An Improved Synthesis of 4-Hydroxypropranolol

An improved synthesis of 4-hydroxypropranolol(4) is described.     

Free Radicals as a Double-Edged Sword: The Cancer Preventive and Therapeutic Roles of Curcumin

Free radicals, generally composed of reactive oxygen species (ROS) and reactive nitrogen species (RNS), are generated in the body by various endogenous and exogenous systems. The overproduction of free radicals is known to cause several chronic diseases including cancer. However, increased production of free radicals by chemotherapeutic drugs is also associated with apoptosis in cancer cells, indicating the dual nature of free radicals. Among various natural compounds, curcumin manifests as an antioxidant in normal cells that helps in the prevention of carcinogenesis. It also acts as a prooxidant in cancer cells and is associated with inducing apoptosis. Curcumin quenches free radicals, induces antioxidant enzymes (catalase, superoxide dismutase, glutathione peroxidase), and upregulates antioxidative protein markers–Nrf2 and HO-1 that lead to the suppression of cellular oxidative stress. In cancer cells, curcumin aggressively increases ROS that results in DNA damage and subsequently cancer cell death. It also sensitizes drug-resistant cancer cells and increases the anticancer effects of chemotherapeutic drugs. Thus, curcumin shows beneficial effects in prevention, treatment and chemosensitization of cancer cells. In this review, we will discuss the dual role of free radicals as well as the chemopreventive and chemotherapeutic effects of curcumin and its analogues against cancer.     

Anti-Inflammatory Dysidazirine Carboxylic Acid from the Marine Cyanobacterium Caldora sp. Collected from the Reefs of Fort Lauderdale,Florida

Dysidazirine carboxylic acid (1) was isolated from the lipophilic extract of a collection of the benthic marine cyanobacterium Caldora sp. from reefs near Fort Lauderdale, Florida. The planar structure of this new compound was determined by spectroscopic methods and comparisons between HRMS and NMR data with its reported methyl ester. The absolute configuration of the single chiral center was determined by the conversion of 1 to the methyl ester and the comparison of its specific rotation data with the two known methyl ester isomers, 2 and 3. Molecular sequencing with 16S rDNA indicated that this cyanobacterium differs from Caldora penicillata (Oscillatoriales) and represents a previously undocumented and novel Caldora species. Dysidazirine (2) showed weak cytotoxicity against HCT116 colorectal cancer cells (IC₅₀ 9.1 µM), while dysidazirine carboxylic acid (1) was non-cytotoxic. Similar cell viability patterns were observed in RAW264.7 cells with dysidazirine only (2), displaying cytotoxicity at the highest concentration tested (50 µM). The non-cytotoxic dysidazirine carboxylic acid (1) demonstrated anti-inflammatory activity in RAW264.7 cells stimulated with LPS. After 24 h, 1 inhibited the production of NO by almost 50% at 50 µM, without inducing cytotoxicity. Compound 1 rapidly decreased gene expression of the pro-inflammatory gene iNOS after 3 h post-LPS treatment and in a dose-dependent manner (IC₅₀ ~1 µM); the downregulation of iNOS persisted at least until 12 h.     

A convenient method for the syntheses of tetrahydrofuran moiety from furan by catalytic transfer of hydrogenation with ammonium formate

Pd-C/ammonium formate efficiently and selectively reduces hetero-aromatic furan ring to the corresponding tetrahydrofuran moiety. Under this reaction condition, carbon-carbon double bond and α,β-unsaturated ketones also reduced to the corresponding alkanes and saturated ketones.     

Macropolyhedral boron-containing cluster chemistry. The unique nido-five-vertex-<B2>-nido-ten-vertex conjuncto structure of [(eta5-C5Me5)2Rh2B11H15] via an unexpected cluster-dismantling

B16H20 and [RhCl2(eta5-C5Me5)]2 with tmnd give [(eta5-C5Me5)2Rh2B11H15], which has an unprecedented thirteen-vertex macropolyhedral cluster core based on a nido ten-vertex {MB9} subcluster and a nido five-vertex {MB4} subcluster fused with their open-face {B2} edges in common.     

A super-pixel QWIP focal plane array for imaging multiple waveband temperature sensor

The multi-waveband temperature sensor (MWTS) array, in which each super-pixel (2 × 2 pixel cell) operates at four distinct thermal infrared (IR) wavebands is being developed. Using this high spatial resolution, four-band thermal IR band detector array, accurate temperature measurements on the surface of an object can be made without prior knowledge of its exact emissivity. This multi-band detector involves intersubband transition in III–V semiconductor-based quantum layered structures. Each detector stack absorbs photons within the specified wavelength band while allowing the transmission of photons in other spectral bands, thus efficiently permitting multi-band detection. This produces multiple, spectrally resolved images of the scene that are recorded simultaneously in a single snapshot on the FPA. From the multispectral images and calibration information about the system, computational algorithms are used to evaluate the temperature on the surface of a target.     

Oxidation of threonine residues with IBX reagents

The treatment of protected Thr peptides with excess polymer-bound IBX effects sequential oxidation of the Thr secondary alcohol to the ketone, followed by hydroxylation of the alpha carbon of the Thr residues with loss of stereochemistry at this position.     

Switchgrass PviCAD1: Understanding Residues Important for Substrate Preferences and Activity

Cinnamyl alcohol dehydrogenase (CAD) catalyzes the final step in monolignol biosynthesis. Although plants contain numerous genes coding for CADs, only one or two CADs appear to have a primary physiological role in lignin biosynthesis. Much of this distinction appears to reside in a few key residues that permit reasonable catalytic rates on monolignal substrates. Here, several mutant proteins were generated using switchgrass wild type (WT) PviCAD1 as a template to understand the role of some of these key residues, including a proton shuttling HL duo in the active site. Mutated proteins displayed lowered or limited activity on cinnamylaldehydes and exhibited altered kinetic properties compared to the WT enzyme, suggesting that key residues important for efficient catalysis had been identified. We have also shown that a sorghum ortholog containing EW, instead of HL in its active site, displayed negligible activity against monolignals. These results indicate that lignifying CADs require a specific set of key residues for efficient activity against monolignals.     

Synthesis and structural characterization of heterometallic thorium aluminum polynuclear molecular clusters

Aluminum can undergo hydrolysis in aqueous solutions leading to the formation of soluble molecular clusters, including polynuclear species that range from 1 to 2 nm in diameter. While the behavior of aluminum has been extensively investigated, much less is known about the hydrolysis of more complex mixed-metal systems. This study focuses on the structural characteristics of heterometallic thorium-aluminum molecular species that may have important implications for the speciation of tetravalent actinides in radioactive waste streams and environmental systems. Two mixed metal (Th(4+)/Al(3+)) polynuclear species have been synthesized under ambient conditions and structurally characterized by single-crystal X-ray diffraction. [Th(2)Al(6)(OH)(14)(H(2)O)(12)(hedta)(2)](NO(3))(6)(H(2)O)(12) (ThAl1) crystallizes in space group P2(1)/c with unit cell parameters of a = 11.198(1) ?, b = 14.210(2) ?, c = 23.115(3) ?, and β = 96.375° and [Th(2)Al(8)(OH)(12)(H(2)O)(10)(hdpta)(4)](H(2)O)(21) (ThAl2) was modeled in P1? with a = 13.136(4) ?, b = 14.481(4) ?, c = 15.819(4) ?, α = 78.480(9)°, β = 65.666(8)°, γ = 78.272(8)°. Infrared spectra were collected on both compounds, confirming complexation of the ligand to the metal center, and thermogravimetric analysis indicated that the thermal degradation of these compounds resulted in the formation of an amorphous product at high temperatures. These mixed metal species have topological relationships to previously characterized aluminum-based polynuclear species and may provide insights into the adsorption of tetravalent actinides on colloidal or mineral surfaces.