A facile regio- and stereoselective synthesis of novel spiro[indolin-3,2′-pyrrolidin]-2-one’s via 1,3-dipolar cycloaddition of azomethine ylides

A facile regio and stereoselective synthesis of novel spiro[indolin-3,2′-pyrrolidin]-2-one’s have been accomplished through 1,3-dipolar cycloaddition of azomethine ylides generated in situ from the reaction of isatin and benzyl amine with quinoline bearing dipolarophiles in good yields. The synthesized compounds were well characterized through different spectroscopic techniques, such as single crystal XRD, FTIR, NMR, and mass spectral analysis.     

Enantioselective approach towards the synthesis of spiro-indeno [1,2-b] quinoxaline pyrrolothiazoles as antioxidant and antiproliferative

The 1,3-dipolar cycloaddition reactions of azomethine ylide generated in situ from indeno quinoxaline and thiazolidine-2-carboxylic acid to a series of quinoline bearing dipolarophile afforded novel spiro indeno-quinoxaline pyrrolo thiazoles in quantitative yields. The newly synthesized compounds were characterized using different spectroscopic techniques. Furthermore, the molecular structure of compound 5c was confirmed by single crystal X-ray crystallography. The synthesized compounds were screened for their in vitro antioxidant activity and in vitro cytotoxic activity against breast cancer cell line MCF-7 and adenocarcinomic cancer cell line A-549. Compound containing more electron donors in quinoline site were found to be more potent with good IC₅₀ values.     

Design,synthesis and therapeutic potential of 3-(2-(1<Emphasis Type="Italic">H</Emphasis>-benzo[<Emphasis Type="Italic">d</Emphasis>]imidazol-2-ylthio)acetamido)-<Emphasis Type="Italic">N</Emphasis>-(substituted phenyl)benzamide analogues

Background

The emergence of bacterial resistance is a major public health problem. It is essential to develop and synthesize new therapeutic agents with better activity. The mode of actions of certain newly developed antimicrobial agents, however, exhibited very limited effect in treating life threatening systemic infections. Therefore, the advancement of multi-potent and efficient antimicrobial agents is crucial to overcome the increased multi-drug resistance of bacteria and fungi. Cancer, which remains as one of the primary causes of deaths and is commonly treated by chemotherapeutic agents, is also in need of novel and efficacious agents to treat resistant cases. As such, a sequence of novel substituted benzamides was designed, synthesized and evaluated for their antimicrobial and anticancer activities.

Methodology

All synthesized compounds were characterized by IR, NMR, Mass and elemental analysis followed by in vitro antimicrobial studies against Gram-positive (Staphylococcus aureus), Gram-negative (Salmonella typhi and Klebsiella pneumoniae) bacterial and fungal (Candida albicans and Aspergillus niger) strains by the tube dilution method. The in vitro anticancer evaluation was carried out against the human colorectal carcinoma cell line (HCT116), using the Sulforhodamine B assay.

Results, discussion and conclusion

Compound W6 (MIC_{sa, st, kp}?=?5.19 µM) emerged as a significant antibacterial agent against all tested bacterial strains i.e. Gram-positive (S. aureus), Gram-negative (S. typhi, K. pneumoniae) while compound W1 (MIC_{ca, an}?=?5.08 µM) was most potent against fungal strains (A. niger and C. albicans) and comparable to fluconazole (MIC?=?8.16 µM). The anticancer screening demonstrated that compound W17 (IC₅₀?=?4.12 µM) was most potent amongst the synthesized  compounds and also more potent than the standard drug 5-FU (IC₅₀?=?7.69 µM).

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Bonding isomerism in the η-P coordination of the P4X3 (X=S, Se) molecules toward 16e rhodium fragments stabilized by tripodal tetradentate ligands

The reaction of tetraphosphorus trichalcogenides P₄X₃ (X=S, Se) with the electronically and coordinatively unsaturated 16 electron systems [(EP₃)Rh]⁺ [E=N, NP₃=tris(2-diphenylphosphanylethyl)amine, (1); E=P, PP₃=tris(2-diphenylphosphanylethyl)phosphane, (2)] in tetrahydrofuran affords new tetraphosphorus trichalcogenide derivatives of formula [(EP₃)Rh(P₄X₃)]CF₃ SO₃ [E=N; X=Se (3), S (5). E=P; X=Se (4), S (6)]. In the P₄Se₃ derivatives 3 and 4 the heptatomic cage is bound to the metal through the apical phosphorus atom. The P₄S₃ derivatives 5 and 6 are obtained as pairs of coordination isomers, with the cage linked to the metal either through the apical or through one of the basal P atoms; the former isomer is predominant and its amount depends on the nature of the trans-disposed apical donor (N or P) of the tripodal ligand. The monometal species [(NP₃)Rh(η¹-P₄S₃)]CF₃SO₃ (5) reacts with 1 affording the dimetal compound [{(NP₃)Rh}₂(μ,η^1:1-P_apical,-P_basal-P₄S₃)](CF₃SO₃)₂, where the cage exhibits both modes of bonding. All of the compounds have been characterized by ³¹P NMR spectra and elemental analyses.     

PHOTOOXYDATION SENSIBILISEE DE COMPOSES APPARENTES AUX CAROTENOIDES

Abstract— The sensftized photooxidation of methyl β ionylidene acetates (I) in methanol was studied. After reduction three products were isolated and their structures determined: a peroxide (II) and two isomeric alcohols (III and IV). The formation of (IV) is particularly interesting, its allenic structure being closely related to those of several important carotenoids.     

Structural evidence for the radical scavenging mechanism of some aminothiol group of radioprotectants

Aminothiols constitute an important group of radioprotectants. The structures of a few well-known compounds belonging to the family of radioprotectants have been determined by single crystal x-ray diffraction methods. The sulphur and the amino nitrogen atoms are separated by two tetrahedral carbon atoms in these compounds. Thegauche conformation of the sulphur and the nitrogen atoms and the consequent non-bonded intramolecular S … N interaction observed in some of the crystal structures appear to favour the hypothesis that the protective mechanism of these compounds is by free radical scavenging.     

Probing ligand-protein recognition with sum-frequency generation spectroscopy: the avidin-biocytin case.

Infrared/visible sum-frequency generation (SFG) spectroscopy is used to study the recognition of a protein (avidin) by a derived vitamin (biocytin) adsorbed on a calcium fluoride substrate. The specificity of the process is tested by replacing avidin with bovine serum albumin or presaturated avidin. The SFG spectroscopy shows drastic modifications in the CH and NH spectral ranges only upon exposure of the biocytin film to avidin. The comparison of the SFG data with Fourier transform infrared reflection absorption spectra (FT-IRRAS) in the same spectral ranges illustrates the advantages of nonlinear spectroscopy for studying and detecting recognition between biomolecules.     

Radioassay of serum vitamin B12 using a competitive protein binding technique

A method has been developed for the radiassay of serum vitamin B₁₂ using a competitive binding technique. By this method, vitamin B₁₂ levels as low as 50 pg per ml of serum can be estimated in test samples. Egg yolk has been used as a test binding protein, which has several advantages over serum or plasma protein binding agents, as described in this paper. This binder is quite suitable and reliable for the assay of vitamin B₁₂.     

Ring oxidized retinals form unusual bacteriorhodopsin analogue pigments.

Three ring oxidized retinal analogues have been isolated from the exhaustive oxidation of all-trans retinal. All-trans 4-oxoretinal and 2,3-dehydro-4-oxoretinal have similar absorption maxima to that of all-trans retinal and have been shown to be in the 6-s-cis conformation in solution. Pigments formed with bacterioopsin exhibit absorption maxima (520 nm) blue-shifted from that of bacteriorhodopsin (bR), indicating a disturbance of the external point charge by the electronegative carbonyl moiety at the 4 position. The third analogue contains a ring contracted to a cyclopentenyl-alpha,beta-dione. Unlike the majority of retinals, this analogue displays a 6-s-trans conformation in solution and has a red-shifted absorption maximum at 435 nm. The resulting bR analogue pigment (515 nm) is formed five times faster than the other oxoretinal pigments. All three oxoretinal pigments show an irreversible 20 nm blue shift upon exposure to white light. The 4-oxo and 2,3-dehydro-4-oxoretinal pigments, after irradiation, undergo a small reversible blue shift (4-8 nm) on dark adaptation. These two pigments pump protons, although with slowed photocycle kinetics, demonstrating that these structural changes (addition of the carbonyl at the C-4 and insertion of a double bond in the ring) do not block the function of the pigment. Extraction of the C-15 tritiated analogue retinals from illuminated and non-illuminated pigments of all three oxoretinals yield identical results. Therefore, any crosslinking of these oxoretinals to the protein is by linkages which are unstable to the extraction procedures.