Nanosized Aspirin-Arg-Gly-Asp-Val: Delivery of Aspirin to Thrombus by the Target Carrier Arg-Gly-Asp-Val Tetrapeptide

Resistance and nonresponse to aspirin dramatically decreases its therapeutic efficacy. To overcome this issue, a small-molecule thrombus-targeting drug delivery system, aspirin-Arg-Gly-Asp-Val (A-RGDV), is developed by covalently linking Arg-Gly-Asp-Val tetrapeptide with aspirin. The 2D ROESY NMR and ESI-MS spectra support a molecular model of an A-RGDV tetramer. Transmission electron microscopy images suggest that the tetramer spontaneously assembles to nanoparticles (ranging from 5 to 50 nm in diameter) in water. Scanning electron microscopy images and atomic force microscopy images indicate that the smaller nanoparticles of A-RGDV further assemble to bigger particles that are stable in rat blood. The delivery investigation implies that in rat blood A-RGDV is able to keep its molecular integrity, while in a thrombus it releases aspirin. The <i>in vitro</i> antiplatelet aggregation assay suggests that A-RGDV selectively inhibits arachidonic acid induced platelet aggregation. The mechanisms of action probably include releasing aspirin, modifying cyclic oxidase, and decreasing the expression of GPIIb/IIIa. The <i>in vivo</i> assay demonstrates that the effective antithrombotic dose of A-RGDV is 16700-fold lower than the nonresponsive dose of aspirin

Folded Conformation, Cyclic Pentamer, Nanostructure, and PAD4 Binding Mode of YW3-56

The physical and chemical mechanisms of small molecules with pharmacological activity forming nanostructures are developing into a new field of nanomedicine. By using ROESY 2D NMR spectroscopy, tandem mass spectroscopy, transmission electron microscopy, and computer-assisted molecular modeling, this paper demonstrates the contribution of the folded conformation, the intra- and intermolecular π–π stacking, the intra- and intermolecular hydrogen bonds, and the receptor binding free energy of 6-dimethylaminonaph-2-yl-{<i>N</i>-<i>S</i>-[1-benzylcarba-moyl-4-(2-chloroacetamidobutyl)]-carboxamide (YW3-56) to the rapid formation of nanorings and the slow formation of nanocapsules. Thus we have developed a strategy that makes it possible to elucidate the physical and chemical mechanisms of bioactive small molecules forming nanostructures

Poly-α,β-dl-Aspartyl‑l‑Cysteine: A Novel Nanomaterial Having a Porous Structure, Special Complexation Capability for Pb(II), and Selectivity of Removing Pb(II)

Poly-α,β-dl-aspartic acid is known as a green chelant of various metal ions. To provide a novel nanochelant for treating Pb­(II) poisoning, poly-α,β-dl-aspartic acid was modified with l-Cys to form poly-α,β-dl-aspartyl-l-cysteine (PDC; MW, 27273). dl-Asp was converted into polysuccinimide through a thermal polycondensation, and the amidation of polysuccinimide with l-Cys provided PDC. In water, PDC formed various porous nanospecies. In the mouse lead intoxication model, both intraperitoneal and oral administration of PDC (0.1, 1.0, and 10.0 nmol/kg) dose dependently removed Pb­(II) accumulated in the organ, bone, and blood. PDC did not remove the essential metals including Cu²⁺, Fe²⁺, Mn²⁺, Zn²⁺, and Ca²⁺ of the treated mice. The porous feature and size of the pH- and concentration-dependent nanospecies of PDC benefited the removal of Pb­(II)

Synthesis and <i>In Vivo</i> Lead Detoxification Evaluation of Poly-α,β-dl-aspartyl-l-methionine

To increase the metal selectivity of polyaspartic acid, a so-called green chelant, poly-α,β-dl-aspartyl-l-methionine (PDM) was synthesized as a novel lead chelating agent. The phosphoric acid (80%) catalyzed thermal poly condensation of dl-aspartic acid provided poly succinimide, which was amidated with l-methionine to form PDM (MW: 29161). At the doses of 0.1, 1.0, and 10.0 nmol/kg, either by intraperitoneal injection (i.p.) or oral administration, PDM removed Pb from the spleens, hearts, and kidneys of mice, especially dose-dependently decreasing the accumulation of Pb in the brains, livers, and femurs of the mice, and did not interfere with the essential metals, including Cu, Fe, Mn, and Ca. Even at the dose of 0.1 nmol/kg, the i.p. injection of PDM removed Pb from the spleens, hearts, and kidneys of mice and increased the amount of urinary volume and urinary Pb, and the amount of fecal matter and the amount of fecal Pb, resulting in effective removal of Pb from the body of mice given Pb by i.p. injection. Our findings revealed that in aqueous solution PDM formed diverse nanospecies

Pyranoflavones: A Group of Small-Molecule Probes for Exploring the Active Site Cavities of Cytochrome P450 Enzymes 1A1, 1A2, and 1B1

Selective inhibition of P450 enzymes is the key to block the conversion of environmental procarcinogens to their carcinogenic metabolites in both animals and humans. To discover highly potent and selective inhibitors of P450s 1A1, 1A2, and 1B1, as well as to investigate active site cavities of these enzymes, 14 novel flavone derivatives were prepared as chemical probes. Fluorimetric enzyme inhibition assays were used to determine the inhibitory activities of these probes toward P450s 1A1, 1A2, 1B1, 2A6, and 2B1. A highly selective P450 1B1 inhibitor 5-hydroxy-4′-propargyloxyflavone (5H4′FPE) was discovered. Some tested compounds also showed selectivity between P450s 1A1 and 1A2. α-Naphthoflavone-like and 5-hydroxyflavone derivatives preferentially inhibited P450 1A2, while β-naphthoflavone-like flavone derivatives showed selective inhibition of P450 1A1. On the basis of structural analysis, the active site cavity models of P450 enzymes 1A1 and 1A2 were generated, demonstrating a planar long strip cavity and a planar triangular cavity, respectively

Intrinsic Strain-Mediated Ultrathin Ceria Nanoantioxidant

Metal oxide nanozymes have emerged as the most efficient and promising candidates to mimic antioxidant enzymes for treatment of oxidative stress-mediated pathophysiological disorders, but the current effectiveness is unsatisfactory due to insufficient catalytic performance. Here, we report for the first time an intrinsic strain-mediated ultrathin ceria nanoantioxidant. Surface strain in ceria with variable thicknesses and coordinatively unsaturated Ce sites was investigated by theoretical calculation analysis and then was validated by preparing ∼1.2 nm ultrathin nanoplates with ∼3.0% tensile strain in plane/∼10.0% tensile strain out of plane. Compared with nanocubes, surface strain in ultrathin nanoplates could enhance the covalency of the Ce–O bond, leading to increasing superoxide dismutase (SOD)-mimetic activity by ∼2.6-fold (1533 U/mg, in close proximity to that of natural SOD) and total antioxidant activity by ∼2.5-fold. As a proof of concept, intrinsic strain-mediated ultrathin ceria nanoplates could boost antioxidation for improved ischemic stroke treatment in vivo, significantly better than edaravone, a commonly used clinical drug

A Ligand-Based Drug Design. Discovery of 4‑Trifluoromethyl-7,8-pyranocoumarin as a Selective Inhibitor of Human Cytochrome P450 1A2

In humans, cytochrome P450 1A2 is the major enzyme metabolizing environmental arylamines or heterocyclic amines into carcinogens. Since evidence shows that planar triangle-shaped molecules are capable of selectively inhibiting P450 1A2, 16 triangular flavone, and coumarin derivatives were designed and synthesized for these studies. Among these compounds, 7,8-furanoflavone time-dependently inhibits P450 1A2 with a <i>K</i>_I value of 0.44 μM. With a 5 min preincubation in the presence of NADPH, 0.01 μM 7,8-furanoflavone completely inactivates P450 1A2 but does not influence the activities of P450s 1A1 and 1B1. Another target compound, 7,8-pyrano-4-trifluoromethylcoumarin, is found to be a competitive inhibitor, showing high selectivity for the inhibition of P450 1A2 with a <i>K</i>_i of 0.39 μM, 155- and 52-fold lower than its <i>K</i>_i values against P450s 1A1 and 1B1, respectively. In yeast AhR activation assays, 7,8-pyrano-4-trifluoromethyl­coumarin does not activate aryl hydrocarbon receptor when the concentration is lower than 1 μM, suggesting that this compound would not up-regulate AhR-caused P450 enzyme expression. In-cell P450 1A2 inhibition assays show that 7,8-pyrano-4-trifluoromethyl­coumarin decreases the MROD activity in HepG2 cells at concentrations higher than 1 μM. Thus, using 7,8-pyrano-4-trifluoromethyl­coumarin, a selective and specific P450 1A2 action suppression could be achieved, indicating the potential for the development of P450 1A2-targeting cancer preventive agents

A Ligand-Based Drug Design. Discovery of 4‑Trifluoromethyl-7,8-pyranocoumarin as a Selective Inhibitor of Human Cytochrome P450 1A2

In humans, cytochrome P450 1A2 is the major enzyme metabolizing environmental arylamines or heterocyclic amines into carcinogens. Since evidence shows that planar triangle-shaped molecules are capable of selectively inhibiting P450 1A2, 16 triangular flavone, and coumarin derivatives were designed and synthesized for these studies. Among these compounds, 7,8-furanoflavone time-dependently inhibits P450 1A2 with a <i>K</i>_I value of 0.44 μM. With a 5 min preincubation in the presence of NADPH, 0.01 μM 7,8-furanoflavone completely inactivates P450 1A2 but does not influence the activities of P450s 1A1 and 1B1. Another target compound, 7,8-pyrano-4-trifluoromethylcoumarin, is found to be a competitive inhibitor, showing high selectivity for the inhibition of P450 1A2 with a <i>K</i>_i of 0.39 μM, 155- and 52-fold lower than its <i>K</i>_i values against P450s 1A1 and 1B1, respectively. In yeast AhR activation assays, 7,8-pyrano-4-trifluoromethyl­coumarin does not activate aryl hydrocarbon receptor when the concentration is lower than 1 μM, suggesting that this compound would not up-regulate AhR-caused P450 enzyme expression. In-cell P450 1A2 inhibition assays show that 7,8-pyrano-4-trifluoromethyl­coumarin decreases the MROD activity in HepG2 cells at concentrations higher than 1 μM. Thus, using 7,8-pyrano-4-trifluoromethyl­coumarin, a selective and specific P450 1A2 action suppression could be achieved, indicating the potential for the development of P450 1A2-targeting cancer preventive agents