ABSTRACT
In the present study, both short-range and long-range structural features of an ionic bridged silsesquioxane, specifically one containing the 1,4-diazoniabicyclo[2.2.2]octane chloride group (ISSQ), were elucidated. This ionic silsesquioxane was synthesized via direct polycondensation of a bridged organosilane precursor, without any additional functionalization step. Si-O-Si cage structures typical of Polyhedral Oligomeric Silsesquioxanes (POSS) were identified. The average interatomic distances of the POSS cages, including the open T8 cage and the T12 cage for the ISSQ, as well as the T8 cage for a commercially available pendant POSS were determined. It is the first report of the interatomic distance determination of POSS cage; achieved by using total pair distribution function G(r) values obtained through high-resolution synchrotron X-ray diffraction combined with density functional theory (DFT) calculations. The application of DFT was crucial for accurately assigning X-ray peaks and verifying structural details. Furthermore, the analysis of X-ray diffraction peaks and the examination of crystalline domains via transmission electron microscopy enabled the proposal of a hexagonal arrangement of Si-O-Si cages over long ranges within the ionic bridged silsesquioxane. This proposed arrangement highlights a distinctive structural organization that could impact the material's properties and applications.
ABSTRACT
Cancer is a disease caused by uncontrolled cell growth that is responsible for several deaths worldwide. Breast cancer is the most common type of cancer among women and is the leading cause of death. Chemotherapy is the most commonly used treatment for cancer; however, it often causes various side effects in patients. In this study, we evaluate the antineoplastic activity of a parent compound based on a combretastatin A4 analogue. We test the compound at 0.01 mg mL- 1, 0.1 mg mL- 1, 1.0 mg mL- 1, 10.0 mg mL- 1, 100.0 mg mL- 1, and 1,000.0 mg mL- 1. To assess molecular antineoplastic activity, we conduct in vitro tests to determine the viability of Ehrlich cells and the blood mononuclear fraction. We also analyze the cytotoxic behavior of the compound in the blood and blood smear. The results show that the molecule has a promising antineoplastic effect and crucial anticarcinogenic action. The toxicity of blood cells does not show statistically significant changes.
Subject(s)
Stilbenes , Stilbenes/pharmacology , Animals , Cell Survival/drug effects , Mice , Leukocytes, Mononuclear/drug effects , Antineoplastic Agents/pharmacology , Humans , Carcinoma, Ehrlich Tumor/drug therapyABSTRACT
Hybrid naphthalenediimide/zinc phosphonate materials (NDI/Zn) were prepared by mixing solutions of N,N'-bis(2-phosphonoethyl)-1,4,5,8-naphthalenediimide (PNDI) and zinc nitrate, resulting in the precipitation of the desired compounds. Samples precipitated from water and N,N-dimethylformamide (DMF) were produced. The obtained samples had the expected elemental composition, and the presence of naphthalenediimides (NDI) was ascertained by infrared and UV-visible spectroscopy. All the samples were crystalline, according to powder X-ray diffraction. Nitrogen adsorption isotherms showed the presence of porosity in the NDI/Zn samples. Mesopores with a diameter = 4.1 nm were present in the sample from DMF, with total pore volume reaching 0.13 cm3/g.
ABSTRACT
Recently, the U.S. Food and Drug Administration (FDA) approved the first oral antiviral drug to treat mild to moderate cases of coronavirus disease. The combination of nirmatrelvir with an already used protease inhibitor class drug, ritonavir, has led to Paxlovid®. Several studies considered drug repositioning as the first trial for new drugs. The precise identification and quantification of polymorphs in raw materials and finished products are important to researchers involved in pharmaceutical development and quality control processes. In this work, we study the solid-state behavior of the antiretroviral drugs ritonavir and lopinavir in raw materials and in milled compositions. The results indicate that mixtures of ritonavir Forms I and II are found in different batches of raw materials from the same manufacturer; besides three equal crystalline samples, an amorphous batch was found in lopinavir. Furthermore, the milling process of the already amorphous lopinavir seems to facilitate the amorphization of ritonavir as well as the production of some unexpected crystalline forms of ritonavir. A phase transition of ritonavir Form I to Form II is only observed when co-milling with amorphous lopinavir. These findings reveal significant variations in phase purity of raw materials that affect the processing and solid-state properties, representing risks for the product quality.
Subject(s)
Coronavirus Infections , Ritonavir , Humans , Lopinavir/chemistry , Antiviral Agents , Coronavirus Infections/drug therapy , Drug CombinationsABSTRACT
The zwitterionic l-tripeptide glycylphenylalanylglycine self-assembles into very long crystalline fibrils in an aqueous solution, which causes the formation of an exceptionally strong gel phase (G' â¼ 5 × 106 Pa). The Rietveld refinement analysis of its powder X-ray diffraction (PXRD) pattern reveals a unit cell with four peptides forming a P212121 space group and adopting an inverse polyproline II conformation, that is, a right-handed helical structure that occupies the "forbidden" region of the Ramachandran plot. This unusual structure is stabilized by a plethora of intermolecular interactions facilitated by the large number of different functional groups of the unblocked tripeptide. Comparisons of simulated and experimental Fourier transform infrared and vibrational circular dichroism (VCD) amide I' profiles corroborate the PXRD structure. Our experimental setup reduces the sample to a quasi-two-dimensional network of fibrils. We exploited the influence of this reduced dimensionality on the amide I VCD to identify the main fibril axis. We demonstrate that PXRD, vibrational spectroscopy, and amide I simulations provide a powerful toolset for secondary structure and fibril axis determination.
Subject(s)
Amides , Peptides , Amides/chemistry , Circular Dichroism , Peptides/chemistry , Powders , Protein Structure, Secondary , Spectroscopy, Fourier Transform InfraredABSTRACT
The search for new prominent chemosensors is significantly related to the rationalization of possible multiple pathways of excited-state deactivation. We have prepared and studied compound α-(2-hydroxyphenyl)-N-phenylnitrone (Nit-OH), observing that Nit-OH is stable in acetonitrile solution under UV-vis light. The experimentally observed 540 nm fluorescence for Nit-OH was shown to be related to excitation at 360 nm from the highest occupied molecular orbital to the lowest unoccupied molecular orbital (HOMO-LUMO transition). Potential energy curves (PECs) for the S1 state of Nit-OH did show that there are structures associated with excited-state intramolecular proton transfer (ESIPT), and the existence of an intramolecular H-bonding was confirmed using X-ray powder diffraction (XRD). Twisted intramolecular charge transfer (TICT) took place following ESIPT, and a nonradiative deactivation at the S1/S0 conical intersection occurred; aggregation-induced emission was observed at 540 nm associated with the formation of a stacked dimer. Anti-Kasha emission from the S2 was proposed based on the dependence of the fluorescence excitation wavelength on Nit-OH concentration. From the calculation of the PEC for the S2 state, we obtained radiative transitions at 379 and 432 nm, similar to the obtained experimental values of 383 and 453 nm. We proposed a Jablonski-like diagram that depicts all experimental and theoretical electronic transitions for Nit-OH, summarizing the unique intricate photophysical behavior of this nitrone derivative.
Subject(s)
Electronics , Protons , Acetonitriles , Models, Molecular , Spectrometry, FluorescenceABSTRACT
Flubendazole (FBZ) is a poorly water-soluble drug, and different methodologies have been proposed to improve its oral bioavailability. Obtaining the amorphous drug phase is an alternative to improve its water solubility. Several techniques for drug amorphization, such as spray drying, lyophilization, melt quenching, solvent-evaporation, and ball milling, can yield various types of structural disorder and possibly render variations in physicochemical properties. Herein, we focus on evaluating the influence of the ball-milling process on the amorphization of FBZ. The characterization of the average global and local structures before, during, and after the milling process is described by sequential Rietveld refinements, pair distribution function analysis, and the Reverse Monte Carlo method. We show that preserving the local structure (nearest molecules) can be responsible for avoiding the fast structure recrystallization commonly observed when using the solvent-evaporation process for the studied drug.
Subject(s)
Water , Calorimetry, Differential Scanning , Drug Stability , Mebendazole/analogs & derivatives , Powder Diffraction , Powders , Solubility , Solvents , Water/chemistry , X-Ray Diffraction , X-RaysABSTRACT
Ciprofibrate (CIP) is a highly lipophilic and poorly water-soluble drug, typically used for dyslipidemia treatment. Although it is already commercialized in capsules, no previous studies report its solid-state structure; thus, information about the correlation with its physicochemical properties is lacking. In parallel, recent studies have led to the improvement of drug administration, including encapsulation in polymeric nanoparticles (NPs). Here, we present CIP's crystal structure determined by PXRD data. We also propose an encapsulation method for CIP in micelles produced from Pluronic P123/F127 and PEO-b-PCL, aiming to improve its solubility, hydrophilicity, and delivery. We determined the NPs' physicochemical properties by DLS, SLS, ELS, SAXS and the loaded drug amount by UV-Vis spectroscopy. Micelles showed sizes around 10-20 nm for Pluronic and 35-45 nm for the PEO-b-PCL NPs with slightly negative surface charge and successful CIP loading, especially for the latter; a substantial reduction in ζ-potential may be evidenced. For Pluronic nanoparticles, we scanned different conditions for the CIP loading, and its encapsulation efficiency was reduced while the drug content increased in the nanoprecipitation protocol. We also performed in vitro release experiments; results demonstrate that probe release is driven by Fickian diffusion for the Pluronic NPs and a zero-order model for PEO-b-PCL NPs.
ABSTRACT
Currently, antimicrobial photodynamic therapy (APDT) is limited to the local treatment of topical infections, and a platform that can deliver the photosensitizer to internal organs is highly desirable for non-local ones; SPIONs can be promising vehicles for the photosensitizer. This work reports an innovative application of methylene blue (MB)-superparamagnetic iron oxide nanoparticles (SPIONs). We report on the preparation, characterization, and application of MB-SPIONs for antimicrobial photodynamic therapy. When exposed to light, the MB photosensitizer generates reactive oxygen species (ROS), which cause irreversible damage in microbial cells. We prepare SPIONs by the co-precipitation method. We cover the nanoparticles with a double silica layer - tetraethyl orthosilicate and sodium silicate - leading to the hybrid material magnetite-silica-MB. We characterize the as-prepared SPIONs by Fourier transform infrared spectroscopy, powder X-ray diffraction, and magnetic measurements. We confirm the formation of magnetite using powder X-ray diffraction data. We use the Rietveld method to calculate the average crystallite size of magnetite as being 14 nm. Infrared spectra show characteristic bands of ironoxygen as well as others associated with silicate groups. At room temperature, the nanocomposites present magnetic behavior due to the magnetite core. Besides, magnetite-silica-MB can promote ROS formation. Thus, we evaluate the photodynamic activity of Fe3O4-silica-MB on Escherichia coli. Our results show the bacteria are completely eradicated following photodynamic treatment depending on the MB release time from SPIONs and energy dose. These findings encourage us to explore the use of magnetite-silica-MB to fight internal infections in preclinical assays.
Subject(s)
Escherichia coli Infections/drug therapy , Light , Magnetic Iron Oxide Nanoparticles/chemistry , Methylene Blue/chemistry , Humans , Microscopy, Electron, Scanning , Photochemotherapy/methods , Powder Diffraction , Proof of Concept Study , Spectrometry, X-Ray Emission , Spectroscopy, Fourier Transform InfraredABSTRACT
In this study, we synthesized a new congener series of N-sulphonylhydrazones designed as candidate ROCK inhibitors using the molecular hybridization of the clinically approved drug fasudil (1) and the IKK-ß inhibitor LASSBio-1524 (2). Among the synthesized compounds, the N-methylated derivative 11 (LASSBio-2065) showed the best inhibitory profile for both ROCK isoforms, with IC50 values of 3.1 and 3.8 µM for ROCK1 and ROCK2, respectively. Moreover, these compounds were also active in the scratch assay performed in human breast cancer MDA-MB 231 cells and did not display toxicity in MTT and LDH assays. Molecular modelling studies provided insights into the possible binding modes of these N-sulphonylhydrazones, which present a new molecular architecture capable of being optimized and developed as therapeutically useful ROCK inhibitors.
Subject(s)
Hydrazones/chemistry , Isoquinolines/chemistry , Protein Kinase Inhibitors/chemical synthesis , Protein Kinase Inhibitors/pharmacology , rho-Associated Kinases/antagonists & inhibitors , 1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine/analogs & derivatives , 1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine/chemistry , 1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine/pharmacology , Animals , Cell Line, Tumor , Female , Humans , Hydrazones/chemical synthesis , Hydrazones/pharmacology , Models, Molecular , Powder Diffraction , Spectrum Analysis/methodsABSTRACT
PIK-75 is a phosphoinositide-3-kinase (PI3K) α-isoform-selective inhibitor with high potency. Although published structure-activity relationship data show the importance of the NO2 and the Br substituents in PIK-75, none of the published studies could correctly determine the underlying reason for their importance. In this publication, we report the first X-ray crystal structure of PIK-75 in complex with the kinase GSK-3ß. The structure shows an unusual U-shaped conformation of PIK-75 within the active site of GSK-3ß that is likely stabilized by an atypical intramolecular Brâ â â NO2 halogen bond. NMR and MD simulations show that this conformation presumably also exists in solution and leads to a binding-competent preorganization of the PIK-75 molecule, thus explaining its high potency. We therefore suggest that the site-specific incorporation of halogen bonds could be generally used to design conformationally restricted bioactive substances with increased potencies.
ABSTRACT
A new series of sixteen multifunctional N-benzyl-piperidine-aryl-acylhydrazones hybrid derivatives was synthesized and evaluated for multi-target activities related to Alzheimer's disease (AD). The molecular hybridization approach was based on the combination, in a single molecule, of the pharmacophoric N-benzyl-piperidine subunit of donepezil, the substituted hydroxy-piperidine fragment of the AChE inhibitor LASSBio-767, and an acylhydrazone linker, a privileged structure present in a number of synthetic aryl- and aryl-acylhydrazone derivatives with significant AChE and anti-inflammatory activities. Among them, compounds 4c, 4d, 4g and 4j presented the best AChE inhibitory activities, but only compounds 4c and 4g exhibited concurrent anti-inflammatory activity in vitro and in vivo, against amyloid beta oligomer (AßO) induced neuroinflammation. Compound 4c also showed the best in vitro and in vivo neuroprotective effects against AßO-induced neurodegeneration. In addition, compound 4c showed a similar binding mode to donepezil in both acetylated and free forms of AChE enzyme in molecular docking studies and did not show relevant toxic effects on in vitro and in vivo assays, with good predicted ADME parameters in silico. Overall, all these results highlighted compound 4c as a promising and innovative multi-target drug prototype candidate for AD treatment.
Subject(s)
Anti-Inflammatory Agents, Non-Steroidal/pharmacology , Cholinesterase Inhibitors/pharmacology , Drug Discovery , Hydrazones/pharmacology , Indans/pharmacology , Neuroprotective Agents/pharmacology , Piperidines/pharmacology , Acetylcholinesterase/metabolism , Alzheimer Disease/drug therapy , Alzheimer Disease/metabolism , Anti-Inflammatory Agents, Non-Steroidal/chemical synthesis , Anti-Inflammatory Agents, Non-Steroidal/chemistry , Cholinesterase Inhibitors/chemical synthesis , Cholinesterase Inhibitors/chemistry , Donepezil , Dose-Response Relationship, Drug , Hep G2 Cells , Humans , Hydrazones/chemistry , Indans/chemical synthesis , Indans/chemistry , Models, Molecular , Molecular Structure , Neuroprotective Agents/chemical synthesis , Neuroprotective Agents/chemistry , Piperidines/chemical synthesis , Piperidines/chemistry , Structure-Activity RelationshipABSTRACT
The N-acylhydrazone (NAH) moiety is considered a privileged structure, being present in many compounds with diverse pharmacological activities. Among the activities attributed to NAH derivatives anti-inflammatory and analgesic ones are recurrent. As part of a research program aiming at the design of new analgesic and anti-inflammatory lead-candidates, a series of cyclohexyl-N-acylhydrazones 10-26 were structurally designed from molecular modification on the prototype LASSBio-294, representing a new class of cycloalkyl analogues. Compounds 10-26 and their conformationally restricted analogue 9 were synthetized and evaluated as analgesic and anti-inflammatory agents in classical pharmacologic protocols. The cyclohexyl-N-acylhydrazones 10-26 and the cyclohexenyl analogue 9 showed great anti-inflammatory and/or analgesic activities, but compound 13 stood out as a new prototype to treat acute and chronic painful states due to its important analgesic activity in a neuropathic pain model.
Subject(s)
Analgesics , Anti-Inflammatory Agents, Non-Steroidal , Hydrazines , Neuralgia/drug therapy , Analgesics/chemical synthesis , Analgesics/chemistry , Analgesics/pharmacology , Animals , Anti-Inflammatory Agents, Non-Steroidal/chemical synthesis , Anti-Inflammatory Agents, Non-Steroidal/chemistry , Anti-Inflammatory Agents, Non-Steroidal/pharmacology , Disease Models, Animal , Hydrazines/chemical synthesis , Hydrazines/chemistry , Hydrazines/pharmacology , Mice , Neuralgia/pathologyABSTRACT
We have developed a nonenzymatic biosensor for the detection of ammonia and urea oxidation based on the deposition of peptide microstructures onto thiolated gold electrodes. FF-MNSs/MCP/Au assemblies were obtained by modifying gold substrates with 4-mercaptopyridine (MCP), followed by coating with l,l-diphenylalanine micro/nanostructures (FF-MNSs) grown in the solid-vapor phase. Benzene rings and amide groups with peptide micro/nanostructures interact with synthetic NH4(+) receptors through cation-π and hydrogen bonding. AuOH clusters on the Au surface provided the catalytic sites. The application of a predetermined concentration of analytes at the peptide interfaces activated the catalytic sites. We observed a relationship between the stability of films and the crystal structure of peptides, and we organized the FF-MNSs into an orthorhombic symmetry that was the most suitable assembly for creation of our biosensors. At 0.1 mol L(-1) NaOH, these FF-MNSs/MCP/Au electrodes have electrocatalytic properties regarding ammonia and urea oxidation that are comparable to those of enzyme-based architectures. Under optimal conditions, the electrocatalytic response is proportional to the ammonia and urea concentration in the range 0.1-1.0 mmol L(-1). The sensitivity was calculated as 2.83 and 81.3 µA mmol L(-1) cm(-2) for ammonia and urea, respectively, at +0.40 V (vs SCE). Our detection method is easy to follow, does not require a mediator or enzyme, and has strong potential for detecting urea via nonenzymatic routes.
Subject(s)
Ammonia/analysis , Ammonia/chemistry , Biosensing Techniques , Gold/chemistry , Peptides/chemical synthesis , Urea/analysis , Urea/chemistry , Electrochemical Techniques , Electrodes , Oxidation-Reduction , Particle Size , Peptides/chemistry , Surface PropertiesABSTRACT
With the use of X-ray powder diffraction data and the Rietveld method, we verified that both microcrystalline cellulose PH-101 and PH-102 presented differences in the crystallinity degree. The results revealed these samples are semicrystalline in nature and via Rietveld refinements, it was possible, adding a known amount of an internal standard of corundum to the samples, to perform quantitative phase analyses, which allowed us to determine the amorphous amount of the studied samples: 63.7(11) wt % in microcrystalline cellulose PH-101 and 51.0(11) wt % in microcrystalline cellulose PH-102. An important contribution of this work refers to the attempt of using this simple method, permitting to evaluate the degree of crystallinity of microcrystalline cellulose.
Subject(s)
Cellulose/chemistry , Excipients/chemistry , Crystallization/methods , Powders/chemistry , X-Ray Diffraction/methodsABSTRACT
The identification and quantification of crystalline phases of antihypertensive drugs - Losartan potassium (LOS-K), Hydrochlorothiazide (HCTZ) and Chlorthalidone (CTD) were carried out by means of X-ray powder diffraction data and the Rietveld method. Quantitative phase analyses of Losartan potassium/Chlorthalidone (LOS-K/CTD) and Losartan potassium/Hydrochlorothiazide (LOS-K/HCTZ) combinations were also evaluated. The results indicated that for diuretics (HCTZ and CTD) only one crystalline phase was found in samples, and for LOS-K the crystal structure showed similarity between the Bragg peaks to the phase described as monoclinic and space group P21/c. After one year storage, the orthorhombic one was also observed in this sample.
Subject(s)
Antihypertensive Agents/analysis , Chlorthalidone/analysis , Hydrochlorothiazide/analysis , Losartan/analysis , Angiotensin II Type 1 Receptor Blockers/analysis , Chemistry, Pharmaceutical , Crystallization , Diuretics/chemistry , Drug Stability , Powders , Temperature , Time Factors , X-Ray DiffractionABSTRACT
The self-assembly of short amino acid chains appears to be one of the most promising strategies for the fabrication of nanostructures. Their solubility in water and the possibility of chemical modification by targeting the amino or carboxyl terminus give peptide-based nanostructures several advantages over carbon nanotube nanostructures. However, because these systems are synthesized in aqueous solution, a deeper understanding is needed on the effects of water especially with respect to the electronic, structural and transport properties. In this work, the electronic properties of L-diphenylalanine nanotubes (FF-NTs) have been studied using the Self-Consistent Charge Density-Functional-based Tight-Binding method augmented with dispersion interaction. The presence of water molecules in the central hydrophilic channel and their interaction with the nanostructures are addressed. We demonstrate that the presence of water leads to significant changes in the electronic properties of these systems decreasing the band gap which can lead to an increase in the hopping probability and the conductivity.
Subject(s)
Nanotubes/chemistry , Peptides/chemistry , Water/chemistry , Dipeptides , Electric Conductivity , Electrons , Hydrophobic and Hydrophilic Interactions , Models, Molecular , Nanostructures/chemistry , Phenylalanine/analogs & derivatives , Phenylalanine/chemistry , Protein Conformation , Quantum Theory , SolubilityABSTRACT
The present work shows that the heated carbamazepine (CBZ) powder form III can be described as purely triclinic form I or a mixture of triclinic form I and monoclinic form III, depending on the resolution of the X-ray diffraction equipment used. Visual identification of the minor phase is possible when high-resolution synchrotron light is used. Quantitative phase analyses of CBZ forms I and III, after thermal treatment, were performed by using both synchrotron and conventional copper rotating anode X-ray powder diffraction data and the Rietveld method. Also, the Rietveld method could be adequately applied to determine the phase percentage in the heated material, even when usual resolution data are acquired.
Subject(s)
Anticonvulsants/chemistry , Carbamazepine/chemistry , Crystallography, X-Ray , Hot Temperature , Least-Squares Analysis , Models, Chemical , Powder Diffraction , Technology, Pharmaceutical/methods , Calorimetry, Differential Scanning , Chemistry, Pharmaceutical , Crystallization , Molecular Structure , PowdersABSTRACT
The crystal structure determination of mebendazole form A, an anthelmintic drug, was performed for the first time by applying the DASH software program to synchrotron X-ray powder diffraction data, and supported by a satisfying Rietveld fit. This polymorph of mebendazole crystallizes in a triclinic (P1) space group, with unit-cell parameters a = 5.5044(2) A, b = 11.2872(2) A, c = 12.5276(5) A, alpha = 66.694(2) degrees, beta = 82.959(2) degrees, gamma = 78.443(2) degrees, V = 699.52(5) A(3), Z = 2, M = 295.293 g mol(-1), rho(calc) = 1.4021 g cm(-3), and rho(meas) = 1.3935(66) g cm(-3), which were obtained by means of the unit-cell formula weight and a picnometric measurement, respectively. The goodness-of-fit and R-factors were, respectively: chi(2) = 1.746, R(F)(2) = 1.69%, R(wp) = 5.72%, and R(p) = 4.37%. A weak nonclassical hydrogen bond involving the atoms N(3)-H(23)...O(11) may be responsible for the greater stability of the polymorphic form A of mebendazole due to the strongest electronegativity of nitrogen.
Subject(s)
Anthelmintics/chemistry , Crystallography, X-Ray/methods , Mebendazole/chemistry , Algorithms , SoftwareABSTRACT
The crystal and local atomic structure of monoclinic ReO2 (alpha-ReO2) under hydrostatic pressure up to 1.2 GPa was investigated for the first time using both X-ray absorption spectroscopy and high-resolution synchrotron X-ray powder diffraction and a home-built B4C anvil pressure cell developed for this purpose. Extended X-ray absorption fine-structure (EXAFS) data analysis at pressures from ambient up to 1.2 GPa indicates that there are two distinct Re-Re distances and a distorted ReO6 octahedron in the alpha-ReO2 structure. X-ray diffraction analysis at ambient pressure revealed an unambiguous solution for the crystal structure of the alpha-phase, demonstrating a modulation of the Re-Re distances. The relatively small portion of the diffraction pattern accessed in the pressure-dependent measurements does not allow for a detailed study of the crystal structure of alpha-ReO2 under pressure. Nonetheless, a shift and reduction in the (011) Bragg peak intensity between 0.4 and 1.2 GPa is observed, with correlation to a decrease in Re-Re distance modulation, as confirmed by EXAFS analysis in the same pressure range. This behavior reveals that alpha-ReO2 is a possible inner pressure gauge for future experiments up to 1.2 GPa.