One-pot synthesis of new hydantoin (thiohydantoin) derivatives and evaluation of their antibacterial and antioxidant activities

One-pot four-component reactions of phenacyl bromides, parabanic or thioparabanic acids, thiophenols, and triphenylphosphine in the presence of triethylamine afforded new derivatives of hydantoin or thiohydantoin in good to high yields (65%-90%). Their antibacterial activities were evaluated against two Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis) and two Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa). Among the synthesized compounds, the obtained products from 2-hydroxythiophenol exhibited higher antibacterial activity than those obtained from 2-aminothiophenol. Compound 9l including N,N′^′-diphenyl thiohydantoin moiety showed the highest antibacterial activity (26.0 ± 01.4) against B subtilis, in comparison with other synthesized samples. The antioxidant activities of the synthesized hydantoins and thiohydantoins were investigated by DPPH radical-scavenging based on Blois method. The results showed that all the compounds have high DPPH inhibition potency (77.4%-83.9%) that it could be due to existence of heteroatoms with lone pair electrons and exchangeable protons on their NH₂ and OH groups.     

Rapid and green synthesis of 4H-benzo[b]pyrans using triethanolamine as an efficient homogeneous catalyst under ambient conditions

Research on Chemical Intermediates - 4H-benzo[b]pyrans were obtained rapidly in high yields using triethanolamine as an efficient, eco-friendly and low-cost basic catalyst. One-pot three-component...     

Determination of personal care products in water using UHPLC–MS after solid phase extraction with mesoporous silica‐based MCM‐41 functionalized with cyanopropyl groups

A silica‐based MCM‐41 mesoporous material functionalized with cyanopropyl groups has been synthesized by cocondensation, characterized and applied to preconcentrate six parabens and three UV filters in river and swimming‐pool waters. The analytes were quantified by ultra‐high performance liquid chromatography‐tandem mass spectrometry, according to the Directive 96/23/EC. Even though matrix effect was negligible, quantification in river water samples with the standard addition approach improved the recoveries obtained using solvent‐based and even with matrix‐matched calibration. The method quantification limits in river water samples were 0.05 ng/mL for 2,4‐dihydroxybenzophenone and 0.01 ng/mL for the rest. Recoveries, evaluated for a concentration level of 0.5 ng/L, were in the range 93.5‐107.6% for parabens and in the range 64.2‐85.8% for UV filters, with relative standard deviations intraday ≤10.2 and 10.8%, respectively. This parameter, evaluated for a concentration level of 0.1 ng/L, ranged between 98.3 and 110.4% for parabens and between 61.9 and 89.9% for UV filters, with relative standard deviation intraday ≤15.3 and 15.5%, respectively. The two UV filters with lower recoveries were the most affected by the addition of sodium chloride. River and swimming pool waters were analyzed and all the personal care products were found in the swimming pool water, whereas only methylparaben was detected in the river water.     

Effect of polymerization of synthetic glycolipids on their supramolecular assemblies

Sugar-derived surfactants bearing a polymerizable acryloyl moiety on one of the branches of the double-chain hydrophobic tail were prepared. The non–ionic hydrophilic head and the biantennary hydrophobic tail were built on, respectively, an aspartic acid and a tris(hydroxymethyl)aminomethane core. Ultraviolet irradiation of aqueous dispersions of these surfactants above their transition phase temperature (T_c) was achieved. The morphology of self-assemblies produced in such a way were investigated by transmission electron microscopy. TEM photographs revealed that irradiation leads to the formation of unilamellar vesicles. Neither fibers nor tubules were detected in contrast to what was observed before polymerization.     

Reactions of p-quinone monoimines with lawesson reagent and phosphorus pentasulfide

2, 4-Bis-(4-methoxyphenyl)-1, 3, 2, 4-dithiadiphosphetane-2, 4-disulfide [Lawesson reagent (LR)] 1 reacts with p-quinone monoimine- 2a to give the novel benzo-1,3,2-oxathiaphosphol-5-(methanesulfonamido)-2-(4-methoxyphenyl)-2-sulfide 4 . On the other hand, the reaction of 2b and 3 with LR 1 leads to the formation of the benzo- and the naphtho-1,3,2-dithiaphosphol-5 -(benzenesulfonamido)- 2- (4-methoxyphenyl) -2-sulfide 5 , 6 . Thiation of 2a , 2b , and 3 with P₄S₁₀ yields phenoxathiin derivatives 8a , 8b , and 9 , respectively. The identity of the new products is established from analytical and spectroscopic evidence.     

Synthesis and crystal structure of a new lithium cyclohexaphosphate hydrate: Li6P6O18·10H2O

The synthesis and crystal structure of a novel hydrate of lithium cyclohexaphosphate are reported. Li₆P₆O₁₈·10H₂O crystallizes in the space group C2/c with a = 15.113(5), b = 12.006(2), c = 15.892(2) Å, = 122.85(2)°, and Z = 4. The structure consists of P₆O₁₈ ring layers stacked along the c direction in between which are located the lithiumions and water molecules. Two LiO₄ tetrahedra share common edges with LiO₅ pseudosquare pyramids to form two independant Li₃O₉ units. About 50% of the water molecules have fractional occupancy rates and form fragments of molecules. A linear relationship is established between the relative cell volume V/Z and the hydration degree, n, for all the known hydrates: Li₆P₆O₁₈·nH₂O.     

Design and development of a fiber-optic immunosensor utilizing near-infrared fluorophores

The design and application of a fluorescent fiber-optic immunosensor (FFOI) are reported. The FFOI is utilized for the detection of antibody/antigen binding within the near-infrared (NIR) spectral region. The technique is developed through the combined use of fiber-optic, semiconductor laser-excitation, fluorescence detection, NIR dye, and immunochemical techniques. The antibody is immobilized on the FFOI and utilized as a recognition component for trace amounts of specific antigen. The FFOI is constructed to utilize an antibody sandwich technique. The assay involves the immobilization of the capture antibody on the sensing tip of the FFOI followed by the exposure of the immobilized sensing tip to the antigen. The antigen-coated FFOI is then introduced to a second antibody previously labeled with the NIR dye. Typical measurements are performed in about 15 min. A semiconductor laser provides the excitation (780 nm) of the immune complex. The resulting emission is detected by a silicon photodiode detector (820 nm). The intensity of the resulting fluorescence is directly proportional to the concentration of the antigen. The sensitivity of the analysis reaches 10 ng/ml and the response time is 10–15 min.     

Development of the analytical methods and reference materials program for dietary supplements at the National Institutes of Health

The need for validated analytical methods and reference materials to identify and measure constituents in dietary supplements is essential. Such methods allow for the documentation that products meet manufacturer's specifications and contain what their labels declare. In March 2003, the U.S. Food and Drug Administration issued a proposed rule that would establish specific current good manufacturing practices for dietary supplements. This proposed rule requires that companies create a quality control unit to set specifications and ensure compliance with these specifications using scientifically valid procedures. This report provides insights and lessons learned from 3 meetings the Office of Dietary Supplements (ODS) at the National Institutes of Health helped organize. These meetings were structured to (1) educate individuals about the importance and need for validated analytical methods and reference materials to identify and quantify constituents of dietary supplements; (2) identify resources required to fulfill this need; and (3) serve as a platform to obtain input from interested parties to help frame the research agenda for the Dietary Supplements Methods and Reference Materials Program within ODS. Stakeholder's opinions and views expressed at these 3 meetings are outlined in this report.