Structure of hydroxycinnamic acid derivatives established by high-perfomance liquid chromatography with photodiode-array detection

Summary The present paper describes the development of a method for the differentiation of hydroxycinnamic acid derivatives by HPLC with photodiode-array detection. Furthermore spectral data of the compounds under investigation are given. Whereas p-coumaric acid derivatives are distinguishable from caffeic and ferulic acid derivatives by the positions of their spectrum maxima and their convexity interval value, it is not possible to distinguish between caffeic and ferulic acid derivatives because of overlapping spectrum maxima and convexity interval values.     

Indirect spectrophotometric determination of cyanide

A spectrophotometric method for cyanide based on its inhibition of the colour formation reaction between nickel(II) and 3-(4,5-dimethyl-2-thiazolylazo)-2,6-dihydroxybenzoic acid has been developed, and allows the determination of down to 0.1 g of cyanide. Most of the interferences can be avoided by displacement of the hydrogen cyanide using an arsine generator.     

Polarographic study of the dipropyldithiophosphinate complexes of Pd(II), Pb(II), Cd(II), and Zn(II) ions

The complexes of the dithiophosphinic acids with Pd(II), Pb(II), Cd(II), and ZN(II) in a toluene-ethanol medium produce single polarographic waves. The half-wave potential is a linear function of the ligand concentration. The stabilities of these chelates, which are characterized by a sulphur-metal bond, are in the order: Pd(II) > Pb(II) > Cd(II) > Zn(II).     

New approach to nonracemic 1-alkylamino-3-aryloxypropan-2-ols belonging to β-blockers via cyclic sulfites

Nonracemic -blockers, viz., (S)-propranolol and (S)-timolol, were prepared from (S)-glycidol in three steps consisting in the reaction with SOCl₂ followed by the reaction of the resulting (4S)-4-chloromethyl-2-oxo-1,3,2-dioxathiolanes with the corresponding phenol and the final cleavage of (4R)-aryloxymethyl sulfites under the action of amines in DMF.     

Photochemistry and phototoxicity studies of flutamide, a phototoxic anti-cancer drug

The phototoxic anti-cancer drug flutamide is photolabile under UV-B light in either aerobic or anaerobic conditions. Irradiation of a methanol solution of this drug produces several photoproducts, one by photoreduction of the nitro group, one by rupture of the aromatic-NO2 bond of the parent compound, two as a result of the rupture of the CO-NH bond and one derived from the photoreduction product by scission of the aromatic-NH2 bond. Flutamide shows a photohemolytic effect on human erythrocytes and photoinduces lipid peroxidation. Studies on peripheral blood polymorphonuclear cells (neutrophils) demonstrated the phototoxicity of flutamide as well as inhibition of the cytotoxicity respiratory burst by the photoproduct derived from its photoreduction. The results suggest that the inhibition of the respiratory burst observed in phorbol myristate acetate (PMA)-activated cells is mediated by photosensitization and concomitant singlet oxygen production and/or formation of toxic photoproducts.     

Coupling continuous flow systems to instruments based on discrete sample introduction

The interfaces between low-pressure continuous sample treatment systems and high-level information instruments such as gas chromatographs, capillary electrophoresis equipment and graphite furnace atomic spectroscopic instruments, which are characterized by conventional discrete sample introduction devices, are presented. The present and future developments are discussed of (directly) linking real samples and those analytical equipments with the main objective of avoiding or minimizing manually implemented preliminary operations of the analytical process. Received: 27 January 1998 / Revised: 5 March 1998 / Accepted: 7 March 1998     

Thermodynamic properties of solutions of water-soluble mixed cellulose esters

The thermodynamics of the mixing of water-soluble mixed cellulose esters with water has been studied. A dependence of the affinity of a water-soluble cellulose acetate for water on the nature of a new radical introduced into the macromolecule and the competing interaction of molecules of the same and different types has been shown. Thermodynamic analysis has demonstrated the dominating role of solvation among the various factors determining the interaction of cellulose acetomaleate and acetophthalate with a solvent. A fall in affinity in the cellulose aminoacetate-water system is due to the contribution of entropy effects, leading to an increase in the Flory-Huggins parameter.Tashkent Institute of Chemical Technology. Translated from Khimiya Prirodnykh Soedinenii, Vol. 33, No. 1, pp. 97–101, January–February, 1997.     

Lipase from a Brazilian StrainPenicillium citrinum Cultured in a Simple and Inexpensive Medium st]Heat-Denaturation, Kinetics, and pH Stability

This work is a study of lipase production by a Brazilian strain ofPenicillium citrinum using an inexpensive and simple medium without organic nitrogen sources and of some important industrial properties, including thermostability in relation to ionic strength. The maximal lipase activity (1585 U/L) was obtained whenPenicillium citrinum was cultured on 0.75% ammonium sulfate complemented with minerals salts instead of yeast extract. Although this activity was about 55% lower than that produced in medium with yeast extract (2850 U/L), the specific activity (7.8 U/mg proteins) was higher than that obtained with the yeast extract (4.9 U/mg proteins). The morphology of fungus changed totally, with yeast extract there are smooth, solid, and spherical pellets whereas on ammonium sulfate there are small “hairy” pellets uniformly suspended in the medium. The effect of ferrous (Fe⁺⁺) ions was carried out using medium MA with and without Fe⁺⁺ ions. Lipase production byPenicillium citrinum in medium MA requires Fe⁺⁺ ions, the absence of which caused a decreased of about 50% in the specific activity (3.5 U/mg proteins). The utilization of commercial, locally available oils as carbon sources, such as soybean oil (236 U/L) and corn oil (74 U/L) resulted in lower activity compared to olive oil, showing that lipase production byPenicillium citrinum is specifically induced by olive oil. Potassium concentration in the medium can effects the production of lipase (1 mM (1585 U/L), 10 mM (1290 U/L), and 30 mM (1238 U/L), 50 mM (195 U/L), and 100 mM (2 U/L). The crude culture filtered was susceptable to thermal deactivation. It was stable at pH 6.0, but was not stable at the optimum pH (8.0-8.5) at 50 mM. At the low ionic concentration (1-25 mM) this lipase was stable at low pH (3.5-4.0). The activation energy was 22.4 ±2.2 Kcal. mol 1.     

BISPHENYLENECOSAN as highly selective Cs+ extraction agent

A new reagent for the highly selective extraction of cesium (e-1,7–2,2)4,8–8,4-(bis--o-phenylene)bisdicarbollidocobalt(1–)ate, [(C₂B₉H₉)₂(C₆H₄)₂Co]^–, abbreviated as BISPHECOSAN is described in this paper. The choice of organic solvent and solubilizer, dependence of distribution ratio of Cs⁺ on acidity and other parameters are studied. The extraction mechanism based on selective binding of Cs⁺ cation between two phenylene rings is presented and factors influencing the chemical stability of the reagent are determined.     

Coordination-based self-assembled capsules (SACs) for protein,CRISPR–Cas9, DNA and RNA delivery

Biologics, such as functional proteins and nucleic acids, have recently dominated the drug market and comprise seven out of the top 10 best-selling drugs. Biologics are usually polar, heat sensitive, membrane impermeable and subject to enzymatic degradation and thus require systemic routes of administration and delivery. Coordination-based delivery vehicles, which include nanosized extended metal–organic frameworks (nMOFs) and discrete coordination cages, have gained a lot of attention because of their remarkable biocompatibility, in vivo stability, on-demand biodegradability, high encapsulation efficiency, easy surface modification and moderate synthetic conditions. Consequently, these systems have been extensively utilized as carriers of biomacromolecules for biomedical applications. This review summarizes the recent applications of nMOFs and coordination cages for protein, CRISPR–Cas9, DNA and RNA delivery. We also highlight the progress and challenges of coordination-based platforms as a promising approach towards clinical biomacromolecule delivery and discuss integral future research directions and applications.

SACs can be efficiently used to load biologics such as proteins, CRISPR–Cas9, DNA and RNA and release them on-demand.