DHPs may exert their effect as P-gp efflux inhibitors. Therefore, it is our conclusion that the stereochemistry cannot be neglected during the development of novel 1,4-dihydropyridine derivatives.
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| 7. |
- Okamoto, Kenta, et al.
(författare)
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Acquired Functional Capsid Structures in Metazoan Totivirus-like dsRNA Virus
- 2020
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Ingår i: Structure. - : Elsevier BV. - 0969-2126 .- 1878-4186. ; 28:8, s. 888-
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Tidskriftsartikel (refereegranskat)abstract
- Non-enveloped icosahedral double-stranded RNA (dsRNA) viruses possess multifunctional capsids required for their proliferation. Whereas protozoan/fungal dsRNA viruses have a relatively simple capsid structure, which suffices for the intracellular phase in their life cycle, metazoan dsRNA viruses have acquired additional structural features as an adaptation for extracellular cell-to-cell transmission in multicellular hosts. Here, we present the first atomic model of a metazoan dsRNA totivirus-like virus and the structure reveals three unique structural traits: a C-terminal interlocking arm, surface projecting loops, and an obstruction at the pore on the 5-fold symmetry axis. These traits are keys to understanding the capsid functions of metazoan dsRNA viruses, such as particle stability and formation, cell entry, and endogenous intraparticle transcription of mRNA. On the basis of molecular dynamics simulations of the obstructed pore, we propose a possible mechanism of intraparticle transcription in totivirus-like viruses, which dynamically switches between open and closed states of the pore(s).
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