NEW NATURAL SULFOXIDES OF NUPHAR ORIGIN. STRUCTURE,CHEMISTRY, PUMMERER REARRANGEMENT

Abstract

Further studies on basic compounds from Nuphar luteum L. Sm. resulted in isolation of a new group of sulfoxides with thiohemiaminal type of structure.     

Synthesis of α-Methylenecarbonyl Compounds: An Unexpected Product from the Mannich Reaction On 2-Carbomethoxycyclohexanone

During a study of a general synthesis of α-methylenecarbonyl compounds,¹ we investigated the Mannich reaction of 2-carbomethoxycyclohexanone with formaldehyde and various secondary amines. The unexpected formation of 6-methylene-2-carbomethoxycyclohexanone, existing mainly in the enol form, as the only isolable product is the subject of this report.     

Fluorescent Nitric Oxide Photodonors Based on BODIPY and Rhodamine Antennae

Two novel NO photodonors (NOPDs) based on BODIPY and Rhodamine antennae activatable with the highly biocompatible green light are reported. Both NOPDs exhibit considerable fluorescence emission and release NO with remarkable quantum efficiencies. The combination of the photoreleasing and emissive performance for both compounds is superior to those exhibited by other NOPDs based on similar light-harvesting centres, making them very intriguing for image-guided phototherapeutic applications. Preliminary biological data prove their easy visualization in cell environment due to the intense green and orange-red fluorescence and their photodynamic action on cancer cells due to the NO photo-liberated.     

Transverse-Momentum Distributions and Spherical Symmetry

Transverse-momentum dependent parton distributions (TMDs) are studied in the framework of quark models. In particular, quark model relations among TMDs are reviewed and their physical origin is discussed in terms of rotational-symmetry properties of the nucleon state in its rest frame.     

A Validated Quantification of Benzocaine in Lozenges Using TLC and a Flatbed Scanner

We present a video-densitometric quantification method for benzocaine in lozenges. The quantification is based on a derivatisation reaction with 4-dimethylaminobenzaldehyde. Measurements were carried out using a 16-bit flatbed scanner. Benzocaine was separated to a distance of 50 mm in a vertical developing chamber without vapour saturation. We present an RP-18 phase separation on a cyanopropyl plate (Merck, Darmstadt, Germany) using water, CH₃CN, dioxane, ethanol, and NH₃ (25 %) (8 + 2 + 1 + 1 + 0.05, v/v) as the mobile phase. We also separated benzocaine in a normal phase system on silica gel 60 LiChrospere^® plates (Merck, Darmstadt, Germany) with the mobile phase MTBE/cyclohexane (1 + 1, v/v). The calibration functions for benzocaine in both separations were linear in the range from 1 to 1,000 ng per spot. The range of linearity covers two magnitudes of power because the Kubelka–Munk expression was used for data transformation. In the cyanopropyl-system, the benzocaine amount was quantified as 242.5 ± 18.2 ng in a spot or 6.86 ± 0.52 mg in a single lozenge. The amount of 7.0 mg benzocaine per lozenge was labelled. The combined uncertainty of sample and calibration measurements was statistically calculated using a significance level of α = 0.05 to a total relative uncertainty of 7.49 %. The separation method is inexpensive, fast and reliable.     

Studies on the Glycosylation of N-Acetylneuraminic Acid

Abstract

Glycal derivatives of N-acetylneuraminic acid were prepared and their N-iodosuccinimide-mediated glycosylation shown to proceed only with most reactive alcohols, Their reduced enol ether reactivity is attributed to the α unsaturated ester reature. Thus several reduced glycal derivatives were synthesized. These couid be glycosyiatec with simple alcohols as well as otner saccnarides as aglycones in averaae to modest yields with the trans-diaxiai additions compounas prevailing. A number or selective and specific prepparation led to both the anomeric phenylthioglycosides or N dcety Ineuraminic acid. These could be used in phenylmercurl triflate-promoted glycosylations to afford several derivatives.     

Preparation of Mannac Containing Chitooligomers By Isomerisation and their Binding to Nkr-P1 Protein

Abstract

4-O-(2-Acetamido-2-deoxy-β-D-glucopyranosyl)-2-acetamido-2-deoxy-D-mannopyranose (2) was prepared from diacetylchitobiose (1) by Lobry de Bruyn-Alberda van Ekenstein rearrangement under catalysis of Ca(OH)₂. The disaccharide 2 shows about ten times higher affinity than 1 towards NKR-P1 protein acting as a crucial activating receptor of rat natural killer cells (leukocytes). Chitotriose (3) can be epimerized analogously to give GlcNAcβ1-4GlcNAcβ1-4ManNAc (4) and its binding properties to NKR-P1 are also about ten times higher than those of 3.