Synthesis and characterization of oxazine bearing pyridine scaffold as potential antimicrobial agents

A series of novel compounds 1-((1-(4-(2H-benzo[e][1,3]oxazin-3(4H)-yl)phenyl)ethylidene)amino)-6-((benzylidene)amino)-2-oxo-4-phenyl-1,2-dihydropyridine-3,5-dicarbonitriles (7a–o) were synthesized by a sequence of multistep reactions. IR, ¹H NMR, ¹³C NMR, and mass spectral techniques were used to confirm the structures newly synthesized compounds. Antimicrobial activity of the title compounds (7a–o) was studied against strains of bacteria (Staphylococcus aureus and Streptococcus pyogenes, Escherichia coli and Pseudomonas aeruginosa) and fungi (Candida albicans, Aspergillus niger and Aspergillus clavatus) by serial dilution method. Compounds 7f and 7k exhibited significant antimicrobial activity.     

Synthesis of glycolipid analogs via highly regioselective macrolactonization catalyzed by lipase

Highly regioselective lipase catalyzed macrolactonization has been used in synthesizing first feedstock based glycolipid analogs. These macrolides containing common disaccharides maltose (4-O-α-d-glucopyranosyl-β-d-glucose) and melibiose (6-O-α-d-galactopyranosyl-β-d-glucose) were synthesized by employing chemoenzymatic methodologies. Maltose and Melibiose were coupled with methyl 15-hydroxy pentadecanoate and then subjected to a highly regioselective macrolactonization at the C-6″ position using Candida antarctica lipase-B to yield the desired products.     

Cu-assisted C–N bond formations in six-membered N-heterocycle synthesis

Abstract

One of the highly emerging and important aspect of organic chemistry is the metal-catalyzed synthesis of the heterocycles. The methodologies used earlier for its synthesis were less approachable to the organic chemist because of their high cost, highly specified instrumentation and inconvenient methods. For both the stereoselective and regioselective synthesis of six-membered nitrogen-containing heterocycles, cyclic reactions that are Cu-catalyzed have known to be very efficient. The presented review covers the varied applications of Cu as a catalyst and its importance in the formation of six-membered nitrogen-containing heterocycles. The fascinating research that has been done in this area is also enclosed in this review.     

Nanohybrids from liquid crystalline extended amphiphilic dendrimers

A novel extended amphiphilic dendrimer with linear poly(ethylene oxide) (PEO) attached to a PEO-like dendritic core as hydrophilic fraction and eight docosyl chain branches as hydrophobic fraction has been prepared for the use as structure-directing agent for silica-type materials. The extended dendrimer exhibits a hexagonal columnar liquid crystalline phase in the melt. Organically modified inorganic precursors and the extended dendrimer co-assemble into nanostructured hybrids. Hybrids with 0.44 weight fraction (fw) of aluminosilicate show a lamellar morphology, while hybrids with 0.21 fw exhibit a cylindrical structure. Nanostructures were characterized by a combination of small-angle X-ray scattering (SAXS), transmission electron microscopy (TEM), and atomic force microscopy (AFM). The results suggest that dendrimer-based amphiphiles may provide an exciting platform for the formation of multifunctional organic-inorganic nanostructured hybrid materials with unique structural characteristics.     

Application of titanium catalysts for the syntheses of heterocycles

The metal catalyzed synthesis of heterocycles is becoming an important and highly rewarding protocol in organic synthesis. Traditional approaches require expensive or highly specialized equipment or would be of limited use to the synthetic organic chemist due to their highly inconvenient approaches. Titanium-mediated cyclization reactions have been recognized as some of the simplest and useful tools for regio- as well as stereoselective syntheses of five-membered N-heterocycles. This review summarizes the applications of titanium catalysts with emphasis of their synthetic applications for different heterocylces. This review covered interesting discoveries in the past few years.     

Structure solution of a novel aluminium methylphosphonate using a new simulated annealing program and powder X-ray diffraction data

The structure of a novel layered aluminium methylphosphonate, formula Al2(CH3PO3)3, has been solved from laboratory X-ray powder diffraction data by simulated annealing of five independent structural sub-units, revealing a combination of four- and five-fold coordinated aluminiums within the inorganic lamellae that is unique for this kind of solid.     

Geometrical solution of some cubic equations with non-real roots

A general cubic equation ax ³ + bx ² + cx + d = 0 where a, b, c, d ∈R, a ≠ 0 has three roots with two possibilities—either all three roots are real or one root is real and the remaining two roots are imaginary. Dealing with the second possibility this paper attempts to give the geometrical locations of the imaginary roots of the equation under three different sets of conditions. These sets of conditions include: (i) the real root of the given cubic equation is given, (ii) the real part of an imaginary root is given, and (iii) the imaginary part of an imaginary root is given.     

Comparison and correlation of in vitro, in vivo and in silico evaluations of alpha, beta and gamma cyclodextrin complexes of curcumin

In the present study investigated the effect of curcumin (CUR) alpha (α), beta (β) and gamma (γ) cyclodextrin (CD) complexes on its solubility and bioavailability. CUR the active principle of turmeric is a natural antioxidant agent with potent anti-inflammatory activity along with chemotherapeutic and chemopreventive properties. Poor solubility and poor oral bioavailability are the main reasons which preclude CUR use in therapy. Extent of complexation was β-CD complex (82 %) > γ-CD (71 %) > α-CD (65 %). Pulverization method resulted in significant enhancement of CUR (0.002 mg/ml) solubility with CUR α-CD complex (0.364 mg/ml) > CUR β-CD complex (0.186 mg/ml) > CUR γ-CD complex (0.068 mg/ml). Gibbs-free energy and in silico molecular docking studies favour formation of α-CD complex > β-CD complex > γ-CD complex. With reference to CUR, relative bioavailability of CUR α-CD, CUR β-CD and CUR γ-CD complexes were 460, 365 and 99 % respectively. CUR–CD complexes exhibited increased bioavailability with an increase in t_½, tmax, Cmax, AUC, Ka, and MRT; and a decrease in Ke, clearance and Vd values. AUC increase was CUR α-CD complex > CUR β-CD complex > CUR γ-CD complex. Significant difference (p < 0.05) was observed between CUR α-CD complex and CUR γ-CD complex by one-way ANOVA and Dunnett’s post hoc test for multiple comparison analysis. Correlation observed between in vitro, in vivo and in silico methods indicates potential of in silico and in vitro methods in CD selection.